Anthocyanin degradation and the underlying molecular mechanism in a red-fleshed grape variety

Whole-field mulching and removal indicated the flavonoid plasticity in Marselan grapes and wines: Insights from the metabolome and transcriptome

As an eco-friendly vineyard floor management, mulching can effectively control weeds, preserve soil moisture, reduce irrigation requirements, and modify the grapevine microclimate. However, its impact on the grapevine microclimate, as well as the variation in grape and wine flavonoids across different growth stages under mulching conditions remains insufficiently studied. Therefore, in the vineyard of a semi-arid region, the whole-field mulching (M) of black geotextile mulch was applied to Vitis vinifera Marselan grapevines from anthesis and removed at three phenological stages. The grape and wine flavonoids during the growing season were evaluated through HPLC-MS, and the transcriptomic data was analyzed in three vintages (2015-2017). Results showed that mulching weakened over 30°% of reflected light, and especially light with longer wavelengths. Mulching helped to reduce water evaporation and lead to higher soil water content. As for berry composition, M slightly decreased the berry weight and accelerated sugar accumulation when mulch removal. Controlled grapes presented higher flavonols at harvest while mulch removal around veraison enhanced the accumulation of anthocyanins. The reflected photosynthetic active radiation, cluster temperature, and soil moisture played important roles in flavonoid regulation. Key genes including VviFLS1, VviLAR1, and VviANR, as well as MYB transcription factors MYBF1, MYBA1, and MYB3 are responsible for flavonoid regulation. M slightly affected the wine flavor profile but improved the wine's appearance. In conclusion, M effectively suppresses weed growth and modifies grapevine microclimate in semi-arid climates, mulch removal around veraison favored the accumulation of grape flavonoids.

Effects of foliar applications of γ-polyglutamic acid and alginic acid on the quality and antioxidant activity of Marselan grapes and wines

This study investigated the effects of γ-polyglutamic acid (PGA) and alginic acid (ALA) on grapes and wines. Marselan grapes were utilized to assess the accumulation and synthesis of phenolic compounds and antioxidant activity. The 0.35 % (v/v) PGA (PGA2) significantly enhanced the antioxidant activity of both grapes and wines in both years. Overall, treatments with 0.45 % (v/v) PGA (PGA3), 0.45 % (v/v) ALA (ALA3), and 0.25 % (v/v) ALA (ALA1) notably increased the total phenolic and anthocyanin content in both grapes and wines. Among these, PGA3 treatment significantly upregulated the levels of Delphinidin-3-O-(6-acetyl)-glucoside, Cyanidin-3-O-(6-acetyl)-glucoside, Peonidin-3-O-glucoside, and Malvidin-3-O-(trans-6-O-coumaryl)-glucoside in both years. Additionally, PGA3 treatment elevated the expression of the VvPAL, VvCHS, VvDFR and VvLDOX genes across both years. In contrast, ALA3 and ALA1 treatments increased anthocyanin content by upregulating the expression of VvCHS, VvF3'H and VvUFGT genes. In summary, PGA3 treatment significantly enhanced the phenolic compounds and antioxidant activity in both grapes and wines. These findings demonstrate the potential of PGA and ALA as biostimulants to significantly enhance grape and wine quality in viticulture.

Anthocyanin profiles and color parameters of fourteen grapes and wines from the eastern foot of Helan Mountain in Ningxia

To identify wine grape cultivars (Vitis vinifera) with superior color properties for wine production, the anthocyanin composition and color characteristics of fourteen cultivars and their wines were investigated. Grapes and wines from 'Dornfelder', 'Dunkelfelder', and 'Malbec' cultivars exhibited significantly higher total phenolic contents. At harvest, 'Dornfelder' grapes and wines exhibited the highest total anthocyanin contents, with values of 249.94 mg/kg in grapes and 1686.76 mg/L in wines, significantly higher than other cultivars. PCA and PLS-DA analyses identified malvidin-3-O-(trans-6-O-coumaryl)-glucoside as a common differential metabolite in both grapes and wines across all cultivars. Correlation analysis revealed that non-acylated anthocyanins (r = 0.68) have a more significant impact than acylated anthocyanins (r = 0.28) on color chromatic diversity in grapes and wines (P < 0.05). These findings suggest that wines produced from 'Dornfelder' grapes are particularly valuable for their superior color properties and high individual anthocyanin contents. This study addresses a gap in comparative anthocyanin analysis among cultivars and provides valuable insights for grape growers and winemakers seeking to optimize grape selection for improved wine quality.

