Resistant starch formation through intrahelical V-complexes between polymeric proanthocyanidins and amylose

The Procyanidin C1-Dependent Inhibition of the Hydrolysis of Potato Starch and Corn Starch Induced by Pancreatin

Procyanidins are contained in various foods, and their effects on starch hydrolysis have been reported. In Japan, black soybeans, which contain a trimeric procyanidin, procyanidin C1 (proC1), are cooked with rice and used to prepare dumplings. In this study, the effects of proC1 on the pancreatin-induced formation of reducing sugars and starch hydrolysis were studied using potato starch and corn starch. ProC1 inhibited both reactions; the inhibition was greater in potato starch than corn starch when added to heated potato starch and corn starch. When heated with proC1, its inhibitory effects decreased, especially in potato starch, suggesting the important role of proC1 itself for the inhibition of potato starch hydrolysis. ProC1 also inhibited the hydrolysis when added to heated, longer amylose (average molecular weight: 31,200), and the inhibition decreased when heated with the amylose. On the other hand, proC1 could not inhibit the hydrolysis when added to heated, shorter amylose (average molecular weight: 4500), but could when heated with the amylose, suggesting the important role of the degradation products of proC1 for the inhibition. We discuss the mechanism of the proC1-dependent inhibition of amylose hydrolysis, taking the molecular weight into account.

Recent Progress on Improving the Quality of Bran-Enriched Extruded Snacks

The incorporation of milling by-products, in particular bran, into starch-based extruded snacks allows manufacturers to address two consumer demands at once, i.e., those for goods that are more sustainably produced and of higher nutritional value. However, the higher fiber content in bran than in refined cereal flours poses a limit to the amount that can be included without compromising the quality of extruded snacks, which crucially depends on expansion. Thus, several studies have focused on the effect of bran on the physicochemical characteristics of extruded snacks, leading to the need to review the recent findings in this area. Opportunities, challenges, and potential solutions of bran-enriched snacks are addressed, and several current knowledge gaps are highlighted. Specifically, the first part of the review presents the effects of extrusion cooking on bran's compositional aspects, focusing on structural changes and product quality. After summarizing the main quality traits of extruded snacks (e.g., expansion rate, bulk density, and textural attributes), the effects of bran enrichment on the physical and sensory characteristics of the final product are discussed. Finally, bran pre-treatments as well as processing optimization are discussed as approaches to improve the quality of bran-enriched snacks.

Ultrasound-Assisted Extraction Optimization of Proanthocyanidins from Kiwi (Actinidia chinensis) Leaves and Evaluation of Its Antioxidant Activity

Using ultrasound (US) in proanthocyanidin (PA) extraction has become one of the important emerging technologies. It could be the next generation for studying the US mechnophore impact on the bioactive compound's functionality. The objective of this study was to demonstrate the potential of US treatment on PAs extracted from kiwifruit (Actinidia chinensis) leaves, and to provide a comprehensive chemical composition and bioactivity relationship of the purified kiwifruit leaves PAs (PKLPs). Several methods like single-factor experiments and response surface methodology (RSM) for the four affected factors on US extraction efficiency were constructed. HPLC-QTOF-MS/MS, cytotoxicity analysis, and antioxidant activity were also demonstrated. In the results, the modeling of PA affected factors showed that 40% US-amplitude, 30 mL/g dry weight (DW) solvent to solid ration (S/S), and 70 °C for 15 min were the optimum conditions for the extraction of PAs. Furthermore, PKLPs exhibited significant radical scavenging and cellular antioxidant activity (p < 0.05). In conclusion, this study's novelty comes from the broad prospects of using US in PKLP green extraction that could play an important role in maximizing this phytochemical functionality in drug discovery and food science fields.

Reactivity of flavanols: Their fate in physical food processing and recent advances in their analysis by depolymerization

Flavanols, a subgroup of polyphenols, are secondary metabolites with antioxidant properties naturally produced in various plants (e.g., green tea, cocoa, grapes, and apples); they are a major polyphenol class in human foods and beverages, and have recognized effect on maintaining human health. Therefore, it is necessary to evaluate their changes (i.e., oxidation, polymerization, degradation, and epimerization) during various physical processing (i.e., heating, drying, mechanical shearing, high-pressure, ultrasound, and radiation) to improve the nutritional value of food products. However, the roles of flavanols, in particular for their polymerized forms, are often underestimated, for a large part because of analytical challenges: they are difficult to extract quantitatively, and their quantification demands chemical reactions. This review examines the existing data on the effects of different physical processing techniques on the content of flavanols and highlights the changes in epimerization and degree of polymerization, as well as some of the latest acidolysis methods for proanthocyanidin characterization and quantification. More and more evidence show that physical processing can affect content but also modify the structure of flavanols by promoting a series of internal reactions. The most important reactivity of flavanols in processing includes oxidative coupling and rearrangements, chain cleavage, structural rearrangements (e.g., polymerization, degradation, and epimerization), and addition to other macromolecules, that is, proteins and polysaccharides. Some acidolysis methods for the analysis of polymeric proanthocyanidins have been updated, which has contributed to complete analysis of proanthocyanidin structures in particular regarding their proportion of A-type proanthocyanidins and their degree of polymerization in various plants. However, future research is also needed to better extract and characterize high-polymer proanthocyanidins, whether in their native or modified forms.

