【摘要】：黑蒜是新鮮大蒜通過控制溫度和濕度加工一段時間后形成的大蒜深加工產(chǎn)品。經(jīng)過加工后蒜瓣由白色變?yōu)楹诤稚?柔軟并富有彈性,去除了大蒜的辛辣味并增強了其生理活性。黑蒜起源于日本,其加工技術(shù)也來源于日本,需要發(fā)酵60~90天,工藝時間長,產(chǎn)品能耗高。目前,黑蒜生產(chǎn)工藝常采用變溫發(fā)酵方式,可以縮短加工時間,提高黑蒜產(chǎn)品的品質(zhì),節(jié)約能源。但由于工藝不同,造成不同黑蒜的含水量、還原糖等成分不同。大蒜中具有生理功能的成分主要是含硫化合物和多糖,其中多糖約占大蒜干重的75%以上。目前,對大蒜的研究主要集中在大蒜素、大蒜油等成分上,并取得了大量的研究成果。但對大蒜多糖的研究相對較少。新鮮大蒜中的糖主要為多糖,食用無甜的口感,經(jīng)過加工后黑蒜中低聚糖、還原糖含量明顯升高,賦予黑蒜甜味,這些糖的產(chǎn)生途徑未知,且食用加工后的黑蒜是否對便秘及腸道菌群產(chǎn)生影響鮮有報道。因此本研究比較了大蒜與黑蒜中成分差異,提取大蒜中性多糖并分析其結(jié)構(gòu),研究其酸水解規(guī)律及產(chǎn)物益生活性,并對黑蒜加工過程中多糖降解途徑進行探究,采用動物實驗的方式研究黑蒜對小鼠的潤腸通便功能及腸道菌群的影響,為進一步揭示黑蒜品質(zhì)形成機理,提高黑蒜品質(zhì),開發(fā)黑蒜功能具有十分重要的科學意義。主要研究結(jié)果如下:1.大蒜加工成黑蒜后營養(yǎng)成分發(fā)生了顯著變化。與大蒜相比,黑蒜中的含水量、脂肪等成分下降,有機酸、總酚、5-HMF含量顯著升高,特別是還原糖含量由0.46 g/100g升高至39.49 g/100g,升高了上百倍。而對18種游離氨基酸測定發(fā)現(xiàn)部分游離氨基酸含量下降,氨基酸總含量下降。2.大蒜粗多糖經(jīng)DEAE-52纖維柱純化后采用紅外光譜(FITR)分析、凝膠排阻色譜(GPC)分析其分子量、高效液相色譜(HPLC)分析其單糖組成發(fā)現(xiàn)大蒜中性多糖是具有不同聚合度的分散性多糖,其平均分子量為6569 Da,單糖組成為葡萄糖和果糖,摩爾質(zhì)量比為4:1。酸水解實驗發(fā)現(xiàn),底物濃度越低、pH越低、溫度越高,大蒜中性多糖水解速率越快。大蒜中性多糖水解動力學結(jié)果研究發(fā)現(xiàn)其未調(diào)節(jié)pH和pH=3的水解前期,大蒜中性多糖的水解遵循一級反應。3.大蒜中性多糖經(jīng)過酸水解、超濾后獲得大蒜低聚糖。經(jīng)過水解后的分子量明顯下降,低聚糖含量明顯升高,聚合度(DP)10的低聚糖含量由15%以下升高至75%以上。其中單糖含量在0.5%以下,低聚糖的平均分子量為1444 Da,平均聚合度約為8。與大蒜中性多糖相比,水解后的低聚糖抗人造胃液水解能力略低,但其能顯著促進四種乳酸菌的增殖,降低發(fā)酵液pH,具有更強的益生活性。4.通過單因素試驗及正交試驗確定黑蒜多糖的提取工藝為料水比1:12,提取溫度70℃,提取時間60 min。對大蒜和黑蒜中多糖分子量分布分析發(fā)現(xiàn)鮮蒜中的分子量范圍主要在1~15 kDa之間,其中平均分子量4 kDa以上的糖類約占總量的80%以上。而經(jīng)過加工以后,黑蒜中的糖類平均分子量均為2 kDa以下,其中1 kDa以下糖類約占90%以上。5.對黑蒜加工過程中多糖降解規(guī)律研究發(fā)現(xiàn):在黑蒜加工過程中多糖的降解大部分以高溫降解為主,幾乎沒有果聚糖酶的參與。多糖的分子量越來越小,且溫度越高,多糖降解越劇烈。對其動力學分析發(fā)現(xiàn)70~80℃下呈線性降解,85~90℃下曲線偏離線性關(guān)系,對其活化能計算得活化能為110.56 kJ·mol~(-1),前指因子A為3.12×10~(12) h~(-1)。6.動物實驗結(jié)果顯示黑蒜不會對小鼠的血液指標造成不良的影響。黑蒜對便秘模型小鼠具有良好的潤腸通便作用,能明顯提高便秘模型小鼠的小腸內(nèi)容物推進率、縮短首次排黑便時間、增加6 h內(nèi)排黑便粒數(shù)、重量及提高糞便含水量效果。黑蒜能夠改變腸道菌群結(jié)構(gòu),增加腸道菌群的豐度。在門水平上,黑蒜增加擬桿菌門、變形菌門比例,降低厚壁菌門比例,呈現(xiàn)偏向以擬桿菌門為主。在屬水平上對應的擬桿菌屬、擬普雷沃菌屬、阿克曼氏菌屬比例升高,乳酸菌屬、梭菌屬比例下降。黑蒜能夠促進丁酸含量顯著性增加,但不引起小鼠糞便中總短鏈脂肪酸含量的升高。
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圖片說明：低聚果糖的分子結(jié)構(gòu)
[Abstract]:The black garlic is the garlic deep-processing product formed after the fresh garlic is processed for a period of time by controlling the temperature and the humidity. After being processed, the garlic cloves are changed from white to black-brown, soft and elastic, and the pungent taste of the garlic is removed and the physiological activity of the garlic is enhanced. The black garlic originates from Japan, and its processing technology is also from Japan. It needs to be fermented for 60-90 days, the process time is long, and the energy consumption of the product is high. At present, the production process of the black garlic often adopts a temperature-changing fermentation mode, so that the processing time can be shortened, the quality of the black garlic product can be improved, and the energy can be saved. However, due to the different process, the water content, reducing sugar and other components of different black garlic are different. The essential components of the garlic are sulfur-containing compounds and polysaccharides, wherein the polysaccharide accounts for more than 75% of the dry weight of the garlic. At present, the research on garlic is mainly concentrated on the components of garlicin and garlic oil, and a lot of research results have been obtained. However, the research of the garlic polysaccharide is relatively low. The sugar in the fresh garlic is mainly the polysaccharide, and the sweet taste is consumed. After the processing, the sugar content of the oligosaccharide and the reducing sugar in the black garlic is obviously