酵母菌发酵实验报告英文
关于发酵食品的英语作文
The Fascinating World of Fermented FoodsFermentation is one of the oldest and most widespread food preservation techniques known to humanity.This ancient process,which involves the transformation of food by microorganisms,has given rise to a diverse array of flavors,textures,and nutritional benefits.From tangy sauerkraut to creamy yogurt,fermented foods are enjoyed across cultures and have become a staple in many diets.This essay delves into the fascinating world of fermented foods,exploring their history,the science behind fermentation,and the various health benefits they offer.A Brief History of FermentationFermentation has been practiced for thousands of years,with evidence of fermented foods dating back to ancient civilizations.The earliest records of fermentation can be traced to the Neolithic period,around 7000-6600BCE,when people began to ferment grains and fruits to produce alcoholic beverages.Ancient Egyptians,Greeks,and Romans also embraced fermentation,using it to make bread,wine,and cheese.Throughout history,fermentation has played a crucial role in food preservation,allowing communities to store food for extended periods. This was particularly important before the advent of refrigeration. Fermented foods also became integral to cultural and religious practices, with many traditional recipes being passed down through generations. The Science of FermentationFermentation is a metabolic process in which microorganisms such as bacteria,yeast,and molds convert sugars and other carbohydrates into alcohol,acids,and gases.This process not only preserves food but also enhances its flavor,texture,and nutritional value.There are several types of fermentation,each involving different microorganisms and resulting in distinct products:Lactic Acid Fermentation:This type of fermentation is carried out by lactic acid bacteria,which convert sugars into lactic acid.It is responsible for the tangy taste and extended shelf life of foods like yogurt, sauerkraut,kimchi,and pickles.Alcoholic Fermentation:Yeasts,particularly Saccharomyces cerevisiae, convert sugars into alcohol and carbon dioxide.This process is used to produce alcoholic beverages such as beer,wine,and sake,as well as leavened bread.Acetic Acid Fermentation:Acetic acid bacteria convert alcohol into acetic acid,resulting in the production of vinegar.This type of fermentation is used to make various types of vinegar,including apple cider vinegar and balsamic vinegar.Mold Fermentation:Certain molds,such as Aspergillus oryzae and Penicillium roqueforti,are used in the fermentation of foods like soy sauce,miso,and blue cheese.These molds contribute to the unique flavors and textures of these products.Health Benefits of Fermented FoodsFermented foods are not only delicious but also offer a range of health benefits.The fermentation process enhances the nutritional profile of foods and introduces beneficial microorganisms,known as probiotics, which support gut health.Some of the key health benefits of fermented foods include:Improved Digestion:Probiotics in fermented foods help maintain a healthy balance of gut bacteria,which is essential for proper digestion. They can alleviate symptoms of digestive disorders such as irritable bowel syndrome(IBS)and reduce bloating and gas.Enhanced Nutrient Absorption:Fermentation breaks down complex compounds in food,making nutrients more bioavailable.For example, the fermentation of dairy products increases the availability of calcium and B vitamins.Boosted Immune System:A healthy gut microbiome is closely linked to a strong immune system.Probiotics in fermented foods can enhance the body's ability to fight off infections and reduce inflammation. Reduced Risk of Chronic Diseases:Regular consumption of fermented foods has been associated with a lower risk of chronic diseases such as heart disease,diabetes,and certain cancers.The antioxidants and anti-inflammatory compounds produced during fermentation contribute to these protective effects.Mental Health Benefits:Emerging research suggests that gut health is connected to mental health through the gut-brain axis.Probiotics in fermented foods may help alleviate symptoms of anxiety and depression by promoting a healthy gut microbiome.Popular Fermented Foods Around the WorldFermented foods are enjoyed in various forms across different cultures, each with its unique flavors and traditions.Here are some popular fermented foods from around the world:Yogurt:A staple in many diets,yogurt is made by fermenting milk with lactic acid bacteria.It is known for its creamy texture and tangy flavor.Sauerkraut:This German delicacy is made by fermenting shredded cabbage with salt.The result is a tangy,crunchy,and probiotic-rich food.Kimchi:A traditional Korean dish,kimchi is made by fermenting vegetables,usually cabbage and radishes,with chili peppers,garlic, ginger,and fish sauce.It is known for its spicy and pungent flavor.Kombucha:A fermented tea beverage,kombucha is made by fermenting sweetened tea with a symbiotic culture of bacteria and yeast(SCOBY).It is fizzy,tangy,and slightly sweet.Tempeh:Originating from Indonesia,tempeh is made by fermenting soybeans with a mold called Rhizopus.It has a firm texture and nutty flavor,making it a popular plant-based protein source.Miso:A staple in Japanese cuisine,miso is a fermented soybean paste used to flavor soups,sauces,and marinades.It has a rich,umami flavor.Cheese:Various types of cheese,such as blue cheese,cheddar,and brie, are made through fermentation.The process involves the action of bacteria and molds,contributing to the distinct flavors and textures of each cheese.ConclusionThe fascinating world of fermented foods offers a rich tapestry of flavors, textures,and health benefits.From ancient preservation techniques to modern culinary delights,fermentation has played a vital role in shaping our diets and cultures.By embracing fermented foods,we can enjoy their unique tastes and reap the numerous health benefits they provide. Whether it's a spoonful of tangy yogurt,a bite of spicy kimchi,or a sip of fizzy kombucha,fermented foods continue to captivate and nourish people around the world.。
酵母菌实验报告
酵母菌实验报告酵母菌是一种单细胞真菌，广泛存在于自然界中，可以进行无性繁殖和有性繁殖。
酵母菌被广泛应用于食品工业、生物科技、医药领域和环境保护等领域。
为了更好地了解酵母菌的生长和繁殖规律，我们开展了一项实验。
实验设计本次实验主要是研究酵母菌的生长曲线和pH值对其生长的影响。
实验共分为三组。
第一组：不加pH调节液，观察酵母菌的生长情况。
第二组：加入pH调节液，将pH值保持在6左右，观察酵母菌的生长情况。
第三组：加入pH调节液，将pH值保持在4左右，观察酵母菌的生长情况。
实验过程我们选取了常见的酵母菌——啤酒酵母（Saccharomyces cerevisiae）进行实验。
首先，我们制备了发酵液，将其注入培养皿中。
然后，我们将酵母菌取出，在无菌条件下添加到发酵液中。
在第一组中，不进行pH值调节；在第二组和第三组中，加入适量的pH调节液，以调整pH值。
接下来，我们将培养皿放入恒温培养箱中，设置温度为30℃，并对三组实验进行观察。
实验结果我们观察发现，在没有进行pH调节液的情况下，酵母菌在第一组中的生长情况非常不稳定。
在第六天，酵母菌生长达到了峰值，但在第七天开始急剧下降，到第十天时基本上停止生长。
相比之下，加入pH调节液的第二组和第三组，酵母菌的生长情况更加稳定。
在第二组中，pH值维持在6左右，酵母菌的生长情况一直保持在适宜的水平。
在第三组中，pH值维持在4左右，酵母菌的生长速度略有下降，但仍然保持了相对稳定的生长状态。
结论通过此次实验，我们可以得出以下结论：1. pH值对酵母菌的生长有很大的影响。
在酵母菌的生长过程中，pH值的变化会引起酵母菌的代谢和繁殖速度变化，影响其生长状态。
2. 在没有进行pH调节液的情况下，酵母菌的生长非常不稳定，生长速度快慢不一，难以控制。
3. 通过适当调节pH值，可以使酵母菌的生长更加稳定，有利于生产过程的控制和优化。
本次酵母菌实验结果较为成功，我们除了发现了pH值对酵母菌的生长影响外，还得到了很多有利的数据和图表。
酵母菌培养研究报告怎么写
酵母菌培养研究报告怎么写1. 引言酵母（Saccharomyces cerevisiae）是一种常见的单细胞真菌，可广泛应用于食品、药物和生物燃料等领域。
酵母菌培养研究旨在探究酵母生长和代谢特性，以及相关因素对酵母生长的影响。
本报告将介绍酵母菌培养研究的基本步骤、实验设计和数据分析方法。
2. 实验设计2.1 实验目的本实验旨在研究不同培养基组分对酵母菌生长速率的影响。
2.2 实验材料•酵母菌培养基•不同组分的培养基配方•培养皿•离心机•显微镜2.3 实验步骤1.准备不同组分的培养基。
2.将酵母菌菌种接种到不同培养基中。
3.以相同温度（例如25°C）下培养不同组的酵母菌培养基。
4.在培养一定时间后，观察酵母菌的生长情况。
5.通过显微镜观察和计数酵母菌细胞数量。
3. 数据分析3.1 数据采集在实验过程中，观察并记录酵母菌在不同组分培养基中的生长情况，包括菌落大小、颜色和细胞数量。
3.2 数据处理对采集的数据进行统计和分析，计算平均菌落直径、平均菌落颜色的变化以及细胞数量的平均值。
3.3 数据展示使用统计图表展示数据结果，例如绘制柱状图展示不同培养基对酵母菌生长速率的影响。
4. 结果与讨论4.1 实验结果根据数据分析，不同组分的培养基对酵母菌生长速率有显著影响。
结果表明XXX培养基对酵母菌生长的影响最显著，其菌落直径达到最大值，颜色变化明显。
而在XXX培养基中，酵母菌生长速率较低。
4.2 结果讨论从实验结果可以推测，酵母菌对培养基中特定组分的反应较为敏感。
XXX组分可能含有有利于酵母菌细胞生长和繁殖的营养成分，从而促进了菌落的增长和细胞数量的增加。
该实验结果对酵母菌培养研究具有重要意义，为进一步探索酵母菌代谢特性和应用提供了理论基础和实验依据。
5. 结论本研究结果表明，不同组分的培养基对酵母菌生长速率有显著影响。
未来的研究可以进一步探究不同组分对酵母菌代谢产物的影响，以及酵母菌与其它微生物的相互作用。
酵母菌培养实验报告
酵母菌培养实验报告
酵母菌是一类单细胞真菌，广泛存在于自然界中，其具备着高效
的发酵能力，因此在生产中有着极为重要的地位。
为了更好地研究和
利用酵母菌，我们进行了酵母菌的培养实验，下面是本次实验的详细
过程和结果。
材料与方法：
材料：枸杞果酱、葡萄糖、酵母菌（Saccharomyces cerevisiae）方法：
1、准备培养基：按照配方将枸杞果酱、葡萄糖和蒸馏水混合均匀，加热至沸腾，去掉表面的泡沫；
2、接种：在无菌条件下，取一小块酵母菌添加至培养基中；
3、培养：常温下放置培养瓶中，观察酵母菌生长情况并记录；
4、观察和记录：每隔一段时间观察培养瓶中的酵母菌生长情况，如形态、数量、颜色等，并记录；
5、计算生长曲线：根据观察结果，绘制出酵母菌生长曲线。
结果分析：
酵母菌培养过程中，最初的24小时内酵母菌数量迅速增长，然后
逐渐趋于平稳。
观察到酵母菌形态呈圆形或椭圆状，颜色为乳白色或
淡黄色。
而后续的观察结果表明，酵母菌的生长速度会随着时间的推
移而下降。
此时，我们计算了酵母菌生长曲线，发现其呈现出“S”形状，这表明酵母菌的生长具有较好的适应性。
结论：
通过本次实验，我们了解到了酵母菌在不同条件下的生长情况，以及如何绘制酵母菌生长曲线。
同时，我们也将在未来的实验中，更加深入地研究酵母菌的特性与应用，来促进食品、饮料等领域的技术进步。
酵母发酵外文
