In vitro fermentation of different types of α-amylase resistant corn starches

α -amylase resistant corn starches were in vitro fermented (72 h) using cecal content of rat as inoculum. Resistant starches were prepared from native (NCS), retrograded (RS_A ), and retrograded and boiled (RS_B ) corn starch by treatment with α-amylase to remove digestible starch. Short-chain fatty acid (SCFA) production, molar ratios (acetate: propionate: butyrate), fermentability with respect to lactulose and dry matter disappearance were measured. SCFA production was significantly correlated with non-fermented residue (P <0.001). The three starches showed a similar fermentability, although the rate of SCFA production and disappearance of substrate were slower for retrograded starches. NCS was fermented early while RS_A and RS_B prolonged their degradation to 72 h. There were slight differences in the molar ratios of acetate, propionate and butyrate. Structural changes in the materials were observed by scanning electron microscopy (SEM). In summary, commonly utilised domestic cooking and technological treatments modified the in vitro fermentative characteristics of resistant corn starches probably due to structural changes. Received: 15 November 1999 / Revised version: 27 January 2000     

Production of short-chain fatty acids from resistant starch in a pig model

This study was performed to estimate the pool of SCFA produced in the digestive tract of growing pigs after the consumption of diets containing dif-ferent sources of resistant starch (RS) (15 g per meal) (potato starch (PoS), high amylose maize starch (HS) and retrograded extruded HS (RHS)). SCFA production in vitro was respectively 19, 23 and 21 mmol g⁻¹ of fermented PoS, HS and RHS. The highest butyric acid production was observed with PoS. Fifty six, 36 and 19% respectively of ingested PoS, HS and RHS escaped digestion in the small intestine, whereas residual starch was completely fermented in the large bowel. Luminal total SCFA in the caeco-colon 7 h after the experimental meal were respectively 33, 78 and 105 mmol for PoS, HS and RHS, with PoS providing the highest production of butyric acid. Theoretical in vivo SCFA production, calculated on the basis of results for in vitro fermentation and ileal digestibility, differed from in vivo results for PoS (+65%) and HS (-13%), but not for RHS. This study reveals different rates of disappearance of RS both in vitro and in vivo. © 1998 SCI.     

中性大蒜果聚糖体外发酵产短链脂肪酸

大蒜果聚糖是大蒜深加工后废弃蒜渣中的主要成分,不能被人体消化利用,可选择性增殖肠道益生菌,具有开发成新型益生元的潜力。体外发酵产短链脂肪酸的分析对进一步评价大蒜果聚糖对肠道微生态的影响有重要意义。方法:本研究通过体外模拟人体肠道系统的pH、温度和营养条件,接种人体新鲜粪便悬浮液进行间歇式静态厌氧培养,采用高效液相色谱法(HPLC)分析不同聚合度(平均DP为11、16、21)的中性大蒜果聚糖为唯一碳源,培养0、4、8、12、24 h产短链脂肪酸的情况。结果:发酵12 h时短链脂肪酸浓度达到最高,之后便开始下降。其中样a(平均DP为11)的发酵液中总SCFA浓度最高,达86.38μmol/mL。总短链脂肪酸产量为样a(DP 11)>样b(DP16)>样c(DP 21)。24 h时,各发酵液的短链脂肪酸中丁酸和乳酸的比例较乙酸和丙酸高。结论:大蒜果聚糖能被人体肠道微生物发酵利用在体外产短链脂肪酸。其中丁酸和乳酸的摩尔浓度较乙酸和丙酸高。聚合度低的大蒜果聚糖产酸高于聚合度高的果聚糖。     

In vitro faecal fermentation outcomes and microbiota shifts of resistant starch spherulites

In the present study, we prepared A- and B-type polymorph-resistant starch spherulites (RSSs) with a wide range of crystallinity, and elucidated the relation between crystalline structure and faecal microbial fermentation outcomes. A- and B-type polymorphic RSSs displayed similar fermentation rate throughout entire process with final gas production of 11.8–13.2 mL, suggesting that the crystalline pattern and crystallinity cannot effectively control the fermentation rate of starches. The acetate and butyrate concentration of A-type RSS decreased with the increase of crystallinity respectively, and highly crystalline B-type RSS reduced the production of acetate (8.4 mM) and propionate (2.1 mM). RSSs with different crystalline types showed similar microbial community structure but distinct key bacteria species. A-type RSSs greatly promoted the abundance of butyrogenic bacteria (i.e., Roseburia faecis and Lachnospiraceae), whereas B-type RSSs tended to proliferate Prevotella copri associated with propionate production. Our findings shed new light on design and manufacture of starch-based functional ingredients with enhanced gut health.     

