Interactions of arabinan-rich pectic polysaccharides with polyphenols

Valorizing Lycii fructus waste residue into polysaccharide-rich extracts: Extraction methodologies, physicochemical characterization, in vitro activities and economic feasibility

The high polysaccharide content of Lycii fructus agri-food waste should be reclaimed for value liberation from both environmental and economic perspectives. In this study, waste from L. fructus pigment products was valorized on a bench scale by upcycling into active polysaccharide-rich extracts. The methodological feasibility of polysaccharide recovery from L. fructus waste was evaluated using sequential extraction techniques. Three fractions LFP-30, LFP-100, and LFP-121, were obtained under stepwise increases in temperature and pressure. Highly heterogeneous xyloglucan (XG)-pectin macromolecules composed of linear homogalacturonan (HG) and alternating intra-RG-I-linkers, with topological neutral branches and XG participation, were predominant among the L. fructus polysaccharides (LFPs). Antioxidant activities in LFPs were unaffected by waste resources and severe extraction methodology conditions. Additionally, the direct investment potential of polysaccharide recovery was evaluated for full-scale implementation. This study demonstrated the necessity and feasibility of extracting bioactive polysaccharides with potential applications from L. fructus waste, and provided a sustainable strategy for transforming L. fructus waste disposal problems into value-added products using cost-effective methodologies.

The galactomannan-EGCG physical complex: Effect of branching degree and molecular weight on structural and physiological properties

Polysaccharides and polyphenols are bioactive components that co-exist in many plant foods. Their binary interaction in terms of the structure-function relationships, however, has not been well clarified. This study elucidated the correlation between the structural and physiological properties of galactomannan (GM) -catechin monomer complexes and GM with different branching or molecular weight (Mw). Results indicated that locus bean gum with lower branching degree (Gal/Man is 0.259) bound more readily to EGCG with adsorption rate of 19.42 %. EGCG and ECG containing galloyl groups were more inclined to form hydrogen bonds with GMs, significantly improving the adsorption by GMs. The introduction of EGCG could enhance the antioxidant activity and starch digestion inhibition of GM, which positively correlated with the adsorption capacity of EGCG. The guar gum (GG) with higher Mw (7384.3 kDa) could transport 71.51 % EGCG into the colon, while the retention rate of EGCG reaching the colon alone was only 46.33 %. Conversely, GM-EGCG complex with lower Mw (6.9 kDa) could be readily utilized by gut microbiota, and increased production of short-chain fatty acids (SCFAs). This study elucidated the structure-properties relationship of GM-EGCG complexes, and provide a new idea for the development and precision nutrition of polysaccharides-polyphenol complexes fortified functional foods.

Reducing the oil absorption and oil deterioration in fried apple slices by ultrasound integrated in infrared frying

The effects of integrated ultrasonic infrared frying (USIF) on the oil absorption of apple slices and the oil deterioration were studied with frequency of 28 and 40 kHz, respectively. Results showed that the heat transfer and moisture migration was accelerated by the integrated ultrasound in IF. The soluble Gal-A content and esterification degree of pectin was increased, the damages of pectin crystal structure and chemical structure in side chain was aggravated. These damages to pectin were intensified with higher frequency (40 kHz) of ultrasound. Lower retention of phenols was found in USIF apple slices, but the flavonoids content had no significant change compared to CF samples. USIF samples showed a smoother morphology, and the pore volume and porosity were reduced by ultrasonication applied with 28 kHz but increased with 40 kHz. The largest volume fraction of pores was changed from 100-250 μm in IF to 0.02-10 μm and 10-100 μm by the integrated ultrasound at 28 kHz and 40 kHz samples, respectively. The total oil uptake in USIF samples was reduced by 24.9 %-33.2 % compared to the conventional fried (CF) samples, and achieved the lowest with the frequency of 40 kHz. The surficial and structural oil were also decreased by 39.2 %-51.3 % and 20.9 %-32.3 %, respectively. The peroxide value, acid value, carbonyl value, polar component, and the saturated fatty acids ratio of oil in repeated frying for 16 h was reduced in USIF, especially with ultrasonication 40 kHz. These results indicate that USIF is a promising method for producing novel low-oil apple fries.

The synergistic immunomodulatory activity of Lycium barbarum glycopeptide and isochlorogenic acid A on RAW264.7 cells

BACKGROUND

Regulation of the immune system to maintain homeostasis in the organism has become a focus of research, and the synergistic effect of multi-component complexes will effectively improve the immunomodulatory activity. The present study aimed to investigate the interaction and synergistic immunomodulatory activity of isochlorogenic acid A (IAA) and Lycium barbarum glycopeptide (LbGp).

RESULTS

The results obtained indicated that non-covalent intermolecular interactions were employed to form the LbGp-IAA complex, with a binding ratio of 135.15 mg g-1. The formation of LbGp-IAA complex altered the conformation of LbGp, and IAA was mainly bound to LbGp by van der Waals forces and hydrogen bonds. In addition, LbGp-IAA promoted the proliferation of RAW264.7 cells. The IAA and LbGp interaction had a synergistic effect on the promotion of phagocytosis and the expression of nitric oxide, tumor necrosis faction-α and interleukin-1β, which improved the immunomodulatory effect of LbGp. Furthermore, the combination of LbGp and IAA synergistically inhibited lipopolysaccharide-induced inflammatory response.

CONCLUSION

In summary, the binding of IAA enhanced the immunomodulatory activity of LbGp and coordinated the immune response, and did not trigger an inflammatory response, which was potentially attributed to the alteration of spatial structure of LbGp through the binding of IAA. The results provide new perspectives for the study of glycopeptide-polyphenol interactions. © 2024 Society of Chemical Industry.

