第六章 有机酸 发酵工艺
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2
Non-food products
➢Enzyme ➢Vitamins ➢Antibiotics ➢Biotech drugs
3
Organic Acid
1. Lactic acid fermentation
Lactic acid - A Natural Product
It is made by fermentation of different sugars (glucose, sucrose, or lactose) by means of the
➢Lactobacillus bulgaricus and/or acidophilus ➢Streptococcus thermophilus
They work better together than they do separately because…. ➢Acid production rate is much higher ➢Formation of typical yogurt flavour and texture
genera lactobacillus, streptococcus and pediococcus.
wk.baidu.com
Lactobacillus bulgaricus Streptococcus thermophilus
Lactobacteriaceae
• Gram positive, rods or cocci • Obligate anaerobes (no respiratory chain) • Catalase negative (often aerotolerant)
ethanol
pyruvate
lactic acid
C6H12O6＋ADP+Pi→CH3CHOHCOOH＋CH3CH2OH＋CO2+ATP
Homofermentation vs. heterofermentation
Types Path. Products Energy Inversion
rate
glucose + ADP + Pi ➞ lactic acid + ethanol + CO2 + ATP
phosphoketolase pathway (PK)
G → → xylulose 5-phosphate phosphoketolase
acetyl phosphate + glyceraldehyde 3-phosphate
Lactic acid production process
Lactic acid in Food
➢Lactic acid is naturally present in many foodstuffs, such as cheese, yogurt, soy sauce , fermented meat and pickled vegetables, etc. ➢It serves as either a flavoring agent, pH regulator or a preservative.
Chapter 6
Fermented Food Products
Products from Microorganisms
Food and food related products
➢Whole cells products ➢Cheese and yogurt ➢Fermented fruits and vegetables ➢Organic acids ➢Alcoholic beverages ➢Flavoring agents: amino acids and nucleotides
Homolactic fermentation (homofermentation)
•Glucose degraded via EMP pathway, with lactic acid as the only end product
glucose + 2 ADP + 2 Pi ➞ 2 lactic acid + 2 ATP • Important in dairy industry (yogurt, cheese)
homofermentation
Heterolactic fermentation (heterofermentation)
• Glucose degraded via phosphoketolase pathway (PK)
• In addition to lactic acid, also ethanol and CO2 produced
Food Trends
Health Convenience Value Taste
What is Yogurt
A semi-solid casein gel formed by the action of specific lactic acid bacteria on milk
20
Microbes used in Yoghurt Involved
Homo EMP 2 Lactic acid 2ATP high
Hetero PK
1 Lactic acid 1ATP low 1 alcohol 1 CO2
How to recognize heterofermentation strain in lab?
（1） Production of C02 （2） Gram staining
Ingredients and Function
➢Lactose is partial converted to lactic acid, which makes digestion easier for lactose-intolerant people. ➢Containing higher amino acid than milk. ➢Lactic acid causes the milk proteins (casein) to coagulate into a semisolid curd and also restricts spoilage bacteria. ➢Freshly prepared yogurt contains 10,000,000,000 (109) bactria per gram.
Non-food products
➢Enzyme ➢Vitamins ➢Antibiotics ➢Biotech drugs
3
Organic Acid
1. Lactic acid fermentation
Lactic acid - A Natural Product
It is made by fermentation of different sugars (glucose, sucrose, or lactose) by means of the
➢Lactobacillus bulgaricus and/or acidophilus ➢Streptococcus thermophilus
They work better together than they do separately because…. ➢Acid production rate is much higher ➢Formation of typical yogurt flavour and texture
genera lactobacillus, streptococcus and pediococcus.
wk.baidu.com
Lactobacillus bulgaricus Streptococcus thermophilus
Lactobacteriaceae
• Gram positive, rods or cocci • Obligate anaerobes (no respiratory chain) • Catalase negative (often aerotolerant)
ethanol
pyruvate
lactic acid
C6H12O6＋ADP+Pi→CH3CHOHCOOH＋CH3CH2OH＋CO2+ATP
Homofermentation vs. heterofermentation
Types Path. Products Energy Inversion
rate
glucose + ADP + Pi ➞ lactic acid + ethanol + CO2 + ATP
phosphoketolase pathway (PK)
G → → xylulose 5-phosphate phosphoketolase
acetyl phosphate + glyceraldehyde 3-phosphate
Lactic acid production process
Lactic acid in Food
➢Lactic acid is naturally present in many foodstuffs, such as cheese, yogurt, soy sauce , fermented meat and pickled vegetables, etc. ➢It serves as either a flavoring agent, pH regulator or a preservative.
Chapter 6
Fermented Food Products
Products from Microorganisms
Food and food related products
➢Whole cells products ➢Cheese and yogurt ➢Fermented fruits and vegetables ➢Organic acids ➢Alcoholic beverages ➢Flavoring agents: amino acids and nucleotides
Homolactic fermentation (homofermentation)
•Glucose degraded via EMP pathway, with lactic acid as the only end product
glucose + 2 ADP + 2 Pi ➞ 2 lactic acid + 2 ATP • Important in dairy industry (yogurt, cheese)
homofermentation
Heterolactic fermentation (heterofermentation)
• Glucose degraded via phosphoketolase pathway (PK)
• In addition to lactic acid, also ethanol and CO2 produced
Food Trends
Health Convenience Value Taste
What is Yogurt
A semi-solid casein gel formed by the action of specific lactic acid bacteria on milk
20
Microbes used in Yoghurt Involved
Homo EMP 2 Lactic acid 2ATP high
Hetero PK
1 Lactic acid 1ATP low 1 alcohol 1 CO2
How to recognize heterofermentation strain in lab?
（1） Production of C02 （2） Gram staining
Ingredients and Function
➢Lactose is partial converted to lactic acid, which makes digestion easier for lactose-intolerant people. ➢Containing higher amino acid than milk. ➢Lactic acid causes the milk proteins (casein) to coagulate into a semisolid curd and also restricts spoilage bacteria. ➢Freshly prepared yogurt contains 10,000,000,000 (109) bactria per gram.