Influence of Acetaldehyde Induction on Monomeric and Polymeric Polyphenols in Wine using the Polyphenol/Protein-binding Model

Polyphenols make a substantial contribution to the sensory properties of wine, and their evolution is affected by the acetaldehyde present during fermentation and ageing. In this work, five typical monomeric phenolic standards and three different polymeric flavanol fractions separated from wine were tested for polyphenol/protein binding by means of circular dichroism measurement and fluorescence spectrum assay in the presence or absence of acetaldehyde, and the formation of new oligomeric compounds linked by ethyl bridges was observed through HPLC-MS analyses. The results show that the protein-binding ability of these monomers was in the order of gallic acid > caffeic acid > quercetin > (+)-catechin > (-)-epicatechin, while acetaldehyde exerted a stronger effect on (+)-catechin and (-)-epicatechin monomers. Moreover, different wine fractions had different responses when reacted with proteins with the participation of acetaldehyde, while the polymeric proanthocyanidins produced the largest value (84.67%) of the salivary protein precipitation index and the strongest fluorescence-quenching effect

Influence of Different Phenolic Fractions on Red Wine Astringency Based on Polyphenol/Protein Binding

The presence of phenolic compounds can make a great contribution to the perception of astringency in red wines based on their interactions with proteins. Human salivary protein and bovine serum albumin were used in this study to investigate the relationship between astringency and polyphenol composition.  The interactions between polyphenols and proteins were analysed by means of electrophoresis and fluorescence spectra, and they were further confirmed by sensory analysis. The results indicate that a positive correlation existed among the percentage of polymeric proanthocyanidins and the total phenols.  Additionally, astringent wine was generally identified as having a high percentage of polymeric fragments.  In comparison with other fractions, polymeric fractions exhibited the highest affinity for protein, and thus the highest astringency

Nutritional evaluation and functional properties of the antioxidant polypeptide from Zanthoxylum bungeanum Maxim seeds kernel protein hydrolysate

Antioxidant polypeptides of Zanthoxylum bungeanum Maxim seeds kernel (ZBMSK) were investigated based on molecular weight distribution, amino acid composition, and functional properties. The polypeptide had a molecular weight distribution of 1026 ~ 2249 Da and 4926 ~ 6398 Da, and was rich in glutamic acid, arginine, aspartic acid, and leucine, but poor in cysteine and tryptophan. Total amino acids were 56.42 g/100 g, and lysine was the first limiting amino acid. The polypeptide showed excellent solubility, viscosity, emulsifying properties, and foam expansion compared with its original protein. In addition, the polypeptide exhibited favorable reduction power and scavenging capacities for DPPH radicals with an IC50 value of 8.86 mg/mL. These results suggest that the polypeptide derived from ZBMSK has potential future application among functional foods, and may be a promising source of natural antioxidants.Se investigaron los polipéptidos antioxidantes de semillas de Zanthoxylum bungeanum (ZBMSK) en base a la distribución del peso molecular, la composición de aminoácidos y las propiedades funcionales. Los polipéptidos presentaban un peso molecular de 1026~2249 Da y 4926~6398 Da, además eran ricos en ácido glutámico, arginina, ácido aspártico y leucina, aunque pobres en cisteína y triptófano. El total de aminoácidos fue de 56,42 g/100 g y la lisina fue el primer aminoácido de limitación. Los polipéptidos mostraron una excelente solubilidad, viscosidad, propiedades emulsionantes y expansión de espuma en comparación con su proteína original. Además, los polipéptidos exhibieron un poder reductor favorable y capacidades de barrido de radicales DPPH con un valor IC50 de 8,86 mg/mL. Estos resultados sugieren que los polipéptidos derivaros de ZBMSK tienen una futura aplicación potencial entre los alimentos funcionales, además podrían ser una prometedora fuente de antioxidantes naturales

Enrichment and Purification of Polyphenol Extract from Sphallerocarpus gracilis Stems and Leaves and in Vitro Evaluation of DNA Damage-Protective Activity and Inhibitory Effects of α-Amylase and α-Glucosidase

