基于AGDS和静态消化模型的全麦面条体外消化特性研究

采用动态(人工胃模拟系统，AGDS)和静态(振荡水浴)2种体外消化模型，分别对全麦面条的消化特性进行考察，探究不同消化模型在全麦面条消化特性研究中的差异，对消化过程中pH、胃排空情况、粒径变化、淀粉水解和蛋白质胃内降解进行表征。结果表明：全麦面条在AGDS模型胃消化阶段的颗粒降解程度高于静态模型，这可能是由于AGDS模型对胃内机械力的模拟有利于促进全麦面条食糜的物理破碎。全麦面条淀粉组分在2种模型的胃消化阶段均发生少量水解，当小肠消化结束时，静态和AGDS模型的淀粉水解率分别为66.51%和53.49%。同时，全麦面条蛋白质组分在静态消化模型胃消化阶段的水解速度快于AGDS。     

常见大豆制品中蛋白质的体外消化特性

本研究以常见大豆制品（大豆分离蛋白（soy protein isolate,SPI）、微波大豆、水煮大豆、豆浆、氯化钙豆腐和氯化镁豆腐）为研究对象,采用标准的静态体外消化模型——INFOGEST 2.0,测定不同时间点胃肠消化产物的完整蛋白、分子质量分布、游离氨基浓度和粒径大小,以探究大豆蛋白的消化特性。结果表明,不同加工方式均能促进大豆蛋白的消化。经过胃消化阶段后,几种大豆制品中部分蛋白被消化。而肠消化后,大豆蛋白均被彻底消化为短肽。相较于SPI,大豆经微波和水煮处理后,大豆蛋白的游离氨基浓度明显增加,但微波加热后大豆蛋白消化得更彻底;豆浆中大豆蛋白的消化程度低于氯化钙豆腐和氯化镁豆腐,两种豆腐中大豆蛋白的消化程度没有明显差异。总之,不同加工方式处理大豆均能不同程度地促进大豆蛋白的消化。本研究有助于更好地了解不同加工方式得到的大豆制品中大豆蛋白的消化特性,为人们摄取植物蛋白提供参考。     

体外消化模型研究进展及其在食品中的应用

体外消化是对消化过程中生理条件的模拟,是研究食品中营养物质的有效工具。该技术已被广泛应用于食品中蛋白质、碳水化合物及植物次级代谢物等营养物质的消化研究中。目前从静态的单室到动态的多室,各种各样的体外消化模型被开发出来,但各模型的技术复杂性和体内外的生理相关性不同。该文从静态、半动态、动态的角度概述了几种常见模型的起源、结构、机制及局限性的研究进展,简述了体外消化在食品中的应用,包括营养物质的消化研究和功能性食品开发、生物活性物质消化后的抗氧化性评价以及食品过敏原研究等,分析了应用中矛盾结果出现的可能原因,重点强调了相似研究需求下体外消化模型应用时标准化的重要性。     

大豆蛋白纤维聚集体的体外消化特性研究

本研究以大豆分离蛋白为材料,通过在pH 2.0条件下调控大豆蛋白形成大豆蛋白纤维聚集体。采用标准的静态体外消化模型INFOGEST 2.0对大豆蛋白纤维聚集体进行体外模拟消化实验,并对不同消化时间的胃肠消化产物通过十二烷基硫酸钠-聚丙烯酰胺凝胶电泳（SDS-PAGE）、动态激光散射仪（DLS）及液相色谱-质谱联用（LC-MS）对其分子质量、粒径及肽段组成进行鉴定。结果表明,大豆蛋白纤维聚集体通过消化后被水解为小分子的肽,并LC-MS证实消化过程中肽段数量随着消化时间的增加呈阶梯式水解。本实验探究了大豆蛋白在体外模拟消化过程中的消化特性,这将有助于更好地了解植物蛋白在人体中的消化方式及其对健康的影响。     

