蔬菜中亚硝酸盐含量测定

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本科毕业论文

题目：几种蔬菜中亚硝酸盐含量的动态分析

学院：食品科学与工程学院

姓名：XXX

学号：xxxxxxx

专业：食品质量与安全

班级：食安091班

指导教师：xxx 职称：讲师

二〇一三年四月

目录

摘要 ........................................................................................................................................ I ABSTRACT ........................................................................................................................... II 1 引言 . (1)

1.1概述 (1)

1.2测定方法及研究的意义 (1)

2 实验材料与方法 (2)

2.1实验材料 (2)

2.1.1 原材料 (2)

2.1.2 主要仪器 (2)

2.2实验方法 (3)

2.2.1 亚硝酸盐的测定 (3)

2.2.2 菌落总数的测定 (4)

2.3蔬菜在家庭贮藏与加工条件下的亚硝酸盐含量的测定 (6)

2.3.1 不同贮藏温度对蔬菜中亚硝酸盐含量的影响 (6)

2.4煮熟菠菜在常温条件下，亚硝酸盐含量与菌落总数的关系 (6)

3 实验结果与分析 (7)

3.1标准曲线的绘制 (7)

3.2消除抗坏血酸对实验的影响 (7)

3.3家庭加工及加工后贮藏对亚硝酸盐含量的影响 (8)

3.3.1 不同贮藏温度对蔬菜中亚硝酸盐含量的影响 (8)

3.3.2 不同煮沸时间对蔬菜中亚硝酸盐含量的影响 (9)

3.3.3 煮熟菠菜在常温条件下，亚硝酸盐含量与菌落总数的关系 (10)

4 结论 (11)

参考文献 (12)

致谢 (13)

摘要

新鲜蔬菜中的亚硝酸盐含量会随着贮藏和加工条件的改变而变化，本文以分光光度法测定蔬菜中亚硝酸盐含量，分别研究了芹菜、番茄、白菜、白萝卜、菠菜和四季豆在不同贮藏温度、不同煮沸时间条件下，亚硝酸盐含量的变化；蔬菜煮熟后室温放置一定时间，亚硝酸盐含量与菌落总数之间的关系。根据《食品中污染物限量》(GB 2762－2005)规定，蔬菜中亚硝酸盐限量卫生标准≤4 mg/kg。试验结果表明：室温存放叶类、茎类、鲜豆类蔬菜分别不超过三天、四天和四天；根类和茄果类蔬菜中的亚硝酸盐含量在检测周期内（一周）没有超过限量标准；冰箱存放叶类蔬菜不超过四天；茎类、鲜豆类、根类和茄果类蔬菜中的亚硝酸盐含量在检测周期内（一周）没有超过限量标准。蔬菜的煮沸时间在5 min左右为宜；隔夜蔬菜（试验以菠菜为例）中细菌大量滋生，应加热后再食用。

关键词：蔬菜；贮藏温度；煮沸时间；亚硝酸盐含量

Abstract

The content of nitrate in fresh vegetables is changed with the condition of storage and processing. This paper designed a feasible spectrophotometry to measure the nitrate content in vegetables and had studied on how is the nitrate change in celery, tomato, Chinese cabbage, white radish, spinach, kidney bean, respectively, under different temperature and different boiled time and the relationship between nitrate content and aerobic bacterial count after the vegetables has been cooked a period of time. According to contaminants in food (GB 2762-2005), the nitrate(calculated on NaNO2) contented in fresh vegetables cannot be over 4 mg/kg in hygienic standard, the results show that: the storage time cannot be over three days, four days and four days respectively when the leaf, cauline vegetables and fresh bean are under room temperature and the nitrate content of radical and fruit vegetable in the same temperature are within the standard; the time that the leaf vegetable reposited in refrigerate cannot be over four days and the nitrate content of cauline, radical and fruit vegetable and fresh bean in the same temperature are within the standard; the boiled time of vegetables is fit to control around 5 min; the overnight vegetables (the paper had taken the spinach as an example) contain lots of bacterial, so it need to be cooked before eat.

Keywords: vegetables；storage temperature；boiled time；nitrate content