Influence of berry ripeness on accumulation, composition and extractability of skin and seed flavonoids in cv. Sangiovese (Vitis vinifera L.)

Multiple metabolite profiles uncover remarkable bioactive compounds and metabolic characteristics of noni fruit (Morinda citrifolia L.) at various stages of ripeness

This study aimed to investigate the changes in physicochemical properties, bioactive compounds, and metabolic characteristics of noni fruit at different ripeness levels. The results showed that there were significant differences in physicochemical properties. HPLC analysis was conducted, revealing succinic acid, scopoletin, deacetylasperulosidic acid, and asperulosidic acid were key bioactive compounds as the fruit ripened. Additionally, 4 differentbiomarkers (isocitric acid, 4,4-thiodiphenol, lobaric acid, and octocrylene), identified using 1HNMR and LC-IT-TOF-MS, were found to have a VIP value over 1. The results from HS-GC-IMS demonstrated noteworthy that 14 volatile compounds were identified as highly discriminative features during fruit ripening. Furthermore, correlation analysis showed that different ripeness had significant effects on bioactive components and functional activities, e.g., the inhibition rate of enzyme and E. coli of noni fruit with different ripeness exceeded 90% at the last stage. This study contributes new insights into the effective utilization of bioactive ingredients in noni fruit.

Effect of Cap Management Frequency on the Phenolic, Chromatic, and Sensory Composition of Cabernet Sauvignon Wines from the Central Coast of California over Two Vintages

Cabernet Sauvignon from the California Paso Robles AVA was processed with a contrasting array of cap management frequencies, consisting of punch-down (PD) frequencies (0, 1, 2, and 3 PD/day) over two vintages, one of which the fruit was harvested at two contrasting maturity levels. Wines followed with up to 3 years of bottle aging for basic and phenolic chemistry, and the wines of the second harvest of 2020 were submitted to sensory analysis. There were almost non-existent effects due to the frequency of punch downs on parameters such as ethanol, pH, titratable acidity, lactic acid, and glucose + fructose. In 2019, the chromatic differences between different PD regimes were subtle, and minor effects of the punch-down frequency were observed for tannins and total phenolics. During the early stages of alcoholic fermentation, higher levels of all anthocyanin classes were observed in 1 PD wines and the lowest levels in 0 PD wines. The anthocyanin content of the wines of the first harvest (unripe) was 27% higher than that of the wines of the second harvest (ripe), but these differences disappeared after 3 years of bottle aging irrespective of the vintage and harvest date. Acylated anthocyanins were preferentially lost during aging, especially in 2019 wines and, to a lesser extent, in 2020 wines. In 2020, the polymeric pigment content of the wines of the second harvest was higher than in the wines of the first harvest, with 3 PD wines showing higher polymeric pigments and yellow hues than 0 and 2 PD wines after 3 years of bottle aging. Sensory analysis of the second harvest of the 2020 wines showed that the wines of all four PD regimes were perceived as drying, signifying they were perceived as equally astringent, which is consistent with comparable tannin levels on said wines. The perception of bitterness increased with the frequency of punch downs; thus, 3 PD wines showed the highest bitterness perception. It was concluded that in sufficiently warm fermentations and small volumes, phenolic extraction occurs regardless of fruit maturity and under conditions of minimum mixing.

Anthocyanin Addition Alters Tannin Extraction from Grape Skins in Model Solutions via Chemical Reactions

