【作者】 乐碧云；

【导师】 刘成梅；

【作者基本信息】 南昌大学 ， 食品科学， 2010， 硕士

【摘要】 膳食纤维的颗粒大小、水化性质等与功能特性的发挥有着密切的联系,因而超微化作为膳食纤维的一种改性手段,对其生理功能的发挥和应用领域的拓宽具有积极的意义。本研究分别采用动态超高压微射流(DHPM)湿法处理(W-ODF样品)及超微干法粉碎(D-ODF样品)对豆渣膳食纤维(ODF)进行超微化处理,分析处理前后的豆渣膳食纤维理化特性的改变,研究并探讨超微化处理前后豆渣膳食纤维对小鼠肠道菌群的影响,以及在体外对胆固醇的吸附和在体内对血清胆固醇及甘油三酯水平的影响。研究结果如下：DHPM处理的条件为：料液比1：25,处理压力90MPa,处理一次,所得粒径约为260.2nm,干燥后最终粒径约为6.51±1.75μm。超微粉碎处理产品最终粒径约为7.27±2.04μm。以未超微化处理的豆渣膳食纤维(C-ODF)为对照组,超微化处理后D-ODF和W-ODF中可溶性膳食纤维(SDF)的含量均有所提高,分别提高了6.79%和11.69%,且可溶性膳食纤维与不可溶性膳食纤维(IDF)的比例分别提高了20.03%和56.22%。超微化处理使ODF结构变得疏松多孔,比表面积增大,与对照组C-ODF比表面积相比,W-ODF和D-ODF的比表面积分别提高了42.83%和21.70%。D-ODF和W-ODF的膨胀力及持水力均得到改善,尤其是W-ODF的膨胀力由6.53mL/g升高至14.63mL/g(P<0.01),持水力由9.32g/g升高至23.94g/g(P<0.01)。与C-ODF相比,D-ODF及W-ODF能够更为明显的抑制小鼠的进食欲,并降低体重的增长速率。各组小鼠盲肠内容物中的pH值均有所下降,粪便及盲肠内容物含水量得到提高。但由于各组ODF处理方式的不同导致理化性质的差异,其作用效果也明显不同,实验表明,W-ODF的效果均较其他两组更为优异。ODF能够提高小鼠粪便中大肠杆菌的菌群数量,且能够抑制盲肠中大肠杆菌的增殖,其中高剂量的W-ODF均有更为明显的作用(从7.77±0.06降至5.52±0.00log10 CFU/g)。同时,乳酸杆菌、双歧杆菌随粪便排出的量也增加。在灌胃28天后,各实验组盲肠内容物中乳酸杆菌的菌群数均得到提高,但停止灌胃后,低剂量组基本开始回落,而高剂量组则持续上升,其中灌胃高剂量的W-ODF组即(W2组)上升最快；各实验组中,灌胃28天后盲肠内容物中的双歧杆菌菌群数得到提高,但各组组内均无显著差异,其中低剂量的D-ODF组(即D1组)盲肠中双歧杆菌增殖较其他组快(从8.30±0.22升高至9.77±0.03 log10 CFU/g)。灌胃停止后,各组双歧杆菌菌群数均开始回落。体外胆固醇吸附实验中,C-ODF、D-ODF及W-ODF均在用量为0.1g,胆固醇浓度为0.1mg/mL,吸附时间为90min时,吸附效果最好。实验证明,D-ODF及W-ODF对胆固醇体外吸附显著优于C-ODF,而W-ODF效果为最佳。在小鼠体内实验中,灌胃28天后高、低剂量的D-ODF均能降低血清中的TC水平,各灌胃组HDL-C水平及HDL-C/TC比值均较灌胃前提高,其中灌胃高、低剂量W-ODF的小鼠血清HDL-C/TC比值在灌胃28天后显著高于其他组。与灌胃前相比,低剂量的D-ODF和W-ODF组(即D1组和W1组)中的TG水平分别降低了14.67%和29.23%；高剂量的C-ODF、D-ODF和W-ODF组(即C2组、D2组和W2组)分别降低了14.67%、27.54%和29.33%。更多还原

