微波和巴氏杀菌后番茄汁品质动力学

Quality kinetics of microwave and pasteurised processed tomato juice

为了解杀菌方式对番茄汁品质和货架期的影响,研究了经巴氏杀菌(85℃,4min)和微波杀菌(800W,20s)番茄汁的品质动力学,均使其加工到无菌状态,然后在不同恒温条件下(0、4、10、25、37℃)贮藏,每隔一段时间测定菌落总数、维生素C质量分数及色差值。结果表明:2种杀菌方式处理的番茄汁在贮藏期间,菌落总数增值速率,维生素C损失及褐变程度随贮藏时间的延长和贮藏温度的升高而增加,其中,褐变程度和维生素C损失率呈线性关系。0～10℃低温贮藏条件下,基于维生素C保留率微波杀菌的番茄汁与巴氏杀菌的相比,其货架期延长了9.1～17.5d,而基于色泽变化程度货架期延长了14.9～71d,25～37℃高温贮藏条件下,基于维生素C保留率和色泽变化程度2种杀菌方式后番茄汁的货架期差别不显著。基于菌落总数作为评价指标,2种杀菌方式之间差别不显著,为1～2d。应用建立的货架期预测模型,以菌落总数和维生素C质量分数作为评价指标,可以快速准确地预测0～37℃贮藏范围内微波处理后番茄汁的货架期,准确率达到90%。以菌落总数作为评价番茄汁货架期的最终标准,0～10℃低温条件下,经微波杀菌的番茄汁推荐其货架期为5～8d,经巴氏杀菌的番茄汁推荐其货架期为5～9d。为微波技术在果汁加工及贮藏中的应用提供技术依据。

To understand sterilization methods on the impact of the quality and shelf life of tomato juice,a kinetic study of post processing quality loss was conducted after microwave processing（800 W,20 s） or thermal pasteurisation（85℃,4 min） of tomato juice.Selection of processing conditions was only based on microorganism inactivation.Total plate count,Vitamine C,and colour changes were measured at intervals during storage under different isothermal conditions（0,4,10,25,37℃）.The results indicated that the rates of increasing of total plate count,lossing of Vitamine C,the browing rate have increased with the increasing of storage time and temperature for both types of processing,and browing rate was linearly correlated to Vitamine C loss.Based on the remainder of Vitamine C 9.1-17.5 days shelf life for microwave treated tomato juice was longer than the respective values of thermally pasteurised juice at low storage temperatures（0-10℃） used,and based on the degree of browing the difference was 14.9-71 days.however,the difference between pasteurize and microwave sterilization method was not significant at 25-37℃.And based on the total plate count,there was no obvious difference,it was only one or two days.Microwave processing resulted in better retention of the quality of untreated juice and superior sensory characteristics compared to thermal pasteurisation.The remaining shelf-life of microwave treated tomato juice could be predicted at the storage temperature at 0-37℃ based on Vitamine C and the total plate count.It showed from the reliability assessment between predicted and observed shelf-life that accurate rate was within 90% calculated by the prediction model for the shelf-life of tomato juice.It was better to take the total number of colonies of tomato juice as the ultimate standard for shelf life.At low storage temperatures（0-10℃） 5-8 days were proposed as the shelf life of microwave treated tomato juice,and 5-9 days were proposed as the shelf life of thermally pasteurized tomato juice.The results provide the technical basis for the application of microwave technology in processing and storage of fruit juice.