米饭冷藏时间对老年人胃排空和体外动态消化特性的影响

作者旨在定量研究衰老引起的胃肠生理条件变化对米饭的胃排空和动态消化特性的影响。基于老年人与年轻人胃肠道生理条件的差异，利用动态体外人胃消化系统构建了老年人胃生理消化环境，考察了4 ℃下米饭冷藏时间（6、24、48 h）对胃排空和淀粉水解动力学的影响；结合静态浸泡实验，分析了冷藏米饭的水分质量分数、质构和微观结构的变化。结果表明，随着冷藏时间的增加，静态浸泡过程中米饭的微观结构更加致密，米饭的持水力显著下降，而压痕硬度明显提高；冷藏48 h后，胃半排空时间（t_1/2）从303.3 min显著增加到630.6 min，而淀粉消化率从15.4%下降为7.4%。研究结果表明，米饭经较长时间冷藏后，在老年人的消化环境中胃排空速度延缓，淀粉水解速率显著降低。该研究为深入理解米饭在老年人胃内的消化特性，选择和优化食物加工及贮藏方式，开发更加适合老年人的淀粉类主食提供理论指导。     

多酚化合物体外模拟消化的稳定性分析

选取7 种不同种类的酚类化合物,研究体外模拟胃肠道消化对其稳定性的影响。结果表明：不同酚类化合物在胃肠道消化过程中的稳定性不同。高效液相色谱分析结果显示,胃消化过程对酚酸类化合物的影响较小,其含量无显著变化,但类黄酮化合物在胃消化过程中稳定性较差,儿茶素含量下降了16.6%、表儿茶素含量下降了约6%。经模拟肠液处理后,除阿魏酸、对羟基苯甲酸外,其他酚类化合物含量均显著降低,此外,绿原酸在肠液消化过程中生成了新的物质。体外模拟胃肠液消化对混合标准品的作用结果有所不同,模拟胃液消化对混合标准品含量均无显著影响,模拟肠液消化后,仅表儿茶素、没食子酸含量分别降低为76.96%和50.30%,其他酚类化合物含量均无显著变化。     

绿豆蛋白基乳液的稳定性及胃肠消化行为

为了拓展绿豆蛋白在乳液体系中的应用,该研究以大豆蛋白为对照,系统探究了热处理前后绿豆蛋白结构、表面疏水性、油水界面的吸附行为,以及绿豆蛋白稳定的油水乳液的稳定性和胃肠消化行为的变化。蛋白表面疏水性测定结合表面张力分析发现经湿热处理后（120 ℃,20 min）绿豆蛋白的表面疏水性从4 870.80增加到9 482.50,在油水界面上的扩散速率从0.33 mN·m-1·s-0.5增加到0.45 mN·m-1·s-0.5,热处理的绿豆蛋白在油水界面表现出更高的界面活性。在6%的蛋白浓度条件下,与大豆蛋白相比,热处理的绿豆蛋白稳定的油水乳液呈现出更高的热稳定性及物理稳定性。与大豆蛋白类似,体外模拟胃肠消化发现热处理的绿豆蛋白具有良好的胃肠消化特性,主要表现为蛋白的快速消化,乳液液滴在胃消化过程中呈现一定程度的聚集行为。研究表明热处理的绿豆蛋白具有应用于植物基食品乳液的巨大潜力。     

不同浓度银耳多糖的体外模拟消化特性比较

银耳多糖作为一种具有益生元潜力的多糖,其在发挥作用前必需经过体内的消化与吸收。该研究通过探讨银耳多糖体外模拟消化过程中的物质组成与理化性质的变化来研究其在口腔、胃和肠三个阶段的消化特性。研究表明,三个消化阶段结束后,除质量分数0.5%样品略有增加外,不同浓度的多糖样品中的还原糖含量均未产生显著变化;银耳多糖主要由甘露糖、葡萄糖、半乳糖醛酸、半乳糖、葡萄糖醛酸组成,且在整个消化过程中,均未被消化酶分解而产生新的游离单糖;不同浓度银耳多糖经胃液消化后,低pH值的胃消化环境会引起多糖分子量的降解,其中0.5%浓度样品组在经三个阶段消化后逐渐较低到3.91×103、3.52×103与2.92×103 ku。消化过程中多糖的结构与组成变化主要取决于pH值的变化,与消化液中的消化酶关系不大,其中适宜浓度的多糖溶液可在消化过程中由于其粘度特性而保持更稳定的结构性质。     