Electronic Journal of Biotechnology ISSN: 0717-3458DOI: 10.2225/vol14-issue2-fulltext-5 RESEARCH ARTICLE Effects of fermentation temperature on the composition of beer volatile compounds, organoleptic quality and spent yeast densityAdemola O. Olaniran1 · Yushir R. Maharaj1 · Balakrishna Pillay11 Discipline of Microbiology, School of Biochemistry, Genetics and Microbiology, Faculty of Science and Agriculture, University of KwaZulu-Natal, Republic of South AfricaCorresponding author: olanirana@ukzn.ac.zaReceived May 3, 2010 / Accepted January 3, 2011Published online: March 15, 2011© 2011 by Pontificia Universidad Católica de Valparaíso, ChileAbstract Production of good quality beer is dependent largely on the fermentation temperature and yeast strains employed during the brewing process, among others. In this study, effects of fermentation temperatures and yeast strain type on beer quality and spent yeast density produced after wort fermentation by two commercial yeast strains were investigated. Beer samples were assessed for colour, clarity and foam head stability using standard methods, whilst the compositions and concentration of Beer Volatile Compounds (BVCs) produced were assessed using GC-MS. The spent yeast density, measured as dry cell weight, ranged between 1.84 - 3.157 mg/ml for both yeast strains with the highest yield obtained at room temperature fermentation. A peak viable population of 2.56 x 107 cfu/ml was obtained for strain A, also during fermentation at room temperature. The foam head of the beers produced at 22.5ºC was most stable, with foam head ratings of 2.66 and 2.50 for yeast strain A and B, respectively. However, there was no significant (p= 0.242) difference in colour intensity between the beers produced at the different fermentation temperatures. Eight different BVCs were detected in all beer samples and were found to affect the organoleptic properties of the beer produced. Further optimizations are required to determine the effects of other parameters on beer quality. Keywords: beer volatile compounds, fermentation temperature, organoleptic quality, spent yeast densityINTRODUCTIONBeer brewing is an established ancient art from as far back as 6000 B.C., during the building of the ancient cities of Mesopotamia (Cortacero-Ramirez et al. 2003) and has been practised for thousands of years. The practice of producing beer in small micro-breweries has been replaced by magnificent industrial production plants that push out volumes of beer that early brew-masters could only dream about (Rojas and Peterson, 2008). To facilitate effective fermentation process, the yeast is often pitched at a specific population size and allowed to grow via an aerobic step in the fermentation process (Tanguler and Erten, 2008). Fermentation temperature is known to influence beer aroma composition (Bekatorou et al. 2002). Low temperature brewing; in particular, has been reported to result in the production of beer with improved taste and aroma as well as high ethanol and beer productivities (Bardi et al. 1996a; Bardi et al. 1997). Immobilized cell technology processes have been shown to shorten the production time of beer from 12-15 days to 1-3 days, however, the major difficulty is to achieve the correct balance of sensory compounds to create an acceptable flavour profile within the time frame (Willaert and Nedovic, 2006). Beer produced by fermentation of wort by cells immobilized on glutten pellets have been reported to have reduced higher alcohols and higher ethyl acetate (Bardi et al. 1996b).After the fermentation process, there is often a much greater amount of spent yeast present in the fermenter than that present at pitching (Shotipruk et al. 2005). The spent yeast generated during the fermentative process is often used as an inoculum for subsequent fermentations (Blieck et al. 2007). InOlaniran et al.addition, yeast cell wall fractions contain a large percentage of β-glucans, which is highly advantageous in improving the physical and functional properties of foods, as a thickening and water-holding agent (Thammakiti et al. 2004) and for the gelatinization and retrogradation of starch (Satrapai and Suphantharika, 2007). β-glucans isolated from the cell wall fractions of spent brewer’s yeast are good emulsifying stabilizer and are finding application as a form of fat replacement in the production of low-fat mayonnaise (Burkus and Temelli, 2000). The partial replacement of vegetable oil in mayonnaise using β-glucans derived from spent yeast extract has two distinct advantages; firstly, it decreases the calorie content of the emulsification and secondly, it results in the utilisation of industrial by-products (Worrasinchai et al. 2006). In addition, β-glucans have been reported to have been used as a form of immunomodulator in livestock (Eicher et al. 2006).The fermentation step in beer production is facilitated through the metabolic activities of yeast, resulting in the conversion of fermentable sugars to carbondioxide (CO2) and ethanol (Piškur et al. 2006). Whilst these metabolic activities produce the required ethanol from the fermentation, they also result in the production of large amounts of metabolic by-products, beer volatile compounds (BVCs), such as esters, ketones and higher alcohols which if present in high concentrations can influence the final aroma and flavour profile of the beer (Hansen, 1999; Šmogrovičoví and Dömény, 1999; Brown and Hammond, 2003; Vanbeneden et al. 2008). These compounds are derived from precursors of yeast metabolic pathways and some of them are essential for growth of the yeast (Brown and Hammond, 2003). Whilst the presence of these compounds may be considered as detrimental to many (especially those in industry), there are a select few that regard these compounds as important flavour enhancers, especially those with an acquired taste for speciality beers. It is therefore important to determine the effects of these BVCs on beer quality as well as the mechanisms involved in their generation in order to develop methods to facilitate their control.Over the past three decades, research in brewing has focussed on the application of immobilized cells, mainly to facilitate continuous processing, shorten maturation time and consequently reduce production costs (Kopsahelis et al. 2007). However, there appears to be limited studies on the effects of fermentation parameters on the production of BVCs and the consequences on the organoleptic quality of the final product as well as on the spent yeast density produced. This study is therefore aimed at investigating the effects of fermentation temperatures and yeast strain type on the production of spent yeast and BVCs as well as on the overall quality of beer produced. This would have significant repercussions on the South African economy, especially because the beer industry is a considerable player in the country’s economy, and the continuous increase in demand by the consumer.MATERIALS AND METHODSWort preparation and fermentationThe wort used for the fermentation was made using canned-hopped malt extract purchased from National Food Products (Johannesburg, South Africa) and was prepared according to the manufacturer’s instructions. Fermentations were set-up to determine the effects of different fermentation temperatures and commercial yeast strains on beer quality using mini-fermenters (3.5 L) designed to facilitate the fermentation process on a small scale. Two litres of wort was dispensed into each sterile fermenter vessels after being allowed to cool and sterile standard rubber tubing (5 mm inner diameter) was attached to the outlets for sampling. The free end of the tubing was placed into a 2 l flask containing sterile distilled water to form the air-lock. Two commercial yeast strains, National Food Product yeast and Anchor yeast (designated as “strain A” and “strain B”, respectively) were used to pitch the fermentation. The yeast strains were grown in malt extract broth for 24 hrs at 30ºC with shaking at 120 rpm and then pitched at an optical density of 0.4 at an absorbance of 600 nm, which corresponds to a cell density of 5 x 106Colony forming units per millilitre (cfu/ml) according to the McFarland standard. The fermenters containing each type of yeast were then incubated at one of three fermentation temperatures viz., room temperature (RT) (± 18ºC), 22.5ºC and 30ºC for a period of one week. These temperatures were chosen to check the effects of the varying temperature ranges on the composition and concentrations of volatile compounds in the final beer. Gas evolution was monitored from the air-lock mechanism to ensure that fermentations were not stuck.Effects of fermentation temperature on the composition of beer volatile compounds, organoleptic quality and spent yeast density Bottling and bottle conditioningAfter a period of one week, the beer from each fermenter was aseptically transferred into sterile 500 ml sample bottles. To each bottle, a teaspoon of sugar was added prior to the addition of beer for bottle conditioning and the bottles were sealed and allowed to condition for a period of one week. After bottle conditioning, all bottles were stored at 4ºC to facilitate yeast settlement and the maturation process.Measurement of spent yeast density and viabilitySpent yeast density was measured by the method of Soley et al. (2005). Ten millilitre samples were removed from each fermenter after fermentation and centrifuged (6000 rpm for 10 min at 4ºC). The pellet was washed and resuspended in a normal saline solution (0.9% w/v NaCl), filtered through a previously dried and pre-weighed Whatman grade GF/A (Ø 47 mm) glass microfiber filter, and dried to a constant weight at 105ºC. Thereafter, weight of the filter was subtracted from the weight of the filter containing the dried cellular material to acquire the mass of spent yeast produced. Viable yeast cell population was determined by the method of Nagodawithana et al. (1974). Yeast cells present in fermentation reactor were first thoroughly dispersed to ensure equal distribution of cells. Thereafter, a 1-ml sample was serially diluted before spread plating 0.1 ml of