蛋糕真空预冷实验及其货架期预测研究

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摘要

真空预冷技术是一种快速、高效的冷却技术，与传统冷却方式相比，具有冷

却速度快、冷却均匀等特点。为了提高食品安全性，近年来真空冷却应用于熟食

品的快速冷却，使其快速通过微生物繁殖区，减少细菌污染。目前真空预冷在熟

食品的快速冷却方面主要应用于熟肉制品，本研究将真空冷却技术应用于焙烤食

品的冷却中，对蛋糕进行了真空冷却研究。

通过不同预冷终温、预冷压力对蛋糕冷却时间、失重率、硬度、色泽的影响

进行分析，确定了蛋糕真空预冷最佳工艺参数为：预冷压力、预冷终温分别为

1800Pa、24℃。采用将自然冷却与真空预冷联合使用、预冷前适量补水、调整蛋

糕制作工艺的方法研究了减少蛋糕在真空预冷过程中的水分损失的措施。

通过与自然冷却比较，发现真空预冷能显著提高蛋糕的冷却速率，是自然冷

却的 12 倍，并且真空预冷后被冷却物料温度均匀。真空预冷后蛋糕失重率、硬度

高于自然冷却；颜色较自然冷却浅；冷却后菌落总数远低于自然冷却。真空预冷

会对蛋糕的品质造成一定影响，但通过感官评定表明，采用真空预冷与自然冷却

的产品差别不大。因此，真空预冷可以应用于焙烤食品的快速冷却。

通过对真空预冷过程传热传质机理分析，建立了真空冷却过程的非线性数学

模型，模拟蛋糕真空冷却过程的温度变化。模拟结果与实验数据相比较，发现数

值模拟结果与实验数据基本相似，所建立的数学模型能够预测真空冷却过程中产

品的温度变化。

以菌落总数、霉菌数量、大肠菌群为品质指标，通过与自然冷却比较，得出

真空预冷处理蛋糕的货架期明显延长。根据实验数据拟合出不同贮藏温度条件下

蛋糕中微生物的生长速率 k；通过 Arrhenius 方程模拟贮藏温度 T与微生物生长速

率k之间的关系；建立了贮藏温度 T与该温度条件下蛋糕货架期模型。研究结果

表明，所建立的蛋糕货架期预测模型其预测误差小于 12%。利用该模型进行预测，

可为生产厂家提供不同贮藏温度条件下真空预冷蛋糕的货架期，为合理设定蛋糕

的贮藏条件提供参考。

关键词：蛋糕真空预冷品质数学模型货架期

ABSTRACT

Vacuum pre-cooling is a rapid and efficient evaporative cooling method, there are

features of faster, steady and clean than the traditional method. In order to improve the

safety of food, vacuum cooling has been applied in the food industry in recent years, it

can minimize the growth of surviving microorganisms. In this paper, the vacuum

pre-cooling were used on bakery products, the main work of thes paper can be

concluded as follows:

Many experiments have been done in order to analyze the effects of cooling time,

weight loss, hardness, colour by the cooling pressures and cooling end-tempertures

during the vacuum pre-cooling process. The optimum parameters of vacuum

pre-cooling cakes were obtained as follows: the pressure of 1800 Pa and the temp-

erature of 24℃. The measure to reduce weight loss of cakes during the vacuum cooling

process was studied as follows: associate with natural air cooling, pre-wetting on the

cakes and optimize method of baken cakes.

Vacuum pre-cooling showed remarkable effect on the cooling rate of cakes. The

results showed that the vacuum cooling rate was 12 times quicker than the natural air

cooling. The weight loss and handness of cakes by vacuum cooling are more than

nutral air cooling. But the color and the total number of colonies are less than nutral air

cooling. The weight loss of cakes was increased during vacuum pre-cooling. However,

the sensory qualities of cakes, which cooled by vacuum cooling and nuatural air

cooling, were essentially the same. So the vacuum cooling could be applied to cooling

bakery products.

A mathematical model was developed to predict the variations of temperature dur-

ing vacuum cooling based on the elementary princeples and concepts. The predicted

temperature variations are compared with the measured values. It showed that the

simulation results agreed with the experimental data well. The mathematical model can

be used to predict the variations of temperature for understanding the mechanism of

vacuum cooling.

The influence of vacuum pre-cooling cake on the shelf life was studied and

compared with natural air cooling. The changes of total number of bacteria, moulds

and coliforms in cakes during storage at defferent temperatures were studied. Kinetic

models were developed for total number of colonies and moulds as a function of

storage time and temperature based on Arrhenius equation, and a shelf life predition

kinetic model was determined. It shows from the reliability assessment between

predicted and observed shelf that relative error is less than 12% calculated by

prediction model for the shelf life of cake. This model could be used for predicting the

shelf life of cakes.

