【作者】 张孙现；

【导师】 郑宝东；

【作者基本信息】 福建农林大学 ， 农产品加工及贮藏工程， 2013， 博士

【摘要】 鲍鱼(Abalone)因富含蛋白质、脂肪、无机盐等营养成分且味道鲜美,而倍受消费者喜爱。干制是鲍鱼加工贮藏的重要方式。然而,传统的鲍鱼干制加工方法存在能耗高、技术落后、产品品质良莠不齐等问题,因此研究开发一种新型干燥技术是鲍鱼产业发展的必然要求。微波真空干燥是集成了微波干燥及真空干燥各自优势的一项新型的干燥技术,具有干燥速率快、产品质量好、节能环保、可操作性强的特点。本文研究了微波真空干燥技术对鲍鱼干制过程的影响及其作用机制。系统研究了前处理——盐渍、微波功率、真空度和装载量对鲍鱼干燥过程及其品质的影响,建立鲍鱼微波真空干燥动力学模型和复水动力学模型,优化鲍鱼微波真空干燥工艺参数,对比不同干燥方式对鲍鱼主要品质的影响。1、为考察盐渍对鲍鱼干燥过程和品质的影响,以微波真空干燥特性、色泽、复水性及复水后质构特性为指标。实验结果表明,当盐渍食盐浓度为7.5%时,鲍鱼的微波真空干燥速率最大,且色泽为均匀的淡黄色,复水性和质构特性均达到最大值。综合考虑,以7.5%盐溶液浸渍24h,沸水煮2min为鲍鱼微波真空干燥前处理步骤。2、探讨不同微波功率、真空度、装载量对鲍鱼干燥特性的影响,研究发现鲍鱼微波真空干燥过程存在升速,恒速和降速3个阶段。微波功率、真空度、装载量对鲍鱼的干燥速率均有影响,提高微波功率、真空度或减少装载量,能加快失水速率,缩短干燥时间,但并非参数越大越好。应用MATLAB分析软件对鲍鱼微波真空干燥特性进行回归分析,经拟合发现鲍鱼微波真空干燥过程符合Page模型：1nMR=-rtN,其中lnr=-2.8562-0.3875X1-0.0095X2-0.0115X3+0.0001X4,N=1.4738-0.0527X10.0009X2-0.0006X3-0.0098X4,R2=0.9765。经验证,模型的预测值与真实值拟合良好。3、为确定最佳的微波真空干燥工艺参数,研究微波功率、真空度、装载量各工艺参数对鲍鱼品质的影响,并对工艺参数进行优化分析,确定鲍鱼微波真空干燥的最佳工艺条件为：微波功率2000W,真空度-80kPa,装载量150g。4、比较自然晾晒、真空冷冻干燥、热风干燥、微波真空干燥4种方法对鲍鱼质构特性、复水性、色泽和氨基酸的影响。结果表明：真空冷冻干燥对鲍鱼质构特性的保持效果最好,微波真空干燥次之,明显优于其它干燥方法；干燥后鲍鱼氨基酸含量：真空冷冻干燥>热风干燥>微波真空干燥>自然晾晒干燥；微波真空干燥后鲍鱼微观结构呈现较好的多孔结构,且色泽更易于被消费者接受。综合各项指标及生产效能,微波真空干燥是一种较为适合鲍鱼干制的加工方法。5、在鲍鱼微波真空干燥最佳工艺条件下,考察微波真空干燥处理过程对鲍鱼质构特性、微观结构以及风味物质变化的影响。发现随干燥时间的延长,鲍鱼硬度和咀嚼性逐渐增大,弹性下降；电镜扫描结果显示,鲍鱼组织纤维由原来的膨胀状态变得细长并舒展开来,到干燥后期纤维开始变形,纤维间的空隙越来越大；采用顶空固相微萃取(HSSPME)结合气质联用(GC-MS)检测干燥过程产生多种的风味化合物,干燥后共检测出36种物质,含有更多的酯类、羧酸类、吡嗪类、芳香族等,使干燥鲍鱼的香气更加浓郁。6、干制鲍鱼的复水过程是鲍鱼食用及进一步加工成鲍鱼产品必不可少的关键的步骤。本文进一步研究了微波功率、真空度及干燥前盐渍浓度对鲍鱼干制品复水特性的影响,并建立了复水动力学模型：ln(-lnARf)=-1.5376-0.0934X1-0.0077X2-0.0491X3+0.0135X4+0.5547X5+0.0186X1X5+0.0015X2X5+0.0071X3X5-0.0039X4X5-0.0410X52(R2=0.9021)经验证,模型的预测值与真实值拟合良好,说明该模型模型能够准确描述鲍鱼复水过程的水分变化规律。更多还原