appropriate dilutions onto malt extract agar. The plates were incubated at 30ºC for 48 hrs, and the number of colonies on plates for the dilution containing 30 to 300 colonies were counted and expressed as colony forming units per millilitre (cfu/ml).Analysis of BVCsAnalysis of BVCs present in the beer samples was measured using dynamic headspace extraction methods and analyzed by gas chromatography and mass spectrometry (GC-MS). The volatiles from 100 ml of each sample was assessed by enclosing the sample bottle in a polyacetate bag and pumping air from the bag through a small cartridge filled with 1 mg of tenax® and 1 mg of carbotrap® activated charcoal at a flow rate of 50 ml/min for 30 min. A control was taken from an empty polyacetate bag sampled for the same duration. GC-MS analysis of the samples was carried out using a Varian CP-3800 GC (Varian, Palo Alto, California) with a 30 m x 0.25 mm internal diameter (film thickness 0.25 µm) Alltech EC-WAX column coupled to a Varian 1200 quadruple mass spectrometer in electron-impact ionization mode. Cartridges were placed in a Varian 1079 injector equipped with a “Chromatoprobe” thermal desorbtion device. Helium was used as a carrier gas at a flow rate of 1 ml min-1. The injector was held at 40ºC for 2 min with a 20:1 split and then increased to 200ºC at 200ºC min-1 in splitless mode for thermal desorbtion. After a 3 min hold at 40ºC, the GC oven was ramped up to 240ºC at 10ºC min-1and held there for 12 min. Compounds were identified using the Varian workstation software with the NIST05 mass spectral library and verified, where possible, using retention times of authentic standards and published Kovats indices. Compounds present at similar abundance in the control were considered to be contaminants and excluded from analysis. To ensure accuracy with quantification of emission rates, standards were injected into cartridges and thermally desorbed under identical conditions to the samples.Measurement of foam head stabilityThe foam head stability was assessed according to the modified mini foam shake test developed by Van Nierop et al. (2004). A 20 ml sample of each beer (in triplicate) was dispensed into 50 ml glass measuring cylinders and all of the cylinders were sealed with parafilm. Each set of cylinders were shaken at the same time, vigorously up and down 10 times, after which the cylinders were set down on the counter, the parafilm pierced, and a timer set for 15 min. The foam was evaluated visually and the cylinders were arranged from best to worst. Ratings of 1 through 3 were given, where 3 was the greatest stability and 1 the worst.Analysis of beer clarity and colourThe clarity of the beer was determined using a Hach P2100 Turbidimeter, while beer colour was measured spectrophotometrically at a wavelength of 430 nm as described elsewhere (Seaton and Cantrell, 1993). In both cases, distilled water served as a blank and a commercial beer was included in the analysis as positive control.Olaniran et al.Organoleptic quality assessmentThe taste profile of beer produced was assessed by a survey conducted with 10 independent samplers, with no previous beer quality assessment skills. The survey consisted of questionnaires asking the samplers to rate beer from 1 to 10 (1 being very bad and 10 being excellent), for the presence of 10 different characteristics such as; banana aromas, sour apple taste, sweet “butterscotch” aroma, etc. Samplers were asked to give a rating of 0 if they felt a certain trait was absent. These values were assigned categories such that a rating from 0 - 3 was regarded as “low”, 4 - 6 as “medium” and 7 - 10 “high”. The data obtained was then used to determine the percentage of samplers which felt that the presence of the compounds was “low”, ”medium” or “high”. A commercial beer was also sampled to serve as the control.RESULTS AND DISCUSSIONSpent yeast density and viable yeast population recovery after fermentationEffect of the different fermentation temperatures on the spent yeast density and viable yeast population was investigated. Spent yeast density decreases with increasing fermentation temperature (Figure 1a). Fermentation at room temperature produced the most spent yeast density with a yield of 2.47 mg/ml and 3.15 mg/ml obtained for strain A and strain B, respectively. Spent density of strain A produced at a fermentation temperature of 22.5ºC was almost equal to that produced at room temperature, with only 1.215% reduction in the spent yeast density whilst only 8.25% less of strain B spent density was produced at 22.5ºC compared to that produced at the room temperature. It is possible that the available fermentable sugars present at these temperatures were converted into biomass at a similar rate as these temperatures are relatively close to 18ºC, which is the upper temperature limit that is commonly used for lager beer fermentations (Brown and Hammond, 2003). The 30ºC fermentation resulted in the lowest spent yeast density production of both strains with a 25.50% and 32.06% reduction in spent density produced compared to the room temperature fermentations for strain A and strain B, respectively. The reduction of spent yeast density and viable yeast population after fermentation at 30ºC could be attributed to increased metabolic rate at this higher temperature which could have led to faster utilization of sugars, and resulting in cell starvation, cell death and autolysis (Blieck et al. 2007).Similarly, an increase in fermentation temperature led to a steady decrease in the viability of yeast cells (Figure 1b). A peak density of 2.56 x 107 cfu/ml was obtained for strain A at room temperature, which is about 2-fold higher than those obtained for strain B at 22.5ºC fermentation. The least viable population of both strains was observed at 30ºC fermentation, with about 11-fold and 3-fold reduction in population of yeast strain A and B, respectively, obtained compared to the peak population. In this study, fermentations was conducted for a period of 7 days disregarding the specific gravity of the wort, which is generally used to determine the remaining fermentable sugar concentrations in the wort solution in order to know when to terminate the fermentation process. Thus, it is possible that all fermentable sugars have been utilised before termination of the fermentation. Previous studies have shown a decrease in cell density as a result of decrease in fermentable sugars present in the wort. The decrease in cell viability with time has also been attributed to nutrient depletion and early entry of the organisms into the death phase (Blieck et al. 2007).Beer colour, clarity and foam head stabilityThere was no significant (p = 0.242) difference in colour developed between the experimental beers produced by the yeast strains under the different fermentation temperatures; however, the colour intensity of all experimental beers was significantly (p < 0.05) lower than that of the control beer. The control beer had the deepest colour intensity with an absorbance of 0.198, while the maximum absorbance for beer produced with strain A and B at room-temperature was 0.149 and 0.143, respectively, with a maximum absorbance of 0.144 obtained for beer produced with the two strains at 22.5ºC (Figure 2a). Also, the absorbance of beer produced with strain A and B at 30ºC was 0.143 and 0.135, respectively (Figure 2a). Colour development in beer has been mostly attributed to the malt extract used in the respective beers instead of the fermentation parameters (Kopsahelis et al. 2007). Generally, the malt extract used has been reported to have the greatest effect on beer colour as the degree of colour intensity of the malt extract depends on the degree of kilning or roasting of the maltedEffects of fermentation temperature on the composition of beer volatile compounds, organoleptic quality and spent yeast densitybarley (Seaton and Cantrell, 1993; Kopsahelis et al. 2007). Thus, it is possible that the control beer may have been produced from a malt extract which was differentially roasted compared to the malt extract used in this study.There was no direct correlation between fermentation temperature and the clarity of beer produced with the two yeast strains. However, beers produced with strain B were generally clearer compared to those produced using strain A, with 56.13%, 21.46% and 57.58% reduction in turbidity at room temperature, 22.5ºC and 30ºC fermentation temperatures, respectively (Figure 2b). All the experimental beers produced were relatively turbid compared to the control. The extremely good clarity found in the control beer may be attributed to additional processing steps, such as centrifugation and microfiltration, that are used in the production of commercial beers (such as the control) to increase clarity (Seaton and Cantrell, 1993; Kuiper et al. 2002; Shotipruk et al. 2005). The beers produced inthis experiment were bottle conditioned and were not subjected to further processing as the control beer. Also, it has been generally observed that bottle conditioned beers are more turbid than their commercial counterparts due to the presence of the residual yeast used for conditioning (Kuiper et al. 2002). It was also noted that yeast strain A produced beer with higher turbidity than strain B and this could be that yeast strain A produced and released higher concentrations of haze active proteins since the presence of these proteins has been shown to increase turbidity in beer (Seaton and Cantrell, 1993).The control beer used had the best foam head stability compared to the experimental beers. The foam head of the experimental beers produced at 22.5ºC was most stable, retaining as high as 88.67% foam head stability compared to the control beer, while those prepared at room temperature had the least foam head stability rating (Figure 3). This could be due to variations in climatic temperature and lightFig. 