Polysaccharide-polyphenol interactions: a comprehensive review from food processing to digestion and metabolism

Most studies on the beneficial effects of polyphenols on human health have focused on polyphenols extracted using aqueous organic solvents, ignoring the fact that a portion of polyphenols form complexes with polysaccharides. Polysaccharides and polyphenols are interrelated, and their interactions affect the physicochemical property, quality, and nutritional value of foods. In this review, the distribution of bound polyphenols in major food sources is summarized. The effect of food processing on the interaction between polyphenols and cell wall polysaccharides (CWP) is discussed in detail. We also focus on the digestion, absorption, and metabolic behavior of polysaccharide-polyphenol complexes. Different food processing techniques affect the interaction between CWP and polyphenols by altering their structure, solubility, and strength of interactions. The interaction influences the free concentration and extractability of polyphenols in food and modulates their bioaccessibility in the gastrointestinal tract, leading to their major release in the colon. Metabolism of polyphenols by gut microbes significantly enhances the bioavailability of polyphenols. The metabolic pathway and product formation rate of polyphenols and the fermentation characteristics of polysaccharides are affected by the interaction. Furthermore, the interaction exhibits synergistic or antagonistic effects on the stability, solubility, antioxidant and functional activities of polyphenols. In summary, understanding the interactions between polysaccharides and polyphenols and their changes in food processing is of great significance for a comprehensive understanding of the health benefits of polyphenols and the optimization of food processing technology.

Characterization and stability assessment of polyphenols bound to Lycium barbarum polysaccharide: Insights from gastrointestinal digestion and colon fermentation

Polysaccharides and polyphenols are biologically active components that coexist in Lycium barbarum fruit, and there may be interactions between them that affect the release of each other. In this study, polyphenols bound to L. barbarum polysaccharide (LBP) were characterized, and the stability of bound phenolics (BP) was assessed by gastrointestinal digestion and colon fermentation. The results showed that a total of 65 phytochemicals such as flavonoids, phenolic acids, and coumarins were identified by UPLC-MS/MS. Quantitative analysis revealed that the major phenolic constituents were rutin, p-coumaric acid, catechin, ferulic acid, protocatechuic acid, and gallic acid, and their contents were 58.72, 24.03, 14.24, 13.28, 10.39, and 6.7 mg GAE/100 g DW, respectively. The release of BP by gastric digestion and gastrointestinal digestion was 9.67 % and 19.39 %, respectively. Most polyphenols were greatly affected by gastric digestion, while rutin was released in small intestine. The BP were fully released (49.77 %) and metabolized by gut microorganisms, and a considerable number of intermediates and end-products were detected, such as phloroglucinol, phenylacetic acid, and phenyllactic acid. Microbiomics data emphasized the positive impact of LBP on gut bacteria of Bacteroides, Parabacteroides, and Clostridioides. These findings could deepen our understanding of the bioavailability and biological fate of BP and also provide reference data for nutrient release and utilization of L. barbarum as a whole.

In Vitro Gastrointestinal Bioaccessibility, Bioactivities and Colonic Fermentation of Phenolic Compounds in Different Vigna Beans

Beans are widely consumed throughout the world, rich in non-nutrient phenolic compounds and other bioactive constituents, including alkaloids, lectins, and others. However, research about in vitro digestion impacts on the changes of bioactive compounds' release and related antioxidant potential in different Vigna beans is limited. This research aimed to assess the modifications that occur in the content and bioaccessibility of phenolic compounds in four Vigna samples (adzuki bean, black urid whole, black eye bean, and mung bean), their antioxidant properties, and short chain fatty acids (SCFAs) production through static in vitro gastrointestinal digestion and colonic fermentation. Adzuki bean exhibited relatively higher total phenolic content (TPC; 4.76 mg GAE/g) and antioxidant activities after in vitro digestion. The black eye beans' total flavonoid content (0.74 mg QE/g) and total condensed tannins (10.43 mg CE/g) displayed higher tendencies. For colonic fermentation, the greatest TPC value of entire samples was detected through a 2-h reaction. In most selected beans, phenolic compounds were comparably more bioaccessible during the oral phase. Acetic acid showed the highest level through SCFAs production, and the total SCFAs in adzuki beans was the greatest (0.021 mmol/L) after 16-h fermentation. Adzuki beans may be more beneficial to gut health and possess a stronger antioxidant potential after consumption.

