Interactions between Blackcurrant Polyphenols and Food Macronutrients in Model Systems: In Vitro Digestion Studies

Cooking methods determine chemical composition and functional properties of squash blossoms: A study of microstructural and bioaccessibility changes

This research aimed to evaluate the effect of different cooking methods (boiling, stir-frying, and steaming) on the microstructure, moisture, fat, protein, and glucose-derived carbohydrate contents, and the bioactive compounds (total carotenoids: CAR, total chlorophyll: CHLO, and total phenolic compounds: TPC) and antioxidant capacity (AC) of squash blossoms. Furthermore, we characterized polyphenolic compounds using HPLC and evaluated their bioaccessibility via in vitro digestions. Our results show that steaming and boiling do not affect moisture content. Only stir-frying decreased (p < 0.05) this parameter by 8 %. Additionally, the cooking methods increased (p < 0.05) protein and glucose-derived carbohydrate contents. All cooking methods changed the microstructure of the blossoms, probably due to the thermal and mechanical variations that result in moisture loss and degradation of cell wall components. As for the functional properties, boiling caused a greater loss of TPC (up to 96 %) and AC (up to 91 %). Stir-frying caused the greatest loss of CAR (up to 81 %) and CHLO (up to 84 %). The in vitro digestion assays showed changes in the bioaccessibility of CAR, CHLO, TPC, and AC in the cooked flowers compared to the fresh ones. Finally, kaempferol and gallic acid were the most resistant polyphenols to the cooking methods and in vitro digestion.

Preferential Binding of Polyphenols in Blackcurrant Extracts with Milk Proteins and the Effects on the Bioaccessibility and Antioxidant Activity of Polyphenols

Milk proteins are well-known delivery agents; however, there is no clear understanding of the competitive interactions of milk proteins with polyphenols in mixed complex systems. Here, we investigate the preferential competitive interactions of different polyphenols present in blackcurrant extract with milk proteins by quantifying the protein-bound polyphenols and comparing the factors affecting these interactions. In addition, bioaccessibility and antioxidant activity were studied after in vitro gastric digestion. Our results indicated that polyphenols from blackcurrant extracts were preferentially bound to caseins more than whey proteins, with noncovalent interactions causing secondary structural changes in the protein. The hydrophobicity and the charge of the polyphenols were negatively and positively related to the number of polyphenols bound to casein and whey proteins, respectively. Moreover, the bioaccessibility and antioxidant activity of polyphenols were enhanced in the presence of milk proteins in milk-based blackcurrant samples when compared to polyphenol and protein-alone samples in the in vitro gastric phase. These findings underscore the critical role of milk proteins in encapsulating or delivering polyphenols. This will pave the way for boosting the bioavailability of polyphenols by complexing them with milk proteins and formulating functional dairy foods, integrating the beneficial effects of these compounds.

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.

Complexation of starch and phenolic compounds during food processing and impacts on the release of phenolic compounds

Phenolic compounds can form complexes with starch during food processing, which can modulate the release of phenolic compounds in the gastrointestinal tract and regulate the bioaccessibility of phenolic compounds. The starch-phenolic complexation is determined by the structure of starch, phenolic compounds, and the food processing conditions. In this review, the complexation between starch and phenolic compounds during (hydro)thermal and nonthermal processing is reviewed. A hypothesis on the complexation kinetics is developed to elucidate the mechanism of complexation between starch and phenolic compounds considering the reaction time and the processing conditions. The subsequent effects of complexation on the physicochemical properties of starch, including gelatinization, retrogradation, and digestion, are critically articulated. Further, the release of phenolic substances and the bioaccessibility of different types of starch-phenolics complexes are discussed. The review emphasizes that the processing-induced structural changes of starch are the major determinant modulating the extent and manner of complexation with phenolic compounds. The controlled release of complexes formed between phenolic compounds and starch in the digestive tracts can modify the functionality of starch-based foods and, thus, can be used for both the modulation of glycemic response and the targeted delivery of phenolic compounds.