超声改性对辣木籽蛋白体外消化特性的影响

以辣木籽水溶蛋白(MOWP)为原料,采用体外模拟消化模型和体外抗氧化模型探究不同超声功率处理对其体外消化特性及氧化活性的影响。结果表明:在胃肠连续消化期间因超声作用,MOWP消化率、水解度明显提高,随着超声功率的增加消化率先降低后上升,在超声功率650 W时,胃消化和胃肠连续消化的酶解液消化率分别达(68.52±1.70)%和(91.48±0.64)%;经过模拟胃消化和胃肠连续消化,蛋白质分子分解成分子质量更小的蛋白,两阶段内源荧光峰值波长发生变化,胃消化的峰值由351 nm红移至353 nm,胃肠连续消化由353 nm 红移后到达355 nm;超声功率为60%时,MOWP经过胃消化和胃肠连续消化的DPPH·清除能力最优,分别为(78.26±0.85)%和(44.23±0.98)%。MOWP-100在胃肠连续消化阶段ABTS自由基清除率最高,为(91.87±0.19)%。结论:超声改性有助于提高MOWP的消化性能,经超声处理MOWP消化物质具有优良抗氧化活性,为MOWP引入食品并在人体中消化提供参考。     

枯草芽孢杆菌对大豆蛋白-磷脂复合乳液在体外消化中稳定性的影响

为探讨枯草芽孢杆菌在消化过程中对大豆蛋白-磷脂复合乳液稳定性的影响。本试验设计胃肠消化模型,通过对加菌与不加菌的O/W型和W/O型乳液的乳化活性指数（Emulsifying activity index,EAI）、乳化稳定指数（Emulsification stability index,ESI）、浊度、粒径、Zeta电位检测和显微观察,考察乳液是否出现分离、絮凝、聚集上浮等现象。结果表明,在胃消化阶段,O/W型和W/O型乳液EAI、ESI、粒径、电位都明显减小,显微观察显示液滴密度减小,体积增大;加入枯草芽孢杆菌的乳液与不加菌乳液相比,各指标减小的幅度更大。在小肠消化阶段,O/W型和W/O型乳液EAI和ESI整体呈上升趋势,而粒径和电位则明显下降,另外,两者的显微观察显示液滴密度减小,体积也减小。与不加菌的相比,加入枯草芽孢杆菌后乳液EAI、ESI、粒径显著降低,电位显著升高（P<0.05）。综合上述结果,枯草芽孢杆菌促进了大豆蛋白-磷脂复合乳液在消化过程中的破乳现象。     

In vitro digestibility of rare sugar (D-allulose) added pectin–soy protein gels

Confectionery gels are known to be high-caloric products due their high sugar content. Changing their formulations by substituting the sugar with alternative natural sweeteners and functionalising them, the addition of proteins has gained attention. Understanding the rate of digestion of these products is also important for selecting the appropriate formulation. In this study, in vitro gastric digestion behaviour of the gels formulated with D-allulose, a low-calorie rare sugar, soy protein isolate (SPI) (1%, 2.5%) and pectin (4%) were examined. Digestion decreased the hardness of the gels (P < 0.05), but, at 2.5% SPI concentration. Moisture content of the samples increased after digestion and presence of SPI induced higher water uptake. At the end of 2 h of digestion, 1% soy protein isolate containing gels had the highest brix values showing that after a certain concentration, soy protein isolate governed the system due to improved soy protein–pectin interaction or due to improved gelation with Maillard reaction. NMR relaxometry experiments further confirmed the changes in the gels with the increase in T₂ values. Power law model was fitted for the dissolution behaviour using the ^oBrix values of the digestion medium. Dissolution of sugar and the contribution of SPI to the gel network were clearly observed in SEM images. Results showed that these gels had the potential to slow down the emptying rate of stomach thus could lead to ‘fullness’ for a longer time.     

