【作者】 丛海花；

【导师】 薛长湖； 唐炬明；

【作者基本信息】 中国海洋大学 ， 水产品加工及贮藏工程， 2013， 博士

【摘要】 微波杀菌代替传统的热力学杀菌方可获得高品质长货架期的产品,为扩大其在水产品中的应用,建立一种快速、有效的方法寻找加热过程被杀菌食品的冷点是拟解决的关键问题,该论文致力于开发一种新的模拟食品并使用化学指示物结合计算机图像模拟技术来分析微波杀菌过程中的热型,填补了技术空白。以复水干海参为例：研究了不同复水方法得到的复水干海参(Apostichopus japonicas)在300KHz-3000MHz频率范围内、不同温度(温度变化范围20-125℃)下的介电特性差异；研究了复水干海参介电特性随频率、温度的变化规律(温度变化范围20-121.1℃),比较复水干海参不同位置介电特性的差异,并计算915MHz下的能量穿透深度值。复水干海参介电特性与频率、温度之间分别存在着对(指)数、二次曲线的关系。为开发一种与复水干海参介电特性匹配的模拟食品,配置了五种不同配方的模拟食品,研究乳清浓缩蛋白和乳清分离蛋白的含量对模拟食品介电特性的影响；比较915MHz频率下,不同配方模拟食品与复水干海参的介电特性、能量穿透深度随温度的变化规律(温度变化范围20-121.1℃),选定配方为浓缩蛋白(WPC)5%、分离蛋白(WPI)3%,结冷胶1%以及D-核糖0.5%、蒸馏水90.5%配制的模拟食品可用于模拟复水干海参微波杀菌热处理过程中的热型。使用IMQA软件编写一套特定IMAQ图像分析程序,得到模拟食品热处理过程中的3-D模式热型；研究模拟食品热处理后中心Fo值与模拟食品颜色RGB值,存在二次曲线关系；研究微波辅助杀菌过程中不同包装厚度模拟食品的热型和冷点的位置,模拟食品中心横切面冷点位置不受包装厚度的影响,平均位置为(-23.33,-3.44)m,同时对微波杀菌处理的袋装模拟食品及复水干海参进行热型分析,得到受热冷点位置(-21.68,-2.38)mm,与模拟食品中心横切面冷点位置十分接近,根据冷点位置的颜色RGB值估算出该杀菌工艺下样品受热冷点的F0值。相同的微波辅助杀菌工艺下,使用ellab无线测温传感器及其固定装置的使用以及复水干海参模拟食品微波辅助杀菌系统中的摆放位置对热型并无显著影响,冷点位置横纵坐标的误差均在2mm以内；使用ellab传感器记录样品冷点的温度,计算实际杀菌过程中的F0值；通过四组热穿透实验得到F0值与微波加热时间T的函数关系式：F0=105.6*T-245.14(R2=0.9744),利用该结论确立微波辅助杀菌袋装复水干海参的杀菌工艺参数；同时比较了相同系统,相同操作参数条件下,热水杀菌过程达到相同F0值情况下,所需要的加热时间为微波辅助杀菌加热时间的7倍多；使用计算机模拟法验证袋装复水干海参微波辅助杀菌过程,结果显示,复水干海参计算机模拟结果与实际的模拟食品热型基本一致,进一步验证了：化学指示物结合计算机图像模拟技术可以建立一套快速的、稳定的、准确的方法来确立微波杀菌过程中模拟食品以及复水干海参的冷点位置,该技术同时可以用于估算被杀菌样品冷点位置的F0值,为进一步确立微波杀菌过程参数提供基础。研究了其他几种常见的即食水产品原料：贻贝(Mytilus edudis linne)、章鱼(Octopus ocellatus)、扇贝(Patinopecten yessoensis)的介电特性随频率、温度的变化规律,并得到介电特性与频率呈对(指)数函数关系,为进一步的配置介电特性与之匹配的模拟食品提供数据支持,为计算机模拟微波辅助杀菌过程提供参数,为开发新的微波辅助设备提供依据。更多还原

【Abstract】 Microwave sterilization process is a promising alternative to conventional retorting methods for producing high quality shelf stable foods. In order for this technology to produce high quality shelf stable aquatic products there is a need for a rapid and reliable method to determine the location of cold spots in food. My dissertation overcomes the limitations of no model food for low dielectric loss factor seafood with a special focus on the development of a new model food to determine heating patterns using chemical maker M-2based computer vision method for microwave sterilization. A case study of rehydrated sea cucumber was as follows:The dielectric constant (ε’) and loss factor (ε") of rehydrated sea cucumber (Apostichopus japonicas) were investigated over the frequency range of300KHz-3000MHz at temperatures ranging from20to125℃. Influences of frequency and temperature on rehydrated sea cucumber dielectric properties as well as that of penetration depth were analyzed at915MHz in the temperature range20to121.1℃. Logarithmic (exponential) and quadratic relationship were observed, respectively.Study the effect of whey protein concentrate (WPC) and whey protein isolation (WPI) on dielectric properties of model food with five different formulation for development a model food for rehydrated sea cucumber; based on comparison of the measured dielectric properties of the rehydrated sea cucumbers and model food samples with different formulations and the calculated microwave power penetration depths among the sea cucumbers and model foods in the temperature range20to121.1℃at915MHz, appropriate formulation (WPC5%, WPI3%, gellan gum1%, D-ribose0.5%and distilled water90.5%) was chosen as the model food for rehydrated sea cucumbers for the purpose of predicting heating pattern in microwave processing development.Through interactive programming an IMAQ Vision Builder script was designed to get the3-D heating pattern in model food to predict the heating patterns in rehydrated sea cucumber during thermal processing; relationship among thermal lethality (Fo) and color RGB value with model food was studied, quadratic curve was observed; Sensitivities to the heating patterns were tested for model food with different thickness. Results indicated that microwave heating patterns were similar, the average cold spot was located at the point23.33mm from the right edge and3.44mm from the front edge in the middle layer; heating patterns were tested for model food and rehydrated sea cucumber and cold spots were analyzed which is close to model food,(-21.68,-2.38) mm; F0value in cold spot was calculated through color RGB value during microwave sterilization.The method here was further improved to facilitate the comparison of the heating patterns for model food with ellab sensor and frame or without sensor and frame; model food in different belt position during the same processing, the results showed that the heating patterns were similar, and the errors (within2mm) were acceptable; the temperature of the cold spot predicted by the model food was validated using ellab sensors, F0value was calculated; data sets were collected from four heat penetration test runs, relationship of Fo value and microwave heating time (T) was analyzed: Fo=105.6*T-245.14(R2=0.9744), microwave-assist processing parameters were determined for package rehydrated sea cucumbers; Septuple heating time was needed for the same F0value in hot water sterilization processing using the same system with the same processing parameters; the method here was further improved to facilitate the comparison of heating patterns between computer simulation and microwave processing. The result showed the similar heating pattern:Validation tests confirmed that the method based on chemical marker M-2and computer vision can accurately determine the cold spot location in pre-package model food and rehydrated sea cucumber processed by microwave, Fo value in cold spot was calculated through microwave heating time for developing microwave-assist sterilization processing parameters.The dielectric constant (ε’and ε " of mussel (Mytilus edudis linne), octopus (Octopus ocellatus) and scallop (Patinopecten yessoensis) were investigated. Influences of frequency were analyzed in the temperature range20.to121.1℃, Logarithmic(exponential) relationships were observed, and those data could be used for developing model food, simulating with computer and designing new equipment for microwave sterilization processing.更多还原