Key Words: Cakes, Vacuum pre-cooling, Quality, Mathematical

model, Shelf life

中文摘要

ABSTRACT

第一章绪论................................................................................................................... 1

§1.1 立题背景及意义................................................................................................... 1

§1.2 焙烤食品的预冷方法........................................................................................... 1

§1.3 真空预冷的原理及特点....................................................................................... 2

§1.3.1 真空预冷技术的原理.................................................................................... 2

§1.3.2 真空预冷技术的特点.................................................................................... 3

§1.3.3 真空冷却设备................................................................................................ 4

§1.4 真空预冷技术的应用........................................................................................... 5

§1.4.1 在农产品中的应用........................................................................................ 5

§1.4.2 在熟食品中的应用........................................................................................ 5

§1.4.3 在其它食品中的应用.................................................................................... 7

§1.4.4 与其它技术的联合应用................................................................................ 7

§1.5 熟食品真空预冷技术的研究进展....................................................................... 8

§1.5.1 预冷工艺的研究进展.................................................................................... 8

§1.5.2 机理、数学模拟的研究进展........................................................................ 9

§1.6 本课题的主要研究内容..................................................................................... 10

第二章蛋糕真空预冷实验研究................................................................................... 11

§2.1 前言..................................................................................................................... 11

§2.2 实验材料与方法................................................................................................. 11

§2.2.1 仪器与材料.................................................................................................. 11

§2.2.2 实验方法...................................................................................................... 11

§2.3 结果与分析......................................................................................................... 14

§2.3.1 预冷参数对冷却时间的影响...................................................................... 14

§2.3.2 预冷参数对失重率的影响.......................................................................... 14

§2.3.3 预冷参数对硬度的影响.............................................................................. 15

§2.3.4 预冷参数对色泽的影响.............................................................................. 16

§2.3.5 真空预冷最佳参数的确定.......................................................................... 16

§2.3.6 真空室压力变化.......................................................................................... 17

§2.3.7 真空室湿度变化.......................................................................................... 18

§2.4 本章小结............................................................................................................. 19

第三章真空预冷与自然冷却对蛋糕品质的影响....................................................... 20

§3.1 前言..................................................................................................................... 20

§3.2 实验材料与方法................................................................................................. 20

§3.2.1 仪器与材料.................................................................................................. 20

§3.2.2 实验方法...................................................................................................... 20

§3.3 结果与分析......................................................................................................... 22

§3.3.1 初温对蛋糕预冷的影响.............................................................................. 22

§3.3.2 补水量对蛋糕预冷的影响.......................................................................... 24

§3.3.3 制作工艺对蛋糕预冷的影响...................................................................... 25

§3.3.4 冷却方式对蛋糕冷却时间的影响.............................................................. 26

§3.3.5 冷却方式对蛋糕品质的影响...................................................................... 27

§3.3.6 冷却方式对蛋糕感官品质的影响.............................................................. 27

§3.4 本章小结............................................................................................................. 28

第四章蛋糕真空预冷过程数学模拟........................................................................... 29

§4.1 前言..................................................................................................................... 29

§4.2 数学模型的建立................................................................................................. 29

§4.2.1 质量守恒方程.............................................................................................. 29

§4.2.2 能量守恒方程.............................................................................................. 30

§4.2.3 初始及边界条件.......................................................................................... 30

§4.2.4 数值模拟...................................................................................................... 31

§4.2.5 样品的物性参数.......................................................................................... 33

§4.3 模型的验证与分析............................................................................................. 33

§4.4 本章小结............................................................................................................. 34

第五章真空预冷对蛋糕货架期的影响....................................................................... 35

§5.1 前言..................................................................................................................... 35

§5.2 试验材料与方法................................................................................................. 35

§5.2.1 仪器与材料.................................................................................................. 35

§5.2.2 实验方法...................................................................................................... 35

§5.3 结果与分析......................................................................................................... 37

§5.3.1 冷却方法对蛋糕中微生物的影响.............................................................. 37

§5.3.2 微生物动力学初级模型.............................................................................. 38

§5.3.3 微生物动力学二级模型.............................................................................. 40

§5.3.4 蛋糕货架期模型的建立与验证.................................................................. 41

§5.4 本章小结............................................................................................................. 42

第六章结论与展望....................................................................................................... 43

§6.1 主要结论............................................................................................................. 43

§6.2 进一步研究建议................................................................................................. 44

附录............................................................................................................................... 45

参考文献......................................................................................................................... 47

在读期间公开发表的论文和参加的科研项目............................................................. 52

致谢............................................................................................................................... 53

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摘要：

摘要真空预冷技术是一种快速、高效的冷却技术，与传统冷却方式相比，具有冷却速度快、冷却均匀等特点。为了提高食品安全性，近年来真空冷却应用于熟食品的快速冷却，使其快速通过微生物繁殖区，减少细菌污染。目前真空预冷在熟食品的快速冷却方面主要应用于熟肉制品，本研究将真空冷却技术应用于焙烤食品的冷却中，对蛋糕进行了真空冷却研究。通过不同预冷终温、预冷压力对蛋糕冷却时间、失重率、硬度、色泽的影响进行分析，确定了蛋糕真空预冷最佳工艺参数为：预冷压力、预冷终温分别为1800Pa、24℃。采用将自然冷却与真空预冷联合使用、预冷前适量补水、调整蛋糕制作工艺的方法研究了减少蛋糕在真空预冷过程中的水分损失的措施。通过与...

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