苹果浓缩汁非酶褐变动力学及影响因素(英文)  

Kinetics and Influencing Factors of Nonenzymatic Browning in Apple Juice Concentrate

作　　者：郭善广[1] 仇农学[2] 

机构地区：[1]华南农业大学食品学院,广东广州510642 [2]陕西师范大学食品工程与营养科学学院,陕西西安710062

出　　处：《食品科学》2010年第23期79-83,共5页Food Science

基　　金：国家"863"计划项目(2002AA245091)

摘　　要：通过检测苹果汁的色值(T440nm)、褐变指数(A420nnm)、氨基态氮、5-羟甲基糠醛含量等指标研究加工过程对苹果汁褐变的影响以及在不同贮藏温度(5、20℃和37℃)下苹果浓缩汁(70.5°Brix)的非酶褐变速率。3个贮藏温度下的苹果浓缩汁褐变速率均符合一级反应动力学模式,而且高温情况下褐变更明显。随着贮藏时间的延长,氨基态氮含量明显下降而5-羟甲基糠醛含量上升,尤其是贮藏在37℃的苹果汁这一变化更明显。5-羟甲基糠醛与果汁褐变效应呈指数关系,可以说明苹果汁在贮存中的褐变主因是发生美拉德反应,而且氨基态氮含量与果汁褐变效应的线性关系也验证了这一结论。在果汁的初始加工过程中,破碎、压榨、酶解、超滤、前巴氏杀菌等单元操作中美拉德反应并不明显;吸附操作可以去除果汁中的氨基态氮以及其他色素物质;而其他操作过程如浓缩和后巴氏杀菌则促进了美拉德反应,导致果汁氨基态氮含量明显下降。The effects of various processing operation units on browning and the rate of nonenzymatic browning in commercial apple juice concentrates （70.5 °Brix） stored at 5, 20 or 37 ℃ were investigated. The changes of color value （T440）, browning index （A420nm）, amino nitrogen content and 5-hydroxymethylfurfural content were evaluated. The rates of browning at all three temperatures obeyed the first-order kinetic model. Browning reaction occurred more obviously at high temperature. There was a general decrease in amino nitrogen content and an increase in 5-hydroxymethylfurfural content with prolonged storage; this effect was most pronounced for samples stored at 37 ℃. The relation between 5-hydroxymethylfurfural content and fruit browning could be described as an exponential explanation for the reason why browning occurs in apple juice concentrate during storage is Maillard reaction, which could also be validated by the linear relation between amino nitrogen and browning. During the early processing stages, including crushing, pressing, enzymolysis, ultrafiltration and first pasteurization, no obvious Maillard reaction was found. The follow-up operation unit, adsorption, resulted in the removal of amino nitrogen and other dark colored compounds. However, Maillard reaction was undesirably promoted, leading to an obvious reduction of amino nitrogen in apple juice.

关 键 词：非酶褐变 苹果浓缩汁 加工过程 贮藏 美拉德反应 

分 类 号：TS255.44[轻工技术与工程—农产品加工及贮藏工程]