Cell wall alterations occurring in an evolved multi-stress tolerant strain of the oleaginous yeast Rhodotorula toruloides

The oleaginous yeast species Rhodotorula toruloides is a promising candidate for applications in circular bioeconomy due to its ability to efficiently utilize diverse carbon sources being tolerant to cellular stress in bioprocessing. Previous studies including genome-wide analyses of the multi-stress tolerant strain IST536 MM15, derived through adaptive laboratory evolution from a promising IST536 strain for lipid production from sugar beet hydrolysates, suggested the occurrence of significant modifications in the cell wall. In this study, the cell wall integrity and carbohydrate composition of those strains was characterized to gain insights into the physicochemical changes associated to the remarkable multi-stress tolerance phenotype of the evolved strain. Compared to the original strain, the evolved strain exhibited a higher proportion of glucomannans, fucogalactomannans, and chitin relative to (1→4)-linked glucans, and an increased presence of glycoproteins with short glucosamine derived oligosaccharides, which have been found to be associated to ethanol stress tolerance and physical strength of the cell wall. Furthermore, the evolved strain cells were found to be significantly smaller than the original strain and more resistant to thermal and mechanical disruption, consistent with higher proportion of beta-linked polymers instead of glycogen, conferring a more rigid and robust cell wall. These findings provide further insights into the cell wall composition of this basidiomycetous red yeast species and into the alterations occurring in a multi-stress tolerant evolved strain. This new information can guide yeast genome engineering towards more robust strains of biotechnological relevance.

Valorisation of Blackcurrant Pomace by Extraction of Pectin-Rich Fractions: Structural Characterization and Evaluation as Multifunctional Cosmetic Ingredient

Blackcurrant pomace is a widely available waste stream derived from the industrial production of juice rich in pectin and unextracted polyphenols. Since pectin, an emerging class of gastrointestinal prebiotics, is also a common cosmetic ingredient, the aim of this work was to evaluate blackcurrant pomace as a source of pectin-rich fractions suitable for application in prebiotic cosmetics. Hereby, this raw material was valorised by sequential extraction of acid-soluble (by citric acid, CAP) and Ca-bound (by ammonium oxalate, AOPP) pectic polysaccharides. Both fractions had favourable physicochemical features and a similar degree of methyl-esterification between low- and high-methoxyl pectin (approx. 50%), but CAP had significantly higher galacturonic acid content (72.3%), branching, and purity. Regardless of that, both had very high oil (18.96 mL/g for CAP and 19.32 mL/g for AOPP) and water (9.97 mL/g for CAP and 7.32 mL/g for AOPP)-holding capacities and excellent emulsifying properties, making them promising cosmetic ingredients. The polyphenol content was 10 times higher in CAP, while corresponding antioxidant activity was 3-fold higher. Finally, the influence of varying CAP and AOPP concentrations on common skin pathogen, Staphylococcus aureus, and beneficial skin bacteria, Staphylococcus epidermidis, was examined. The results show significant prebiotic potential of two pectic fractions since they were capable of selectively stimulating S. epidermidis, while S. aureus growth was inhibited, whereas CAP demonstrated a particularly high capacity of up to 2.2, even with methicillin-resistant S. aureus.

Effects of different extraction methods on the structural and biological properties of Hericium coralloides polysaccharides

In current study, polysaccharides from Hericium coralloides were extracted by heat reflux, acid-assisted, alkali-assisted, enzyme-assisted, ultrasonic-assisted, cold water, pressurized hot water, hydrogen peroxide/ascorbic acid system and acid-chlorite delignification methods, which were named as HRE-P, ACE-P, AAE-P, EAE-P, UAE-P, CWE-P, PHE-P, HAE-P, and ACD-P, respectively. Their physicochemical properties, structural characteristics, and antioxidant activities were investigated and compared. Experimental outcomes indicated notable variations in the extraction yields, chemical compositions, monosaccharide constituents and molecular weights of the obtained nine polysaccharides. HRE-P demonstrated the highest activity against ABTS and OH radicals, CWE-P against ABTS, DPPH, and superoxide radicals, and UAE-P against DPPH radicals. In addition, UAE-P, CWE-P, and HAE-P exhibited better protective effects on L929 cells, when compared to the other obtained polysaccharides. Additionally, correlation analysis indicated that monosaccharide composition and total polyphenol content were two prominent variables influencing the bioactivity of H. coralloides polysaccharides.

The effects of inulin on solubilizing and improving anti-obesity activity of high polymerization persimmon tannin

High polymerization persimmon tannin has been reported to have lipid-lowering effects. Unfortunately, the poor solubility restricts its application. This research aimed to investigate the effect and mechanism of inulin on solubilizing of persimmon tannin. Furthermore, we examined whether the addition of inulin would affect the attenuated obesity effect of persimmon tannin. Transmission electron microscope (TEM), Isothermal titration calorimetry (ITC) and Fourier transform infrared spectroscopy (FT-IR) results demonstrated that inulin formed a gel-like network structure, which enabled the encapsulation of persimmon tannin through hydrophobic and hydrogen bond interactions, thereby inhibiting the self-aggregation of persimmon tannin. The turbidity of the persimmon tannin solution decreased by 56.2 %, while the polyphenol content in the supernatant increased by 60.0 %. Furthermore, biochemical analysis and 16s rRNA gene sequencing technology demonstrated that persimmon tannin had a significant anti-obesity effect and improved intestinal health in HFD-fed mice. Moreover, inulin was found to have a positive effect on enhancing the health benefits of persimmon tannin, including improving hepatic steatosis and gut microbiota dysbiosis. it enhanced the abundance of beneficial core microbes while decreasing the abundance of harmful bacteria. Our findings expand the applications of persimmon tannin in the food and medical sectors.

An in-depth investigation of molecular interaction in zeaxanthin/corn silk glycan complexes and its positive role in hypoglycemic activity

Glycans in corn silk could interact with co-existing small molecules during its absorption, digestion, and biological process. In order to understand the exact mechanism of action of zeaxanthin, it is critical to investigate the biomolecular interactions, which were necessary to form a glycan-small molecule complex and yet produce the bioactive effect. So far, the in-depth study of these natural interactions has not been fully elucidated. Here, we probed that the molecular interaction between zeaxanthin (ZEA) and glycans from corn silk (CSGs) was driven by enthalpy. More importantly, it was the first time found that CSGs can bind to lipid-soluble ZEA could be binded with CSGs. It was the first report on the thermostability of insulin structure and natural glycans. This study should facilitate our understanding of the interaction between lipid soluble molecules and glycans, and provide a more comprehensive understanding of the nutrient base in food.

