本文選題：網(wǎng)紋甜瓜 + 壓差膨化干燥��； 參考：《沈陽農(nóng)業(yè)大學(xué)》2017年碩士論文

【摘要】：網(wǎng)紋甜瓜是葫蘆科甜瓜屬的一種變異類型,屬于厚皮甜瓜的一種,因其果皮表面帶有網(wǎng)狀裂紋,所以稱為網(wǎng)紋甜瓜。網(wǎng)紋甜瓜因其獨特美麗的外觀和特有的芳香以及優(yōu)良的風(fēng)味口感,受到了廣大消費者的喜愛。但因其果實中糖含量較高,同時含有兒茶素、表兒茶素等酚類物質(zhì),所以加工中易發(fā)生酶促褐變和非酶褐變,嚴(yán)重影響產(chǎn)品的品質(zhì),限制了網(wǎng)紋甜瓜的工業(yè)產(chǎn)業(yè)化發(fā)展。本試驗通過對網(wǎng)紋甜瓜壓差膨化干燥過程中褐變規(guī)律及壓差膨化加工中抑制褐變工藝參數(shù)的研究,為網(wǎng)紋甜瓜的加工提供理論依據(jù)。本文研究的主要內(nèi)容包括網(wǎng)紋甜瓜壓差膨化干燥過程中褐變規(guī)律、壓差膨化加工中抑制褐變工藝參數(shù)的優(yōu)化兩大部分。壓差膨化加工中抑制褐變工藝參數(shù)的控制包括復(fù)合護色劑的篩選以及預(yù)干燥溫度、抽空溫度、抽空時間的優(yōu)化。第一部分研究了網(wǎng)紋甜瓜壓差膨化干燥過程中褐變規(guī)律。(1)在原料預(yù)處理過程中,使用單一護色劑護色過程中產(chǎn)品仍然發(fā)生酶促褐變,同鮮樣相比,褐變度上升0.018,含水量變化不顯著,總酚含量下降了 2.69mg/100g;(2)預(yù)干燥階段同時發(fā)生了酶促和非酶褐變。同護色過程相比,含水率下降64.75%,總酚含量下降3.64mg/100g,5-羥甲基糠醛(5-HMF)相對含量上升至0.0122%,可溶性蛋白相對含量下降了 0.40%,還原糖相對含量下降了 20.01%;(3)回軟階段對褐變影響不顯著。(4)膨化階段主要發(fā)生了非酶褐變。同回軟過程相比,含水率從29.30%下降至4.02%,樣品恢復(fù)了弱堿性,酚物質(zhì)含量下降1.64mg/100g,還原糖相對含量下降16.24%,可溶性蛋白相對含量下降了 0.31%,5-HMF相對含量達到0.0211%。第二部分通過護色劑的篩選和變溫壓差膨化干燥過程工藝參數(shù)的優(yōu)化明顯降低了產(chǎn)品的褐變。得到的具體優(yōu)化參數(shù)如下:由0.6%的NaCl、0.15%的CaCl2、0.1%的L-半胱氨酸和0.6%的檸檬酸組成的復(fù)合抑制劑對網(wǎng)紋甜瓜預(yù)干燥階段褐變的抑制效果最好,褐變度降低了 0.256。通過對比兩組試驗發(fā)現(xiàn),試驗組護色后的pH值比對照組低1.56,多酚氧化酶(PPO)和過氧化物酶(POD)活性分別比優(yōu)化前下降2.2U/min·mL-1和14.2 U/min·mL-1,還原糖的相對含量比對照組高2.50%,說明添加該復(fù)合護色劑可以抑制預(yù)干燥階段的酶促褐變、預(yù)干燥和膨化干燥階段的美拉德反應(yīng),減少褐變的發(fā)生;膨化干燥中預(yù)干燥溫度、抽空溫度、抽空時間三個因素,抽空溫度影響最大,其次是抽空時間、預(yù)干燥溫度,正交試驗優(yōu)化后的工藝參數(shù)為:預(yù)干燥溫度70℃,抽空溫度70℃,抽空時間150 min。優(yōu)化后,最終褐變度為0.775,相比優(yōu)化前下降了 20.51%,5-HMF相對含量比優(yōu)化前低0.0036%,說明優(yōu)化條件后抑制了 5-HMF生成類黑素等有色物質(zhì)的過程,即美拉德反應(yīng)的第三階段,改善了膨化階段的變色程度。優(yōu)化工藝后,產(chǎn)品的硬度為412g、脆度值為4、含水率為4.02%、紅度a*為11.39,產(chǎn)品品質(zhì)優(yōu)異。
[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，

本文編號：1813074