In vitro bio-accessibility and antioxidant activity of grape polyphenols

The bio-accessibility (the release of compounds from solid food matrices) of grape polyphenols using an in vitro model simulating gastro-intestinal conditions has been investigated. In vitro studies are needed to unravel factors affecting the release of antioxidants during digestion. The amount of bio-accessible polyphenols, flavonoids and anthocyanins increases during gastric digestion. The transition in the intestinal environment causes a decrease in all the analyzed classes of polyphenols followed by a renewal in the extraction of polyphenols and flavonoids but not of anthocyanins. The stability under gastro-intestinal conditions of pure phenolic acids, flavonoids and resveratrol has been analysed. Gastric digestion had no effect on any phenolic tested. Phenolic acids and resveratrol were degraded under pancreatic conditions whereas catechin and quercetin were not. Changes in antioxidant activity during digestion were correlated to the changes in polyphenols concentration as well as to the pH. Our results suggest that the gastro-intestinal tract may act as an extractor where polyphenols are progressively released from solid matrix and made available for the absorption or to exert their biological effects in the gastro-intestinal tract.     

Influence of in vitro gastrointestinal digestion on the bioavailability and antioxidant activity of polyphenols from Ipomoea batatas leaves

Sweet potato leaves (SPL) are natural by‐products rich in bioactive compounds, particularly polyphenols, and can be consumed as a vegetable. This work aims to investigate the influence of in vitro gastrointestinal digestion on the bioavailability and antioxidant activities of polyphenols from SPL. The phenolic compounds of sweet potato leaf extracts (SPLE) were quite stable in gastric phase. However, the amount of phenolic compounds decreased during transition from the acidic gastric environment to the alkaline intestinal environment. The bioavailability of phenolic compounds of SPLE was 13.36%. The ABTS^·+ scavenging capabilities and reducing power of SPLE were not affected during gastric digestion. Antioxidant activity increased after intestinal digestion. This research suggested that phenolic compounds of SPLE were sufficiently available for absorption. This study also provides useful information on the potential commercial value of SPL.     

The effect of various heat treatments on the antioxidant capacity of milk before and after simulated gastrointestinal digestion

Various reactions take place between compounds of milk during heat treatment including denaturation and aggregation of whey proteins, and formation of new complexes. In this study, the antioxidant capacities of raw, pasteurised and sterilised milk were determined both before and after an enzymatic in vitro digestion process, using a radical cation decolorisation assay. The mean values of raw, pasteurised and sterilised milk before simulated digestion were 4.02, 4.47 and 4.18 mM trolox/g, respectively, and these did not differ significantly. The antioxidant capacity of all milk types increased significantly at the end of the simulated gastrointestinal digestion, being 11.13, 12.33, 11.88 mM trolox/g for raw, pasteurised and sterilised milk, respectively.     

In vitro gastrointestinal digestion of polyphenols from different molasses (pekmez) and leather (pestil) varieties

In this study, to evaluate the in vitro bioaccessibility of eight different pekmez and pestil samples, total phenolics, flavonoids, proanthocyanidins, anthocyanins and antioxidant capacity were determined at different phases of simulated gastrointestinal (GI) digestion. For the analysis of antioxidant activity, four different methods were used including 2,2‐azinobis(3‐ethylbenzothiazoline)‐6‐sulfonic acid, 1,1‐diphenyl‐2‐picrylhydrazil, ferric reducing antioxidant power and cupric ion reducing antioxidant capacity. The results revealed that the dialysed fraction (IN) represented 12–50%, 3–17% and 3–72% of the total phenolics, flavonoids and proanthocyanidins, respectively. Moreover, total antioxidant capacity of IN fraction was 2–57% of the initial values obtained for pekmez and pestil samples. To identify the influence of simulated in vitro GI digestion on total anthocyanins, only black mulberry molasses (pekmez) and plum leather (pestil) were analysed and according to the results no anthocyanins were detected in the IN fraction for both samples. The present study presented a detailed insight of bioaccessibility of polyphenols in various pekmez and pestil samples.     

Optimisation of antioxidant hydrolysate production from sweet potato protein and effect of in vitro gastrointestinal digestion

In this study, response surface methodology (RSM) was applied to optimise antioxidant hydrolysate production from sweet potato protein (SPP). The effects of enzyme‐to‐substrate ratio, pH value and reaction temperature on ·OH radical scavenging activity and Fe²⁺‐chelating activity of antioxidant hydrolysates from SPP were investigated. The maximum ·OH radical scavenging activity (40.10%) and Fe²⁺‐chelating activity (74.37%) of SPP hydrolysates (SPPH) were obtained at an enzyme‐to‐substrate ratio of 4%, pH value of 7.8 and reaction temperature of 57 °C, which was in agreement with the predicted value (40.11% and 74.83%, respectively) estimated by RSM. The simulated in vitro gastrointestinal digestion (GID) dramatically modified molecular weights distribution, increased peptide (<3 kDa) concentration and highly retained antioxidant activity of SPPH, indicating potentially utilisation of SPPH as a functional supplement in food system.     