Effects of goat milk enriched with oligosaccharides on microbiota structures,and correlation between microbiota and short-chain fatty acids in the large intestine of the mouse

In this study, we explored the effects of combining goat milk and oligosaccharides on the large intestine environment of mice. A combination of goat milk with each of 3 oligosaccharides—stachyose, fructo-oligosaccharide (FOS), and a prebiotics mix—were independently fed to mice. We investigated composition changes in the microbiota of the large intestine using 16S rRNA gene sequencing; measured short-chain fatty acid content using gas chromatography–mass spectrometry; and performed a Spearman correlation analysis between microorganisms and short-chain fatty acids. Our results showed that microbial diversity in the large intestine decreased significantly in the FOS group. In terms of α diversity, microbial richness significantly declined in all 3 treatment groups; in terms of β diversity, the intestinal microbial structures clearly changed in the FOS group. The abundance of Bifidobacterium and Lactobacillus increased markedly in the FOS group compared with the other groups. Functional predictions showed that FOS reduced intestinal bacterial infections and improved the endocrine and immune systems. Spearman correlation analysis showed that propionic, isobutyric, and valeric acids were all positively correlated with certain microbiota. Our findings suggest that FOS-enriched goat milk is beneficial for improving the large intestine environment in the host.     

三种粗粮粉体外调节肠道菌群的作用研究

通过在体外模拟构建消化和发酵体系,研究不同来源的三种麸皮(小麦麸皮、黑小麦麸皮和燕麦麸皮)配制成的粗粮粉对肠道菌群调节作用的影响。采用高通量测序技术16S rRNA对肠道菌群的多样性和组成进行分析,结果表明,粗粮粉发酵后微生物多样性降低,肠道菌群组成发生了较大变化,拟杆菌门比例下降,厚壁菌门比例升高,代谢产生的短链脂肪酸含量显著增多(p<0.05);其中,燕麦粗粮粉促进双歧杆菌体外增殖的效果优于其他两组粗粮粉,分别是小麦粗粮粉和黑小麦粗粮粉的1.45和2.14倍。本研究为调制加工性能好、保健价值高的粗粮粉配方提供了理论依据。     

甘薯交联抗性淀粉热力学性质与消化性研究

根据膨胀度、糊化度及差示扫描量热仪(DSC)测得热力学参数,综合分析甘薯交联抗性淀粉和原淀粉热力学性质,并采用Jenkins提出In–vitro模型测定淀粉体外消化性。结果表明:在同一温度下,甘薯交联抗性淀粉膨胀度和糊化度均较原淀粉低,且交联剂用量越高,淀粉膨胀度和糊化度越小;DSC测试结果显示,甘薯交联抗性淀粉相转变温度To、Tp、Tc随交联剂用量增加而升高,Tc–To和△H均比原淀粉低。In–vitro消化模拟实验表明,甘薯交联抗性淀粉消化性比原淀粉低,并随交联剂含量增加,消化产物量减少,消化速度降低。     

In vitro batch fecal fermentation comparison of gas and short-chain fatty acid production using "slowly fermentable" dietary fibers

Abstract: Sustained colonic fermentation supplies beneficial fermentative by‐products to the distal colon, which is particularly prone to intestinal ailments. Blunted/delayed initial fermentation may also lead to less bloating. Previously, we reported that starch‐entrapped alginate‐based microspheres act as a slowly fermenting dietary fiber. This material was used in the present study to provide a benchmark to compare to other “slowly fermentable” fibers. Dietary fibers with previous reports of slow fermentation, namely, long‐chain inulin, psyllium, alkali‐soluble corn bran arabinoxylan, and long‐chain β‐glucan, as well as starch‐entrapped microspheres were subjected to in vitro upper gastrointestinal digestion and human fecal fermentation and measured over 48 h for pH, gas, and short‐chain fatty acids (SCFA). The resistant fraction of cooked and cooled potato starch was used as another form of fermentable starch and fructooligosaccharides (FOS) served as a fast fermenting control. Corn bran arabinoxylan and long‐chain β‐glucan initially appeared slower fermenting with comparatively low gas and SCFA production, but later fermented rapidly with little remaining in the final half of the fermentation period. Long‐chain inulin and psyllium had slow and moderate, but incomplete, fermentation. The resistant fraction of cooked and cooled potato starch fermented rapidly and appeared similar to FOS. In conclusion, compared to the benchmark slowly fermentable starch‐entrapped microspheres, a number of the purported slowly fermentable fibers fermented fairly rapidly overall and, of this group, only the starch‐entrapped microspheres appreciably fermented in the second half of the fermentation period. Practical Application: Consumption of dietary fibers, particularly commercial prebiotics, leads to uncomfortable feelings of bloating and flatulence due to their rapid degradation in our large intestine. This article employs claimed potential slowly fermenting fibers and compares their fermentation rates with a benchmark slow fermenting fiber that we fabricated in an in vitro simulation of the human digestive system. Results show a variety of fermentation profiles only some of which have slow and extended rate of fermentation.     

