The Physical Adsorption of Gelatinized Starch with Tannic Acid Decreases the Inhibitory Activity of the Polyphenol against α-Amylase

Structural characteristics of cell wall pectic polysaccharides from wampee and their decreased binding with pectinase by wampee polyphenol

To investigate the structural characteristics of cell wall pectic polysaccharides from wampee, water soluble pectin (WSP), chelator-soluble pectin (CSP) and sodium carbonate-soluble pectin (SSP) were purified. And the inhibitory effects of wampee polyphenol (WPP) on pectinase when these cell wall pectic polysaccharides were used as substrates were also explored. Purified WSP (namely PWSP) had the lowest molecular weight (8.47 × 105 Da) and the highest GalA content (33.43%). While purified CSP (called PCSP) and SSP contained more abundant rhamnogalacturonan I side chains. All of them were low-methoxy pectin (DE < 50%). Enzyme activity and kinetics analysis showed that the inhibition of pectinase by wampee polyphenol was reversible and mixed type. When SSP was used as the substrate, WPP had the strongest inhibition (IC50 = 1.96 ± 0.06 mg/mL) on pectinase. Fluorescence quenching results indicated that WPP inhibited enzyme activity by interacting with substrates and enzymes. Therefore, WPP has the application potential in controlling softening of fruits and vegetables.

Effect of polyphenols from Ascophyllum nodosum seaweeds on the rheology and digestion of corn starch gels and gluten-free bread features

The main objective of this work is to study the effect of polyphenols, from the brown seaweed Ascophyllum nodosum, on the structure and digestion behaviour of gels at two corn starch concentrations (1.95 and 5.00% w/w) as well as the structure, color and texture features of crumbs from gluten-free breads. Adsorption isotherms of polyphenols on native and gelled starches were carried out and modelled by means of Langmuir and Henry models, respectively. The formation and characteristics of tested gels were rheologically monitored by means of heating ramp, time sweep at high temperature, cooling ramp and frequency sweep at 25 °C. Elastic modulus values decreased with the presence of polyphenols. Additionally, the polyphenols significantly decreased the digestion rate, measured by both chemical and rheological procedures, and the final concentration of digested starch. Finally, the presence of polyphenols in breads increased the hardness and chewiness values and decreased the cohesiveness and resilience values as well as the crumb hardening during storage.

The changed structures of Cyperus esculentus protein decide its modified physicochemical characters: Effects of ball-milling, high pressure homogenization and cold plasma treatments on structural and functional properties of the protein

Three physical treatments, including ball-milling (BM), high pressure homogenization (HPH) and cold plasma (CP) were applied to modify structural and functional properties of Cyperus esculentus protein (CEP). The results showed that three treatments significantly altered morphology and reduced particle size of CEP. Both primary and secondary structures of CEP were hardly changed, while disulfide bonds and hydrophobic forces between amino acid residues of CEP were interrupted by three treatments, releasing free sulfhydryls and hydrophobic groups. With the free moiety accumulation, the reformed interactions between them enhanced the crystallinity and thermostability of CEP. Besides, solubility and emulsifying properties of CEP were significantly improved within a certain range of treatment duration and intensity, and three treatments decreased water but increased oil holding capacity of CEP. Conclusively, the modified physicochemical properties of CEP were decided by the changed molecular structures of CEP, and different treatments may satisfy different processing requirements for the protein.

Soluble dietary fibres decrease α-glucosidase inhibition of epigallocatechin gallate through affecting polyphenol-enzyme binding interactions

The effects of soluble dietary fibres (SDFs) on α-glucosidase inhibition of EGCG were studied. Three arabinoxylans and polygalacturonic acid (PGA) significantly decreased inhibitory activity of EGCG against α-glucosidase, while two β-glucans hardly affected the inhibition. Although arabinoxylans and PGA weakened the competitive inhibition character of EGCG, they maintained the fluorescence quenching effect of EGCG. Then, arabinoxylans and PGA significantly decreased the particle size and turbidity of EGCG-enzyme complex. These results suggest that there formed SDFs-EGCG-enzyme ternary complexes. The stronger decreasing-effects of arabinoxylans and PGA on α-glucosidase inhibition of EGCG than β-glucans resulted from the stronger non-covalent interactions of arabinoxylans and PGA with EGCG. This is considered to arise from the short-branches of arabinoxylans that provided more opportunity for capturing EGCG, and from the strong polarity of PGA carboxyl that promoted hydrogen bondings with EGCG. Conclusively, SDFs should be considered as an impact factor when evaluating α-glucosidase inhibition of dietary polyphenols.