Fabrication of zein-tamarind seed polysaccharide-curcumin nanocomplexes: their characterization and impact on alleviating colitis and gut microbiota dysbiosis in mice

In this work, a zein-tamarind seed polysaccharide (TSP) co-delivery system was fabricated using an anti-solvent precipitation method. The formation mechanism, characterization, and effect on alleviating colitis and gut microbiota dysbiosis in mice of zein-TSP-curcumin (Z/T-Cur) nanocomplexes were investigated. Hydrogen bonding and the hydrophobic effect played a key role in the formation of Z/T-Cur nanocomplexes, and the interactions were spontaneous and driven by enthalpy. The encapsulation efficiency, loading capacity, and bioavailability increased from 60.8% (Zein-Cur) to 91.7% (Z/T-Cur1:1), from 6.1% (Zein-Cur) to 18.3% (Z/T-Cur1:1), and from 4.7% (Zein-Cur) to 20.0% (Z/T-Cur1:1), respectively. The Z/T-Cur significantly alleviated colitis symptoms in DSS-treated mice. Additionally, the prepared nanocomplexes rebalanced the gut microbiota composition of colitis mice by increasing the abundance of Akkermansia. Odoribacter and Monoglobus were rich in the Z-T-Cur treatment group, and Turicibacter and Bifidobacterium were rich in the zein-TSP treatment group. This study demonstrated that the TSP could be helpful in the targeted drug delivery system.

Multiscale structure changes and mechanism of polyphenol-amylose complexes modulated by polyphenolic structures

This study was designed to investigate the effect of polyphenolic structure on the interaction strength and process between polyphenols (gallic acid (GA), epigallocatechin gallate (EGCG) and tannic acid (TA)) and amylose (AM). The results of Fourier transform infrared spectroscopy, isothermal titration calorimetry, X-ray photoelectron spectroscopy and molecular dynamic simulation (MD) suggested that the interactions between the three polyphenols and AM were noncovalent, spontaneous, low-energy and driven by enthalpy, which would be enhanced with increasing amounts of pyrogallol groups in the polyphenols. The results of turbidity, particle size and appearance of the complex solution showed that the interaction process between polyphenols and AM could be divided into three steps and would be advanced by increasing the number of pyrogallol groups in the polyphenols. At the same time, MD was intuitively employed to exhibit the interaction process between amylose and polyphenols, and it revealed that the interaction induced the aggregation of amylose and that the agglomeration degree of amylose increased with increasing number of pyrogallol groups at polyphenols. Last, the SEM and TGA results showed that TA/AM complexes had the tightest structure and the highest thermal stability (TA/AM˃EGCG/AM˃GA/AM), which could be attributed to TA having five pyrogallol groups.

Antioxidant polysaccharide-enriched fractions obtained from olive leaves by ultrasound-assisted extraction with α-amylase inhibition, and antiproliferative activities

Polysaccharide-rich materials were extracted from the alcohol-insoluble solids of Olea europaea l. **leaves. Structural characteristics were determined by colorimetric techniques, FT-IR, GC-MS, SEC/MALS/VD/DRI, and NMR (1H,13C). The extract and its main macromolecular components were characterized to assess their ability toward antioxidant, α-amylase inhibition, and antiproliferative activities. Results revealed that the ultrasound olive leave extract comprises polysaccharides with uronic acid, galactose, arabinose, and glucose in molar percentages of 11.7%, 11.3%, 7.5%, and 4.9% respectively, constituting 41% of the total mass. In addition, polyphenols (21%) and proteins (9%) are associated with these polysaccharides. Further, the extract showed noticeable ORAC and free radical scavenging abilities, in addition to high in vitro antiproliferative activity against Caco-2 colon carcinoma cell lines. Similarly, the extract exhibited a strong, uncompetitive inhibition of α-amylase by 75% in the presence of the extract with 0.75 µg/mL of concentration. This research concludes that ultrasound extraction method can be used for the extraction of polysaccharide-polyphenol-protein complexes. These conjugates exhibit the potential for combined biological activities resulting from a synergistic effect of its compounds, making them promising ingredients for the development of functional food.

Saccharide branched cellulose with controllable molecular structure and excellent water retention ability

In this work, saccharide branched cellulose (saccharide b-Cel) was synthesized by combining reducing saccharides with cellulose molecules using Ugi four-component reaction (Ugi-4CR). First, the carboxyl groups required for Ugi-4CR are obtained by carboxymethylating cellulose molecules. Then, saccharide b-Cel with a controlled molecular structure is formed when the terminal aldehyde group of reducing saccharides combines with the carboxyl group and auxiliary functional group. The types of saccharides, the degree of substitution of carboxymethyl groups, and the degree of branching all affect the molecular structure of saccharide b-Cel. Through molecular structural regulation, the relationship between the branching structure and water retention ability of saccharide b-Cel was examined in detail. This work not only provides new insights into the synthesis of cellulose derivatives, but it also provides a template for the synthesis of other biomass derivatives.

Non-starch polysaccharides from kidney beans: comprehensive insight into their extraction, structure and physicochemical and nutritional properties

Kidney beans (Phaseolus vulgaris L.) are an important legume source of carbohydrates, proteins, and bioactive molecules and thus have attracted increasing attention for their high nutritional value and sustainability. Non-starch polysaccharides (NSPs) in kidney beans account for a high proportion and have a significant impact on their biological functions. Herein, we critically update the information on kidney bean varieties and factors that influence the physicochemical properties of carbohydrates, proteins, and phenolic compounds. Furthermore, their extraction methods, structural characteristics, and health regulatory effects, such as the regulation of intestinal health and anti-obesity and anti-diabetic effects, are also summarized. This review will provide suggestions for further investigation of the structure of kidney bean NSPs, their relationships with biological functions, and the development of NSPs as novel plant carbohydrate resources.

Development of a cell-based quaternary system to unveil the effect of pectic polysaccharides on oral astringency

Phenolic compounds are responsible for food unpleasant taste properties, including astringency, due to their ability to interact with salivary proteins and oral constituents. Astringency is a crucial attribute for consumer's acceptability. To fulfill the demand for both healthy and tasty food, polysaccharides raise as a good alternative to modulate astringency. In this work, a cell-based quaternary system was developed to evaluate the ability of polysaccharides to reduce the interaction between two classes of hydrolysable tannins - gallotannins (tannic acid) and ellagitannins (punicalagin) - and oral constituents (cells, salivary proteins and mucosal pellicle). So, pectic polysaccharide fractions isolated from grape skins, imidazole soluble polysaccharides (ISP) and carbonate soluble polysaccharides (CSP), as well as a commercial pectin, were tested. Results showed that the polysaccharide's effect depends on the structural features of the molecules involved. CSP fraction and pectin were the most effective, reducing the interactions between both tannins and the oral constituents, mainly in the complete oral model. The highest uronic acid content and the presence of methyl esterified groups could explain their high reduction ability. For tannic acid, the reduction effect increased along with the galloylation degree, while the interaction of β-punicalagin with the oral constituents was practically inhibited at 3.0 mg.mL-1.