Effects of simulated gastric and intestinal digestion on chitooligosaccharides in two in vitro models

Chitooligosaccharides (COS) with different degree of polymerisation (DP) have different physiological activities such as anti-tumour and anti-hyperlipidemia activities. However, the digestive process might lead to the change of DP of COS as well as cause the change of physiological activities in vivo. In this study, two in vitro digestion models (static and dynamic) were used to investigate digestion behaviours of COS and the influencing factors during digestion with or without food matrix. The results showed that COS with DP 2–5 were indigestible and COS with DP 6–10 degraded with time during gastric and intestinal digestion. Pepsin, pancreatin and lipase were the main factors leading to degradation. Food matrix could protect COS with DP 6–10 from degradation during gastric digestion. However, the degradation of COS with DP 6–10 accelerated and the degradation of COS with DP 5 occurred during intestinal digestion with food matrix due to pancreatin, lipase and bile salt.     

Angiotensin I-Converting Enzyme Inhibitory Activity of Soy Protein Digests in a Dynamic Model System Simulating the Upper Gastrointestinal Tract

ABSTRACT: The objective of this study was to investigate whether peptides with inhibitory activity against angiotensin I-converting enzyme (ACE) would be produced by digestion of isolated soy protein (ISP) in a dynamic model system simulating gastrointestinal conditions. Using the model system, 5% ISP solution was pumped into the stomach reactor containing pepsin and HCl. The peptic digest was continuously pumped into the duodenum reactor containing pancreatin and Oxgall bile. The effects of blanching (100°C, 10 min) followed by pasteurization (75°C, 15 s) or sterilization (121°C, 20 min) of ISP before digestion on the inhibitory activity were also investigated. During the first 30 min of digestion, significantly higher ( P < 0.05) ACE-inhibitory activity was generated from unheated ISP after sequential digestion in both reactors compared with after peptic digestion only in the stomach reactor. However, at 90 min, subsequent digestion by pancreatin of unheated and blanched-sterilized ISP decreased ACE-inhibitory activity compared with peptic digestion alone. The IC₅₀ values at the end of 90 min digestion in both reactors were 0.38 ±0.01, 0.37 ± 0.02, and 0.44 ± 0.02 mg/mL for unheated, blanched-pasteurized, and blanched-sterilized ISP, respectively. The results suggest the potential production of peptides with ACE-inhibitory activity upon physiological digestion of soy protein, including products that have been subjected to heat processing. Although clinical trials would be required to provide final evidence of efficacy of the soy peptides, the present findings support the application of soy protein as an ingredient for functional foods.     

Gastric digestion of milk protein ingredients: Study using an in vitro dynamic model

The coagulation behavior and the kinetics of protein hydrolysis of skim milk powder, milk protein concentrate (MPC), calcium-depleted MPC, sodium caseinate, whey protein isolate (WPI), and heated (90°C, 20 min) WPI under gastric conditions were examined using an advanced dynamic digestion model (i.e., a human gastric simulator). During gastric digestion, these protein ingredients exhibited various pH profiles as a function of the digestion time. Skim milk powder and MPC, which contained casein micelles, formed cohesive, ball-like curds with a dense structure after 10 min of digestion; these curds did not disintegrate over 220 min of digestion. Partly calcium-depleted MPC and sodium caseinate, which lacked an intact casein micellar structure, formed curds at approximately 40 min, and a loose, fragmented curd structure was observed after 220 min of digestion. In contrast, no curds were formed in either WPI or heated WPI after 220 min of digestion. In addition, the hydrolysis rates and the compositions of the digesta released from the human gastric simulator were different for the various protein ingredients, as detected by sodium dodecyl sulfate-PAGE. Skim milk powder and MPC exhibited slower hydrolysis rates than calcium-depleted MPC and sodium caseinate. The most rapid hydrolysis occurred in the WPI (with and without heating). This was attributed to the formation of different structured curds under gastric conditions. The results offer novel insights about the coagulation kinetics of proteins from different milk protein ingredients, highlighting the critical role of the food matrix in affecting the course of protein digestion.     