Condensed tannin extraction and stable color formation are two of the cornerstones of red wine production. Without condensed tannin, red wine would lack the tactile feeling of astringency, and without the formation of modified pigments, it would lack color stability for long-term aging. To understand how malvidin-3,5-diglucoside interacts with condensed tannin under nonoxidative conditions, an experiment was designed conducting model-wine skin extractions of Sauvignon blanc grapes harvested at various dates of maturity. Monomeric malvidin-3,5-diglucoside was isolated from color concentrate and added during these extractions. Following a 72 h extraction, solutions were evaluated for recovery of monomeric anthocyanins, skin tannin concentration, skin tannin extractability, and impact of anthocyanins on condensed tannin size. Anthocyanins showed a significant impact on the extraction of flavan-3-ol material in the early stages of ripening that declined in the latter stages of ripening. Furthermore, anthocyanins significantly decreased the size of the condensed tannin extracted. These results suggest that anthocyanins are not only enhancing the extractability of condensed tannin but also readily incorporating into the polymeric material, leading to a decrease in the average molecular mass of the condensed tannin polymer. The extent of reaction in 72 h suggests that the rate of interflavan bond cleavage may be higher than previously reported and merits closer scrutiny.

Nitrogen Fertilization Influences the Quantity, Composition, and Tissue Association of Foliar Phenolics in Strawberries

Unlike quantitative changes, the compositional changes of plant phenolics and changes in their tissue association as influenced by the nutrient supply are less well understood. We evaluated the quantity, composition, and tissue association of phenolics in leaves of two Fragaria ananassa cultivars in response to different levels of nitrogen (N) fertilization using global metabolomic approaches. Influence of N supply on phenolic content in both cultivars was similar, but the magnitude of this response was compound specific. Ellagitannins, the most abundant class of phenolic oligomers, were less responsive to the applied N treatments, whereas proanthocyanidins, the less abundant class of phenolic oligomers, exhibited higher fold change. Within mono-phenolics, the hydroxycinnamates were more abundant but showed lower fold change than the hydroxybenzoates. Among flavonoids, the hydroxylated flavonols showed higher abundances than the flavones, with a preferential accumulation of dihydroxylated flavonol at lower N levels. Furthermore, glycosylated flavonols were higher than the acylated forms. The extractable fraction of phenolics was more influenced by the N treatment than the fiber-bound fraction. The extensive compositional modification of phenolics and a greater response of non-bound fractions in response to N rates highlight the potential to use precise management of N supply as an effective strategy to enhance the bioactive compounds in crops.

Extended Harvest Date Alter Flavonoid Composition and Chromatic Characteristics of Plavac Mali (Vitis vinifera L.) Grape Berries

This study delivers a comprehensive flavonoid fingerprint profile, physiochemical and external color characterization of Plavac Mali grapes through four harvest dates at two distinct vineyards (Split and Zadar) in the Eastern Adriatic region. The experimental harvest lasted 56 days, at total soluble solids content from 18.4 to 22.4°Brix in Split and 16.8 to 20.4°Brix in Zadar. Patterns of 27 skin and seed flavonoid compounds at each location indicate unique flavonoid composition of berries at each harvest date. Extended harvest increased six compounds in skin with maximum values of main anthocyanin malvidin-3-O-glucoside in H3 (4406.6 and 6389.5 mg kg⁻¹, Split and Zadar, respectively) followed by a decrease in October. Peak values of seed and skin catechins and galloylated flavan-3-ol subunits are seen in H1 and H2 at Split, while constantly high values are reported in the case of Zadar, with an incoherent pattern of those in skin extracts. Minimal values of epigallocatechin were detected with an extended harvest date at both locations. Berries of extended harvest dates underwent colorimetric improvements, trough decrease in L*, a*, b* and C characteristics and increase in skin color index for red grapes CIRG. The extended harvest date promotes flavonoid composition, and improves the quality of Plavac Mali grape berries.

Management of high-quality dehydrated grape in vinification to produce dry red wines

Grape controlled dehydration of "Cesanese" and "Sangiovese" wine grapes, followed by an innovative vinification protocol, was studied. Fresh grapes of both varieties were processed into basic wines (IW = initial wine). 'Cesanese' must from pressed dehydrated grapes (solid and liquid) was directly added (15 and 30% v/v) into the IW activating a refermentation. 'Sangiovese' must (solid and liquid) from pressed dehydrated grapes was fermented and, when the wine reached 5% alcohol concentration, every day, the IW was added until a final concentration of 40 or 60% (v/v). The produced "blended wines" (BW) had significantly higher alcohol, glycerol, extract, and polyphenol concentration. Malolactic fermentation was completely ended in all BW with no malic acid and formation of lactic acid (0.5-1 g/L). All wines showed a significant higher concentration in 4-vinylguaiacol, acetovanillone, and 3-oxo-α-ionol, providing spicy and fruity notes at the sensory analyses, and being appreciated for their body balance, less acidity, and flavor intensity.