Progress on molecular modification and functional applications of anthocyanins

Anthocyanins have attracted a lot of attention in the fields of natural pigments, food packaging, and functional foods due to their color, antioxidant, and nutraceutical properties. However, the poor chemical stability and low bioavailability of anthocyanins currently limit their application in the food industry. Various methods can be used to modify the structure of anthocyanins and thus improve their stability and bioavailability characteristics under food processing, storage, and gastrointestinal conditions. This paper aims to review in vitro modification methods for altering the molecular structure of anthocyanins, as well as their resulting improved properties such as color, stability, solubility, and antioxidant properties, and functional applications as pigments, sensors and functional foods. In industrial production, by mixing co-pigments with anthocyanins in food systems, the color and stability of anthocyanins can be improved by using non-covalent co-pigmentation. By acylation of fatty acids and aromatic acids with anthocyanins before incorporation into food systems, the surface activity of anthocyanins can be activated and their antioxidant and bioactivity can be improved. Various other chemical modification methods, such as methylation, glycosylation, and the formation of pyranoanthocyanins, can also be utilized to tailor the molecular properties of anthocyanins expanding their range of applications in the food industry.

Phenolic profile, antioxidant capacity and oxidoreductase enzyme activity in autochthonous grape varieties from Bosnia and Herzegovina

The variability of phenolic compounds among grape varieties has an important role in selecting winemaking techniques, but the use of phenolic profiles for quality control is still fragmented and incomplete. Given the recent climate change and global warming, biochemical characterisation of secondary metabolites in autochthonous grape varieties is a very important factor for their preservation and sustainable agriculture. Two autochthonous grape varieties from the western Herzegovina region in Bosnia and Herzegovina have been selected for the research targeting at the evaluation of their phenolic profiles, antioxidant activities, and the correlation with oxidoreductase enzymes polyphenol oxidase and Class III peroxidase, in different berry tissues. The obtained results indicate a similar qualitative profile of phenolic compounds in exocarp and mesocarp in both varieties, but their concentrations and antioxidant activity vary significantly. The correlation between phenolic compounds and oxidoreductase enzyme activities in different grape berry tissues is discussed in this article.

Inter- and intra-varietal genetic variations co-shape the polyphenol profiles of Vitis vinifera L. grapes and wines

Inheritance and mutations are important factors affecting grape phenolic composition. To investigate the inter- and intra-varietal differences in polyphenolic compounds among grapes and wines, 27 clones belonging to eight varieties of Vitis vinifera L. were studied over two consecutive years. A total of 24 polyphenols (nine anthocyanins, three flavanols, five flavonols, and seven phenolic acids) were analyzed, and the physicochemical parameters of the grapes and wines were determined. Polyphenol profiles showed significant varietal and clonal polymorphisms, and malvidin-3-O-glucoside, peonidin-3-O- glucoside, and epicatechin were identified as key biomarkers distinguishing different grapes and wines when using an orthogonal partial least squares discriminant analysis. Further multivariate analysis classified these genotypes into three subclasses, and a somatic variant of 'Malbec', MBVCR6, had the most abundant polyphenolic compounds that were related to the titratable acid content. The current results reveal that varietal and clonal variations are important for obtaining wines with high polyphenol content.