1 Spent yeast density (a) and Total yeast viable population (b) produced by different yeast strains at the different fermentation temperatures. Values are average from six values ± standard deviationOlaniran et al.intensity at room temperature which could have stressed the yeast cells and hence led to alterations in the yeast cell membranes, resulting in the release of free fatty acids into the beer samples (Rodriguez-Vargas et al. 2007). Also, at 30ºC fermentations, yeast cell density may have been lost due to autolysis and could have resulted in an increase in free fatty acid concentrations in the beer because of solubilisation of membrane lipids, thus resulting in lower foam head stability. It has been previously reported that the presence of lipids or free fatty acids in beer could lead to a decrease in beer foam head stability (Dickie et al. 2001; Van Nierop et al. 2004).Fig. 2 Colour profiles (a) and clarities (b) of beer produced by different yeast strains under varying fermentation conditions. Values are average from six values ± standard deviation.Fig. 3 Foam head stability of beer produced by the different strains at varying fermentation temperatures. Values are average from six values ± standard deviation.Effects of fermentation temperature on the composition of beer volatile compounds, organoleptic quality and spent yeast density Beer volatile compounds and organoleptic quality assessmentThe relative percentages of the important volatile compounds detected in the beer samples are indicated in Table 1. Higher alcohol, isoamyl alcohol, constituted a large percentage of the BVCs in most samples, constituting up to 49% of the total BVCs in beer samples produced with strain B at room temperature fermentation. Most of the other compounds constituted below 15% of the total BVCs, however, isoamyl acetate constituted approximately 30% of the BVCs in the control sample and between 8.345-17.712% and 8.382-10.247% of the total BVCs in beer produced with strain A and B, respectively, at the different temperatures. Furthermore, ethyl caproate constituted roughly 10% or more of the volatiles found in all samples, while 2-phenylethyl acetate constituted between 4% and 7% in most samples except for the control, and beer samples produced at 22.5ºC where it constituted greater than 10% of the total BVCs (Table 1). GC-MS chromatogram of beer samples showing the different peaks representing the BVCs detected is shown in Figure 4. The seven volatile compounds detected in the beer samples produced in this study have also been found in beer produced from a previous study (Kopsahelis et al. 2007).quality of the different beer samples. As represented in Figure 5, about 35% of the samplers felt that the beers produced had a moderate sour apple taste. This taste profile is usually characteristic of the flavour, volatile esters; ethyl caprylate and ethyl caproate (Verstrepen et al. 2003). Also, roughly 65% of the samplers felt that all beers produced had a moderate warm mouth-feel and this characteristic is generally attributed to the presence of ethanol produced from fermentation as well as the presence of fusel alcohols (Ter Schure et al. 1998). Roughly 40% of samplers felt that a moderate medicinal aroma was present in beers produced at the 22.5ºC and 30ºC fermentations using strain A as well as the room-temperature fermentation for strain B. Generally, these characteristics are attributed to the presence of volatile phenolic compounds in beers (Vanbeneden et al. 2008), while the moderate solvent aroma felt by the samplers in some of the beers is usually attributed to the presence of ethyl acetate (Verstrepen et al. 2003). The non-detection of phenolic compounds could explain the general moderate medicinal smell feelings by most of the samplers. Perhaps, some of these compounds were not present in these beer samples since their generation depends on the activities of the yeast (Peddie, 1990; Brown and Hammond, 2003) as well as the composition of the wort (Kobayashi et al. 2008). Alternatively, the lack of detection could be attributed to limitation of the methods used for the analysis. Previous studies by Saison et al. (2008) and Pinho et al. (2006) have shown that fibres used for headspace analysis are efficient for detection of different classes of volatiles in beer. Thus, it is possible that the Tenax and Carbotrap fibres used in this analysis lacked the affinity required to detect some of the volatiles in the beer. This is a subject of further investigation in our laboratory.Olaniran et al.The percentage of samplers that agreed that specfic flavour or aroma characteristics were present in moderate levels in beers produced by different yeast strains at different fermentation temperatures.Effects of fermentation temperature on the composition of beer volatile compounds, organoleptic quality and spent yeast density CONCLUDING REMARKSResults from this study have shown that different yeast strains and fermentation temperatures affects beer quality, especially turbidity, foam head stability, spent yeast density and yeast viability. However, these parameters had not much effect on the colour profiles of the beers produced and no effect on the qualitative properties of volatiles produced but rather on the relative quantities of the BVCs as evident in the headspace GC-MS analysis. However, in order to increase accuracy of volatile detection, it would be prudent to investigate the effect of the different headspace trapping fibres on detectable BVCs profile. The presence of varying concentrations of BVCs appeared to affect the organoleptic properties of the beer; however, the employment of qualified beer samplers is required to provide a more accurate view. Further optimization is required to determine the effects of other fermentation parameters on overall beer quality as well as investigate gene expression profiles by the different yeast strains under the different fermentation conditions.Financial support:This study was supported by the South African Breweries and Competitive Research Grant of the University of KwaZulu-Natal, Durban, South Africa.REFERENCESBARDI, E.P.; KOUTINAS, A.A.; SOUPIONI, M.J. and KANELLAKI, M.E. (1996a). Immobilization of yeast on delignified cellulosic material for low temperature brewing. Journal of Agricultural and Food Chemistry, vol.44, no. 2, p. 463-467. [CrossRef]BARDI, E.P.; SOUPIONI, M.; KOUTINAS, A.A. and KANELLAKI, M. (1996b). Effect of temperature on the formation of volatile by-products in brewing by immobilized cells. Food Biotechnology, vol. 10, no. 3, p. 203-217.[CrossRef]BARDI, E.; KOUTINAS, A.A. and KANELLAKI, M. (1997). Room and low temperature brewing with yeast immobilized on gluten pellets. Process Biochemistry, vol. 32, no. 8, p. 691-696. [CrossRef] BEKATOROU, A.; SARELLAS, A.; TERNAN, N.G.; MALLOUCHOS, A.; KOMAITIS, M.; KOUTINAS, A.A. and KANELLAKI, M. (2002). Low-temperature brewing using yeast immobilized on dried figs. Journal of Agricultural and Food Chemistry, vol. 50, no. 25, p. 7249-7257. [CrossRef]BLIECK, L.; TOYE, G.; DUMURTIER, F.; VERTSTREPEN, K.J.; DELVAUX, F.R.; THEVELEIN, J.M. and VAN DIJCK, P. (2007). Isolation and characterization of brewer's yeast variants with improved fermentation performance under high-gravity conditions. Applied and Environmental Microbiology, vol. 73, no. 3, p. 815-824. [CrossRef]BROWN, A.K. and HAMMOND, J.R.M. (2003). Flavour control in small-scale beer fermentations.Food and Bioproducts Processing, vol. 81, no. 1, p. 40-49. [CrossRef]BURKUS, Z. and T EMELLI, F. (2000). Stabilization of emulsions and foams using barley β-glucan. Food Research International, vol. 33, no. 1, p. 27-33. [CrossRef]CORTACERO-RAMIREZ, S.; DE CASTRO, M.H.B.; SEGURA-CARRETERO, A.; CRUCES-BLANCO, C. and FERNANDEZ-GUTIERREZ, A. (2003). Analysis of beer components by capillary electrophoretic methods.TrAC Trends in Analytical Chemistry, vol. 22, no. 7, p. 440-455. [CrossRef]DICKIE, K.H.; CANN, C.; NORMAN, E.C.; BAMFORTH, C.W. and MULLER, R.E. (2001). Foam negative materials.Journal of the American Society of Brewing Chemists, vol. 59, no. 1, p. 17-23. [CrossRef]EICHER, S.D.; McKEE, C.A.; CARROLL, J.A. and PAJOR, E.A. (2006). Supplemental vitamin C and yeast cell wall β-glucan as growth enhancers in newborn pigs and as immunomodulators after an endotoxin challenge after weaning. Journal of Animal Science, vol. 84, no. 9, p. 2352-2360. [CrossRef]HANSEN, J. (1999). Inactivation of MXR1 abolishes formation of dimethyl sulfide from dimethyl sulfoxide in Saccharomyces cerevisiae. Applied and Environmental Microbiology, vol. 65, no. 9, p. 3915-3919. KOBAYASHI, M.; SHIMIZU, H. and SHIOYA, S. (2008). Beer volatile compounds and their application to low-malt beer fermentation. Journal of Bioscience and Bioengineering, vol. 106, no. 4, p. 317-323. [CrossRef] KOPSAHELIS, N.; KANELLAKI, M. and BEKATOROU, A. (2007). Low temperature brewing using cells immobilized on brewer’s spent grains. Food Chemistry, vol. 104, no. 2, p. 480-488. [CrossRef]KUIPER, S.; VAN RIJN, C.; NIJDAM, W.; RASPE, O.; VAN WOLFEREN, H.; KRIJNEN, G. and ELWENSPOEK, M.(2002). Filtration of lager beer with microsieves: Flux, permeate haze and in-line microscope observations.Journal of Membrane Science, vol. 196, no. 2, p. 159-170. [CrossRef]NAGODAWITHANA, T.W.; CASTELLANO, C. and STEINKRAUS, K.H. (1974). Effect of dissolved oxygen, temperature, initial cell count and sugar concentration on the viability of Saccharomyces cerevisiae in rapid fermentations. Applied and Environmental Microbiology, vol. 28, no. 3, p. 383-391.PEDDIE, H.A.B. (1990). Ester formation in brewery fermentations. The Journal of the Institute of Brewing and Distilling, vol. 96, no. 5, p. 327-331.PINHO, O.; FERREIRA, I.M.P.L.V.O. and SANTOS, L.H.M.L.M. (2006). Method optimization by solid-phase microextraction in combination with gas chromatography with mass spectrometry for analysis of beer volatile fraction. Journal of Chromatography A, vol. 1121, no. 2, p. 145-153. [CrossRef]。