Impact of condensed tannin interactions with grain proteins and non-starch polysaccharides on batter system properties

Proanthocyanidins (PA) cross-link wheat gluten proteins and dramatically enhance batter viscosity; PA could similarly affect related grains. This study aimed to determine PA effect on viscosity and pasting properties of barley, rye, and oat flours, and the relative contributions of PA interactions with proteins and non-starch polysaccharides (NSP). PA significantly increased batter viscosity, stability, and RVA peak viscosity in rye and barley flours (2.8× and 1.2×, respectively). Interestingly, viscosity peaked distinctively ~75 °C in PA-treated rye and barley flours, and their isolated protein-starch systems, indicating prolamins unravelled and complexed with PA during heating. Oat was largely unaffected by PA, likely because of its protein composition. Furthermore, water-soluble rye NSP and arabinoxylans, but not barley β-glucans, significantly increased starch pasting viscosity with PA; oxidative gelation was not a factor. Thus, rye flour viscosity dramatically increased through interactive effects of PA on rye proteins and NSP, which could expand its food applications.

Study on the structure and digestibility of high amylose Tartary buckwheat (Fagopyrum tataricum Gaertn.) starch-flavonoid prepared by different methods

Tartary buckwheat (Fagopyrum tataricum Gaertn.) is the only food rich in flavonoid bioactive substances in grains. Studies have shown that flavonoids interaction with amylose has an important impact on the physical and chemical properties and structure of starch. In this study, Tartary buckwheat was used as a raw material. It was then threshed with pullulanase, and a high amylose Tartary buckwheat starch flavonoid complex (HBS/BF) was prepared by physical mixing (PM), water bath treatment (WT), acid-base precipitation (AP), microwave treatment (MT), and ultrasonic treatment (UT); the physical and chemical properties were then evaluated. The results show that HBS/BF-UT and HBS/BF-MT have a higher iodine binding rate than HBS/BF-PM; X-ray diffraction results show that HBS/BF-AP has a V-type crystal form, but the relative crystallinity was reduced. Fourier infrared spectroscopy showed that there is no new covalent bond between Tartary buckwheat starch and flavonoids. In vitro digestion showed that adding flavonoid significantly increased the digestibility of Tartary buckwheat starch. PRACTICAL APPLICATION: These results will provide a theoretical basis for further starch anti-digestion mechanisms and the preparation of resistant starch. These steps will provide insights into the application of Tartary buckwheat starch and flavonoids in the food industry.

Food Matrix and Macronutrient Digestion

Food digestion may be regarded as a physiological interface between food and health. During digestion, the food matrix is broken down and the component nutrients and bioactive compounds are absorbed through a synergy of mechanical, chemical, and biochemical processes. The food matrix modulates the extent and kinetics to which nutrients and bioactive compounds make themselves available for absorption, hence regulating their concentration profile in the blood and their utilization in peripheral tissues. In this review, we discuss the structural and compositional aspects of food that modulate macronutrient digestibility in each step of digestion. We also discuss in silico modeling approaches to describe the effect of the food matrix on macronutrient digestion. The detailed knowledge of how the food matrix is digested can provide a mechanistic basis to elucidate the complex effect of food on human health and design food with improved functionality.

Food matrixes play a key role in the distribution of contaminants of lipid origin: A case study of malondialdehyde formation in vegetable oils during deep-frying

Vegetable oils are increasingly replacing animal fats in diets, but malondialdehyde (MDA), a peroxidation product of these oils, has been regarded as toxic; this necessitated investigation of MDA formation during consumption. This study investigated MDA formation in four vegetable oils during frying French fries (FF) and fried chicken breast meat (FCBM) at 180 °C for 7 h. Results showed that MDA contents were lower in oils used for frying foods than in control oils, mainly because MDA was incorporated into the foods. MDA content was lower in FF, but higher in FCBM, due to the different food components. Model oil and food system analyses yielded similar results. MDA bound the hydrophobic helical structure in starch-based FF, but was exhibited greater reactivity with nucleophilic groups in protein-based FCBM, resulting in stronger interaction with FCBM than with FF. Our results indicated the existence of distinct mechanisms underlying MDA migration in different food matrixes.