【Abstract】 The particle size and hydration properties of dietary fiber are closely related to its functional properties, so as a modification method, the micronization treatment might play an important role in the physiological functions and application of dietary fiber.In the present study, okara dietary fiber (ODF) was micronized with wet granulating method by dynamic high pressure microfluidization (DHPM) (W-ODF sample) and with dry grinding method by ultra-micro pulverizer (D-ODF sample) respectively, and then the physical and chemical properties before and after treated were determined. And the effect of ODF to microflora populations in the cecum, cholesterol absorption capacity in vitro, and the levels of serum cholesterol and triglyceride in vivo were measured. The results were as follows:The conditions for DHPM were as follows:ratio of liquid to ODF was 1:25, treatment pressure was 90MPa for one cycle. The particle size was about 260.2nm, and after drying it was about 6.51±1.75μm. The particle size of sample treated by ultra-micro pulverizer was about 7.27±2.04μm. As the ODF before micronization treatment (C-ODF) was control, after micronization treatment, the content of soluble dietary fiber (SDF) was increased 6.79% in D-ODF and 11.69% in W-ODF, and the ratio of SDF to insoluble dietary fiber (IDF) was increased by 20.03% in D-ODF and 56.22% in W-ODF, respectively. Micronization treatment made the structure of ODF be loose and porous, and the specific surface area was increased. Compared with control group, the specific surface area was increased by 42.38% in W-ODF and 21.70% in D-ODF. Swell capacities and water holding capacities of D-ODF and W-ODF were also enhanced. Especially in W-ODF, swell capacity were increased from 6.53mL/g to 14.63mL/g(P<0.01), and water holding capacity increased from 9.32g/g to 23.94g/g(P<0.01).Compared with C-ODF, D-ODF and W-ODF could decreased the appetite and body weight growth rate of mice more obviously. The pH value of all groups decreased, and the moisture content of both feces and cecal contents were increased. But different treatment methods could lead to differences in physical and chemical properties, finally result in different functional effects, and the study indicated that the effect of W-ODF was superior to other two groups.The intake of ODF not only increased the counts of fecal E.coli, but also inhibited its proliferation in cecum, and effects of low doses W-ODF were more obvious (decreased from 7.77±0.06 to 5.52±0.00 log10 CFU/g). Meanwhile, the counts of lactobacilli and bifidobacterium excreted in the feces were also increased. After feeding for 28 days, lactobacilli counts in cecum were increased in all groups. After termination of feeding, lactobacilli counts in cecum of low dose groups were decreased, but high dose groups kept rising, especially in group W2. Bifidobacterium counts in cecum were increased with no significant difference in every group after feeding for 28 days, and in group D1 the proliferation was more quickly than other groups (increased from 8.30±0.22 to 9.77±0.03 log10 CFU/g). After termination of feeding, the counts of bifidobacterium in cecum were declined in all groups.In vitro experiments of cholesterol absorption, the optimized conditions of absorption were that C-ODF, D-ODF and W-ODF were respectively in the amount of 0.1g, cholesterol concentration was 0.1mg/mL, the absorption time was 90min. The results showed that cholesterol absorption capacities of D-ODF and W-ODF in vitro were better than C-ODF, and W-ODF was the best. In vivo, after feeding for 28 days both high and low doses of D-ODF decreased the levels of serum TC, and the HDL-C levels and HDL-C/TC ratio in all groups were improved compared to before feeding. The HDL-C/TC ratios in the groups which fed with high and low doses of W-ODF, were significantly higher than other groups after feeding for 28 days. Compared with feeding for 0 day, the levels of TG in group D1 and group W1 were decreased by 14.67% and 29.23%, respectively; and in the high dose group, the levels of TG in group C2, group D2 and Group W2 were decreased by 14.67%,27.54% and 29.33%, respectively.更多还原