人造鸡肉的蛋白质消化特性研究

比较基于大豆蛋白的人造鸡肉、市售鸡肉以及大豆分离蛋白（SPI)的蛋白质消化特性,研究纤维状结构和蛋白质消化特性的相关性。结果表明,人造鸡肉较好地模拟了鸡肉的产品特性,两者质构特性和组织化度接近。微观结果显示人造鸡肉纤维较粗,分布不均匀和松散,间隙较大;而鸡肉纤维较细,分布密集、均匀和规则,间隙较小。消化后食糜粒径结果显示,与SPI和鸡肉相比,人造鸡肉在胃和小肠的消化过程中,粒径变化最大。可溶性氮含量和游离氨基酸总量结果均显示,人造鸡肉的蛋白质消化程度最低,鸡肉次之,SPI最高,在消化结束后得到17种主要氨基酸总量分别为382、397.3、444 mg/10 mL消化液,表明人造鸡肉的纤维结构不利于大豆蛋白的消化。     

Effect of actinidin from kiwifruit (Actinidia deliciosa cv. Hayward) on the digestion of food proteins determined in the growing rat

This study aimed to determine the effect of dietary actinidin (provided as Hayward kiwifruit) on the gastric and small intestine digestion of six food protein sources in rats. For each protein source, two semi-synthetic test diets were formulated containing either freeze-dried Hayward kiwifruit (actinidin present) or freeze-dried Hort16A kiwifruit (actinidin absent). Actinidin activity is extremely low in Hort16A kiwifruit. Titanium dioxide was also included as an indigestible marker. Rats were fed freshly-prepared diets, euthanised and the gastric and ileal contents collected. The chyme and digesta samples were subjected to electrophoresis (SDS–PAGE), densitometry and titanium analysis and the degradability of individual proteins calculated. Dietary actinidin had no (p > 0.05) effect on the gastric degradability of zein and whey protein isolate but increased gastric degradability of beef muscle protein, gelatin, soy protein isolate and gluten by 40%, 60%, 27% and 29% units, respectively. Dietary actinidin had little or no effect on ileal protein degradability. Overall, dietary actinidin enhanced the gastric digestion of some food proteins.     

Effects of genetic variants and sialylation on in vitro digestibility of purified κ-casein

Milk with different κ-casein (CN) phenotypes has previously been found to influence its gastric digestion rate. Therefore, the aim of the present study is to disentangle contributions of genetic variation and its related sialylation on the in vitro digestion process of κ-CN. Accordingly, κ-CN was purified from milk representing homozygous cows with κ-CN phenotypes AA, BB, or EE and used as substrate molecules in model studies using the INFOGEST 2.0 in vitro static digestion model. Furthermore, the effect of removal of the terminal sialic acids present on the O-linked oligosaccharides of the purified κ-CN A, B, and E protein variants were studied by desialylation enzymatic assays. The κ-CN proteins were purified by reducing anion exchange chromatography with purities of variants A, B, and E of 93.0, 97.1, and 90.0%, respectively. Protein degradations of native and desialylated κ-CN isolates in gastric and intestinal phases were investigated by sodium dodecyl sulfate-PAGE, degree of hydrolysis (DH), and liquid chromatography electrospray ionization mass spectrometry. It was shown that after purification, the κ-CN molecules reassembled into multimer states, which then constituted the basis for the digestion studies. As assessed by DH, purified variants A and E were found to exhibit faster in vitro digestion rates in both gastric and intestinal phases compared with variant B. Desialylation increased both gastric and intestinal digestion rates for all variants, as measured by DH. In the gastric phase, desialylation promoted digestion of variant B at a rate comparable with native variants A and E, whereas in the intestinal phase, desialylation of variant B promoted better digestion than native A or E. Taken together, the results confirm that low glycosylation degree of purified κ-CN promotes faster in vitro digestion rates, and that desialylation of the O-linked oligosaccharides further promotes digestion. This finding could be applied to produce dairy products with enhanced digestibility.