Microencapsulated grape pomace extract as an antioxidant ingredient added to Greek-style yogurt: Storage stability an in vitro bioaccessibility

This study investigated the microencapsulation of phenolic compounds from grape pomace extract (GPE) obtained from Sonora, Mexico, with maltodextrin and gum arabic through spray-drying for application in Greek-style yogurt. The microencapsulated GPE (MGPE) showed high encapsulation efficiency 97.82 % and average particle size (3.48 μm) below of sensory perception. The main identified phenolic compounds were gallic acid, quercetin, malvidin 3-O-glucoside, catechin, epicatechin, and proanthocyanidins. During a 90-day shelf-life assay, the MGPE was stable, while GPE decreased in total phenolic content (TPC), monomeric anthocyanins, and antioxidant activity. Incorporation of MGPE into the Greek-style yogurt significantly improved the antioxidant activity determined by ABTS, DPPH, and FRAP assays. After in vitro gastrointestinal digestion, MGPE added in yogurt preserved phenolic compounds stability and increased its bioaccessibility at the intestinal phase. These suggest maltodextrin and gum arabic are an effective vehicle to deliver the antioxidant compounds from grape pomace through Greek-style yogurt and improve health.

Effect of vacuum frying on the structure and bioactivity of proanthocyanidins in Chinese quince (Chaenomeles sinensis Koehne) fruit

The consumption of Chinese quince is hindered by the lack of suitable processing method. Vacuum-frying technology, as an efficient processing method, can help address this issue. However, the effect of vacuum frying on the structure and activity of bioactive components in Chinese quince, such as proanthocyanidins, is currently unknown. In this study, Chinese quince was vacuum fried at 70 °C-100 °C. Proanthocyanidins were extracted, characterized, and analyzed for their bioactivity. Results revealed that increasing the vacuum-frying temperature decreased the total proanthocyanidin content. Vacuum frying reduced samples' degrees of polymerization. Proanthocyanidin extracts vacuum fried at 70 °C exhibited the greatest antioxidant capacity. Proanthocyanidin extracts vacuum fried at 80 °C demonstrated pronounced hypoglycemic potential. These results show that vacuum frying can reduce the degree of polymerization of Chinese quince proanthocyanidins while enhancing their antioxidant activity and retaining their hypoglycemic capacity. This study offers valuable insights for the development of functional foods using Chinese quince.

Synthesis, characterization and application of oligomeric proanthocyanidin-rich dual network hydrogels

A structurally dense hydrogel, with strong hydrogen bonding networks, was formed from poly(vinyl alcohol), sodium alginate, and oligomeric proanthocyanidins, using a combination of freeze-thaw cycles and calcium ion cross-linking. The structure of the hydrogel was characterized by scanning electron microscopy and Fourier transform infrared spectroscopy. Mechanical testing and thermogravimetric analysis showed that incorporation of proanthocyanidins enhanced both the mechanical properties and the thermal stability of the hydrogel. The hydrogel was also demonstrated to have excellent ultraviolet resistance and antioxidant properties. The hydrogel was further shown that this hydrogel is also capable of generating electrochemical reactions, which strongly suggests that this hydrogel has exciting potential in many fields.

A Food-Grade Method for Enhancing the Levels of Low Molecular Weight Proanthocyanidins with Potentially High Intestinal Bioavailability

Proanthocyanidins (PACs) are a group of bioactive molecules found in a variety of plants and foods. Their bioavailability depends on their molecular size, with monomers and dimers being more bioavailable than those that have a higher polymerization degree. This study aimed to develop a method to convert high-molecular-weight PACs to low-molecular-weight ones in a grape seed extract (GSE) from Vitis vinifera L. Therefore, GSE was subjected to alkaline treatment (ATGSE), and its difference in chemical composition, compared to GSE, was evaluated using a molecular networking (MN) approach based on results obtained from HPLC-ESI HRMS/MS characterization analysis. The network analysis mainly noted the PAC cluster with about 142 PAC compounds identified. In particular, the obtained results showed a higher content of monomeric and dimeric PACs in ATGSE compared to GSE, with 58% and 49% monomers and 31% and 24% dimers, respectively. Conversely, trimeric (9%), polymeric (4%), and galloylated PACs (14%) were more abundant in GSE than in ATGSE (6%, 1%, and 4%, respectively). Moreover, in vitro antioxidant and anti-inflammatory activities were investigated, showing the high beneficial potential of both extracts. In conclusion, ATGSE could represent an innovative natural matrix rich in bioavailable and bioaccessible PACs for nutraceutical applications with potential beneficial properties.

A novel thiolysis-HPLC method for the determination of proanthocyanidins in grape seeds

A novel thiolysis-HPLC method for quantitative determination of total proanthocyanidins and mean degree of polymerization in grape seeds has been developed. Following thiolysis with formic acid and benzyl mercaptan, reaction products were separated and purified. Three proanthocyanidin monomers and three derivatives were obtained and their structures were identified by LC-MS, fourier transform infrared spectroscopy, and NMR. A decomposition model of the thiolysis products and a correction formula for proanthocyanidins concentration were established. This thiolysis-HPLC method displayed good calibration linearity (R² > 0.999 over the concentration range 0.01 to 10 mg/mL), and excellent accuracy (recoveries of 97.9-99.6%) and precision (repeatability relative standard deviations of 0.45-0.75%). This method is suitable for the quantitative analysis of proanthocyanidins in grape seed products. This article is protected by copyright. All rights reserved.

Component and Structure of Aspergillus flavipes sp.-Biodegraded Bayberry Tannins: A Potential Routine for Condensed Tannin Cleaner Degradation and Disposal

Chemical degradation is widely used for producing lower-molecular-weight tannin compounds and tannin disposal, but it has negative effects on the environment, such as causing secondary pollution and consuming energy. For overcoming these disadvantages, a cleaner and sustainable degradation and disposal method for condensed tannins was developed through biodegradation. In this study, bayberry tannin solution, one kind of condensed tannin, was biodegraded by Aspergillus flavipes sp. at first; then, gel permeation chromatography and high-performance liquid chromatography were used for separating the biodegraded and original tannins to analyze the differences in components; finally, the changes in the tannin structure after biodegradation were characterized by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and nuclear magnetic resonance. The results showed that the high-molecular-weight components decreased while the low-molecular-weight components increased when bayberry was subjected to A. flavipes sp. biodegradation; furthermore, the molecular weight of the biodegraded bayberry tannin decreased from 3371 to 2658 Da. Meanwhile, the structure of bayberry tannin polyflavonoids, especially A ring and C ring together with the galloyl group, was destroyed and some small fragments were generated during biodegradation. These structural changes resulted in the increase of low-molecular-weight phenols but the decrease of polyflavonoids after bayberry biodegradation. These would be the pieces of evidence showing that A. flavipes sp. consumed simple phenols as nourishment for growth and converted polyflavonoids into low-molecular-weight substances at the same time. To sum up, biodegradation can be used in every field where condensed tannins should be degraded or removed for a cleaner and ecofriendly routine.