【作者】 邹兴华；

【导师】 过世东；

【作者基本信息】 江南大学 ， 食品科学， 2005， 硕士

【摘要】 本课题旨在探讨和研究一种新的太湖银鱼干燥工艺。通过多种不同的干燥试验,发现采用真空冷冻干燥和真空微波联合干燥不但能够生产出质量优良的干燥银鱼,同时能够大幅度地降低加工费用。干燥试验之前,对银鱼的组成和营养成分等进行了分析,包括水分含量、矿物质、脂肪、蛋白质和氨基酸组成等。银鱼具有良好的营养组成,其蛋白质含量达到85.24g/100g干物质,远远高于其它淡水鱼类的含量。同时其人体必需氨基酸组成非常合理。如每天摄入一定量的银鱼,能够满足人体对于必需氨基酸的需求。银鱼良好的营养品质提升了其深加工的价值。干燥实验中采用了程序升温的冷冻干燥方法对银鱼进行冻干,所采用的冻干条件为:中速冻结的预冻(3.9cm/h)方式将银鱼冷冻至～16℃以下,在10Pa左右的真空度、冷凝器温度为一45℃的条件下,采用的加热板加热程序为0℃保持3h,10℃保持0.5h,20。C保持0.5h,然后将温度升高至40℃,直到物料的温度接近加热板的温度,整个干燥过程大约持续6。5—7h。这一干燥方法所得的银鱼干的品质远高于传统热风干燥所得的银鱼干。程序升温的加热方式虽然能够获得优良的银鱼干并在一定程度上降低干燥的时间。但是,如果将其应用于工业化的生产,其能耗成本仍过高。为了在保证产品质量的前提下进一步降低干燥成本,尝试将真空冷冻干燥和微波真空干燥相联合的工艺方式进行银鱼干燥。在干燥的初始阶段采用真空冷冻干燥脱除一部分水分,在干燥的后期,也就是冷冻干燥的解析阶段,采用微波真空干燥,由此大大降低了总的干燥时间。具体的工艺条件如下:采用冷冻干燥将银鱼的含水率降至2.6±0.1(干基),后采用微波真空干燥,其真空度为2000Pa、功率为330W。经该工艺生产出来的干制银鱼同单独采用冷冻干燥生产出来的银鱼的质量差异不大,并大大好于采用传统热风干燥所生产出来的产品。通过对各种干燥方法干燥过程能量利用率和单位能耗成本的分析和对比,联合干燥的成本要比冷冻干燥低得多。本课题研究表明::联合干燥可以获得高质量的脱水银鱼干,且干燥成本较低。更多还原

【Abstract】 The objective of this work was to develop a new method to process Taihuwhitebait.Three different drying methods were applied in the processing ofwhitebait,including hot air drying,vacuum freeze drying,combination of freezedrying and vacuum microwave. Before drying experiment,the nutrition and component of this fish wasanalyzed.The results shows whitebait owns a very good nutrition.The content ofprotein is nearly 85.24g/100g drying material which is much higher than otherfresh fish.Furthermore,constitutes of necessary amino acid is very rational.Acertain amount of whitebait is eaten each day will satisfy human need ofnecessary amino acid.The good nutrition of whitebait increases the value ofprocessing. Then freeze drying of heating procedure was used to dry whitebait,thedrying condition is followed:pre-freezing the whitebait at medium cooling rate(3.9cm/h),a pressure about 1 0 Pa,a condenser temperature of-45℃.Inaddition.the setting of heating plate procedure that kept the temperature inO℃ for 3 hours,then increased to 10℃for half an hour,then last half an hourat 20~C,finally kept 40"C till the temperature of sample as high as the platetemperature.The whole process last 6.5-7h.The quality of product of thismethod is much better than hot air. Though freeze drying of heating procedure can get excellent product anddecrease freeze drying time.The capital cost is still very high if it is usedin the producing of industrialization.To lower the cost further,we attempt to combinevacuum microwave drying and freeze drying.The plan is freeze drying was usedin the first stage,then whitebait was dried by vacuum microwave drying to finalmoistu re content leSs than 0.06(dry basis).The detail condition is following:the water content of white bait is lowered to 2.6±0.1 by freeze drying.microwaveoven power about 330W,pressure about 2000Pa.To compare the quality ofwhitebait dried by the current method was close to that of freeze dried whitebaitand much better than that of conventional hot.air dried ones. The cost of combination vacuum microwave drying and freeze drying wasmuch less than that offreeze drying. The result of this work show that the combination vacuum microwave drying and freeze drying may be used as an alternative to dehydrate the foodin high quality and in very low cost.更多还原