【作者】 乐胜锋；

【导师】 曹学丽；

【作者基本信息】 北京工商大学 ， 生物化工， 2010， 硕士

【摘要】 膳食纤维作为“第七营养素”越来越受到人们的重视,人们已利用各种天然原料来生产膳食纤维,而苹果渣就是一种良好的膳食纤维原料来源。本文使用酶法和化学法两种工艺制备膳食纤维,并对产品的理化性质及内在结构、功能特性三者之间内在联系方面进行有意义的探索,考察工艺对产品性能所产生的影响。原苹果渣的主要组成:蛋白质5.97%、淀粉5.27%、脂肪12.5%、总膳食纤维(Total Dietary Fibre, TDF)72.13%、可溶性膳食纤维(Solubal Dietary Fibre, SDF)13.06、不可溶性膳食纤维(Insolubal Dietary Fiber, IDF)57.51%、水分3.27%和灰分2.17%。使用酶法和化学法提取果渣中的膳食纤维。酶法提取的最优工艺是纤维素酶加酶量为8%,温度50℃,提取时间为3h,pH为4.8,料液比为1:20,ESDF提取率为15.93%,EIDF提取率为63.4%。化学法采用酸碱法,最优条件是调节pH值为1、温度90℃、时间70min、料液比1:20,使用碱法对酸提后的残渣提取,最优条件为NaOH浓度为0.8%、温度70℃、反应时间90min、料液比1:8,最终得到ACSDF23.4%、ALSDF13.5%、IDFA7.43%、IDFB51.8%。并且在研究中发现冷冻干燥制得的产品的性能要好于真空干燥的产品,高效凝胶色谱测得ESDF、ACSDF、ALSDF的相对分子质量分布集中在12780~159300、23310~815000、259600~554500。化学法得到的产品的持水力、膨胀力都优于酶法;化学法中碱提部分具有相对较强的阳离子交换作用。但是两者的阳离子交换能力差异不大。酶法产品对胆酸酸的吸附效果要比化学法产品的吸附效果好,各部分吸附量为ESDF为50.29mg/g,ACSDF为35.43 mg/g,ALSDF为48 mg/g,EIDF为55.43mg/g,IDFA为25.71 mg/g,IDFB为35.42 mg/g。化学试剂的作用减弱了膳食纤维对胆酸钠的吸附能力。ESDF、ACSDF、ALSDF三种可溶性膳食纤维的溶解度在常温下很低,分别为16.2%、12.7%、42.9%,溶解度随温度的增大而增大,ALSDF在高温时溶解良好。各种SDF在pH 2.0下的粘度要小于pH 7.0的;浓度5%的SDF溶液粘度要高于2.5%和1.2%的粘度。在模拟肠胃蠕动的低速运动中呈现出非牛顿流体的特性。ALSDF给溶液体系带来的粘度改变最大,并通过分子量结果得以验证。膳食纤维的纤维素非定型区发生了降解,且化学试剂的作用程度比酶法要高;化学法制备的不溶性膳食纤维超微结构具有比酶法的更多的空腔和孔隙,根据前述结论推断此种结构有利于保持更多的水分。而可溶性部分结构均呈片状结构。两种方法处理后粒径减小。两种方法得到的产品均有多糖的特征吸收峰,EIDF含内α-吡喃糖,EIDF含有β-吡喃糖,碱法虽然得率高,但是碱处理造成了分子间氢键和分子内氢键发生了变化,此外对其中的羰基产生了影响。酶法制备的ESDF含有对产品的单糖组分分析表明,各产品主要成分是纤维素,包括可溶和不可溶。同时,结果还显示酶法水解没有化学法彻底,化学法能富集到更多半纤维素成分。ESDF中主要含有葡萄糖、阿拉伯糖和半乳糖三类单糖组成,其摩尔比为1.6:1.9:1;ACSDF主要单糖组成是葡萄糖;ALSDF主要单糖组成是葡萄糖和少量的阿拉伯糖、木糖和半乳糖,其摩尔比2.2:1.1:1:1;而EIDF中主要含有葡萄糖和少量的鼠李糖和半乳糖,其摩尔比为5.9:1.6:1;IDFA主要单糖组成为葡萄糖、鼠李糖、木糖和半乳糖,其摩尔比为3.7:1:2:1.2;IDFB主要单糖组成为葡萄糖,还包括少量的阿拉伯糖、木糖、半乳糖,其摩尔比为5.5:1:1.2:1.3。更多还原