Supramolecular study of the interaction between mannoproteins from Torulaspora delbrueckii and flavanols

In this work, three mannoprotein extracts were obtained from T. delbrueckii by enzymatic and chemical treatments. The obtained mannoprotein extracts showed important differences in their molecular weight distribution and monosaccharide composition, although no significant differences were found in their protein content. In order to evaluate the possible influence of mannoprotein characteristics in the interaction with flavanols, mannoprotein-flavanol interactions were studied by HPLC-DAD-MS and ITC. The results obtained indicate that the mannoprotein extracts were able to precipitate flavanols to a different extent. Furthermore, the degree of flavanol precipitation seemed not to be related to the affinity of the interaction but to the type of intermolecular forces. In this sense, a higher proportion of hydrogen bonding could favor a greater crosslinking between aggregates promoting flavanol precipitation. This, in turn, could be related to the MP characteristics since the presence of β-glucan moieties might have an effect on the formation of hydrogen bonds.

Exploring apple pectic polysaccharides: Extraction, characterization, and biological activities - A comprehensive review

Apple (Malus domestica) is a popular and ancient fruit of the Myrtaceae family. Apple fruit is well-known for its great nutritional and phytochemical content consisted of beneficial compounds such as polyphenols, polysaccharides, sterols, and organic acids. Polysaccharides extracted from different parts of the apple fruit, including the peel, pomace, or the whole fruit, have been extensively studied. Researchers have investigated the structural characteristics of these polysaccharides, such as molecular weight, type of monosaccharide unit, type of linkage and its position and arrangement. Besides this, functional properties and physicochemical and of apple polysaccharides have also been studied, along with the effects of extraction procedures, storage, and processing on cell wall polysaccharides. Various extraction techniques, including hot water extraction, enzymatic extraction, and solvent-assisted extraction, have been studied. From the findings, it was evident that apple polysaccharides are mainly composed of (1 → 3), (1 → 6): α-β-glycosidic linkage. Moreover, the apple polysaccharides were demonstrated to exhibit antioxidant, hepatoprotective, anti-cancer, hypoilipidemic, and enzyme inhibitory properties in vitro and in vivo. The potential applications of apple polysaccharides in the food, cosmetic, pharmaceutical, nutraceutical industries have also been explored in the present review. Overall, the research on apple polysaccharides highlights their significant potential as a source of biologically active compounds with various health benefits and practical applications.

Effects of sunflower pectin on thermal stability of purple sweet potato anthocyanins at different pH

The present study aimed to examine the impact of sunflower pectin (SFP) on the thermal stability and antioxidant activity of purple sweet potato anthocyanins (PSPA) at varying pH levels. It was observed that the pH value significantly influenced the ability of pectin to protect anthocyanins from thermal degradation, which was found to be associated with the rate of binding between PSPA and SFP. The binding rate of PSPA-SFP was observed to be highest at pH 4.0, primarily due to the influence of electrostatic interaction and hydrogen bonding. Monoacylated anthocyanins exhibited a binding rate approximately 2-4 % higher than that of diacylated anthocyanins. The PSPA-SFP demonstrated its highest thermal stability at pH 4.0, with a corresponding half-life of 14.80 h at 100 °C. Molecular dynamics simulations indicated that pectin had a greater affinity for the flavylium cation and hemiketal form of anthocyanins. The antioxidant activity of anthocyanins in PSPA and PSPA-SFP increased with increasing pH, suggesting that anthocyanins at high pH had higher antioxidant activity than anthocyanins at low pH.

Lowering glycemic levels via gastrointestinal tract factors: the roles of dietary fiber, polyphenols, and their combination

Dietary fiber (DF) and polyphenols (DP) are typical blood sugar-lowering components, and both play distinct yet interconnected roles in exerting their blood sugar-lowering effects. We comprehensively summarized the single and combined effects of DF and DP on blood glucose homeostasis through regulating the relevant factors in the upper gastrointestinal tract (UGT) and lower gastrointestinal tract (LGT). In the UGT, DF slowed down glucose metabolism by enhancing digesta viscosity and hindering enzyme-substrate interaction. DP primarily targeted enzymes and substrates. When combined, DP enhanced the adsorption capacity of DF for glucose. DF weakened DP's inhibitory effect on enzymes. Both DF and DP disrupted glucose intestinal uptake via physical or genomic modulation, but the co-consumption of DF and DP demonstrated a lower inhibitory effect on glucose uptake than DP alone. In the LGT, DF and DP showed synergistic or antagonistic effects on gut microbiota. Remarkably, whole foods exhibited potent prebiotic effects due to their compound-rich matrix, potentially enhancing glucose homeostasis and expanding dietary options for glucose regulation research.

Polyphenols and polyphenols-based biopolymer materials: Regulating iron absorption and availability from spontaneous to controllable

Iron is an important trace element in the body, and it will seriously affect the body's normal operation if it is taken too much or too little. A large number of patients around the world are suffering from iron disorders. However, there are many problems using drugs to treat iron overload and causing prolonged and unbearable suffering for patients. Controlling iron absorption and utilization through diet is becoming the acceptable, safe and healthy method. At present, many literatures have reported that polyphenols can interact with iron ions and can be expected to chelate iron ions, depending on their types and structures. Besides, polyphenols often interact with other macromolecules in the diet, which may complicate this phenols-Fe behavior and give rise to the necessity of building phenolic based biopolymer materials. The biopolymer materials, constructed by self-assembly (non-covalent) or chemical modification (covalent), show excellent properties such as good permeability, targeting, biocompatibility, and high chelation ability. It is believed that this review can greatly facilitate the development of polyphenols-based biopolymer materials construction for regulating iron and improving the well-being of patients.