An efficient preparative separation method for Sphallerocarpus gracilis stems and leaves polyphenols (SGslP) was established in this study. An X-5 macroporous adsorption resin was selected for the purification of the SGslP, and the polyphenol content of the purified SGslP (PSGslP) was increased 5.11-fold from 8.29% to 42.38% after one treatment run. The chemical composition of the PSGslP was analyzed by HPLC-MS/MS, and the predominant compounds were found to be luteolin-7-glucoside, acacetin-7-acetyglycoside and its isomers. In addition, the PSGslP was evaluated in vitro to determine the DNA damage-protective activity and inhibitory effects of α-amylase and α-glucosidase. The results indicated that the PSGslP exhibited significant protective activities against both ROO• and •OH radical-induced DNA damage. Moreover, the PSGslP exerted a dose-dependent inhibition effect on α-glucosidase but no inhibitory effect on α-amylase. These findings indicate that the Sphallerocarpus gracilis stems and leaves are good natural sources of antioxidants and are potent inhibitors of α-glucosidase activity and are potential anti-diabetic inhibitor

A Novel Tree Height Extraction Approach for Individual Trees by Combining TLS and UAV Image-Based Point Cloud Integration

Research Highlights: This study carried out a feasibility analysis on the tree height extraction of a planted coniferous forest with high canopy density by combining terrestrial laser scanner (TLS) and unmanned aerial vehicle (UAV) image–based point cloud data at small and midsize tree farms. Background and Objectives: Tree height is an important factor for forest resource surveys. This information plays an important role in forest structure evaluation and forest stock estimation. The objectives of this study were to solve the problem of underestimating tree height and to guarantee the precision of tree height extraction in medium and high-density planted coniferous forests. Materials and Methods: This study developed a novel individual tree localization (ITL)-based tree height extraction method to obtain preliminary results in a planted coniferous forest plots with 107 trees (Metasequoia). Then, the final accurate results were achieved based on the canopy height model (CHM) and CHM seed points (CSP). Results: The registration accuracy of the TLS and UAV image-based point cloud data reached 6 cm. The authors optimized the precision of tree height extraction using the ITL-based method by improving CHM resolution from 0.2 m to 0.1 m. Due to the overlapping of forest canopies, the CSP method failed to delineate all individual tree crowns in medium to high-density forest stands with the matching rates of about 75%. However, the accuracy of CSP-based tree height extraction showed obvious advantages compared with the ITL-based method. Conclusion: The proposed method provided a solid foundation for dynamically monitoring forest resources in a high-accuracy and low-cost way, especially in planted tree farms

Enrichment and Purification of Polyphenol Extract from Sphallerocarpus gracilis Stems and Leaves and in Vitro Evaluation of DNA Damage-Protective Activity and Inhibitory Effects of α-Amylase and α-Glucosidase

An efficient preparative separation method for Sphallerocarpus gracilis stems and leaves polyphenols (SGslP) was established in this study. An X-5 macroporous adsorption resin was selected for the purification of the SGslP, and the polyphenol content of the purified SGslP (PSGslP) was increased 5.11-fold from 8.29% to 42.38% after one treatment run. The chemical composition of the PSGslP was analyzed by HPLC-MS/MS, and the predominant compounds were found to be luteolin-7-glucoside, acacetin-7-acetyglycoside and its isomers. In addition, the PSGslP was evaluated in vitro to determine the DNA damage-protective activity and inhibitory effects of α-amylase and α-glucosidase. The results indicated that the PSGslP exhibited significant protective activities against both ROO• and •OH radical-induced DNA damage. Moreover, the PSGslP exerted a dose-dependent inhibition effect on α-glucosidase but no inhibitory effect on α-amylase. These findings indicate that the Sphallerocarpus gracilis stems and leaves are good natural sources of antioxidants and are potent inhibitors of α-glucosidase activity and are potential anti-diabetic inhibitor