酵母菌发酵实验设计
酵母菌发酵实验设计English Answer:The experiment on yeast fermentation can be designed as follows:1. Purpose: To investigate the effect of different sugar concentrations on yeast fermentation.2. Materials:Yeast culture.Different sugar solutions (e.g., glucose, fructose, sucrose)。
Water.Test tubes.Thermometer.Stopwatch.3. Procedure:a. Prepare different sugar solutions with varying concentrations. For example, prepare solutions with 5%, 10%, and 15% sugar concentrations.b. Label the test tubes accordingly.c. Add equal amounts of yeast culture to each test tube.d. Add the respective sugar solution to each test tube, ensuring that the sugar concentration is consistent.e. Mix the contents of each test tube gently.f. Place the test tubes in a warm environment (around 37°C) and start the stopwatch.g. Observe the fermentation process by noting the formation of bubbles or gas production.h. Record the time it takes for each sugar concentration to show signs of fermentation.i. Repeat the experiment multiple times to ensure accuracy and reliability of the results.j. Analyze the data collected and draw conclusions regarding the effect of sugar concentration on yeast fermentation.中文回答：酵母发酵实验可以设计如下：1. 目的，研究不同糖浓度对酵母发酵的影响。
发酵酸奶 实验报告
发酵酸奶实验报告英文回答：Fermented yogurt is a popular dairy product that is enjoyed by people all over the world. It is made through a process called fermentation, where specific bacteria, such as Lactobacillus bulgaricus and Streptococcus thermophilus, are added to milk. These bacteria convert the lactose in the milk into lactic acid, which gives yogurt its tangy taste and thick texture.To conduct an experiment on fermenting yogurt, you will need a few ingredients and equipment. Firstly, you will need fresh milk, preferably whole milk, as it provides a creamier texture. You will also need a starter culture, which can be store-bought yogurt that contains live active cultures. Additionally, you will need a thermometer to monitor the temperature and a clean container to store the yogurt during fermentation.The first step is to heat the milk to a specific temperature. This is usually around 180°F (82°C). Heating the milk helps to kill any unwanted bacteria and denature the proteins, which helps to thicken the yogurt. Once the milk has reached the desired temperature, it should be cooled down to around 110°F (43°C).Next, a small amount of the starter culture is added to the cooled milk. This introduces the beneficial bacteria that will ferment the milk and turn it into yogurt. The milk and starter culture should be mixed well to ensure even distribution of the bacteria.After mixing, the milk and starter culture mixture should be transferred to a clean container and covered tightly. The container should be placed in a warm location, ideally between 100-110°F (38-43°C), to allow the bacteria to grow and ferment the milk. This process usually takes around 4-6 hours, but it can vary depending on the desired thickness and tanginess of the yogurt.Once the desired fermentation time has passed, theyogurt can be refrigerated to stop the fermentation process. At this point, the yogurt should have a thick and creamy consistency with a tangy flavor. It can be enjoyed as is or flavored with fruits, honey, or other additives accordingto personal preference.中文回答：发酵酸奶是一种受到全球人们喜爱的乳制品。
酵母菌发面蒸馒头感悟
酵母菌发面蒸馒头感悟英文回答：The fermentation process of using yeast to make steamed buns is a fascinating experience. It involves the interaction between yeast, flour, and water to create asoft and fluffy texture in the final product. Through this process, I have gained several insights.Firstly, I have come to appreciate the importance of yeast in the fermentation process. Yeast is a microorganism that feeds on sugar and produces carbon dioxide as a byproduct. This gas is what causes the dough to rise and gives the steamed buns their airy texture. Without yeast, the dough would remain dense and flat. It is incredible to witness how these tiny organisms can transform a simple mixture of flour and water into something so delicious.Secondly, I have learned the significance of time and temperature in the fermentation process. Yeast requireswarmth to thrive, but too much heat can kill it. Therefore, finding the right balance of temperature is crucial. Additionally, allowing the dough to rest for an adequate amount of time is essential for the yeast to fully activate and produce the desired texture. Patience is key in this process, as rushing it can lead to disappointing results.Furthermore, I have realized the importance of proper kneading and shaping techniques. Kneading the dough helps to develop gluten, a protein that gives the steamed buns their structure and elasticity. It is important to knead the dough until it becomes smooth and elastic, as this ensures even fermentation and a uniform texture. Shaping the dough into small, round buns is also crucial for the final presentation. It requires practice and precision to achieve perfectly shaped steamed buns.Lastly, I have discovered the joy of experimenting with different ingredients and flavors. While traditional steamed buns are made with plain flour, water, and yeast, there is room for creativity. Adding ingredients such as milk, sugar, or even savory fillings can elevate the tasteand texture of the buns. It is exciting to explore different combinations and discover unique flavors.中文回答：使用酵母制作发面蒸馒头的发酵过程是一次令人着迷的经历。
分离甜酒曲中的酵母菌实验流程
分离甜酒曲中的酵母菌实验流程英文回答：To separate the yeast cells from the sweet wine yeast,I would follow the following experimental procedure:1. Prepare the sweet wine yeast culture: Start by preparing a culture of sweet wine yeast. This can be doneby adding a small amount of sweet wine to a sterile flaskor container. The sweet wine should contain a high sugar content, which will provide nutrients for the yeast to grow.2. Incubate the culture: Place the flask or containerin a warm and dark environment, such as an incubator or a cupboard. The ideal temperature for yeast growth is around 25-30°C. Allow the yeast culture to incubate for a few days, allowing the yeast cells to multiply and ferment the sugar in the sweet wine.3. Harvest the yeast cells: After a few days, the yeastculture will have a thick layer of yeast cells at the bottom. Carefully pour off the liquid portion, leaving behind the yeast cells. Transfer the yeast cells to a sterile container, such as a centrifuge tube or a sterile petri dish.4. Wash the yeast cells: To remove any remaining sweet wine or other impurities, wash the yeast cells with a sterile solution, such as distilled water or a sterile saline solution. This can be done by gently swirling the yeast cells in the solution and then allowing them to settle. Repeat this washing process a few times until the yeast cells are clean.5. Centrifuge the yeast cells: To further separate the yeast cells from any remaining liquid, use a centrifuge. Place the yeast cell suspension in a centrifuge tube and spin it at a high speed for a few minutes. The centrifugal force will cause the yeast cells to settle at the bottom of the tube, while the liquid portion can be carefully poured off.6. Resuspend the yeast cells: After centrifugation, the yeast cells will form a pellet at the bottom of the tube. Carefully remove the remaining liquid and resuspend the yeast cells in a small amount of sterile solution, such as distilled water or a sterile saline solution. This will help to concentrate the yeast cells and remove any remaining impurities.7. Store the yeast cells: Finally, transfer the resuspended yeast cells to a sterile container, such as a sterile vial or a cryovial. Store the yeast cells in a refrigerator or a freezer at a temperature of around 4°C or below. This will help to preserve the yeast cells for future use.中文回答：分离甜酒曲中的酵母菌，我会按照以下实验流程进行操作：1. 准备甜酒曲培养物，首先，准备一份甜酒曲培养物。
用酵母菌制作馒头的流程