Maltoheptaoside hydrolysis with chromatographic detection and starch hydrolysis with reducing sugar analysis: Comparison of assays allows assessment of the roles of direct α-amylase inhibition and starch complexation

The aim was to determine inhibition of human α-amylase activity by (poly)phenols using maltoheptaoside as substrate with direct chromatographic product quantification, compared to hydrolysis of amylose and amylopectin estimated using 3,5-dinitrosalicylic acid. Acarbose exhibited similar IC₅₀ values (50% inhibition) with maltoheptaoside, amylopectin or amylose as substrates (2.37 ± 0.11, 3.71 ± 0.12 and 2.08 ± 0.01 µM respectively). Epigallocatechin gallate, quercetagetin and punicalagin were weaker inhibitors of hydrolysis of maltoheptaoside (<50% inhibition) than amylose (IC₅₀: epigallocatechin gallate = 20.41 ± 0.25 µM, quercetagetin = 30.15 ± 2.05 µM) or amylopectin. Interference using 3,5-dinitrosalicylic acid was in the order punicalagin > epigallocatechin gallate > quercetagetin, with minimal interference using maltoheptaoside as substrate. The main inhibition mechanism of epigallocatechin gallate and punicalagin was through complexation with starch, especially amylose, whereas only quercetagetin additionally binds to the α-amylase active site. Interference is minimised using maltoheptaoside as substrate with product detection by chromatography, potentially allowing assessment of direct enzyme inhibition by almost any compound.

Inhibition effect of three common proanthocyanidins from grape seeds, peanut skins and pine barks on maize starch retrogradation

The inhibition effect of three common proanthocyanidins (PA) on the retrogradation properties of maize starch was investigated (including grape seed proanthocyanidins (GSPA), peanut skin proanthocyanidins (PSPA), and pine bark proanthocyanidins (PBPA)). Differential scanning calorimetry (DSC) and X-ray diffraction (XRD) analysis showed that PA could significantly decrease the values of melting enthalpy of retrogradation (ΔH_r) and the degree of relative crystallinity, suggesting that the starch re-crystallization was retarded by PA. Scanning electron microscope (SEM) characterizations illustrated that retrograded PA-starch samples formed a looser matrix with less appearance of continuous flakes during storage. Overall, 0.5 %-2.0 % of three PAs exhibited suppression of starch retrogradation after 21-day cooling storage, mainly resulting from the PA-starch interaction. Among them, PSPA showed the most substantial inhibition effect on starch retrogradation, which might be attributed to its structural features. This study suggested that PA could be a new type of inhibitor to suppress starch retrogradation.

Proanthocyanidins from Chinese berry leaves modified the physicochemical properties and digestive characteristic of rice starch

Proanthocyanidins extracted from Chinese berry leaves (CBLPs) were heated with rice starch in aqueous solution to prepare polyphenols-starch complexes. The physicochemical properties of the complexes were characterized with XRD, DSC, RVA and FT-IR and starch constituents were also analyzed with an enzyme method. Results indicated that the addition of CBLPs destroyed the long ordered structure of rice starch rather than the short ordered structure, since the crystallinity decreased from 21.96% to 18.90% and the ratio of 1047 cm^-1/1022 cm^-1 showed little difference, consistent with the lower ΔH of complexes with higher CBLPs content. Additionally, the CBLPs-rice starch complexes showed a significantly lower content of rapidly digested starch (RDS, 45.64 ± 3.25%) than that of the native rice starch (67.76 ± 2.15%). These results indicated that CBLPs complexes with rice starch might be a novel way to prepare functional starch with slower digestion.