Foliar application of specific yeast derivative enhances anthocyanins accumulation and gene expression in Sangiovese cv (Vitis vinifera L.)

The effect of elicitors on secondary metabolism in vines is receiving much interest, since it has been shown that they are able to increase the accumulation of phenolics, especially anthocyanins. This research aims to investigate the biochemical and molecular effects of the application of a commercial yeast derivative (Saccharomyces cerevisiae) on the accumulation of anthocyanins in potted Sangiovese vines. Experiments were performed on three consecutive years and the yeast derivative was applied at the beginning and at the end of veraison. Technological ripening, accumulation of anthocyanins and expression of the main genes involved in their biosynthesis were assessed. Technological ripening proceeded in a similar way in both treated and untreated berries in the three years. A significant increase in the concentration of anthocyanins was instead detected, following the induction by the yeast derivative of the expression of the genes involved in their biosynthesis. The research highlights the possibility of applying a specific inactivated yeast to increase the anthocyanin concentration even under the current climate change conditions, in Sangiovese, a cultivar extremely sensitive to high temperatures.

Post-veraison trimming slow down sugar accumulation without modifying phenolic ripening in Sangiovese vines

BACKGROUND

Vineyard strategies have recently been developed to combat the effects of global warming on grapevines, which is causing grapes to ripen quickly, excessive sugar accumulation in berries, and high alcohol levels in wines. We evaluate the effectiveness of post-veraison trimming as a means of slowing down sugar accumulation, without modifying phenolic ripening, in Sangiovese vines grown in highly fertile and well watered soil.

RESULTS

The removal of about two-thirds of the leaf area by shoot trimming after veraison led to a reduction in sugar content without affecting yield. Total and extractable anthocyanins, skin, and seed tannins showed no significant variation at harvest after the treatment during the three-year trial, while the replenishment of carbohydrates in canes at the end of the trial was negatively affected.

CONCLUSIONS

These results indicate that, in highly fertile and well-watered soil, post-veraison trimming may represent a powerful tool for decreasing sugar concentration during harvest without affecting yield or total and extractable phenolic compounds. However, the reduction in starch reserves compared to the control serves as a warning about repeated trimming over the years. © 2018 Society of Chemical Industry.

Effects of delayed winter pruning on vine performance and grape composition in cv. Merlot

Delaying winter pruning until after budburst is a technique that can retard vine phenological phases and reduce grape sugar concentration at harvest. Given these characteristics, many studies have recently been conducted to verify the ability of pruning after budburst to contrast the negative effects of climate change. In our trial, vines of the cv. Merlot, trained to a VSP spur pruned cordon, were pre-pruned leaving 8 nodes per shoot and hand finished when the shoots sprouted by the apical nodes were at BBCH13 (treatment LP) and BBCH18 stage (treatment VLP). Vines refinished during winter were used as control (WP). Anthocyanins and tannins of skin and seeds were analysed after both exhaustive extraction (total content) and extraction conducted with a hydroalcoholic solution (extractable portion). Vines refinished after budburst showed reduced leaf area, yield, cluster and berry weights; technological maturity of these vines was delayed as lower sugar concentration and pH were observed at harvest. Treatment VLP had a stronger effect than LP on these parameters. Considering phenolic compounds, the skin and seed tannin concentration increased only in VLP, while no effect was found on anthocyanins. In conclusion, delaying pruning until after budburst revealed interesting prospects for contrasting the negative effects of climate change.