食品科学

• 基础研究 • 上一篇    下一篇

冻干圣女果粉的水分吸附性质及玻璃化转变温度

刘 华1,钟业俊2,*,李资玲1,2,李积华2,3,林丽静3,周 伟 3   

  1. 1.江西科技师范大学生命科学学院,江西 南昌 330013;2.南昌大学 食品科学与技术国家重点实验室,
    江西 南昌 330047;3.中国热带农业科学院农产品加工研究所,广东 湛江 524001
  • 出版日期:2015-12-15 发布日期:2015-12-24

Water Sorption Characteristics and Glass Transition Temperature of Freeze-Dried Cherry Tomatoes

LIU Hua1, ZHONG Yejun2,*, LI Ziling1,2, LI Jihua2,3, LIN Lijing3, ZHOU Wei3   

  1. 1. School of Life Science, Jiangxi Science and Technology Normal University, Nanchang 330013, China;
    2. State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang 330047, China; 3. Agricultural Products
    Processing Research Institute, Chinese Academy of Tropical Agricultural Sciences, Zhanjiang 524001, China
  • Online:2015-12-15 Published:2015-12-24

摘要:

根据吸附理论,在水分活度为0.11~0.90范围内,环境温度为25 ℃条件下,采用静态称质量法研究冻干圣女果粉的吸附和解吸等温线;通过差示扫描量热仪(differential scanning calorimeter,DSC)测量不同水分含量下的玻璃态转变温度(glass transition temperature,Tg),并采用Gordon-Taylor方程对其进行了非线性拟合。结果表明:冻干圣女果粉在25 ℃条件下的吸附等温线和解吸等温线的类型都为J型,属于Ⅲ型等温线;在水分活度为0.23~0.76范围内存在明显的解吸-吸附滞后现象,属于H3型等温线。GAB和Peleg模型都描述冻干圣女果粉的吸附特性。随着水分含量的增加,冻干圣女果粉的Tg显著降低;Gordon-Taylor方程能够较好地拟合其玻璃化转变曲线。对比水分活度贮藏理论和玻璃化转变理论,发现二者在预测冻干圣女果粉贮藏稳定性上存在一定的差异。

关键词: 圣女果, 吸附等温线, 玻璃化转变, 解吸等温线

Abstract:

Desorption and adsorption isotherms of freeze-dried cherry tomatoes were determined by gravimetric method at
water activities ranging from 0.11 to 0.90 at 25 ℃ based on sorption theory. The glass transition temperatures at different
moisture contents were measured by differential scanning calorimetry (DSC) and fitted with the Gordon-Taylor equation.
Results indicated that the desorption and adsorption isotherms belonged to type III behavior and the hysteresis loop in the
water activity range of 0.23 to 0.76 was type H3 according to the classification method proposed by the International Union
of Pure and Applied Chemistry (IUPAC). Both the GAB and Peleg models were suitable for fitting the moisture absorption
isotherm of freeze-dried cherry tomatoes. The glass transition temperature of freeze-dried cherry tomatoes significantly
decreased with increase in moisture content, and glass transition curve was well fitted with the Gordon-Taylor equation.
A comparison of product stability criteria based on the concepts of water activity and glass transition temperature revealed
that there was a considerable discrepancy in the temperature related to stability criteria predicted by the concepts of water
activity and glass transition.

Key words: cherry tomatoes, adsorption isotherm, glass transition, desorption isotherm

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