用酵母菌制作馒头的流程英文回答：The process of making steamed buns with yeast involves several steps. First, the yeast needs to be activated by mixing it with warm water and a small amount of sugar. This mixture is then left to sit for a few minutes until it becomes foamy, indicating that the yeast is active.While waiting for the yeast to activate, the dry ingredients for the dough are prepared. This typically includes flour, salt, and sugar. Once the yeast is ready,it is added to the dry ingredients, and the mixture is kneaded into a smooth and elastic dough. This dough is then left to rise in a warm place for about an hour, or until it has doubled in size.After the dough has risen, it is punched down torelease the air, and then formed into small individual buns. These buns are placed on a tray and left to rise foranother 30 minutes. During this time, the steamer is prepared by bringing water to a boil.Once the buns have risen for the second time, they are ready to be steamed. They are placed in the steamer, and then steamed for about 15-20 minutes, or until they have puffed up and are cooked through.The steamed buns are then ready to be served and enjoyed, either on their own or with a filling of choice.中文回答：用酵母菌制作馒头的流程包括以下几个步骤。
有关发酵的英文作文
有关发酵的英文作文Fermentation is a natural process that occurs when microorganisms, such as bacteria, yeast, or fungi, break down organic substances. It can happen in various conditions, including in the presence or absence of oxygen.During fermentation, microorganisms consume sugars and produce byproducts such as alcohol, lactic acid, or carbon dioxide. This process is commonly used in the production of foods and beverages, such as bread, yogurt, beer, and wine.One of the most well-known types of fermentation is alcohol fermentation, which occurs when yeast consumes sugars and produces alcohol and carbon dioxide. This process is used in the production of alcoholic beverages such as beer, wine, and spirits.Another type of fermentation is lactic acid fermentation, which is used in the production of foods like yogurt, sauerkraut, and kimchi. In this process, bacteriaconvert sugars into lactic acid, giving these foods their characteristic tangy flavor.Fermentation is also used in the production of bread, where yeast ferments the sugars in the dough, causing it to rise and create a light, airy texture. This process is essential for the production of many types of bread, from sourdough to baguettes.In addition to its use in food and beverage production, fermentation is also used in the production of biofuels, pharmaceuticals, and other industrial products. It is a versatile and essential process that has been used by humans for thousands of years.。
探究酵母菌发酵的最佳条件实验报告
探究酵母菌发酵的最佳条件实验报告
实验原理：酵母菌通过葡萄糖耗氧酶催化发酵，利用葡萄糖水解成乙醇和二氧化碳，即酒精发酵。
实验温度：室温20℃-30℃ ID
实验浓度：酵母种类、温度、葡萄糖浓度、KH2PO4及酒精浓度
实验准备：
（1）蝌蚪型酵母菌乙酸菌1.0g；
（2）蒸馏水1000ml；
（3）铝盖15个；
（4）烧杯3只；
（5）荧光灯管2条；
（6）蒸发器2只；
（7）葡萄糖2克；
（8）KH2PO4 2克；
（9）醋酸4毫升。
实验过程：
（1）将1000 ml蒸馏水放入5000mL烧杯，加入2克葡萄糖和2克KH2PO4 制作培养液；
（2）将1.0g酵母菌乙酸菌置于500ml烧杯中，加入醋酸4毫升；
（3）采用荧光灯管照射酵母菌，用蒸发器进行浓缩；
（4）将酵母菌充分的悬浮在营养液中，用留盖在锅盖上，放置室温20℃-30℃环境下发酵24小时。
实验数据：
发酵1小时pH值下降0.02；
发酵2小时乙醇产量达到2.2g/L；
发酵3小时气泡达到最大；
发酵4小时二氧化碳释放量达到最大20.4g/L。
实验结论：实验结果表明，酵母菌在室温20-30℃、酵母菌浓度2%、营养培养液中葡萄糖浓度2%、KH2PO4浓度2%的环境下，发酵最高。
实验建议：为了更好的控制发酵过程，在发酵过程中应增加对培养液中葡萄糖浓度及高磷酸盐浓度的检测，以提高发酵产品质量。
酵母菌发酵记录内容
酵母菌发酵记录内容The process of yeast fermentation is an essential part of many food and beverage production. It is a natural biological process that involves the conversion of sugars into alcohol and carbon dioxide by the action of yeast. 酵母菌发酵是许多食品和饮料生产过程中必不可少的一部分。
这是一个自然的生物过程，涉及酵母菌将糖转化为酒精和二氧化碳的作用。
In the context of brewing, yeast fermentation is particularly crucial as it is responsible for the production of alcohol in beer and wine. Without yeast fermentation, these alcoholic beverages would not have their characteristic flavors and alcoholic content. 在酿造过程中，酵母菌发酵尤为关键，因为它负责在啤酒和葡萄酒中产生酒精。
如果没有酵母菌发酵，这些酒精饮品就不会有它们特有的风味和酒精含量。
From a scientific perspective, yeast fermentation involves a series of biochemical reactions that result in the conversion of glucose into ethanol and carbon dioxide. This process is facilitated by the enzymes produced by yeast, which enable the breakdown of sugars and the production of alcohol. 从科学的角度来看，酵母菌发酵涉及一系列的生化反应，导致葡萄糖被转化为乙醇和二氧化碳。
酵母,实验报告,英文版
Effect of Type of Sugar on Glycolysis and Fermentation in YeastIntroduction:Many cells go through glycolysis and fermentation to break glucose down to carbon dioxide and ethanol (Black et al. 158 and 172). In glycolysis, glucose is converted to pyruvate, and in fermentation, pyruvate is converted to carbon dioxide and ethanol (Black et al. 158 and 172). Glycolysis and fermentation provide these cells, such as yeast, in this experiment, with energy (Peck). However, yeasts do not utilize all kinds of sugar in the same rate. Some sugars can even not be utilized by yeasts (Peck).This experiment aimed to study whether certain types of sugars can be utilized by yeast, if so, what is the different rate that the yeast utilize them. The rate was studied by measuring the rate that the systems produced carbon dioxide, one of final products of fermentation. The sugars being investigated were fructose, galactose, sucrose, maltose, and sactose. Rate that yeast utilized different sugars were compared with the rate that the yeast utilized glucose. The group of yeasts treated with glucose was positive control and that of yeast not treated by any sugar was negative control.In glycolysis, glucose is turned to fructose-6-phosphate, which is the phosphorylated form of glucose (Black et al. 159). Therefore, we expected that yeast would utilize fructose in similar rate as it utilizes glucose. Galactose is a geometric isomer glucose, which is not involved in the process of glycolysis. Hence we hypothesized that galactose cannot be utilized by yeast. Since each disaccharide molecule contains two subunits of monosaccharide monomers, yeast should decompose disaccharides into monosaccharides before going through glycolysis. Therefore, wehypothesized that yeast would utilize disaccharides in slower rate than it would utilize monosaccharides due to one more process that it needs in the overall process. Among disaccharides, the yeast would decompose sucrose and maltose in identical rates since the former is composed of glucose monomer and fructose monomer and the latter one is composed of two glucose monomer. We also hypothesized that yeast would decompose lactose in a slower rate since we expected that galactose, one of its two monomers, cannot be utilized in glycolysis.Materials and Methods:In this experiment, we studied the types of sugars that yeasts can utilize and the differences in rate that yeasts utilize sugars by applying fructose, galactose, sucrose, maltose, and lactose to five groups of yeast respectively. The positive control was set as the group of yeast that was treated with glucose and the negative control was set as the group of yeast that was only treated with buffer and pure water (Peck). Because carbon dioxide was a final product of the overall reaction, amount of carbon dioxide produced was proportional to the amount of sugar being consumed. Therefore, the rates that yeasts utilized sugars were indicated by amount of carbon dioxide being produced in a certain time period. We measured the amount of carbon dioxide produced by using a respirometer. The increase in volume of gas bubble in the respirometer indicated the volume of carbon dioxide produced. The rate that yeast utilized sugars were calculated by dividing volume of carbon dioxide produced (in milliliter) by time (in hour). This value was positively proportional to the rate that yeast utilized the sugar. We avoided radical change in pH value during the experiment by adding some kind of buffer solutions into all test tubes (Peck).Results:Figure 1: The relationship between the rates that yeasts utilized sugars and type of sugars added to yeasts. The rate is determined by change in volume of the bubble in respirometer divided by time that yeast contacted with sugar. The group that treated with yeast was the positive control in this experiment. The error bars represents standard errors.The rates that yeasts utilized fructose and sucrose were statistically identical to the rate that it utilized glucose, because the differences in rates were less than one standard error (figure 1). The rate that yeast utilized maltose was a half of the rate that it utilized glucose. The changes in volume of gas bubble in respirometers of the group of lactose and galactose are statistically same to the change in negative control.Discussion:The yeasts could go through fermentation process with fructose, sucrose, and maltose, but could not go through fermentation with galactose and lactose, because the changes in volume of respirometer in groups treated with galactose and lactose were statistically same to change involume of the negative control group, in which no fermentation would happen because no sugars were added. However, the rate that yeast utilized maltose was half of the rate that it utilized glucose.The hypothesis about monosaccharides was proved to be correct because the yeast could not utilize galactose and utilized glucose and fructose in the same rate. But the experimental results regarding yeast utilization of disaccharides were different from the hypothesis because sucrose, which was expected to be utilized more slowly than monosaccharides, was utilized in the same rate as glucose was, and the yeast was not able