Protein quality and antioxidant properties of soymilk derived from black soybean after in vitro simulated gastrointestinal digestion

Protein quality and antioxidant properties of soymilk derived from black soybean (eight varieties) in China were analysed following in vitro simulated gastrointestinal digestion (including dialysis). Soymilk from black soybean possessed high okara weight but low yield, protein content and sensory scores. The in vitro digestibility of protein in all black soymilk samples was higher than 60%, and the Shenmu black soybean exhibited the highest digestibility. Non-digested milk from the black soybean exhibited significantly high total phenolic content (TPC) (127.15–173.04 mg/100 mL), ferric-reducing antioxidant power (FRAP) (272.18–366.27 μmol L⁻¹) and DPPH free radical-scavenging activity (61.20–83.81%). These parameters were significantly lower in the non-digested soymilk than those in soymilk after gastric digestion but higher than those of soymilk in the dialysed fraction. Gastric digestion significantly increased bioactive compound levels released from black soymilk, and the bioaccessibility of phenolic compounds was 24.37–36.05%. Hence, black soymilk was sufficiently available for human absorption.     

Effect of in vitro‐simulated gastrointestinal digestion on the stability and antioxidant activity of blueberry polyphenols and their cellular antioxidant activity towards HepG2 cells

In this study we investigated the influence of in vitro‐simulated gastrointestinal digestion on the bioaccessibility and antioxidant activity of polyphenols from blueberries (Vaccinium spp.). Total phenolic, anthocyanin, and flavonoid content was determined, and extract and digesta compositions were analysed by HPLC‐ESI‐MS/MS. The phenolic compounds were relatively stable under a gastric environment, whereas polyphenols and anthocyanins were unstable under an intestinal environment. The bioaccessibility of polyphenol, anthocyanin, and flavonoid was greatly decreased after the intestinal digestion, and the recoveries were only 13.93%, 1.95%, and 15.68% (the IN sample), respectively. Polyphenolic profile alteration occurred during in vitro‐simulated gastrointestinal digestion. Changes of phenolic compound antioxidant activity during digestion correlated with polyphenol, flavonoid, and caffeic acid concentrations. Digested extract cellular antioxidant activity was lower than non‐digested extract activity (P < 0.05). Polyphenol dose–response correlations with cellular antioxidant activity were observed. These results indicated that in vitro‐simulated gastrointestinal digestion significantly impact polyphenols and their antioxidant activity.     

体外模拟消化对酸枣仁蛋白酶解产物抗氧化活性的影响

目的:以具有良好抗氧化活性的酸枣仁蛋白酶解产物(SZPHs)为研究对象,探究体外模拟胃肠消化对其氨基酸组成及抗氧化活性的影响.方法:通过体外模拟胃肠消化,得到酸枣仁蛋白酶解产物消化物(SZPHs-GD),并分析SZPHs消化前后的氨基酸组成以及体外抗氧化活性.结果:体外模拟胃肠消化后,SZPHs-GD中疏水性氨基酸含量...     

Effect of in vitro gastrointestinal digestion on the antioxidant activity of protein hydrolysates prepared from Cape hake by‐products

The antioxidant activity of fish protein hydrolysates may change in the digestive tract during the human gastrointestinal digestion depending on their preparation conditions. Thus, the objective of this study was to assess the antioxidant properties of Cape hake hydrolysates prepared by three different methods (HPH‐A, HPH‐B and HPH‐C) and the effect of their in vitro gastrointestinal digestion on their antioxidant properties. HPH‐A showed the highest reducing power, while HPH‐B and HPH‐C exhibited the highest OH antiradical activity. Fe²⁺‐chelating activity was similar for all hydrolysates, but HPH‐C had a higher Cu²⁺‐chelating activity comparable to that of EDTA. The in vitro gastrointestinal digestion of hydrolysates caused a decrease in the DPPH inhibition, but an increase in scavenging ABTS in all hydrolysates. Copper‐ and iron‐chelating activities increased after digestion of hydrolysates. The results showed that the gastrointestinal digestion of HPHs generally increased their antioxidant properties.     