【Abstract】 Abalone is also known as Haliotidae, which is rich in nutrient with delicious taste. Dehydrated abalone is the one of the main abalone products. It is necessary to develop a new processing technology for dehydrated abalone, because traditional drying methods are lack of energy conservation, technology innovation and quality assurance. Microwave vacuum drying is a new technology integrating microwave drying and vacuum drying, which has characteristics of fast drying rate, environmental protection and operability. The microwave vacuum drying (MVD) technology was applied to abalone drying in this study. The effects of pretreatment, microwave power, vacuum and load on abalone dried by Microwave vacuum technology were studied systematically. The MVD characteristic and drying dynamics model of abalone was established. There was optimized MVD process parameter of abalone. Finally, MVD was compared with the sun drying, hot-air drying and vacuum freeze-drying. The main results were concluded as follows.1. The effects of pre-drying treatments on the drying process for abalone were studied, taking drying characteristic, color, rehydration and texture as the evaluation indexes. The results showed that:when the salt concentration was7.5%, the quality of dehydrated abalone was the best and microwave vacuum drying rate significantly accelerated. Considering the drying efficiency and products quality, a good pretreatment of abalone is immersion in7.5%salt solution and boiling for2min.2. MVD characteristics of abalone were studied by the effects of microwave power, vacuum degree and load on the dehydration rate. It showed that the MVD process of abalone was divided into three stages:speed-up, constant-speed and speed-down. There were obvious effects of microwave power, vacuum degree and load on abalone drying rate. The increasing microwave power and vacuum or the reducing load could speed up the rate of water loss, shorten the drying time, but it did not always follow this rule. Application analysis software MATLAB was used to analyze the regression rule of microwave vacuum drying characteristics of abalone. The drying procedure of abalone could accurately be described by the Page model and satisfied the Page equation: lnMR=-rtN, of which lnr=-2.8562-0.3875X1-0.0095X2-0.0115X3+0.0001X4, N=1.4738-0.0527X10.0009X2-0.0006X3-0.0098X4, R2=0.9765.3. The processing parameters of microwave power, the vacuum and load were optimized. The relatively optimizing processing parameters for microwave vacuum drying of abalone were determined:the microwave power was2kW, the vacuum was-80kPa, the loading was150g.4. The quality of abalone dried by sun drying (SD), freeze drying (FD), hot-air drying (HAD), and microwave-vacuum drying (MVD) were investigated. The quality parameters were compared according to the rehydration, color, texture, content of amino acid and sensory characteristics. The cohesiveness and chewiness of the products dehydrated by MVD were much better than other methods. The color of these products was most acceptable by the consumers. The amino acids content of MVD abalone was more even distributed than the others processing method. It showed porous structure of MVD abalone by electron microscopy. Consequently, the optimal drying method for the abalones was determined to be MVD.5. Under the optimum process conditions of microwave vacuum drying, the influences of MVD on abalone structure characteristics, microstructure and the content of flavor substances were referred. The results showed that hardness, stickiness and chewiness increased with the increasing processing time; SEM showed that tissue fibers of the abalone became slender and stretched state from expanded state, then muscle fibers deformed, and fiber gaps got widen at the end of drying process; the contents of esters, carboxylic acids, pyridines, aromatic of dried abalone increased making it rich in aroma.6. The rehydration process of the dried abalone is an indispensable key step for abalone cooking and further processing. Effects of microwave power, vacuum degree and salt solution concentration were investigated. The rehydration procedure of abalone could accurately be described by the model as: ln(-lnMRf)=-1.5376-0.0934X1-0.0077X2-0.0491X3+0.0135X4+0.5547X5+0.0186X,X5+0.0015X2X5+0.0071X3X5-0.0039X4X5-0.0410X52, R2=0.9021.And the predicted values were nearly consistent with the experimental values.更多还原