to utilize lactose. We can conclude that yeast can utilize fructose, glucose, and sucrose in the same rate and utilize maltose at a half rate than it utilized the former sugars. It cannot undergo fermentation with galactose and lactose. The differences between result and hypothesis suggest that there are other factors determining if yeast can utilize sugars and the rate that yeast utilize them.Since glycolysis is a process in which glucose is turned into pyruvate, the glucose is necessary for glycolysis to happen (Black et al. 158). Therefore, if the yeast doesn’t have enzymes required to convert other kinds of sugars to glucose, glycolysis cannot happen. Since yeast can utilize maltose and sucrose, it must have enzyme that can convert maltose and sucrose into glucose. Similarly, as yeast cannot utilize lactose or galactose, we can deduce that it lacks the enzyme necessary to convert lactose and galactose to glucose. However, fructose is an exception in this experiment. Fructose-6-phosphate, the phoshphyrated form of fructose, is part of glycolysis process (Black et al. 159). Hence the yeast can undergo glycolysis without converting it to glucose. The relatively low rate of utilizing maltose may be caused by low level of enzymes that convert maltose to glucose in yeast. If the yeast converts maltose to glucosemore slowly than it converts sucrose, then the amount of glucose that can undergo glycolysis will be less, and the rate that yeast utilizes maltose will hence be consequently slow.As glycolysis can only take place in cytoplasm, the sugar molecules must first enter the yeast cells (Black et al. 159). Since sugar molecules are polar, they are not likely to enter the cytoplasm through diffusion. Therefore, yeast should have proteins that help transfer certain kind of sugar molecules into its cytoplasm. It is possible that yeast doesn’t have specific type of protein that can help transport galactose and lactose into cytoplasm, and hence cannot undergo the process of glycolysis. The low rate that the yeast utilized maltose might be caused by the low rate that maltose is transported by the specific protein that transports the maltose.Yeast fermentation is a crucial process of making wines and other alcoholic drinks, since ethanol is the ultimate product of this process. Studying the rate of yeast fermentation under different types of sugars can help us find out a more efficient way of producing ethanol. Therefore, results from this experiment may suggest the most efficient type of sugar that we can use to produce wines and other alcoholic drinksAcknowledgement:I would like to thank Professor Peck for helping me set up procedures of the experiment. My partners Maddy and Echo were very helpful during the experiment.Works Cited:1.Peck, Ron. “Glycolysis and Fermentation in Yeast.” Colby College, 2014. Print.2.Black, Michael, Emily Taylor, Jon Monroe, Lizabeth Alliison, Greg Podgorski, andKim Quillin. Biological Science. 5th ed. Glenview: Pearson, 2014. Print.。
发酵菌种实验报告
一、实验目的1. 掌握发酵菌种的制备方法。
2. 了解发酵菌种在食品、医药、化工等领域的应用。
3. 熟悉发酵菌种的筛选、鉴定和保藏方法。
二、实验原理发酵菌种是指用于发酵过程的微生物，包括细菌、真菌、放线菌等。
发酵菌种在适宜的条件下，能够将有机物质转化为人类所需的代谢产物，如酸、酒精、酶、抗生素等。
本实验主要采用固体培养基和液体培养基，通过摇瓶发酵和发酵罐发酵两种方式，对发酵菌种进行制备和筛选。
三、实验材料与仪器1. 实验材料（1）菌种：酵母菌、黑曲霉、乳酸菌等。
（2）培养基：葡萄糖、酵母提取物、蛋白胨、琼脂等。
（3）其他：pH试纸、无菌水、酒精、盐酸、蒸馏水等。
2. 实验仪器（1）摇床：用于摇瓶发酵。
（2）发酵罐：用于发酵罐发酵。
（3）培养箱：用于菌种培养。
（4）显微镜：用于菌种观察。
（5）天平：用于称量。
四、实验方法1. 菌种制备（1）摇瓶发酵：将菌种接种于固体培养基，置于培养箱中培养，待菌落长成后，用无菌水洗涤菌落，收集菌悬液，备用。
（2）发酵罐发酵：将菌种接种于液体培养基，置于发酵罐中，在适宜的温度、pH值和溶氧条件下进行发酵。
2. 菌种筛选（1）平板划线法：将菌悬液涂布于固体培养基表面，待菌落长成后，挑选单菌落进行培养。
（2）稀释涂布平板法：将菌悬液进行系列稀释，涂布于固体培养基表面，待菌落长成后，挑选单菌落进行培养。
3. 菌种鉴定（1）形态特征观察：通过显微镜观察菌落形态、菌丝形态、孢子形态等。
（2）生理生化试验：通过糖发酵试验、产酸试验、产气试验等，鉴定菌种的功能特性。
4. 菌种保藏（1）斜面保藏：将菌种接种于斜面培养基，置于4℃冰箱中保藏。
（2）甘油保藏：将菌种接种于液体培养基，加入适量甘油，置于-20℃冰箱中保藏。
五、实验结果与分析1. 菌种制备通过摇瓶发酵和发酵罐发酵，成功制备了酵母菌、黑曲霉、乳酸菌等发酵菌种。
2. 菌种筛选采用平板划线法和稀释涂布平板法，筛选出了一批具有较高发酵性能的菌种。
菌株的发酵英语作文
菌株的发酵英语作文Fermentation is a biochemical process that involves the metabolic activity of microorganisms, such as bacteria, yeasts, and molds, which convert organic compounds into simpler substances. This process plays a pivotal role in various industries, including food and beverage, pharmaceuticals, and biotechnology. In this essay, we will explore the fermentation process, its importance, and its applications.The Science of FermentationThe process of fermentation begins with the selection of a suitable microorganism, known as a strain, which is capable of producing the desired end product. These microorganisms are anaerobic, meaning they thrive in environments without oxygen. The fermentation process is initiated by providing the microorganisms with a substrate, which is typically a carbohydrate source like glucose or sucrose.Key Factors in FermentationSeveral factors are critical to the success of fermentation, including temperature, pH, and the availability of nutrients. Each microorganism has an optimal range for these factors, and maintaining these conditions is crucial for efficient fermentation. For instance, yeasts used in brewing typically prefer temperatures between 15°C and 25°C.Applications of FermentationFermentation is utilized across a wide array of applications: 1. Food and Beverage Industry: Fermentation is used to produce alcoholic beverages like beer and wine, as well as in the production of bread, yogurt, and cheese.2. Pharmaceuticals: Antibiotics such as penicillin are produced through the fermentation of specific strains of fungi.3. Biofuels: The fermentation of biomass can yield biofuels, such as ethanol, which are renewable energy sources.4. Enzyme Production: Many industrial enzymes are produced through fermentation, used in various processes such as detergent manufacturing and textile processing.Challenges and InnovationsDespite its widespread use, fermentation faces challenges such as contamination, slow process times, and the need for large volumes of substrates. Innovations in genetic engineering and bioprocess optimization are addressing these issues. For example, genetically modified microorganisms can be designed to be more efficient or to produce novel compounds.ConclusionFermentation is a fundamental biological process that has been harnessed by humans for thousands of years. Its versatility and importance in various sectors cannot beoverstated. As we continue to innovate and refine fermentation techniques, the potential for new applications and products is vast, offering exciting prospects for the future.This essay provides a concise overview of the fermentation process, its scientific basis, and its diverse applications. It also touches on the challenges faced and the innovations that are driving the field forward.。
英文版实验报告
Preparation of AspirinPurpose of experimentUnderstand principles and methods of preparation of aspirinLaboratory suppliesAcetic anhydride Salicylic acid Strong phosphoric acid Cold water Ice water Distilled water Graduated cylinder Dryer Distillation flasks Alcohol lamp Tripod Asbestos nets Thermometer Rubber plugs Condenser tube Rubber hose Horn tube Erlenmeyer flask Glue applicator Beaker Filter paper Buchner funnel Smoke filter Vacuum pump filter Glass rods Pallet scalesExperimental principle and stepsStep one : Take 20ml acetic anhydride in the dry distillation of the distillationflask. Take the steam out of 138 °c above the fractions of 6ml and the rest of the collection.As Figure :Phenomena: 136 °c began to slip out of the liquid, to 138 °c will be able to collect the required fraction.Discussion.: New distilled acetic anhydride, as long the acetic anhydride maycontain acetic acid, will affect the response. The distillation is not using oil-bath heating, oil-bath heating is designed to control temperature, distillation of acetic anhydride is direct to let its temperature rises.Step two : Take 4 grams of salicylic acid in the Erlenmeyer flask placed in a dry,6ml new distilled acetic anhydride, and then add 10 drops of concentrated phosphoric acid drops, control heating at 75 ° c water bath for 20 minutes.After this heat, pour the hot water 5ml, full shock, then poured into the 60ml cold water, in the ice water to cool for 15 minutes and see.Phenomena: Water-bath heating finishes, powder reaction of salicylic acid out,only to see the clarification of liquids.Cool in ice water, you can see the solution becomes a white cloudy, with significant crystallization.Discussion: Concentrated phosphoric acid as a catalyst.Water-bath heatingafter the hot water 5ml is designed to remove excess acetic anhydride.Because the material is 0.06 mol of acetic anhydride, salicylic acid is 0.03 mol of substance, it is clear that acetic anhydride is excessive, so the water drop.Becomes cloudy and a large number of crystallization, because Aspirin builds.Step three: These turbid pour liquid as it cools in place in a Buchner funnelfilter paper, cloth under the funnel to pick a filter.Filter received a decompression filter, open decompression filter switch, the pumping filter and observe.50ml distilled water wash each time, then pumping filter, glass rods, gently stirring constantly.After you finish pumping filter, remember to pull the rubber hose, and then turn off the switch.Phenomena: When the switch is open, fluid flow from the pump filter, withlarge numbers of crystallization on the filter paper in the funnel.After adding distilled water wash, white cloudy smoke filtered and white Crystal precipitation.Discussion: Final analysis of the pure crystal Aspirin, Aspirin is ananti-inflammatory.Aspirin smoke filters as dry as possible and avoid affecting experimental results.Step four: Aspirin crystals after the filter using filter paper absorb, on thebalance on the tray, called a mass of 4.2 grams.Aspirin yieldIn theory, aspirin, salicylic acid should be equal to the amount of material generated by the amount of substance, but the actual yield will be less than the theoretical st calculated yield of aspirin is 77.78%.After the end of the experiment, recovery of aspirin, finishing experiment equipment.。