Interactions between Ascophyllum nodosum Seaweeds Polyphenols and Native and Gelled Corn Starches

The effect of several blending procedures between Ascophyllum nodosum seaweed flour (AF) and corn starch (CS) on the interactions between polyphenols and starch was studied in this paper. These methods comprised the blending of AF with native starch (NT) with previously gelled starch gel (GL) and promoting the gelling of corn starch in the presence of AF (CGL). Different AF-CS (g/g) ratios (from 1:0.5 to 1:25) were studied. The liquid phase was chemically characterized by polyphenols (TPC) and carbohydrates content. The antioxidant activity of the liquid phase after achieving the solid-liquid equilibrium was determined by DPPH, ABTS, and FRAP methods. The solid phase was characterized by FT-IR and SEM techniques. The Halsey model successfully fitted the equilibrium TPC in liquid and polyphenols adsorbed/retained by the solid phase of tested systems. NT samples showed lower polyphenols sorption than gelled samples. The differences found between samples obtained with GL and CGL methods suggested different interactions between polyphenols and starch. Specifically, physisorption is predominant in the case of the GL method, and molecular trapping of polyphenols in the starch gel structure is relevant for the CGL method. Results allowed us to determine the enhancement of the retention of polyphenols to achieve starchy foods with high bioactivity.

α-Amylase Changed the Catalytic Behaviors of Amyloglucosidase Regarding Starch Digestion Both in the Absence and Presence of Tannic Acid

The courses of starch digestion with individual α-amylase (AA), amyloglucosidase (AMG), and AA/AMG bi-enzyme system were performed and analyzed by first-order-reaction equations in the absence and presence of tannic acid (TA). An antagonistic effect between AA and AMG occurred at the digestion phase of readily-digestible starch due to the higher catalytic efficiency of AMG for starchy-substrates with more complex structures. This effect caused a faster rate of glucose production with AMG than with AA/AMG bi-enzyme system at this phase both in the absence and presence of TA. TA had a higher binding affinity to AA than to AMG as accessed by several methods, such as inhibition kinetics, fluorescence quenching, isothermal titration calorimetry (ITC), and molecular docking. Besides, differential scanning calorimetry (DSC) indicated that the change in the thermal and structural stabilities of enzymes in the presence of TA was related to the enzyme residues involved in binding with TA, rather than the inhibitory effects of TA. The binding characters of TA to both enzymes resulted in more “free” AMG without TA binding in AA/AMG bi-enzyme system than that in individual AMG. This binding property caused more and faster rate of glucose production at the digestion phase of slowly digestible starch (SDS) in the bi-enzyme system.

Enhanced Interface Properties and Stability of Lignocellulose Nanocrystals Stabilized Pickering Emulsions: The Leading Role of Tannic Acid

Cellulose and tannin are both abundant and biodegradable biopolymers, whose integrations show great potential in the food field due to their nutritional properties and biological activity. Here, lignocellulose nanocrystals (LCNC) isolated from pineapple peel were complexed with tannic acid (TA) through hydrogen-bonding interaction to prepare the LCNC/TA complex for stabilizing Pickering emulsions. Introducing TA decreased the interfacial tension (23.8-20.1 mN/m) and water contact angle (83.2-56.2°) with the LCNC/TA ratio ranging from 1:0 to 1:0.8 (w/w) but increased the size of the LCNC/TA complex. The droplet size of emulsions decreased from 115.0 to 51.3 μm accompanied by improved rheological properties. The emulsions stabilized by the LCNC/TA complex exhibited higher storage and environmental stabilities than those stabilized by LCNC alone. Interestingly, TA effectively promoted the interfacial adsorption of LCNC to build a stronger interfacial layer. The emulsion network structure was enhanced due to the formation of hydrogen-bonding interaction between LCNC and TA in the continuous phase.

Research on the Consumption Trend, Nutritional Value, Biological Activity Evaluation, and Sensory Properties of Mini Fruits and Vegetables

Mini fruits and vegetables (MFV) are pocket fruits and vegetables whose shape and volume are significantly smaller than those widely sold and well-known normal fruits and vegetables (NFV) on the market. Through the research on the market status and consumption trends of MFV, it was found that MFV have recently become a new market favorite. However, compared with NFV, there was found to be no relevant data on sensory quality, nutritional value, safety, etc. of MFV; this could indicate low consumer awareness of MFV, which in turn affects their planting and sales choices, as well as the market scale remaining small. In this context, six MFV with high degree of marketization were selected and compared with their corresponding NFV to evaluate the nutritional value, biological activity, and sensory properties. The results showed the nutritional value of MFV to be mainly related to their species. The nutritional value of MFV derived from immature, tender vegetables was generally lower than that of mature NFV. For example, the content of zeaxanthin in normal maize was 0.43 mg/kg, which was about 2.87 times that of mini maize (0.15 mg/kg). For newly cultivated mini varieties, their nutritional value often had different trends and rules compared with NFV. The nutritional value obtained by consuming MFV is not equal to that obtained by consuming the corresponding NFV of the same weight.