increased, the sweet taste of the black garlic is given, the production route of the sugar is unknown, and whether the black garlic after the edible processing has little influence on the constipation and the intestinal flora is rarely reported. In this study, the composition of garlic and black garlic was compared, the neutral polysaccharide of garlic was extracted and its structure was analyzed, the acid hydrolysis and product benefit of the garlic were studied, and the way of polysaccharide degradation during the processing of black garlic was studied. The effects of black garlic on the function of relaxing bowel and the intestinal flora in mice were studied by animal experiment. It is of great scientific significance to further reveal the formation mechanism of black garlic, improve the quality of black garlic and develop the function of black garlic. The main results are as follows:1. The nutritional components of garlic processed into black garlic have changed significantly. Compared with the garlic, the water content, fat and other components in the black garlic are reduced, and the content of the organic acid, the total phenol and the 5-HMF is increased obviously, in particular, the content of the reducing sugar is increased from 0.46 g/ 100g to 39.49 g/ 100g, and the content of the reducing sugar is increased by 100 times. The results showed that the content of free amino acids decreased and the total content of amino acids decreased in 18 free amino acids. The crude polysaccharide of garlic was purified by DEAE-52 fiber column. The molecular weight and high performance liquid chromatography (HPLC) of the crude polysaccharide of garlic were analyzed by means of infrared spectroscopy (FITR), and its molecular weight and high performance liquid chromatography (HPLC) were used to analyze its monosaccharide composition. It was found that the garlic-neutral polysaccharide was a dispersible polysaccharide with different degree of polymerization, with an average molecular weight of 6569 Da, The monosaccharide composition is glucose and fructose, and the molar mass ratio is 4:1. The acid hydrolysis experiments show that the lower the substrate concentration, the lower the pH, the higher the temperature, and the faster the hydrolysis rate of the garlic neutral polysaccharide. The results of the hydrolysis of the neutral polysaccharide of garlic found that the hydrolysis of the neutral polysaccharide of the garlic was followed by the first-order reaction in the pre-hydrolysis of the unadjusted pH and pH = 3. The garlic neutral polysaccharide is subjected to acid hydrolysis and ultrafiltration to obtain the garlic oligosaccharide. The molecular weight after hydrolysis is obviously reduced, the content of the oligosaccharide is obviously increased, and the oligosaccharide content of the degree of polymerization (DP)10 is increased from below 15% to more than 75%. Wherein the content of the monosaccharide is below 0.5%, the average molecular weight of the oligosaccharide is 1444 Da, and the average degree of polymerization is about 8. Compared with the garlic neutral polysaccharide, the hydrolysis ability of the hydrolyzed oligosaccharide is slightly lower than that of the artificial gastric juice, but can obviously promote the proliferation of the four kinds of lactic acid bacteria, reduce the pH of the fermentation liquid and have a stronger beneficial life. The extraction process of the black garlic polysaccharide was determined by single factor test and orthogonal test as the ratio of water to water of 1:12, the extraction temperature was 70 鈩，

本文編號：2510152