酵母菌实验报告高中英语
IntroductionIn this experiment, we aimed to investigate the fermentation process of yeast and understand the role it plays in the production of bread and other bakery products. Yeast, a single-celled fungus, is capable of converting sugars into carbon dioxide and alcohol through the process of fermentation. This experiment provided us with hands-on experience in monitoring the fermentation process and observing the changes in the dough as a result of yeast activity.Materials and MethodsMaterials:- Active dry yeast- All-purpose flour- Water- Sugar- Measuring cups and spoons- Scale- Mixing bowl- Yeast proofing bowl- Oven- Thermometer- Timer- Whisk- Ruler- ThermometerMethods:1. Yeast Activation: In a small bowl, dissolve 1 tablespoon of sugar in 1 cup of warm water. Sprinkle 1 packet of active dry yeast over the sugar water and let it sit for about 10 minutes, or until it starts to foam.2. Dough Preparation: In a large mixing bowl, combine 2 cups of all-purpose flour, 1 teaspoon of salt, and 1 tablespoon of sugar. Make a well in the center and add the activated yeast mixture. Gradually mix the ingredients until a dough forms.3. Kneading: On a floured surface, knead the dough for about 10 minutes until smooth and elastic. Return the dough to the mixing bowl, cover with a damp cloth, and let it rise in a warm place for about 1 hour, or until it has doubled in size.4. Shaping and Proofing: Punch down the dough to release the air, turn it onto a floured surface, and shape it into a loaf. Place the shaped dough into a greased loaf pan and let it rise for another 30 minutes.5. Baking: Preheat the oven to 375°F (190°C). Place the dough in the preheated oven and bake for 25-30 minutes, or until the loaf is golden brown and sounds hollow when tapped on the bottom.6. Cooling: Remove the bread from the oven and let it cool on a wire rack for at least 15 minutes before slicing.Observations and ResultsThroughout the experiment, we observed several key changes in the dough as a result of yeast fermentation:- Volume Increase: After the yeast was activated and added to the flour mixture, the dough began to rise. After the first rise, the dough had doubled in size, indicating the yeast had started to convert the sugars into carbon dioxide, causing the dough to expand.- Texture Change: As the dough rose, it became softer and more elastic. This was due to the formation of gluten, a protein that strengthens the dough structure.- Color Change: The dough turned a lighter color as the yeast started to consume the sugars and release carbon dioxide. After baking, the bread had a golden brown crust, indicating successful fermentation and baking.- Weight Change: The weight of the dough increased as it rose due to the trapped carbon dioxide. After baking, the bread lost some weight as the carbon dioxide escaped during the cooking process.ConclusionThis experiment demonstrated the role of yeast in the fermentation process and its impact on the production of bread. The yeast converted the sugars in the dough into carbon dioxide, causing it to rise and become airy. The formation of gluten in the dough contributed to its elasticity and ability to hold its shape. By understanding the fermentation process, we can better appreciate the science behind baking and the importance of yeast in the production of bakery products.。
酵母浓缩液检验报告45
酵母浓缩液检验报告45英文回答：Yeast concentrate test Report 45。
The yeast concentrate test report 45 is a document that provides information about the quality of a particular batch of yeast concentrate. This information can be used to ensure that the yeast concentrate is safe and effective for use in brewing.The report will typically include the following information:The name of the yeast concentrate manufacturer。
The batch number of the yeast concentrate。
The date of manufacture of the yeast concentrate。
The expiration date of the yeast concentrate。
The results of the following tests:Viability test。
Purity test。
Attenuation test。
Flocculation test。
Diastatic power test。
The results of these tests will help to ensure that the yeast concentrate is of good quality and that it will perform as expected in brewing.中文回答：酵母浓缩液检测报告45。
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竭诚为您提供优质文档/双击可除酵母菌发酵实验报告英文篇一：发酵实验报告实验报告实验名称：与酵母菌发酵所属课程名称：发酵工程工艺原理班级：20XX级生物技术组长：组员：时间:20XX.11.27—20XX.12.3实验指导教师：黄循吟海南师范大学生命科学学院20XX年12月5日摇瓶的应用与酵母菌发酵摘要：发酵工程属于生物技术的范畴，是指利用微生物的生长繁殖和代谢活动来大量生产人们所需要的产品过程的理论和工程技术体系，是生物工程和生物技术学科的重要组成部分。
本实验通过对酵母菌进行摇瓶培养,并定时取样测定其oD值、ph和菌体数，制作菌体生长曲线，以此判断酵母菌的生长发酵状况。
关键词：发酵、摇床、酵母菌一.目的1.掌握酵母发酵工艺流程及其具体操作方法。
2.了解酵母菌的生长代谢的基本规律。
二．原理千百年来，人类几乎天天离不开酵母菌，例如酒类的生产，面包的制作，乙醇和甘油的发酵，本实验主要通过对酵母菌发酵过程中一些数值的测定，绘制其生长曲线，来了解酵母菌的生长状况。
为获得实验相关数据，需对酵母菌进行培养，首先涂布平板28℃培养48小时后挑取单菌落进行斜面保存，再挑取斜面保存的菌种进行扩大培养，自扩大培养起，每三个小时取一次样，在oD505下测吸光度，在显微镜下观察，计算菌种数量当菌种数量达到108个/ml时（用血细胞计数板计数，以25个中方格的计数板为例，设5个中方格中的总菌数为A，菌液稀释倍数为b，则：1ml菌液中的总菌数=A/5*25*10＾4*b），即可进行发酵培养。
自发酵培养起每三个小时取一次样，测其吸光度值、ph值（用ph计测量）、菌种数量。
结果整理：（1）以时间为横坐标。
oD值为纵坐标作图。
（2）对最终的发酵液进行离心，得湿酵母烘干，称干重，计算得率。
最后对实验结果进行讨论和分析。
三.材料与方法1．实验材料菌种：酵母菌2.培养基配方分离培养基：黄豆芽100g，葡萄糖50g，水100ml，琼脂20g，ph值自然种子培养基：葡萄糖40g，蛋白胨10g，蒸馏水1000ml，ph值自然3．仪器设备分光光度计、旋转式摇床、离心机、冷藏箱、ph计、电子天平、电磁炉等。
4．用具烧杯、三角瓶、量筒、玻璃棒、比色杯、试管、离心管、移液管、接种环、酒精灯、培养皿、滴管、移液枪5．试剂蒸馏水、酒精四．实验步骤与方法1.酵母菌种的分离：1.1分离培养基制备与灭菌：称鲜豆芽100g，放入烧杯中，加水1000ml，煮沸30min，用纱布过滤，用水补足原量，再加入葡萄糖50g，琼脂20g，煮沸溶化，分装三角瓶和试管，包扎，在121℃下灭菌20分钟。
1.2菌种的保存:取酵母粉1g，加10ml无菌水制成菌悬液，并按梯度10﹣1、10-2、10-3进行稀释。
分别取0.2ml涂布平板，在28℃培养48小时，挑单菌落于斜面试管在28℃培养48小时，备用。
2.菌种扩大培养：用接种环挑两环保存在斜面试管上的菌种，放入150ml 的三角瓶(每瓶含有75ml的种子培养液)中进行扩大培养，150r/min,28℃摇瓶培养48小时。
3.发酵培养：将扩大培养后的菌液按10%的接种量接到250ml的三角瓶中进行摇床培养，即取20ml菌种液置于200ml的种子培养液中，150r/min,28℃培养48小时，同扩大培养一样，每三个小时取一次样，测其吸光度值、ph值和菌种数量。
4.数据整理，绘制曲线：以时间为横坐标，分别以菌液浓度，ph，oD值为纵坐标作图。
5.计算得率：发酵完毕，取出摇瓶内培养基装入离心管，离心分离，得湿酵母烘干，称干重，计算得率。
1.扩培过程数据结果1.1每3小时记录一次扩培过程中菌液的ph值、oD505、菌液浓度，结果如表1：表1扩培过程各参数值时间扩配时间h01:0004:0007:0010:0013:0016:0019:0022:0001:0004:000 7:0010:0013:0016:0019:0022:0036912151821242730333639424548282828282828282828282828282828280.1820.5890.7231.3951.7312.0532.2232.1572.1532.1812 .1732.1282.1572.1521.9731.355温度℃oD505菌液浓度（个/ml）2.56×1042.82×1064.20×1075.64×1077.05×1078.25×1072.82×1083.07×1083.33×1084.15×1084.27×1085.12×1085.63×1086.32×1086.65×1087.25×108ph值5.274.974.624.314.324.354.454.444.364.294.324.414.2 94.334.384.36转速r/min1501501501501501501501501501501501501501501501 50取样mL10101010101010101010101010101010篇二：酵母菌酒精发酵实验报告实验方案酵母菌酒精发酵的条件研究学院（部）：生物与化学工程学院专业：生物工程学生姓名：鑫学号：11018150班级：生物工程二班指导教师：肖一、实验目的1、学会实验的设计和操作过程2、找到酵母菌发酵时的最优条件二、培养基和实验方法及材料的确定1、玉米粉的糖化方法玉米粉的糖化采用双酶法，其工艺流程如下玉米粉→加水→液化→糖化→发酵→蒸馏→成品酒精试验中，发酵培养按照三角瓶100ml培养。
本次工做20组是要，共需发酵液20*100=2000ml。
培养液按照100g玉米粉、300ml水。
所以共需玉米粉700g。
液化：取１００ｇ玉米粉，加入３００ｍＬ的水，液化温度为９０℃，ｐＨ值为５．５，液化时间为３．５ｈ，液化酶的添加量为０．０３５ｇ／１００ｇ玉米粉糖化：糖化时的工艺条件为：糖化温度为５８℃，ｐＨ值为４．５，糖化时间为３．５ｈ，糖化酶的添加量为０．３ｇ／１００ｇ玉米粉。
2、活化培养基本实验在进行实验时采用察氏(czapck)培养基的配制，配方如下表一：表一3、扩大培养基扩大培养仍然用察氏(czapck)培养基，由于要用液体的，所以将其中的琼脂配料去掉。
4、发(:酵母菌发酵实验报告英文)酵培养基糖化液稀释至l0%浓度，添加辅料（硫酸铵0.4%），ph5.5灭菌三、培养基的制备及酵母的活化1、准备酵母母菌一支常温下存放一天，增加菌种的活力。
在母菌存放期间制作各时期培养基2、准备固体培养基（察氏培养基）50ml，做成8支试管斜面，扩大培养基800ml（做扩大培养时使用）。
做成8个三角瓶，每瓶200ml。
120℃灭菌30min。
3、发酵液的制备（1）玉米粉的筛选实验前准备粉碎后的玉米粉700g。
（2）玉米粉的液化按照100g玉米粉、300ml水的配比对玉米粉进行液化，液化方案上文已经交代。
在1000ml烧杯里，或者500ml烧杯分两次，水浴液化。
器材：烧杯500ml两个，玻璃棒一个，水浴锅一个，糖化酶0.225g步骤：1、将糖化酶，玉米粉，水按照比例配置好在烧杯里。
2、将配好的玉米液放于水浴锅中90℃液化3.5h。
边液化边搅拌。
（3）玉米粉的糖化将液化后的玉米液中按照0.3g/100ml加入液化液中。
再在水浴锅中，58℃糖化3.5h。
（4）过滤糖化后的糖化液有可能有没有彻底液化的玉米颗粒，会造成浑浊，这时需要对糖化液进行过滤操作。
操作步骤：最后与以上培养基一起进行灭菌处理。
灭菌时，清洗16支移液管，与培养基一起灭菌。
（5）活化步骤器材：酒精灯，接种针，母菌，斜面培养基，消毒酒精。
步骤：1、将器材放于实验台上。
对双手合桌面进行灭菌。
对接种针进行灼烧灭菌。
2、在酒精灯旁按照无菌操作步骤在酒精灯火焰旁取下试管棉塞。
3、将灼烧后的接种针伸入母菌试管取粘取少量母菌，粘取前将接种针放于试管内壁，冷却5~6s。
4、按照无菌操作将取过母钟的接种针移入活化试管内并画曲线。
5在酒精灯火焰旁将试管棉塞塞上，塞前将棉塞烧一下。
如此接种八支试管。
并保存28℃培养2d。
四、酵母的扩大培养器材：液体培养基，活化后菌种，酒精灯，接种针，消毒酒精。
步骤：1、将器材放于试验台上，并对双手和桌面灭菌，接种针进行灼烧灭菌。
2、在酒精灯旁取下棉塞，并用接种针接种少量菌种于液体培养基内。
3、在酒精灯旁塞好棉塞，并于28℃培养。
根据发酵单因素的不同，确定培养时间。
其中变量是菌龄的一瓶瓶号1、2要求培养时间分别为：对数期1：15~16h，对数期2:16~18h，缓冲期：20~24h，稳定期：24~26h。
其他菌种培养20h进行接种。
五、发酵培养1、不同菌龄下的发酵器材：扩大菌种的四个不同阶段即对数期1：15~16h，对数期2:16~18h，缓冲期：20~24h，稳定期：24~26h。
移液管四个，酒精灯，发酵液，洗耳球。
步骤：1、将对数期1的菌种和其他设备放于实验台上。
2、用移液管按照发酵液的10%的比例移取扩大培养液到发酵液中。
3、塞好棉塞将发酵液放于30℃条件下培养2d。
4、按照以上步骤将不同菌龄的扩大菌种移接到发酵液中进行发酵培养。
之后进行酒精检测。
2、不同菌量下的发酵器材：扩大菌种，移液管四个，酒精灯，发酵液，洗耳球。
步骤：1、将实验器材放于实验台上。
2、用移液管移取8%的扩大菌种到发酵液中。
3、塞好棉塞，将发酵液存放于30℃条件下发酵2d。
4、按照以上步骤，分别移取10%、12%、14%的扩大菌种到发酵液中，30℃培养2d，之后进行酒精检测。
3、不同醪液浓度下的发酵器材：扩大菌种，移液管四个，酒精灯，发酵液，洗耳球。
步骤：1、将实验器材放于实验台上。
2、用移液管移取10%的扩大菌种到4个发酵液中。
3、制作不同浓度的醪液，分别按照1:2,1:3,,1:4，1:5。
3、塞好棉塞，将四个发酵液三角瓶编号1、2、3、4。
将发酵液按照序号存放于30℃条件下发酵2d。
4、对发酵后的发酵液进行酒精检测。
4、不同发酵时间下的发酵器材：扩大菌种，移液管四个，酒精灯，发酵液，洗耳球。
步骤：1、将实验器材放于实验台上。
2、用移液管移取10%的扩大菌种到4个发酵液中。
3、塞好棉塞，将发酵液将四个发酵液三角瓶编号1、2、3、4。
存放于30℃条件下发酵。
按照序号分别培养2d、2.5d、3d、3.5d。
4、对发酵后的发酵液进行酒精检测。
六、酒精检测器材：蒸馏设备一套，200ml量筒4个，酒精检测器一个，步骤：1、将100ml发酵液配制成200ml溶液于蒸馏烧瓶中。
2、对200ml发酵液进行蒸馏，蒸馏出100ml酒精溶液。