Effect of thermal processing and digestive protease on the antioxidant capacity of fruit juice–milk beverage model systems under simulated gastrointestinal digestion

The effects of thermal processing and digestive protease on the antioxidant capacity of fruit juice–milk beverage (FJMB) models containing whey protein (WP) and chlorogenic acid or catechin (CAT) under in vitro digestion were investigated. After gastric digestion, the FJMB showed a significant (P < 0.05) increase in ABTS, but little change in ferric reducing antioxidant power (FRAP). Intestinal digestion decreased the FRAP and increased ABTS except in the model containing 0.1% CAT. There were different effects (none, masking, synergistic effect) in the antioxidant activity of the WP and phenolics under digestion. Pasteurisation (63 °C/30 min) had no significant effect on the FJMB's antioxidant capacity, while sterilisation (121 °C/10 min) significantly (P < 0.05) increased, decreased or had no significant effect on ABTS and FRAP under digestion, depending on the model. Pepsin and pancreatin significantly (P < 0.05) decreased the fruit phenolics' ABTS. Ferric reducing antioxidant power was not significantly influenced by pepsin during gastric digestion, but was significantly (P < 0.05) decreased by pancreatin during intestinal digestion. These results would be helpful to improve the efficacy of fruit phenolics in FJMB subjected to thermal processing and to maintain the health benefits of this kind of functional products in the food industry.     

大豆乳清蛋白及其糖基化产物体外模拟胃肠消化特性研究

体外模拟胃液和胰液对大豆乳清蛋白(WSP)及其糖基化产物的消化特性进行研究。结果表明:当胃蛋白酶和胰酶添加量为底物质量的2%~8%时,仅模拟胃液能部分水解WSP,体外消化率为48.0%~50.2%;胃蛋白酶作用后,SDS-PAGE电泳显示WSP的组分脂肪氧合酶和β-淀粉酶条带消失,而大豆血球凝集素以及胰蛋白酶抑制剂KTI、BBI被部分水解后仍有清晰条带;胰酶作用后,SDS-PAGE电泳显示WSP的各组分条带基本不变;使用葡萄糖在60℃的干热条件下对WSP糖基化改性1~7 d能够提高WSP糖基化产物的乳化特性和热稳定性,相比于WSP,此糖基化产物的体外消化率随反应时间的延长先增加后降低。     

Effect of simulated gastrointestinal digestion on phenolic composition and antioxidant capacity of cooked cowpea (Vigna unguiculata) varieties

Consumption of diets rich in phenolic compounds has been associated with reduced risk of chronic diseases. The effect of cooking and simulated gastrointestinal digestion on phenolic compounds and antioxidant properties of two cowpea (Vigna unguiculata) types was determined. Phenolic acids, flavan‐3‐ols and flavonols were the main groups of phenolic compounds identified. Cooking and simulated enzyme digestion of the cooked cowpea samples rendered some phenolics less extractable (possibly by promoting binding with other food components) or more extractable (possibly by release of bound forms). Total phenolic contents and radical scavenging properties of the cowpeas were reduced upon cooking, but increased upon simulated enzyme digestion. Cowpea extracts inhibited human LDL oxidation at a concentration of 2 mg mL^?1 possibly due to their phenolic content. Phenolic compounds in cowpea can potentially protect against cardiovascular diseases for which LDL oxidation is a risk factor.     

Berry fruits-enriched pasta: effect of processing and in vitro digestion on phenolics and its antioxidant activity,bioaccessibility and potential bioavailability

Pasta samples were made by substituting wheat flour (2.5% and 7.5%) for lyophilised raspberry, boysenberry, and redcurrant and blackcurrant. Total polyphenol content showed minimum variation during processing while anthocyanins presented high degradation. In general, the first minutes of cooking showed the major detrimental effect on antioxidant activity. In vitro starch hydrolysis showed the lowest value with the addition of raspberries and boysenberries. During simulated digestion, polyphenols were released from pasta matrix reaching a 2.3- to 4.3-fold increase in bioaccessible polyphenols. Likewise, values observed for reducing power and free radical scavenging activity ranged from a 0.7- to 2.0-fold and 1.6- to 6.8-fold increase in relation to cooked pasta, respectively. In addition, ≈40% of dialysability was observed for scavenging activity. In conclusion, enrichment of pasta with fine fruits is an effective tool to obtain a product with enhanced antioxidant potential.     

Changes in the phenolic contents and antioxidant activities of citrus peels from different cultivars after in vitro digestion

The aim of this study was to investigate the effects of in vitro digestion on the phenolic contents and antioxidant activities of citrus peels. Three different varieties of citrus peels (mandarin, ponkan and red tangerine) were treated with simulated gastric fluid (SGF) and simulated intestinal fluid (SIF). The results showed that the SGF or SIF treatments of the citrus peels did not significantly increase the total phenolic content (TPC) or total flavonoid content (TFC), except for that of the TFC of ponkan peel treated with SGF. However, simulated in vitro digestion did improve the antioxidant activities measured with FRAP and ABTS methods. The effect of SGF was more positive than those of SIF for the FRAP assay, but the opposite was true for ABTS. Notably, both simulated digestion techniques decreased the DPPH free radical scavenging abilities. Simulated digestion in vitro changed the antioxidant activities of the citrus peels.