Preparation of a Dual-Functional Active Film Based on Bilayer Hydrogel and Red Cabbage Anthocyanin for Maintaining and Monitoring Pork Freshness

In this study, a composite film was created with the dual goal of prolonging pork shelf life and showing freshness. Hydrogel materials as solid base films were selected from gelatin (G), sodium alginate (SA) and carboxymethyl cellulose (CMC) based on their antioxidant activity, water vapor permeability, mechanical properties, as well as their stability, antimicrobial activity, and freshness, which indicates effectiveness when combined with anthocyanins. Furthermore, the effects of several concentrations of red cabbage anthocyanin (R) (3%, 6%, 12%, and 24%) on freshness indicators and bacteriostasis were investigated. The antimicrobial activity of the composite films was evaluated against Escherichia coli, Bacillus subtilis, and Staphylococcus aureus. Likewise, the freshness indicates effectiveness was evaluated for NH3. Considering the mechanical properties, antibacterial ability, freshness indicator effect, and stability of the composite film, CS film combined with 12% R was selected to prepare a dual-functional intelligent film for pork freshness indicator and preservation. By thoroughly investigating the effect of composite film on pork conservation and combining with it KNN, the discriminative model of pork freshness grade was established and the recognition rate of the prediction set was up to 93.3%. These results indicated that CSR film can be used for the creation of active food packaging materials.

Phenolic, Polysaccharides Composition, and Texture Properties during Ripening and Storage Time of New Table Grape Cultivars in Chile

The aim of this study is to determine the phenolic and polysaccharidic composition, texture properties, and gene expression of new seedless table grape cultivars Timco™ and Krissy™ and compare them to the traditional table grape variety Crimson Seedless (Vitis vinifera L.), during ripening and in commercial postharvest conditions. According to the results, phenolic compounds were present in very different proportions. The total anthocyanins responsible for skin color increased during maturation and the majority anthocyanin in the three cultivars was peonidin-3-glucoside, followed by malvidin-3-glucoside. The phenolic compounds presented a different behavior (decreasing or increasing) during postharvest. The total skin soluble polysaccharides decreased during ripening and postharvest in Crimson Seedless and Krissy™ and remained constant from technological maturity to postharvest storage in Timco™. In all cultivars, the majority soluble polysaccharide fraction was that with a molecular mass between 500 and 35 KDa. The skin mechanical properties of table grapes were good parameters for differentiating varieties, with better results for the new cultivars, compared to the traditional Crimson Seedless, especially in postharvest. Genes involved in the flavonoid pathway and cell wall metabolism in skins exhibited an increase in expression from veraison to remaining constant at the end of the berry ripening.

Interactions between zein and anthocyanins at different pH: Structural characterization, binding mechanism and stability

Zein-anthocyanin nanoparticles (ZACNPs) at different pH values were successfully developed to stabilize anthocyanins based on the self-assembly properties of zein. The structural characterization by the Fourier infrared spectroscopy, fluorescence spectroscopy, differential scanning calorimetry and molecular docking analysis showed that the interactions between anthocyanins and zein were driven by the hydrogen bonds formed between the hydroxyl and carbonyl oxygen groups on anthocyanin glycoside groups and the amino acid residues (glutamine and serine), as well as the hydrophobic interactions from the A or B ring of anthocyanins and the amino acid residues of zein. The binding energy of zein to two anthocyanin monomers cyanidin 3-O-glucoside and delphinidin 3-O-glucoside was 8.2 and 7.4 kcal/mol. Further property examinations of ZACNPs showed that the thermal stability of anthocyanins at a ratio of zein:ACN = 1:0.3 was improved by 56.64 % (90 °C, 2 h), and the storage stability increased by up to 31.11 % at pH 2. In addition, the antioxidant activity of ZACNPs (zein:ACN = 1:0.3) was significantly enhanced, and the DPPH, ABTS radical scavenging activities, FRAP and ORAC value reached 87.73 %, 87.89 %, 435.5 μg/mL, 90.58 μmol/mL at pH 4, respectively. These results suggested that combining zein to anthocyanins is a feasible method to stabilize anthocyanins.