【Abstract】 Increasing attention has been given to dietary fibre as the seventh of nutrients. A variety of natural raw materials from different sources have been used to preparation of dietary fibre. Dried apple pomace, a fruit industry by-product, is considered as a potential source of raw materials, which has not been fully utilized. This objective of the present study was to prepare dietary fibres with good properties by enzymatic and chemical method, and to characterize the dietary fibre physicochemically, and to study the influence of processing to its structure, functional properties.The content of apple pomace included 5.97% protein, 5.27% starch, 12.5% fat, 72.13% total dietary fiber (TDF), 13.06% soluble dietary fiber (SDF), 57.51% insoluble dietary fiber (IDF), 3.27% moisture and 2.17% ash.The process of extracting dietary fibre using enzymatic and chemical methods precipitation from apple pomace was studied. The optimal conditions of enzymatic precipition were gained by orthogonal test were as follows: the cellulose addition 8%, temperature 50℃, hydrolyzing time 3h, pH 4.8, solid to liquid ratio of 1:20, the yield of ESDF was 15.93%, 63.4% EIDF was recovered as the same time. In the process of chemical hydrolysis, the apple pomace was treated by hydrochloric solution at first, the parameters of acid hydrolysis was pH 1, extraction time of 70 min, extraction temperature of 90℃, the solid to liquid ratio of 1:20. The ACSDF yield was up to 23.4% under this condition. Then,the residue was hydrolysed by the alkaline solution under the optimal conditions for the NaOH concentration 0.8%, temperature 70℃, reaction time of 90min, the solid to liquid ratio of 1:8, 13.5% ALSDF was recovered as well as 7.43% IDFA, 51.8% IDFB. And it was observed that freeze-dried products have a better performance than the vacuum drying of products in the study. GPC data indicates that the relative molecular mass distribution of ESDF, ACSDF, ALSDF concentrates in the region of 12780 ~ 159300, 23310 ~ 815000,259600 ~ 554500.The water-holding capacites of dietary fibre extracted from apple pomace by chemical method is superior to the capacites of products by enzymatic method, as well as swelling capacities. Although the difference of the cation exchange capacity of products between two methods was less, the portion extracted by alkaline solution has a relatively high cation exchange capacity. Enzymatic-hydrolysis products on the adsorption of bile acids is much higher than that of chemical method. The adsorption of ESDF, ACSDF, ALSDF, EIDF,IDFA and IDFB were 50.29 mg/g, 35.43 mg/g, 48 mg/g, 55.43 mg/g, 25.71 mg/g, 35.42 mg/g, respectively. The adsorption of bile acids of dietary fibre was weakened by the role of chemicals. The solubility of ESDF, ACSDF and ALSDF is very low at room temperature, respectively, 16.2%, 12.7%, 42.9%. The solubility can increase with temperature, and ALSDF represent a good dissolved state at high temperature. Every kinds of SDF has a lower viscosity in the pH 2.0 than that in pH 7.0. The viscosity of 5% SDF solution is higher than that of 2.5% and 1.2%. Non-Newtonian fluid characteristics is observed in the test of gastrointestinal motility simulation at a low-speed movement. The contribution by ALSDF to change the viscosity of the solution system is the biggest, and the results can be verified by molecular weight.Cellulose degradation of the dietary fibre occurred in non-stereotypical areas, and the role of chemical reagents is higher than that of enzymatic processing. In the aspect of ultrastructure. Insoluble dietary fiber by chemical method have more cavity and porosity than that by enzymic method. According to these findings, such structure is conducive to holding more water. Soluble dietary fibres had the same ultrastructure and repersented a flake.IR specstrums showed the characteristic absorption peak of polysaccharides of all products by two methods, EIDF within theα-pyranose containing, EIDF containingβ-pyranose, although the high yield of alkaline method, but alkaline treatment resulted in intramolecular hydrogen bonds and hydrogen bonding changes, In addition,it had an impac to the carbonyl. Monosaccharide composition analysis of the products shows that the main ingredient of both of soluble and insoluble portions was cellulose. Meanwhile, the results also show that there was no chemical method and complete enzymatic hydrolysis, chemical method can be enriched to more hemicellulose components.The monosaccharide composition of ESDF was mainly composed of glucose, arabinose and galactose in the molar ratio of 1.6:1.9:1; the major composition of ACSDF was glucose; ALSDF was rich in monosaccharide compositions of glucose and small amounts of arabinose, xylose and galactose in a molar ratio 2.2:1.1:1:1; EIDF was mainly composed of glucose and small amounts of rhamnose and galactose in the molar ratio of 5.9:1.6:1; IDFA was consisted of glucose, rhamnose, xylose and galactose in the molar ratio of 3.7:1:2:1.2; glucose was the most abundant monosaccharide in IDFB, but also small amounts of arabinose, xylose, galactose in the molar ratio of 5.5:1: 1.2:1.3.更多还原