Effects of edible plant polyphenols on gluten protein functionality and potential applications of polyphenol-gluten interactions

Expanding plant-based protein applications is increasingly popular. Polyphenol interactions with wheat gluten proteins can be exploited to create novel functional foods and food ingredients. Polyphenols are antioxidants, thus generally decrease gluten strength by reducing disulfide cross-linking. Monomeric polyphenols can be used to reduce dough mix time and improve flexibility of the gluten network, including to plasticize gluten films. However, high-molecular-weight polyphenols (tannins) cross-link gluten proteins, thereby increasing protein network density and strength. Tannin-gluten interactions can greatly increase gluten tensile strength in dough matrices, as well as batter viscosity and stability. This could be leveraged to reduce detrimental effects of healthful inclusions, like bran and fiber, to loaf breads and other wheat-based products. Further, the dual functions of tannins as an antioxidant and gluten cross-linker could help restructure gluten proteins and improve the texture of plant-based meat alternatives. Tannin-gluten interactions may also be used to reduce inflammatory effects of gluten experienced by those with gluten allergies and celiac disease. Other potential applications of tannin-gluten interactions include formation of food matrices to reduce starch digestibility; creation of novel biomaterials for edible films or medical second skin type bandages; or targeted distribution of micronutrients in the digestive tract. This review focuses on the effects of polyphenols on wheat gluten functionality and discusses emerging opportunities to employ polyphenol-gluten interactions.

Physicochemical and Digestion Properties of Potato Starch Were Modified by Complexing with Grape Seed Proanthocyanidins

Dietary intake of potato starch could induce a dramatic increase in blood glucose and is positively associated with chronic metabolic diseases (type II diabetes, cardiovascular disease, etc.). Grape seed proanthocyanidins (GSP) are known to decrease starch digestion by inhibiting digestive enzymes or changing the physicochemical properties of starch. In the present study, GSP were complexed with potato starch to prepare polyphenol-starch complexes. The physiochemical properties and digestibility of complexes were investigated by in vitro digestion model, X-ray diffraction, differential scanning calorimetry, rapid visco analyzer, Fourier transform infrared spectroscopy as well as texture profile analysis. Results indicated that the peak viscosity, breakdown, trough, and setback of the complexes disappeared, replaced by a special continuous increase in paste viscosity. The complexes showed a lower final viscosity and higher thermal stability with the increasing binding amount of GSP. GSP decreased the hardness of the complexes' gel significantly. FT-IR indicated that GSP might interact with potato starch through noncovalent forces. Additionally, the complexes also showed a higher content of slowly digestible starch and resistant starch than that of the native starch. Thus, we inferred that the addition of GSP could modify the digestibility of potato starch and be an optional way to modify the starch with lower digestion.

Sorghum Grain: From Genotype, Nutrition, and Phenolic Profile to Its Health Benefits and Food Applications

Globally, sorghum is one of the most important but least utilized staple crops. Sorghum grain is a rich source of nutrients and health-beneficial phenolic compounds. The phenolic profile of sorghum is exceptionally unique and more abundant and diverse than other common cereal grains. The phenolic compounds in sorghum are mainly composed of phenolic acids, 3-deoxyanthocyanidins, and condensed tannins. Studies have shown that sorghum phenolic compounds have potent antioxidant activity in vitro, and consumption of sorghum whole grain may improve gut health and reduce the risks of chronic diseases. Recently, sorghum grain has been used to develop functional foods and beverages, and as an ingredient incorporated into other foods. Moreover, the phenolic compounds, 3-deoxyanthocyanidins, and condensed tannins can be isolated and used as promising natural multifunctional additives in broad food applications. The objective of this review is to provide a comprehensive understanding of nutrition and phenolic compounds derived from sorghum and their related health effects, and demonstrate the potential for incorporation of sorghum in food systems as a functional component and food additive to improve food quality, safety, and health functions.

Postprandial Glycemic and Insulinemic Effects of the Addition of Aqueous Extracts of Dried Corn Silk, Cumin Seed Powder or Tamarind Pulp, in Two Forms, Consumed with High Glycemic Index Rice

Several plant-based traditional ingredients in Asia are anecdotally used for preventing and/or treating type 2 diabetes. We investigated three such widely consumed ingredients, namely corn silk (CS), cumin (CU), and tamarind (TA). The aim of the study was to determine the effects of aqueous extracts of these ingredients consumed either as a drink (D) with high-glycemic-index rice or added to the same amount of rice during cooking (R) on postprandial glycemia (PPG), insulinemia (PPI), and blood pressure (BP), over a 3 h measurement period. Eighteen healthy Chinese men (aged 37.5 ± 12.5 years, BMI 21.8 ± 1.67 kg/m²) took part in a randomized crossover trial, each completing up to nine sessions. Compared to the control meal (plain rice + plain water), the addition of test extracts in either form did not modulate PPG, PPI, or BP. However, the extracts when added within rice while cooking gave rise to significantly lower PPI than when consumed as a drink (p < 0.01). Therefore, the form of consumption of phytochemical-rich ingredients can differentially modulate glucose homeostasis. This study also highlights the need for undertaking randomized controlled clinical trials with traditional foods/components before claims are made on their specific health effects.