抗性淀粉的体外产酸发酵研究

分别采用健康成人和健康婴儿的新鲜粪便提取液,在模拟大肠环境下(厌氧,37℃),作用于不同含量的抗性淀粉,发酵不同时间,采用气相色谱法测定不同发酵时间的发酵产物中短链脂肪酸的含量。分析结果表明,对于2种不同的粪便提取液,随着发酵时间的延长和抗性淀粉含量的增加,发酵产物中短链脂肪酸的总含量均逐渐增加,特别是丁酸含量增加显著;但在婴儿粪便提取液的发酵产物中,短链脂肪酸的含量,尤其是丁酸的含量,显著高于成人粪便提取液的发酵产物。     

基于体外模拟肠道微生态体系比较不同果蔬全粉的益生元功效

体外模拟肠道系统逐渐成为研究肠道菌群及其代谢产物的一种操作简便、重现性好的方法。本研究通过建立体外模拟肠道微生态体系,对丝瓜、桑葚、枸杞和香菇冻干粉的益生元功效展开研究。结果表明,经24 h体外发酵后,丝瓜冻干粉对乳酸杆菌属、普氏菌属、拟杆菌属数量和丙酸产量增加的促进作用显著高于其它果蔬组,桑葚对双歧杆菌数量和乙酸产量增加的促进作用显著高于其它果蔬组。以上结果说明基于体外模拟肠道微生态体系,丝瓜和桑葚冻干全粉均具有较为显著的益生元功效。     

Fermentation of resistant food starches by human and rat intestinal bacteria

Resistant starches prepared from maize and peas were fermented in vitro with rat or human intestinal bacteria. With both inoculum types, degradation of pea starch after 24 h incubation (0 and 47% utilised by rat and human organisms, respectively) was markedly slower than that of maize starch (73 and 85%) and was incomplete even after 7 days' incubation; degradation of both starches was slower than with soluble starch or sucrose. The slow degradation of pea starch was not due to the presence of intact cell walls. Qualitatively, the production of C2-C4 volatile fatty acids was similar for all substrates and both inoculum types but there were some quantitative differences. If resistant food starches are to be regarded as dietary fibre, then, like ‘true’ fibre, any physiological effect in vivo may depend on the type of starch involved.     

Different concentrations of grape seed extract affect in vitro starch fermentation by porcine small and large intestinal inocula

BACKGROUND: Grape seed extract (GSE) phenolics have potential health‐promoting properties, either from compounds present within the extract, or metabolites resulting from gastrointestinal tract (GIT) fermentation of these compounds. This study describes how GSE affected the kinetics and end‐products of starch fermentation in vitro using pig intestinal and fecal inocula. Six GSE concentrations (0, 60, 125, 250, 500, and 750 µg ml^?1 were fermented in vitro by porcine ileal and fecal microbiota using starch as the energy source. Cumulative gas production, and end‐point short chain fatty acids and ammonia were measured. RESULTS: GSE phenolics altered the pattern (gas kinetics, and end‐products such as SCFA and NH ) of starch fermentation by both inocula, at concentrations above 250 µg ml^?1. Below this level, neither inoculum showed any significant (P > 0.05) effect of the GSE. CONCLUSION: The results show that GSE phenolics at a concentration over 250 µg ml^?1 can have measurable effects on microbial activity in an in vitro fermentation system, as evidenced by the changes in kinetics and end‐products from starch fermentation. This suggests that fermentation patterns could be conceivably shifted in the actual GIT, though further evidence will be required from in vivo studies. Copyright © 2012 Society of Chemical Industry     