Solid-state fermentation with Zygomycetes fungi as a tool for biofortification of apple pomace with γ-linolenic acid, carotenoid pigments and phenolic antioxidants

In the last few years, there has been a growing interest in the more efficient utilization of agricultural and food by-products. Apples are among the most processed fruits in the world that generate huge quantities of processing waste biomasses. Therefore, the objective of this study was to improve the nutritional value of apple pomaces with γ-linolenic acid (GLA) and carotenoid pigments by solid-state fermentation (SSF) using two Zygomycetes fungi (Actinomucor elegans and Umbelopsis isabellina). The impact of fermentation periods on the polyphenol content and antioxidant capacity of the bioprocessed apple pomace was also investigated. The accumulated lipids were composed primarily of neutral fractions (mostly triacylglycerols). SSF with U. isabellina yielded a 12.72% higher GLA content than with A. elegans (3.85 g GLA/kg DW of pomace). Contrary to the lipogenic capacity, A. elegans showed higher carotenoids and phenolic antioxidants productivity than U. isabellina. The maximum concentrations for β-carotene (433.11 μg/g DW of pomace-SSF with A. elegans and 237.68 μg/g DW of pomace-SSF with U. isabellina), lutein (374.48 μg/g DW- A. elegans and 179.04 μg/g DW- U. isabellina) and zeaxanthin (247.35 μg/g DW- A. elegans and 120.41 μg/g DW- U. isabellina) were registered on the 12th day of SSFs. In the case of SSF with A. elegans, the amount of total phenolics increased significantly (27%) by day 4 from the initial value (2670.38 μg of gallic acid equivalents/g DW) before slowly decreasing for the remaining period of the fungal growth. The experimental findings showed that a prolonged fermentation (between 8 and 12 days) should be applied to obtain value-added apple pomaces (rich in GLA and carotenoids) with potential pharmaceutical and functional food applications. Moreover, the SSF processes of simultaneous bioaccumulation of valuable fatty acids, carotenoids and phenolic antioxidants proposed in the present study may open up new challenges for biotechnological production of industrially important biomolecules using abundant and unexploited apple pomaces.

The antioxidant activity of polysaccharides: A structure-function relationship overview

Over the last years, polysaccharides have been linked to antioxidant effects using both in vitro chemical and biological models. The reported structures, claimed to act as antioxidants, comprise chitosan, pectic polysaccharides, glucans, mannoproteins, alginates, fucoidans, and many others of all type of biological sources. The structural features linked to the antioxidant action include the polysaccharide charge, molecular weight, and the occurrence of non-carbohydrate substituents. The establishment of structure/function relationships can be, however, biased by secondary phenomena that tailor polysaccharides behavior in antioxidant systems. In this sense, this review confronts some basic concepts of polysaccharides chemistry with the current claim of carbohydrates as antioxidants. It critically discusses how the fine structure and properties of polysaccharides can define polysaccharides as antioxidants. Polysaccharides antioxidant action is highly dependent on their solubility, sugar ring structure, molecular weight, occurrence of positive or negatively charged groups, protein moieties and covalently linked phenolic compounds. However, the occurrence of phenolic compounds and protein as contaminants leads to misleading results in methodologies often used for screening and characterization purposes, as well as in vivo models. Despite falling in the concept of antioxidants, the role of polysaccharides must be well defined according with the matrices where they are involved.

Soluble polysaccharides decrease inhibitory activity of banana condensed tannins against porcine pancreatic lipase

The inhibition of soluble polysaccharides (SPs) (arabic gum, dextran and pectin from citrus) on the binding between banana condensed tannins (BCTs) and pancreatic lipase (PL) was studied from variant aspects. Molecular docking simulations predicted that BCTs strongly bound SPs and PL through non-covalent interactions. The experimental results showed that SPs reduced the inhibition of BCTs on PL, and the IC₅₀ value increased. However, the addition of SPs did not change the inhibitory type of BCTs on PL, which all were non-competitive inhibition. BCTs quenched PL fluorescence through static quenching mechanism and changed the secondary structure of PL. The addition of SPs alleviated the trending. The effect of SPs on the binding of BCTs-PL was mainly due to the strong non-covalent interaction between SPs and BCTs. This study emphasized that attention should be paid to the counteracting effects of polysaccharides and polyphenols in dietary intake to maximize their respective roles.

The synergistic ramification of insoluble dietary fiber and associated non-extractable polyphenols on gut microbial population escorting alleviation of lifestyle diseases

Most of the pertinent research which aims at exploring the therapeutic effects of polyphenols usually misapprehends a large fraction of non-extractable polyphenols due to their poor aqueous-organic solvent extractability. These polymeric polyphenols (i.e., proanthocyanins, hydrolysable tannins and phenolic acids) possess a unique property to adhere to the food matrix polysaccharides and protein sowing to their structural complexity with high glycosylation, degree of polymerization, and plenty of hydroxyl groups. Surprisingly resistance to intestinal absorption does not hinder its bioactivity but accelerates its functionality manifolds due to the colonic microbial catabolism in the gastrointestinal tract, thereby protecting the body from local and systemic inflammatory diseases. This review highlights not only the chemistry, digestion, colonic metabolism of non-extractable polyphenols (NEPP) but also summarises the synergistic effect of matrix-bound NEPP exerting local as well as systemic health benefits.

Preparation and physicochemical properties characterization of hesperetin-grafted pectin conjugate

Different ratios of hesperetin (HT) were successfully grafted onto pectin from basic water (PB) molecules via free radical-induced reaction. The structure of PB-HT conjugates was characterized by ultraviolet spectroscopy, infrared spectroscopy, X-ray diffraction and scanning electron microscopy. Results indicated that HT was successfully grafted onto pectin molecules, and PB-HT-0.5 showed the highest HT content (103.18 ± 2.76 mg/g). Thermogravimetric analysis indicated that HT crystals showed good thermal resistance and could improve the thermal stability of PB-HT conjugates. Additionally, PB-HT conjugates showed good cytocompatibility and blood compatibility. This study provides a novel and efficient method to synthesize hesperetin-grafted pectin conjugate, which showed potential application in the fields of functional foods in the future.

Focus on the relationships between the cell wall composition in the extraction of anthocyanins and tannins from grape berries

Concentrations of anthocyanins and tannins after extraction from berries in wines and from skin macerations in model solutions have been studied for two grape varieties, two maturation levels and two vintages berries. Characterization of the cell wall polysaccharides has also been performed, the classical method based on the analysis of the neutral sugars after depolymerization being completed by a comprehensive microarray polymer profiling (CoMPP). Extraction was lower in model solutions than in wines, with the same ranking: non acylated anthocyanins> tannins > p-coumaroylated anthocyanins. The polysaccharidic composition suggested a role of homogalacturonans, rhamnogalacturonans and extensins in the extraction process. A global explanation of the interactions between anthocyanins, tannins and polysaccharides is proposed.

