速冻莲藕片贮藏过程中品质变化动力学模型

Establishment of dynamic model for quality change in frozen lotus root slices during storage

为了探寻贮藏温度对速冻莲藕片品质的影响及预测其货架期,该文研究在贮藏温度?5、?15和?25℃条件下,速冻莲藕片维生素C、色泽和硬度随着贮藏时间的变化,建立了3个指标变化动力学模型。结果表明:随着贮藏温度的升高,速冻莲藕片维生素C、色泽和硬度的变化速率逐渐增加,?5℃条件下贮藏的速冻莲藕片品质快速下降,?15和?25℃条件下贮藏前期莲藕片品质下降不显著(P>0.05),随着时间的延长,?25℃部分玻璃态贮藏的莲藕片品质最佳;不同贮藏温度下速冻莲藕片维生素C和硬度变化符合一级反应,总色差和亮度变化符合零级反应,速冻莲藕片维生素C、色泽和硬度反应速率常数符合Arrhenius方程,并建立莲藕片货架期动力学模型,通过对其验证发现模型拟合度良好(R2>0.9),能预测速冻莲藕片贮藏期各品质指标变化和不同温度下的货架期寿命。研究结果可为速冻莲藕片低温贮藏品质变化和货架寿命预测提供理论依据。

Lotus root is one of the vegetables with huge export production in China.The quality of post-harvest lotus root declined quickly due to its rotting and discoloring.Unsuitable preservation or storage methods can lead to its great loss.Deep processing is an appropriate method to reduce the post-harvest loss of lotus root.Frozen lotus root is the main type of export production,which can retain most of the original quality,flavor and nutrition.During the freezing-storage period,storage temperature can conduct some influence on the product quality and shelf life of frozen lotus root.In order to clarify the influence of storage temperature on quality of lotus root slices and develop the predictive model of shelf life of lotus root slices,Vitamin C content,color and hardness of lotus root slices were examined at-5,-15 and-25℃respectively during different storage time,and the dynamic models of those quality indices were established.The Vitamin C content,color and hardness were chosen as indices representing for the quality of nutrition,appearance and texture,respectively.A series of experiments were carried out to develop and validate the change dynamic model for predicting the quality and remaining shelf life of frozen lotus root slices stored at different temperature.The results showed that the Vitamin C content decreased gradually with the storage time,the stability of Vitamin C became worse,and the degradation rate was accelerated with the increase of storage temperature.The Vitamin C content was more stable during the early storage at-5℃,and the degradation rate of Vitamin C was higher during the late storage.The degradation rate of Vitamin C at-25℃storage was slower thanother storage temperatures.Incase of color indices,the L＊value declined,the a＊and b＊value and the chromatic aberration were increased with the extension of storage time and the increase of storage temperature,resulting that lotus root slices became more dark,red and yellow.The hardness of lotus root slices declined rapidly during the early storage at different temperatures.The decreasing rate of hardness slowed down with the increase of storage time,and became higher with the increasing of storage temperature.Therefore,it can be concluded that the storage temperature influences severely the quality of frozen lotus root slices.After stored at-5℃for 100 d,the Vitamin C content,color and hardness of lotus root slices declined rapidly.The reaction rate constants of Vitamin C,L＊,chromatic aberration and hardness were assumed to have an Arrhenius-type dependence on temperature.The change dynamic model of Vitamin C and hardness followed a first-order reaction,and that of L＊and chromatic aberration followed a zero-order reaction.The activation energy of Vitamin C,L＊,chromatic aberration and hardness were 34.48,44.72,43.94 and 30.26 kJ/mol,respectively,which could reflect their fast change rate during storage.The kinetic models were established with the indices of color,hardness and Vitamin C.There were high regression coefficients between the experimental value and the predicted value at different storage temperatures,which fitted well with the high R2 values.It was suggested that these kinetics model could properly predict the quality change and shelf life expectancy of lotus root slices at different storage temperatures.The research conclusions are expected to provide a theoretical basis for shelf life prediction of frozen lotus root during storage and transportation.