基于酶动力学方程的双孢蘑菇气调贮藏呼吸速率模型

为了给气调贮藏设计提供理论设计依据,采用酶动力学方程,建立了双孢蘑菇呼吸速率随贮藏时间变化的理论模型;研究了在贮藏温度为5℃、气体体积分数为20%O_2、80%N2的贮藏条件下,贮藏时间对双孢蘑菇采后呼吸速率的影响,并建立了双孢蘑菇呼吸速率随贮藏时间变化的数学模型,模型决定系数R~2为0.9766、0.9331。模型与实测值进行配对T检验差异不显著(P0.05),呼吸速率值的绝对误差小于5 m L/(kg·h),相对误差变化范围为0.06%~24.95%。在已建模型基础上,研究不同贮藏温度(5、10、15、20℃)对已建模型参数的影响,利用Arrhenius方程来描述贮藏温度对果蔬呼吸速率的影响,建立了包含温度和贮藏时间因子的呼吸速率模型,模型决定系数R~2为0.9073、0.9350。验证试验结果表明,模型与实测值进行配对T检验差异不显著(P0.05),呼吸速率值的绝对误差小于17 m L/(kg·h),相对误差变化范围为1.00%~25.25%。该模型可为双孢蘑菇气调贮藏期间呼吸速率的预测及贮藏品质研究提供参考。

Respiration rate model of Agaricus bisporus based on enzyme kinetics equation under controlled atmosphere storage

Agaricus bisporus is highly perishable horticultural product. It does not have a protective skin cover, which consequently leads to high moisture loss and a short shelf life of 1-3 d when held at ambient temperature. And with the improvement of people's living standards, the requirement of the quality of food is also more and more strict. The shelf life of 1-2 d after harvest has not satisfied the market. How to control the quality of theAgaricus bisporus is an urgent problem to be solved. During the storage and transportation of postharvest fruits and vegetables, respiration is the main postharvest physiological and biochemical process of fruits and vegetables. Respiration is the most important cause of physiological tissue changes in fruits and vegetables. The respiration rate of fruits and vegetables is an important indicator of senescence and ethylene production in fruits. A major factor contributing to postharvest losses is the product respiration, which converts the stored sugar or starch to energy in the presence of O2 substrate, thus advancing ripening. Shelf life is directly proportional to the rate of senescence and inversely proportional to the respiration rate. Respiration plays a central role in the overall metabolism of a plant and is therefore often used as a general measure of metabolic rate. Controlling the respiration rate of fruits and vegetables is one of the important means to improve the value of the fruits and vegetables. Changes in respiration rate are influenced by many factors, such as storage time, storage temperature, environmental conditions. Storage temperature plays a major role in the respiration rates of fruits and vegetables, and when storage temperature decreased to lower levels, it causes a reduction in the biochemical reaction rate and consequently increases its shelf life. At present, there are many fresh-keeping methods to inhibit the respiration and keep the quality of fruits and vegetables. And a model of the respiratory rate of fruit and vegetable can provide important theoretical guidance and design basis for the storage and preservation method. Although the storage time is an important factor to affect the respiration rate of fruits and vegetables, there are few models to consider the storage time. A theoretical model of respiration rate ofAgaricus bisporusrelated to storage time, based on the enzyme kinetics equation, was established. The effect of storage time on the respiration rate ofAgaricus bisporus was studied at 5℃ and 20% oxygen concentration under the controlled atmosphere storage, and the respiration models ofAgaricus bisporusbased on this were established, with the coefficients of determination of 0.9766 and 0.9331 respectively. The difference between the model and the measured value was not significant (P>0.05), the absolute error of the respiration rate was less than 5 mL/(kg·h), and the relative error was 0.06%-24.95%. After that, the effects of storage temperature (5, 10, 15 and 20℃) on the respiration rate were studied as well as the established model parameters. Based on the model, the temperature dependence of the model parameters was evaluated using an Arrhenius plot, and the model incorporating temperature and time was established, whose coefficients of determination were 0.9073 and 0.9350 respectively. The difference between the model and the measured value was not significant (P>0.05), the absolute error of the respiration rate was less than 17 mL/(kg·h), and the relative error was 1.00%-25.25%. The verification tests showed that, the respiration of Agaricus bisporusin terms of time and temperature during the storage was well described by the obtained models, and agreed well with the experiment data. The respiration rate model can provide the important theoretical basis for the prediction of respiratory rate and the research of storage quality in the process of storage and transportation of fruits and vegetables.