Correlation between Mechanical and Morphological Properties of Polyphenol-Laden Xanthan Gum/Poly(vinyl alcohol) Composite Cryogels

This study aimed to evaluate the effect of the synthesis parameters and the incorporation of natural polyphenolic extract within hydrogel networks on the mechanical and morphological properties of physically cross-linked xanthan gum/poly(vinyl alcohol) (XG/PVA) composite hydrogels prepared by multiple cryo-structuration steps. In this context, the toughness, compressive strength, and viscoelasticity of polyphenol-loaded XG/PVA composite hydrogels in comparison with those of the neat polymer networks were investigated by uniaxial compression tests and steady and oscillatory measurements under small deformation conditions. The swelling behavior, the contact angle values, and the morphological features revealed by SEM and AFM analyses were well correlated with the uniaxial compression and rheological results. The compressive tests revealed an enhancement of the network rigidity by increasing the number of cryogenic cycles. On the other hand, tough and flexible polyphenol-loaded composite films were obtained for a weight ratio between XG and PVA of 1:1 and 10 v/v% polyphenol. The gel behavior was confirmed for all composite hydrogels, as the elastic modulus (G') was significantly greater than the viscous modulus (G″) for the entire frequency range.

Structure-function relationships of pectic polysaccharides from broccoli by-products with in vitro B lymphocyte stimulatory activity

To study structure-function relationships of pectic polysaccharides with their immunostimulatory activity, broccoli by-products were used. Pectic polysaccharides composed by 64 mol% uronic acids, 18 mol% Ara, and 10 mol% Gal, obtained by hot water extraction, activated B lymphocytes in vitro (25-250 μg/mL). To disclose active structural features, combinations of ethanol and chromatographic fractionation and modification of the polysaccharides were performed. Polysaccharides insoluble in 80 % ethanol (Et80) showed higher immunostimulatory activity than the pristine mixture, which was independent of molecular weight range (12-400 kDa) and removal of terminal or short Ara side chains. Chemical sulfation did not promote B lymphocyte activation. However, the action of pectin methylesterase and endo-polygalacturonase on hot water extracted polysaccharides produced an acidic fraction with a high immunostimulatory activity. The de-esterified homogalacturonan region seem to be an important core to confer pectic polysaccharides immunostimulatory activity. Therefore, agri-food by-products are a source of pectic polysaccharide functional food ingredients.

Synchronous Extraction, Antioxidant Activity Evaluation, and Composition Analysis of Carbohydrates and Polyphenols Present in Artichoke Bud

This study investigated the optimization of ultrasonic-assisted aqueous two-phase synchronous extraction of carbohydrates and polyphenols present in artichoke bud, evaluated their antioxidant activities in vitro, and analyzed the composition of carbohydrates and polyphenols by high-performance liquid chromatography (HPLC). The powder mass, ultrasonic time, ammonium sulfate concentration, and alcohol-water ratio were considered the influencing factors based on the single-factor experiment results, and a dual-response surface model was designed to optimize the synchronous extraction process to extract carbohydrates and polyphenols. The antioxidant activity was evaluated by measuring the scavenging capacity of ABTS⁺· and DPPH· and the reducing capacity of Fe³⁺. The optimal process conditions in this study were as follows: the powder mass of 1.4 g, ammonium sulfate concentration of 0.34 g/mL, alcohol-water ratio of 0.4, and ultrasonic time of 43 min. The polyphenol content in artichoke bud was 5.32 ± 0.13 mg/g, and the polysaccharide content was 74.78 ± 0.11 mg/g. An experiment on in vitro antioxidant activity showed that both carbohydrates and polyphenols had strong antioxidant activities, and the antioxidant activity of polyphenols was stronger than that of carbohydrates. The HPLC analysis revealed that the carbohydrates in artichoke bud were mannose, rhamnose, glucuronic acid, galacturonic acid, glucose, galactose, and arabinose, and the molar ratio was 10.77:25.22:2.37:15.74:125.39:48.62:34.70. The polyphenols comprised chlorogenic acid, 4-dicaffeoylquinic acid, caffeic acid, 1,3-dicaffeoylqunic acid, isochlorogenic acid B, isochlorogenic acid A, cynarin, and isochlorogenic acid C, and the contents were 0.503, 0.029, 0.022, 0.017, 0.008, 0.162, 1.621, 0.030 mg/g, respectively. This study also showed that the carbohydrates and polyphenols in artichoke bud could be important natural antioxidants, and the composition analysis of HPLC provided directions for their future research. Carbohydrates and polyphenols in artichoke buds can be separated and enriched using the optimized process technology, and it is an effective means of extracting ingredients from plants.

Complexation of soybean protein isolate with β-glucan and myricetin: Different affinity on 7S and 11S globulin by QCM-D and molecular simulation analysis

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The ternary complex of SPI, β-glucan and myricetin was prepared, and the interaction mechanism was studied.

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QCM-D was used to explore the binding affinity of 7S and 11S to β-glucan and myricetin.

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Molecular docking analysis indicated that 11S protein has a stronger binding capacity compared with 7S.

The complexation of soybean protein isolate (SPI) with β-glucan (DG) and myricetin (MC) was focused in this study. UV-Vis, circular dichroism and 3D fluorescence analysis jointly proved that interaction with DG and MC altered the structures of SPI, whose β-sheet decreased to 29 % and random coil increased to 35 %, respectively. Moreover, the microenvironment of tryptophan and tyrosine from protein were changed. The ternary complex performed a different molecular weight distribution, showing a larger molecular weight of 1.17×10⁶ g/mol compared with SPI verified by gel permeation chromatography (GPC). And it was further evidenced by Quartz Crystal Microbalance with Dissipation (QCM-D) and molecular docking that glycinin (11S) possessed a better affinity toward DG and MC compared with β-conglycinin (7S), which indicated stronger binding ability through hydrogen bonds. The successful preparation of SPI-DG-MC complex will advance the application of soybean resource as a functional food ingredient.