掺入外源淀粉的魔芋豆腐体外消化和发酵性能研究

通过体外模拟口腔、胃、小肠消化,探讨掺入淀粉的魔芋豆腐体外消化性能,并将消化后的剩余部分作为小鼠盲肠内容物体外发酵底物,研究其在盲肠中的发酵性能。结果表明,纯魔芋豆腐在口腔、胃、小肠中均不被消化,掺入魔芋豆腐中的淀粉从口腔开始被水解,在胃部不被水解,进入小肠后20 min内即可完成大部分水解,但与纯淀粉相比,掺入魔芋豆腐中的淀粉的快消化淀粉含量减少,总水解率无显著变化,说明脱乙酰基魔芋葡甘聚糖可延缓淀粉消化,但不能阻止淀粉消化。体外模拟盲肠发酵过程中,掺入淀粉的魔芋豆腐降低pH值的能力高于纯魔芋豆腐,但前者生成的短链脂肪酸及发酵24 h后乳酸菌含量少于后者。综上表明,食用掺入淀粉的魔芋豆腐相较纯魔芋豆腐会快速升高血糖和降低魔芋豆腐的肠道益生作用。     

高链玉米淀粉-不饱和脂肪酸复合物的体外大肠发酵特性及其对肠道菌群的影响规律

该研究以高直链玉米淀粉（High-Amylose Maize Starch,HAMS）与四种饱和度不同的脂肪酸为原料,制备淀粉-不饱和脂肪酸复合物,研究不同复合物体外大肠发酵特性及菌群调控的影响。结果表明,随着脂肪酸不饱和度的增加,除淀粉-油酸复合物（34.87%）外,形成的复合物V型结晶越少（30.42%~32.93%）。淀粉-不饱和脂肪酸复合物在整个发酵过程中发酵速率无显著性差异（p>0.05）,最终产气量基本一致（13.8~14.2 mL）。淀粉-不饱和脂肪酸复合物产丁酸浓度（14.83~17.91 mmol/L）低于HAMS （22.42 mmol/L）,但产较多乙酸（60.25~63.73 mmol/L）和丙酸（21.22~24.81 mmol/L）。淀粉-不饱和脂肪酸复合物均能显著促进Prevotella的相对丰度,这与其较高的丙酸产量有关。综上,淀粉-不饱和脂肪酸复合物大肠发酵特性受脂肪酸饱和度的影响较小,主要与淀粉-脂质复合物自身结构有关,复合物中脂肪酸的饱和度对高链玉米淀粉-不饱和脂肪酸复合物菌群结构具有一定影响。     

气相色谱-质谱法测定酵素产品中短链脂肪酸

建立了用气相色谱-质谱法（GC-MS）测定酵素样品中5种短链脂肪酸（SCFA）的定性定量方法。结果表明,该方法可以有效分离测定酵素样品中5种SCFA,该方法检出限低（0.030～0.100 mg/kg）,加标回收率80.1%～110.6%,相对标准偏差（RSD）1.36%～10.0%。用该方法分析37种酵素样品中SCFA,结果表明,86.5%的酵素产品检出乙酸（1.02～36.1 g/kg）,仅有一种酵素产品检出丁酸（含量为0.056 g/kg）,其余均未检出。该方法适用于酵素产品中短链脂肪酸的检测。     

低分子量硫酸软骨素体外酵解特征及其对肠道菌群的调节作用

硫酸软骨素（Chondroitinsulfate,CS）具有调节肠道微生物的作用,但不同分子量对其益生活性的影响鲜有报道。该研究比较了硫酸软骨素（80 ku）及其光催化降解产物（Low Molecular Weight Chondroitin Sulfate,LWCS,4 ku）体外酵解特征及其对肠道代谢物的影响。通过化学法、气相色谱质谱联用、高通量测序等方法测定了不同时间发酵液中p H值、CS和LWCS含量、还原糖含量、短链脂肪酸浓度以及肠道微生物的变化。结果显示,在发酵48 h内,CS、LWCS以及还原糖含量均显著降低（P<0.05）,说明肠道微生物能够降解利用硫酸软骨素及其降解产物。且降解后的硫酸软骨素更显著地增加了拟杆菌门和副杆菌属等有益菌的丰度（P<0.05）,更明显的抑制了潜在致病菌型埃希氏-志贺氏菌属（P<0.05）。此外,LWCS发酵能维持24 h的酸性环境,并产生更多的乙酸、丙酸和总短链脂肪酸（分别增加1.15、1.03和1.09倍）。以上结果表明,光催化降解后的硫酸软骨素具有更强的肠道益生作用,该研究为硫酸软骨素的开发应用提供了科学依据。