网纹甜瓜压差膨化干燥过程中的褐变规律及其抑制工艺研究

发布时间：2018-04-28 00:52

  本文选题：网纹甜瓜 + 压差膨化干燥　； 参考：《沈阳农业大学》2017年硕士论文

【摘要】：网纹甜瓜是葫芦科甜瓜属的一种变异类型,属于厚皮甜瓜的一种,因其果皮表面带有网状裂纹,所以称为网纹甜瓜。网纹甜瓜因其独特美丽的外观和特有的芳香以及优良的风味口感,受到了广大消费者的喜爱。但因其果实中糖含量较高,同时含有儿茶素、表儿茶素等酚类物质,所以加工中易发生酶促褐变和非酶褐变,严重影响产品的品质,限制了网纹甜瓜的工业产业化发展。本试验通过对网纹甜瓜压差膨化干燥过程中褐变规律及压差膨化加工中抑制褐变工艺参数的研究,为网纹甜瓜的加工提供理论依据。本文研究的主要内容包括网纹甜瓜压差膨化干燥过程中褐变规律、压差膨化加工中抑制褐变工艺参数的优化两大部分。压差膨化加工中抑制褐变工艺参数的控制包括复合护色剂的筛选以及预干燥温度、抽空温度、抽空时间的优化。第一部分研究了网纹甜瓜压差膨化干燥过程中褐变规律。(1)在原料预处理过程中,使用单一护色剂护色过程中产品仍然发生酶促褐变,同鲜样相比,褐变度上升0.018,含水量变化不显著,总酚含量下降了 2.69mg/100g;(2)预干燥阶段同时发生了酶促和非酶褐变。同护色过程相比,含水率下降64.75%,总酚含量下降3.64mg/100g,5-羟甲基糠醛(5-HMF)相对含量上升至0.0122%,可溶性蛋白相对含量下降了 0.40%,还原糖相对含量下降了 20.01%;(3)回软阶段对褐变影响不显著。(4)膨化阶段主要发生了非酶褐变。同回软过程相比,含水率从29.30%下降至4.02%,样品恢复了弱碱性,酚物质含量下降1.64mg/100g,还原糖相对含量下降16.24%,可溶性蛋白相对含量下降了 0.31%,5-HMF相对含量达到0.0211%。第二部分通过护色剂的筛选和变温压差膨化干燥过程工艺参数的优化明显降低了产品的褐变。得到的具体优化参数如下:由0.6%的NaCl、0.15%的CaCl2、0.1%的L-半胱氨酸和0.6%的柠檬酸组成的复合抑制剂对网纹甜瓜预干燥阶段褐变的抑制效果最好,褐变度降低了 0.256。通过对比两组试验发现,试验组护色后的pH值比对照组低1.56,多酚氧化酶(PPO)和过氧化物酶(POD)活性分别比优化前下降2.2U/min·mL-1和14.2 U/min·mL-1,还原糖的相对含量比对照组高2.50%,说明添加该复合护色剂可以抑制预干燥阶段的酶促褐变、预干燥和膨化干燥阶段的美拉德反应,减少褐变的发生;膨化干燥中预干燥温度、抽空温度、抽空时间三个因素,抽空温度影响最大,其次是抽空时间、预干燥温度,正交试验优化后的工艺参数为:预干燥温度70℃,抽空温度70℃,抽空时间150 min。优化后,最终褐变度为0.775,相比优化前下降了 20.51%,5-HMF相对含量比优化前低0.0036%,说明优化条件后抑制了 5-HMF生成类黑素等有色物质的过程,即美拉德反应的第三阶段,改善了膨化阶段的变色程度。优化工艺后,产品的硬度为412g、脆度值为4、含水率为4.02%、红度a*为11.39,产品品质优异。
[Abstract]:Netted muskmelon is a variant type of Cucurbitaceae, which belongs to muskmelon with thick skin. Netted muskmelon is loved by consumers because of its unique beautiful appearance, unique aroma and good taste. However, due to the high sugar content in the fruit and phenolic substances such as catechin and epicatechin, enzymatic browning and non-enzymatic browning occurred easily in the processing, which seriously affected the quality of the product and restricted the industrial development of muskmelon. In this experiment, the rule of browning in pressure-differential drying of reticulated muskmelon and the technological parameters of inhibiting browning in the process of pressure-differential expansion were studied in order to provide theoretical basis for the processing of netted muskmelon. The main contents of this paper include two parts: browning law in pressure-differential drying process of muskmelon and optimization of technological parameters for inhibiting browning in pressure-differential extrusion process. The control of the process parameters of inhibiting browning in differential pressure extrusion process includes the screening of composite color preservatives and the optimization of pre-drying temperature, emptying temperature and pumping time. In the first part, the browning law of muskmelon during pressure-differential expansion drying was studied. In the process of raw material pretreatment, enzymatic browning still occurred in the process of using single color protector, which was compared with fresh sample. The browning degree increased by 0.018, but the water content did not change significantly, and the total phenol content decreased by 2.69 mg / 100 g / 2) during the pre-drying period, both enzymatic and non-enzymatic browning occurred simultaneously. Compared with the color protection process, Water content decreased 64.75%, total phenol content decreased 3.64 mg / 100 g / 100 g / 100g HMP 5-HMF) relative content increased to 0.0122%, soluble protein relative content decreased 0.40%, reducing sugar relative content decreased 20.01% ~ 3%) the effect on browning was not significant in the soft stage. 4) the relative content of soluble protein decreased by 0.40%, and the relative content of reducing sugar decreased by 20.01%. Non-enzymatic browning occurred mainly. Compared with the softening process, the moisture content decreased from 29.30% to 4.02%, the sample recovered weak alkalinity, the content of phenols decreased 1.64 mg / 100 g, the relative content of reducing sugar decreased 16.24%, the relative content of soluble protein decreased 0.31% and 5-HMF reached 0.0211%. In the second part, the browning of the product was obviously reduced by the screening of color preservatives and the optimization of the process parameters. The optimized parameters are as follows: the composite inhibitor composed of 0.6% NaCl-0.15% CaCl2Ca-0.1% L- cysteine and 0.6% citric acid has the best inhibition effect on the browning of muskmelon during pre-drying, and the browning degree is reduced by 0.256%. By comparing the two groups of experiments, we found that The pH value of the experiment group was 1.56 lower than that of the control group, and the activities of polyphenol oxidase (PPO) and peroxidase (POD) were decreased by 2.2U/min mL-1 and 14.2 U/min mL-1, respectively, and the relative content of reducing sugar was 2.50% higher than that of the control group. Enzymatic browning during pre-drying, The Maillard reaction in pre-drying and puffing drying stage can reduce browning, and the predrying temperature and time are the most important factors in the predrying, followed by the extraction time, the pre-drying temperature, the pre-drying temperature, The optimized process parameters of orthogonal test are as follows: predrying temperature 70 鈩，

本文编号：1813074