An updated review on the stability of anthocyanins regarding the interaction with food proteins and polysaccharides

The health benefits of anthocyanins are compromised by their chemical instability and susceptibility to external stress. Researchers found that the interaction between anthocyanins and macromolecular components such as proteins and polysaccharides substantially determines the stability of anthocyanins during food processing and storage. The topic thus has attracted much attention in recent years. This review underlines the new insights gained in our current study of physical and chemical properties and functional properties in complex food systems. It examines the interaction between anthocyanins and food proteins or polysaccharides by focusing on the "structure-stability" relationship. Furthermore, multispectral and molecular computing simulations are used as the chief instruments to explore the interaction's mechanism. During processing and storage, the stability of anthocyanins is generally influenced by the adverse characteristics of food and beverage, including temperature, light, oxygen, enzymes, pH. While the action modes and types between protein/polysaccharide and anthocyanins mainly depend on their structures, the noncovalent interaction between them is the key intermolecular force that increases the stability of anthocyanins. Our goal is to provide the latest understanding of the stability of anthocyanins under food processing conditions and further improve their utilization in food industries. Practical Application: This review provides support for the steady-state protection of active substances.

Functional implications of bound phenolic compounds and phenolics-food interaction: A review

Sizeable scientific evidence indicates the health benefits related to phenolic compounds and dietary fiber. Various phenolic compounds-rich foods or ingredients are also rich in dietary fiber, and these two health components may interrelate via noncovalent (reversible) and covalent (mostly irreversible) interactions. Notwithstanding, these interactions are responsible for the carrier effect ascribed to fiber toward the digestive system and can modulate the bioaccessibility of phenolics, thus shaping health-promoting effects in vivo. On this basis, the present review focuses on the nature, occurrence, and implications of the interactions between phenolics and food components. Covalent and noncovalent interactions are presented, their occurrence discussed, and the effect of food processing introduced. Once reaching the large intestine, fiber-bound phenolics undergo an intense transformation by the microbial community therein, encompassing reactions such as deglycosylation, dehydroxylation, α- and β-oxidation, dehydrogenation, demethylation, decarboxylation, C-ring fission, and cleavage to lower molecular weight phenolics. Comparatively less information is still available on the consequences on gut microbiota. So far, the very most of the information on the ability of bound phenolics to modulate gut microbiota relates to in vitro models and single strains in culture medium. Despite offering promising information, such models provide limited information about the effect on gut microbes, and future research is deemed in this field.

Hohenbuehelia serotina polysaccharides self-assembled nanoparticles for delivery of quercetin and their anti-proliferative activities during gastrointestinal digestion in vitro

In this study, the self-assembled nanoparticles based on Hohenbuehelia serotina polysaccharides (QC-HSP NPs) were fabricated to encapsulate quercetin for improving its bioavailability. The structural characteristics, physicochemical properties as well as the cytotoxicity activities of QC-HSP NPs during gastrointestinal digestion in vitro were respectively investigated. The results showed that QC-HSP NPs possessed the spherical and smooth surface morphology, with the average particle size of 360 nm and zeta potential of -38.8 mV. Moreover, QC-HSP NPs had excellent physiochemical stabilities, and presented sustained-release characteristics during gastrointestinal digestion in vitro. Compared with undigested ones, QC-HSP NPs after gastrointestinal digestion exhibited the more significant anti-proliferative activity on HeLa cells through accumulation of intracellular ROS, arrest of cell cycle at G2/M phase by regulation of cyclin B1, CDK1, p53 and p21 and induction of apoptosis by ER apoptosis pathway. This study provides a new strategy for designing quercetin-loaded nanoparticles based on natural polysaccharides to improve the bioavailability of quercetin.

Polyphenol-Polysaccharide Complex: Preparation, Characterization and Potential Utilization in Food and Health

Polysaccharides and polyphenols coexist in many plant-based food products. Polyphenol-polysaccharide interactions may affect the physicochemical, functional, and physiological properties, such as digestibility, bioavailability, and stability, of plant-based foods. In this review, the interactions (physically or covalently linked) between the selected polysaccharides and polyphenols are summarized. The preparation and structural characterization of the polyphenol-polysaccharide conjugates, their structural-interaction relationships, and the effects of the interactions on functional and physiological properties of the polyphenol and polysaccharide molecules are reviewed. Moreover, potential applications of polyphenol-polysaccharide conjugates are discussed. This review aids in a comprehensive understanding of the synthetic strategy, beneficial bioactivity, and potential application of polyphenol-polysaccharide complexes. Expected final online publication date for the Annual Review of Food Science and Technology, Volume 13 is March 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Effect of dietary fiber addition on the content and in vitro bioaccessibility of antioxidants in red raspberry puree

The aim of the present study was to understand how the addition of pectin (2.5% and 5%) affected the content and bioaccessibility of phenolics in red raspberry puree. The results showed that the concentration of antioxidants in red raspberry puree was reduced with the addition of pectin. Similarly, addition of pectin to red raspberry puree significantly reduced the total phenolic content (15-20%), total antioxidant capacity (18-70%), and total monomeric anthocyanin (25-30%) after in vitro digestion. On the other hand, significant decreases in the bioaccessible amount of cyanidin (41%), cyanidin-3-glucoside (14%), cyanidin-3-rutinoside (17%), pelargonidin 3-glucoside (16%), and peonidin (28%) were observed after the addition of pectin (5% (w/w)) compared to the control (p < 0.05) as analyzed with the HPLC method. According to the LC-MS/MS analysis of red raspberry samples, five flavonoids (rutin, quercetin, kaempferol, myricetin, and phlorizin) and six phenolic acids (gallic acid, caffeic acid, chlorogenic acid, sinapic acid, p-coumaric acid, and ferulic acid) were detected. The effect of in vitro gastrointestinal digestion varied depending on the type of the phenolic compounds. Sinapic acid and phlorizin were not detected at all in the intestinal phase, indicating that they were completely degraded during digestion. The percentage bioaccessibility of gallic acid (49-88%), rutin (6-16%), and quercetin (23-33%) was decreased proportionally with the increase in the pectin content in red raspberry purees (p < 0.05). On the other hand, only 5% pectin addition to red raspberry puree resulted with a significant decrease in the amount of bioaccessible caffeic acid (8% to 5%), kaempferol (24% to 13%), ferulic acid (26% to 10%), and myricetin (91% to 57%) (p < 0.05). Overall, the present study highlighted that incorporation of pectin to red raspberry puree reduced the amount of bioaccessible polyphenols.