A review of in vitro methods to evaluate the bioaccessibility of phenolic compounds in tropical fruits

International guidelines strongly advise about the frequent and varied intake of plant in diet. In this scenario, the consumption of fruits is closely related to health benefits due to the abundant presence of bioactive substances. Accordingly, the production of tropical fruits has stood out worldwide, reaching records since the past decade. However, to ensure that phenolic substances are indeed used by the body, they need to be accessible for absorption. For this purpose, several methods are used to assess the phenomenon of bioaccessibility. We provide information on i) in vitro methods for the evaluation of the bioaccessibility of phenolic compounds in tropical fruits, including their derivatives and by-products; ii) a study performed using a semi-dynamic in vitro digestion model; iii) simulated digestion with a dialysis membrane step, polyphenol transport/uptake using cell culture, and in vitro colonic fermentation process. Although standardized static and semi-dynamic in vitro digestion methods already exist, few studies use these protocols to assess the bioaccessibility of polyphenols in tropical fruits. To guarantee that in vitro digestion assays reproduce consistent results compared to in vivo reference methods, it is essential to universalize standardized methods that allow the comparison between results, enabling the validation of in vitro digestion methods.

Sensory and process optimization of a mango bagasse-based beverage with high fiber content and low glycemic index

This research aimed to develop and optimize a mango bagasse (MB) powdered beverage with high fiber content and low glycemic index, acceptable by their potential consumers. The powdered beverage contained 40 g of mango bagasse (Manguifera indica L., var. Manila), xanthan gum (XG), carboxymethyl cellulose (CMC), and silicon dioxide (SDO). The amount of MB remained constant and, 0.5.%, 1.0%, and 2.0% of CMC, XG and SDO were added according to a factorial design 3³. The independent variables evaluated were relative viscosity, sedimentation index, solids (ºBx), and color. Statistical optimization was carried out, looking for low values of viscosity and sedimentation index, obtaining the formulation, 0.5% XG, 0.5% CMC, and 0.5% SDO. A preference test was performed with this formulation using a commercial powdered beverage as a reference, 60 consumers participated. Data showed a preference similar to that of the commercial powered beverage, moreover, the MB beverage had a content of 40.90% of total fiber, from which 15.03% was soluble fiber. The beverage had a low glycemic index (45.99) and its postprandial glycemic curve was stable for 120 min, indicating that the beverage shows potential as a functional food.

Influence of extrusion process on the release of phenolic compounds from mango (Mangifera indica L.) bagasse-added confections and evaluation of their bioaccessibility, intestinal permeability, and antioxidant capacity

Extruded polyphenol-rich by-products like mango bagasse (MB) could be used to manufacture functional confections. However, few reports have assessed the extrusion impact on MB polyphenols within a food matrix. This research aimed to evaluate the impact of extrusion on the bioaccessibility, intestinal permeability, and antioxidant capacity of phenolic compounds (PC) from non-extruded and extruded MB-added confections (EMBC and MBC, respectively). The inhibition of 2,2-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and 2,2-diphenyl-1-picrylhydrazyl radicals and in silico approaches were used to evaluate the antioxidant capacity. MBC displayed the highest gastric bioaccessibility (%) of xanthones and flavonoids, whereas selective release of gallic acid, mangiferin, and quercetin glucoside was shown for EMBC. Lower PC' apparent permeability coefficients were found in EMBC compared to MB (0.11 to 0.44-fold change, p < 0.05). EMBC displayed the highest antioxidant capacity by the DPPH method for the non-digestible fraction, being mangiferin the highest in silico contributor (-4 kcal/mol). Our results showed that the extrusion process helps release selective phenolics from MBC, which increases their bioaccessibility and intestinal permeability.

Gastrointestinal metabolism of monomeric and polymeric polyphenols from mango (Mangifera indica L.) bagasse under simulated conditions

Mango bagasse (MB) is an agro-industrial by-product rich in bioactive polyphenols with potential application as a functional ingredient. This study aimed to delineate the metabolic fate of monomeric/polymeric MB polyphenols subjected to simulated gastrointestinal digestion. The main identified compounds by LC/MS-TOF-ESI were phenolic acids [gallic acid (GA) and derivates, and chlorogenic acid], gallotannins and derivatives [di-GA (DA) and 3GG-to-8GG], benzophenones [galloylated maclurins (MGH, MDH)], flavonoids [Quercetin (Quer) and (QuerH)] and xanthones [mangiferin isomers]. The bioaccessibility depended on the polyphenols' structure, being Quer, 5G to 8G the main drivers. The results suggested that the gastrointestinal fate of MB polyphenols is mainly governed by benzophenones and gallotannins degalloylation and spontaneous xanthone isomerization in vitro to sustain GA bioaccessibility.

