杀菌方式对石榴浊汁微生物和色泽的影响

为探讨不同杀菌方式对石榴浊汁在4℃冷藏期间微生物和色泽品质的影响,本研究采用超高压技术(HPP,450 MPa/1 min、450 MPa/5 min、550 MPa/1 min、550 MPa/5 min)、巴氏杀菌技术(PT,85℃/30 s)和高温短时杀菌技术(HTST,110℃/8.6 s)对石榴浊汁进行杀菌处理,并重点研究了抗坏血酸和色泽参数变化的动力学特征。结果表明,冷藏期间,HPP和HTST处理石榴浊汁微生物在标准范围内。HPP处理能较好地保留石榴浊汁中脱氢抗坏血酸(DHAA)的含量,而PT和HTST处理后DHAA含量较未处理样品(第0天)分别降低了21%和35%;冷藏期间不同杀菌方式处理后DHAA含量均呈下降趋势;经一级动力学模型拟合发现,HPP处理组DHAA的降解速率常数k值高于PT和HTST处理组。与热处理(PT和HTST)相比,冷藏前期,HPP处理能保持石榴浊汁较高的L^*、a^*、b^*值和较低的ΔE值,保持较优的色泽品质;采用一级分数转换动力学模型对L^*、a^*和ΔE值进行拟合,发现HPP处理样品色泽参数在冷藏过程中的k值同样高于热处理样品,即随着冷藏时间的延长,HPP处理组色泽品质逐渐降低。综上所述,HPP处理能在保证石榴浊汁冷藏期间微生物安全的同时,较好地保持其色泽品质。本研究为石榴浊汁工业化生产中杀菌方式的选择提供了理论依据。

Effects of Sterilization Methods on Microorganism and Color of Cloudy Pomegranate Juice

In order to explore effect of different sterilization methods on the microorganism and color changes of the cloudy pomegranate juice during refrigeration at 4℃, high pressure processing technology (HPP, 450 MPa/1 min, 450 MPa/5 min, 550 MPa/1 min, 550 MPa/5 min), pasteurization technology (PT, 85℃/30 s), and high temperature short time sterilization technology (HTST, 110℃/8.6 s) were used in this study. The kinetics characteristics of ascorbic acid and color parameters changes were studied. HPP and HTST showed good inactivation effect on microorganism in cloudy pomegranate juice during cold storage, and the microorganism was within the standard range. The content of DHAA could be better preserved using HPP treatment, while the DHAA content in PT and HTST treatments were 21% and 35%, which were lower than that of untreated cloudy pomegranate juice, respectively (day 0). The changes of DHAA during cold storage showed a downward trend, and could be fitted by first-order kinetic model. The degradation rate constant k values of DHAA in HPP-treated samples were higher than those of PT and HTST samples. Compared with thermal treatments (PT and HTST), in the early stage of cold storage, HPP treatment can maintain higher L^*, a^*, b^* values and lower ΔE values of cloudy pomegranate juice, and maintain better color quality. The L^*, a^* and ΔE values were fitted by the first-order fractional transformation kinetic model, and the reaction rate k values of HPP samples during cold storage were all also higher than those of thermal treatment samples. The color quality of the HHP-treated samples gradually deteriorated with the prolongation of the cold storage time. In conclusion, HPP treatment could ensure the microbial safety of cloudy pomegranate juice during cold storage, which could also maintain its color quality. This study provides a theoretical basis for the selection of sterilization methods in the industrial production of cloudy pomegranate juice.