Influence of polysaccharide concentration on polyphenol-polysaccharide interactions

Non-covalent interactions between polysaccharides and phenolics affect the physical properties of polysaccharide solutions. These interactions may in turn be influenced by polysaccharide-polysaccharide interactions. To test this hypothesis, we studied the influence of polysaccharide concentration (with guar, β-glucans, and xanthan) on the variations of rheological and water-binding properties upon addition of phenolics compounds (vanillin, caffeic acid, gallic acid, and epigallocatechin gallate). Addition of phenolics led to increased flow behavior index and decreased flow consistency index, with maximum effects at polysaccharide concentrations ranging between 0.6 × C* and 1.4 × C*, where C* is the critical overlap concentration of each polysaccharide. Water mobility was generally not significantly influenced by the addition of phenolics. The results showed that the ability of phenolic compounds to induce aggregation of polysaccharides in solution was strongly influenced by polysaccharide concentration around C* and therefore by polysaccharide-polysaccharide interactions.

Recent advances in interactions between polyphenols and plant cell wall polysaccharides as studied using an adsorption technique

Polyphenols include flavonoids, phenolic acids, tannins and lignans which are known to have antioxidant, UV protection and antimicrobial properties. Among them the most commonly investigated are flavonoids and phenolic acids, which, due to their plant origin, may interact with the plant cell wall (PCW) components, specifically with its polysaccharides. Knowledge concerning the nature of the interactions between these components may be used in the production of functional food or in the development of food packaging materials with additional properties. The content of polyphenols in such products is responsible for their colour and taste, and may also act as a natural preservative. On the other hand, the PCW components may have protective role of polyphenols which has impact on their release in the human digestive system. Therefore, this review is an attempt to summarize the current state of knowledge that emerged after 2017 concerning the interaction of PCW components with polyphenols, with a particular focus on hemicellulose and pectin.

Co-extruded wheat/okra composite blends result in soft, cohesive and resilient crumbs rich in health-promoting compounds

This work investigates the partial solubilization of cell wall polysaccharides in okra flours and the changes in the profile of free and bound phenolics through twin-screw extrusion. The comparison between extruded wheat flour-native okra flour (EWF-OF) and extruded wheat flour-extruded okra flour (EWF-EOF) composite blends revealed that extrusion led to an increase of soluble dietary fiber from 7.76 to 10.02 g/100 g. Extrusion of okra also resulted in a significant increase of free and bound phenolic acids, the latter consisting mostly of ferulic acid, as well as the thermal degradation of free epigallocatechin, and the binding of a small portion of quercetin-3-O-glucoside likely to a carbohydrate fraction. Bread crumbs from EWF-EOF (at 15% replacement level) exhibited a significantly lower hardness and higher elasticity, cohesiveness and resilience (from 28.28 N, 0.94, 0.49 and 0.17 to 7.54 N, 0.99, 0.70 and 0.35, respectively), which closely resembled the textural attributes of wheat bread.

Recent advances on bioactive polysaccharides from mulberry

Mulberry (Moraceae family), commonly considered as a folk remedy, has a long history of usage in many regions of the world. Polysaccharides regarded as one of the major components in mulberry plants, and they possess antioxidant, antidiabetic, hepatoprotective, prebiotic, immunomodulatory and antitumor properties, among others. In recent decades, mulberry polysaccharides have been widely studied for their multiple health benefits and potential economic value. However, there are few reviews providing updated information on polysaccharides from mulberry. In this review, recent advances in the study of isolation, purification, structural characterization, biological activity and the structure-activity relationship of mulberry polysaccharides are summarized and discussed. Furthermore, a thorough analysis of the current trends and perspectives on mulberry polysaccharides is also proposed. Hopefully, these findings can provide a useful reference value for the development and application of natural polysaccharides in the field of functional food and medicine in the future.

Extrusion Processing of Pure Chokeberry (Aronia melanocarpa) Pomace: Impact on Dietary Fiber Profile and Bioactive Compounds

The partial substitution of starch with dietary fiber (DF) in extruded ready-to-eat texturized (RTE) cereals has been suggested as a strategy to reduce the high glycemic index of these food products. Here, we study the impact of extrusion processing on pure chokeberry (Aronia melanocarpa) pomace powder (CPP) rich in DF and polyphenols (PP) focusing on the content and profile of the DF fractions, stability of PP, and techno-functional properties of the extrudates. Using a co-rotating twin-screw extruder, different screw speeds were applied to CPP with different water contents (cw), which resulted in specific mechanical energies (SME) in the range of 145-222 Whkg-1 and material temperatures (TM) in the range of 123-155 °C. High molecular weight soluble DF contents slightly increase with increasing thermomechanical stress up to 16.1 ± 0.8 g/100 g dm as compared to CPP (11.5 ± 1.2 g/100 g dm), but total DF (TDF) contents (58.6 ± 0.8 g/100 g dm) did not change. DF structural analysis revealed extrusion-based changes in the portions of pectic polysaccharides (type I rhamnogalacturonan) in the soluble and insoluble DF fractions. Contents of thermolabile anthocyanins decrease linearly with SME and temperature from 1.80 ± 0.09 g/100 g dm in CPP to 0.24 ± 0.06 g/100 g dm (222 Whkg-1, 155 °C), but phenolic acids and flavonoids appear to be largely unaffected. Resulting techno-functional (water absorption and water solubility) and physical properties related to the sensory characteristics (expansion, hardness, and color) of pure CPP extrudates support the expectation that granulated CPP extrudates may be a suitable food ingredient rich in DF and PP.

Bean phenolic compound changes during processing: Chemical interactions and identification

The common bean (Phaseolus vulgaris L.) represents one of the main crops for human consumption, due to its nutritional and functional qualities. Phenolic compounds have beneficial health effects, and beans are an essential source of these molecules, being found mainly in the seed coat and its color depends on the concentration and type of phenolic compounds present. The bean during storage and processing, such as cooking, germination, extrusion, and fermentation, undergoes physical, chemical, and structural changes that affect the bioavailability of its nutrients; these changes are related to the interactions between phenolic compounds and other components of the food matrix. This review provides information about the identification and quantification of phenolic compounds present in beans and the changes they undergo during processing. It also includes information on the interactions between the phenolic compounds and the components of the bean's cell wall and the analytical methods used to identify the interactions of phenolic compounds with macromolecules.