Gelatin Improves the Performance of Oregano Essential Oil Nanoparticle Composite Films-Application to the Preservation of Mullet

In this study, the addition of oregano oil chitosan nanoparticles (OEO-CSNPs) was conducted to enhance the comprehensive properties of gelatin films (GA), and the optimal addition ratio of nanoparticles was determined for its application in the preservation of mullet. Oregano oil chitosan nanoparticles were organically combined with gelatin at different concentrations (0%, 2%, 4%, 6% and 8%) to obtain oregano oil-chitosan nanoparticle-GA-based composite films (G/OEO-CSNPs), and thereafter G/OEO-CSNPs were characterized and investigated for their preservative effects on mullet. Subsequent analysis revealed that OEO-CSNPs were uniformly dispersed in the GA matrix, and that G/OEO-CSNPs had significantly improved mechanical ability, UV-visible light blocking performance and thermal stability. Furthermore, the nanoparticles exhibited excellent antioxidant and antibacterial properties, and they improved the films' suitability as edible packaging. The attributes of the G/OEO-CSNPs were optimized, the films had the strongest radical scavenging and lowest water solubility, and electron microscopy also showed nanoparticle penetration into the polymer when the concentration of OEO-CSNPs was 6% (thickness = 0.092 ± 0.001, TS = 47.62 ± 0.37, E = 4.06 ± 0.17, water solubility = 48.00 ± 1.11). Furthermore, the GA-based composite film containing 6% OEO-CSNPs was able to inhibit microbial growth, slow fat decomposition and protein oxidation, reduce endogenous enzyme activity, and delay the spoilage of mullet during the refrigeration process, all of which indicate its excellent potential for meat preservation application.

Antioxidant and Antidiabetic Properties of Phlorotannins from Ascophyllum nodosum Seaweed Extracts

Seaweeds have gained considerable attention in recent years due to their potential health benefits and high contents of bioactive compounds. This review focuses on the exploration of seaweed's health-promoting properties, with particular emphasis on phlorotannins, a class of bioactive compounds known for their antioxidant and antidiabetic properties. Various novel and ecofriendly extraction methods, including solid-liquid extraction, ultrasound-assisted extraction, and microwave-assisted extraction are examined for their effectiveness in isolating phlorotannins. The chemical structure and isolation of phlorotannins are discussed, along with methods for their characterization, such as spectrophotometry, nuclear magnetic resonance, Fourier transform infrared spectroscopy, and chromatography. Special attention is given to the antioxidant activity of phlorotannins. The inhibitory capacities of polyphenols, specifically phlorotannins from Ascophyllum nodosum against digestive enzymes, such as α-amylase and α-glucosidase, are explored. The results suggest that polyphenols from Ascophyllum nodosum seaweed hold significant potential as enzyme inhibitors, although the inhibitory activity may vary depending on the extraction conditions and the specific enzyme involved. In conclusion, seaweed exhibits great potential as a functional food ingredient for promoting health and preventing chronic diseases. Overall, this review aims to condense a comprehensive collection of high-yield, low-cost, and ecofriendly extraction methods for obtaining phlorotannins with remarkable antioxidant and antidiabetic capacities.

Wheat Starch Modified with Ligustrum robustum (Rxob.) Blume Extract and Its Action Mechanism

We investigated the modification of wheat starch with Ligustrum robustum (Rxob.) Blume extract (LRE) and determined the action mechanism. Based on differential scanning calorimetry, LRE decreased the gelatinization enthalpy of wheat starch from 19.14 to 7.15 J/g and changed gelatinization temperatures (including the variation in gelatinization onset temperature, peak temperature and conclusion temperature in different degrees). Moreover, LRE affected the pasting viscosity curve of wheat starch, and changed its rheological parameters (including the decrease in storage modulus and loss modulus, as well as the increase in loss tangent). Based on the analysis of scanning electron microscopy and wide-angle X-ray diffraction, LRE increased the hole size and the roughness of the gel microstructure, and decreased the crystallinity of wheat starch. Meanwhile, the evaluation results of the texture analyzer and the colorimeter showed that LRE could change the quality properties (including decrease hardness, fracturability and L* values, as well as increase a* and b* values) of wheat starch biscuits after hot air baking (170 °C). Furthermore, with molecular dynamics simulation analysis, phenolic compounds of LRE combined with starch molecules via H-bonds and affected the formation of molecular bonds (including intra- and intermolecular hydrogen bonds), so as to change the spatial conformation and properties of wheat starch during gelatinization and retrogradation. The present results suggest that LRE can modify the physicochemical properties of wheat starch and further improve its processing properties, indicating its potential in the design and development of starch foods (such as steamed buns, bread, biscuits, etc.).