Technological Applications of Natural Colorants in Food Systems: A Review

Natural colorants have emerged as an alternative to their synthetic counterparts due to an existing health concern of these later. Moreover, natural-food colorants are a renewable option providing health benefits and interesting technological and sensory attributes to the food systems containing them. Several sources of natural colorants have been explored aiming to deliver the required wide color range demanded by consumers. This review aimed to compare and discuss the technological applications of the main natural-food colorants into food system in the last six years, giving additional information about their extraction process. Although natural colorants are promising choices to replace synthetic ones, optimization of processing conditions, research on new sources, and new formulations to ensure stability are required to equate their properties to their synthetic counterparts.

In Vitro Gastrointestinal Digestion and Colonic Catabolism of Mango (Mangifera indica L.) Pulp Polyphenols

Mango (Mangifera indica L.), a fruit with sensorial attractiveness and extraordinary nutritional and phytochemical composition, is one of the most consumed tropical varieties in the world. A growing body of evidence suggests that their bioactive composition differentiates them from other fruits, with mango pulp being an especially rich and diverse source of polyphenols. In this study, mango pulp polyphenols were submitted to in vitro gastrointestinal digestion and colonic fermentation, and aliquots were analyzed by HPLC-HRMS. The main phenolic compounds identified in the mango pulp were hydroxybenzoic acid-hexoside, two mono-galloyl-glucoside isomers and vanillic acid. The release of total polyphenols increased after the in vitro digestion, with an overall bioaccessibility of 206.3%. Specifically, the most bioaccessible mango polyphenols were gallic acid, 3-O-methylgallic acid, two hydroxybenzoic acid hexosides, methyl gallate, 3,4-dihydroxybenzoic acid and benzoic acid, which potentially cross the small intestine reaching the colon for fermentation by the resident microbiota. After 48 h of fecal fermentation, the main resultant mango catabolites were pyrogallol, gallic and 3,4-dihydroxybenzoic acids. This highlighted the extensive transformation of mango pulp polyphenols through the gastrointestinal tract and by the resident gut microbiota, with the resultant formation of mainly simple phenolics, which can be considered as biomarkers of the colonic metabolism of mango.

Effect of drying methods on the gastrointestinal fate and bioactivity of phytochemicals from cocoa pod husk: In vitro and in silico approaches

Cocoa pod husk (CPH) contains many nutraceutical phytochemicals whose gastrointestinal fate and bioactivity can be affected by drying methods. Microwave (MW), forced-air drying (AF), and AF plus extrusion (AF-E) dried CPH samples were chemically characterized, and their phenolic and theobromine (THB) contents were evaluated under oral-gastric-intestinal (in vitro) and colonic fermentation (ex vivo). Absorption, distribution, metabolism, excretion, and toxicity (ADEMT) properties of CPH's small molecules were evaluated in silico. The chemical composition of CPH [mostly carbohydrates/insoluble dietary fiber], polyphenol [total polyphenols > condensed tannin (CT) > monomeric flavonoids] differed minimally among samples, except for THB content (AF/AF-E > MW) and antioxidant capacity (MW > AF/AF-E). Time- trend gastrointestinal (X³ behavior) and colonic bioaccessibility were AF/AF-E > MW, but phenolic acids, procyanidins, and THB fluctuated in a sample-specific fashion. In silico modeling showed that bioactives of CPH easily crossed the intestinal epithelium illustrating their bioaccessibility and, permeability. These bioactives can act as receptor ligands in a structure-dependent manner, suggesting their use as a functional ingredient.

Challenges in confectionery industry: Development and storage stability of innovative white tea-based candies

The aim of this study was the development of innovative candies formulations accordant with the present trends in the confectionery industry. Steviol glycosides, sorbitol, and agave syrup were used as sucrose alternatives, while agar and pectin were included instead of gelatin for the formulation of vegan candies. Additionally, white tea extract was used as a candy base and source of bioactive compounds. Bioactive quality (total phenolic content, antioxidant capacity, epigallocatechin gallate, and caffeine content) and physicochemical (dry matter, springiness, hardness, color) parameters of candies were monitored during 4 months of storage at 4 and 22 °C. Pectin candies with the highest content of dry matter (79.8%) showed the longest shelf life, while those with agar (52.0% and 66.2%) were the most susceptible to spoilage. Candies prepared with agar were less hard (0.4 and 0.6 N) and with less elastic texture (1.5 and 3.4 mm) and showed the highest stability of physicochemical parameters during storage, while those with pectin were also less hard (0.5 N) but with more elastic texture (10.7 mm) than gelatin candies (3.6 and 4.4 mm; 2.4 and 4.1 N). Although gelatin samples were characterized with the greatest bioactive quality parameters immediately after production, they showed a higher instability of the same parameters during storage compared to the agar and pectin candies. PRACTICAL APPLICATION: According to the consumers' demands for healthier confectionery products, formulations of candies with sucrose alternatives, non-animal hydrocolloids, and natural bioactive compounds were developed. Giving a deeper insight into their physicochemical and bioactive properties, this paper could contribute to confectionery industry in development and optimization of formulations in order to obtain candies with desirable and attractive properties.