A recessive mutation in muscadine grapes causes berry color-loss without influencing anthocyanin pathway

Anthocyanins, a major class of flavonoids, are important pigments of grape berries. Despite the recent discovery of the genetic cause underlying the loss of color, the metabolomic and molecular responses are unknown. Anthocyanin quantification among diverse berry color muscadines suggests that all genotypes could produce adequate anthocyanin quantities, irrespective of berry color. Transcriptome profiling of contrasting color muscadine genotypes proposes a potential deficiency that occurs within the anthocyanin transport and/or degradation mechanisms and might cause unpigmented berries. Genome-wide association studies highlighted a region on chromosome-4, comprising several genes encoding glutathione S-transferases involved in anthocyanin transport. Sequence comparison among genotypes reveals the presence of two GST4b alleles that differ by substituting the conserved amino acid residue Pro₁₇₁-to-Leu. Molecular dynamics simulations demonstrate that GST4b2–Leu₁₇₁ encodes an inactive protein due to modifications within the H-binding site. Population genotyping suggests the recessive inheritance of the unpigmented trait with a GST4b2/2 homozygous. A model defining colorless muscadines’ response to the mutation stimulus, avoiding the impact of trapped anthocyanins within the cytoplasm is established.

Transcriptome profiling and mutational analysis suggest a potential deficiency in anthocyanin transport by glutathione S-transferases and/or degradation mechanisms that might cause unpigmented berries.

Quantitative Analysis of Anthocyanins in Grapes by UPLC-Q-TOF MS Combined with QAMS

A method for quantifying the anthocyanins in grapes was firstly developed by ultra-high performance liquid chromatography-quadrupole-time of flight mass spectrometry (UPLC-Q-TOFMS) combined with quantitative analysis of multi-components by single marker (QAMS). A total of 10 main anthocyanins were analyzed by using peonidin 3-O-glucoside as the reference standard. The accuracy of this method was evaluated by an established and validated external standard quantification method with 10 reference compounds. The standard method difference (SMDs) of the quantification results between QAMS and the external standard methodwasless than 15%. Furthermore, the QAMS method was used to analyzefour batches of grapes and the data was compared with those obtained using the external standard method. No significant difference wasobtained in the results obtained by both methods. These results indicated that the QAMS method could accurately determine the anthocyanins in grapes. This method can provide a basis to address the absence of reference standards for analyzing anthocyanins in other foods.

Development and Characterization of Arrowroot Starch Films Incorporated with Grape Pomace Extract

Grape processing residues are a good source of bioactive and nutritional compounds. The incorporation of grape pomace extract (GPE) in starch films can be a strategy for the elaboration of new food packaging products for applications such as edible films or fruit strips. In this context, the objective of this research was to analyze the effect of incorporation and variation of concentration of GPE (0, 20, 30, and 40% mass/mass starch solids) on the physical chemical properties of arrowroot starch edible films created by casting. The GPE was characterized for moisture content, pH, total titratable acidity, total soluble solids, and anthocyanin content. Starch films with and without GPE were evaluated by analyzing their visual appearance, water activity, water content, thickness, water solubility, and water vapor permeability. The GPE had high water content, acidity, and anthocyanins content. The films with GPE showed a noticeable reddish color, similar to observed for the GPE. Increasing the concentration of GPE in the film resulted in significantly increased (p < 0.05) thickness (from 0.060 to 0.106 mm), water content (from 8.17 to 12.48%), solubility in water (from 13.33 to 33.32%), and water vapor permeability (from 3.72 to 6.65 g.mm/m2 day kPa). GPE increased the hydrophilic portion of the film, in addition to acting as a plasticizer, decreasing the molecular interactions of the polymer chain, and favoring its solubilization, which is desirable for applications such as edible films. The elaboration of arrowroot starch films with the incorporation of grape pomace is a good alternative for the reduction of by-products of grape processing.