Hawthorn Juice Simulation System for Pectin and Polyphenol Adsorption Behavior: Kinetic Modeling Properties and Identification of the Interaction Mechanism

The interaction between polyphenols and polysaccharides plays an important role in increasing the turbidity stability of fruit juice and improving unpleasant sensory experiences. The binding adsorption behavior between hawthorn pectin (HP) and polyphenols (epicatechin and chlorogenic acid) accorded with the monolayer adsorption behavior driven by chemical action and were better fitted by pseudo-second order dynamic equation and Langmuir model. The HP binding sites (Qm) and adsorption capacity (Qe) to epicatechin were estimated at 75.188 and 293.627 μg/mg HP, respectively, which was about nine and twelve times higher than that of chlorogenic acid. The interaction between HP and polyphenols exhibited higher turbidity characteristics, particle size and lower zeta potential than epicatechin and chlorogenic acid alone. Meanwhile, according to Fourier Transform Infrared Spectroscopy (FT-IR) analysis, it could be speculated that the interaction between HP and polyphenols resulted in chemical combination. Moreover, ΔH < 0 and TΔS < 0, which indicated that the interaction between HP and polyphenols was mainly driven by hydrogen bonds and van der Waals forces.

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.

Influence of Carboxymethyl Cellulose on the Stability, Rheological Property, and in-vitro Digestion of Soy Protein Isolate (SPI)-Stabilized Rice Bran Oil Emulsion

In this study, carboxymethyl cellulose (CMC) was added to soybean protein isolate (SPI)-stabilized rice bran oil (RBO) emulsion to improve its physicochemical stability and free fatty acid (FFA) release characteristics. RBO emulsions stabilized by SPI and various contents of CMC were prepared and assessed by measuring zeta potential, particle size, transmission, and microstructure, the rheological properties were analyzed by dynamic shear rheometer. In addition, its chemical stability was characterized by a storage experiment, and the FFA release was explored by a simulated gastrointestinal tract (GIT) model. It showed that the negative charge of the droplets of RBO emulsion was increased with increasing CMC content. The decrease in transmission of SPI-stabilized RBO emulsion with increasing CMC content was due to the droplets not being free to move by the special network interaction and an increase in the viscosity. According to the determination of the reactive substances of lipid hydroperoxide and thiobarbituric acid during 30 days storage at 37°C, the chemical stability of the emulsion added with CMC was enhanced compared with the SPI-stabilized RBO emulsion. In-vitro digestion studies not only evaluated the structural changes of RBO emulsions at different stages, but also found that RBO emulsion with CMC showed a higher level of free fatty acids release in comparison with that without CMC. It indicated that the utilization of CMC can improve the bioavailability of RBO emulsions.

Use of Oleogels to Replace Margarine in Steamed and Baked Buns

Bakery products are usually formulated with solid fats, like margarines and shortenings, which contain high levels of saturated and trans-fatty acids and have negative effects on human health. In this study, hydroxypropyl methylcellulose (HPMC) and xanthan gum (XG) were used as oleogelators to prepare oleogels, using sunflower and olive oil, as substitutes for margarine in baked or steamed buns. The effect of oleogels on the physical properties of the buns was evaluated by analyzing the crumb structure, specific volume, height, and texture. In addition, a triangular discriminatory sensory test was conducted, and lipid digestibility was assessed through in vitro digestion studies. Replacement of margarine with oleogels produced steamed buns with no differences in the crumb structure, volume, height, and texture; however, in baked buns, a less porous and harder structure was produced. No differences in texture were observed between the margarine buns and buns made with oleogels when the triangular test was conducted. The extent of lipolysis was not affected when margarine was replaced by oleogels in the baked and steamed buns. The results suggest that using oleogels instead of margarine in buns could represent an interesting strategy to prepare healthier bakery products.