First-Pass Metabolism of Polyphenols from Selected Berries: A High-Throughput Bioanalytical Approach

Small berries are rich in polyphenols whose first-pass metabolism may alter their ultimate physiological effects. The antioxidant capacity and polyphenol profile of three freeze-dried berries (blackberry, raspberry, Red Globe grape) were measured and their apparent permeability (Papp) and first-pass biotransformation were tracked with an ex vivo bioanalytical system [everted gut sac (rat) + three detection methods: spectrophotometry, HPLC-ESI-QTOF-MS, differential pulse voltammetry (DPV)]. Total polyphenol (ratio 0.07-0.14-1.0) and molecular diversity (anthocyanins>flavan-3-ols), antioxidant capacity (DPPH, FRAP), anodic current maxima and Papp (efflux> uptake) were in the following order: blackberry > raspberry > Red Globe grape. Epicatechin, pelargonidin & cyanin (all), callistephin (raspberry/blackberry), catechin (grape), cyanidin glycosides (blackberry) and their derived metabolites [quinic acid, epicatechin, cyanidin/malvidin glucosides, and chlorogenic/caffeic acids] were fruit-specific and concentration-dependent. Time-trend DPV kinetic data revealed concurrent epithelial permeability & biotransformation processes. Regular permeability and high-biotransformation of berry polyphenols suggest fruit-specific health effects apparently at the intestinal level.

Mango phenolics increase the serum apolipoprotein A1/B ratio in rats fed high cholesterol and sodium cholate diets

BACKGROUND

Serum lipoproteins are in dynamic equilibrium, partially controlled by the apolipoprotein A1 to apolipoprotein B ratio (APOA1/APOB). Freeze-dried mango pulp (FDM) is a rich source of phenolic compounds (MP) and dietary fiber (MF), although their effects on lipoprotein metabolism have not yet been studied.

RESULTS

Thirty male Wistar rats were fed with four different isocaloric diets (3.4 kcal g^-1 ) for 12 weeks: control diet, high cholesterol (8 g kg^-1 ) + sodium cholate (2 g kg^-1 ) diet either alone or supplemented with MF (60 g kg^-1 ), MP (1 g kg^-1 ) or FDM (50 g kg^-1 ). MP and FDM reduced food intake, whereas MF and MP tended to increase serum APOA1/APOB ratio, independently of their hepatic gene expression. This suggests that lipoprotein metabolism was favorably altered by mango bioactives, MP also mitigated the non-alcoholic steatohepatitis that resulted from the intake of this diet.

CONCLUSION

We propose that phenolics are the most bioactive components of mango pulp, acting as anti-atherogenic and hepatoprotective agents, with a mechanism of action tentatively based on changes to the main protein components of lipoproteins. © 2018 Society of Chemical Industry.

Effect of the in vitro gastrointestinal digestion on free-phenolic compounds and mono/oligosaccharides from Moringa oleifera leaves: Bioaccessibility, intestinal permeability and antioxidant capacity

Moringa oleifera is a plant recognized for its compounds such as dietary fiber (oligosaccharides, amongst others) and polyphenols, with biological activities. These properties depend on bioactive compounds (BC) interactions with food matrix/digestion conditions, which have not been evaluated. Thus, the aim of this study was to evaluate the bioaccessibility, intestinal permeability and antioxidant capacity of BC (free-phenolic compounds (PC); and mono/oligosaccharides (MOS)) from Moringa oleifera leaves (ML) powder during in vitro gastrointestinal digestion. The gallic/caffeic acids, morin, kaempferol, mannose and stachyose showed the highest bioaccessibilities (~6-210%). The PC correlated with the antioxidant capacity (R²: 0.59-0.98, p < .05), whereas gallic/caffeic acids were the highest. The apparent permeability coefficients of bioactive compounds (0.62-36.65 × 10^-4 cm/s) and water flux/glucose transport confirmed the model similarity to in vivo experiments. The results suggest that ML digestion dynamically modifies PC/MOS bioaccessibility/antioxidant capacity while most of them are not completely absorbed in the small intestine.