Background: Basal leaf removal is widely practiced to increase grape cluster sunlight exposure that controls berry rot and improves quality. Studies on its influence on volatile compounds in grape berries have been performed mostly in Mediterranean or marine climate regions. It is uncertain whether similar efficiency can be achieved when grape berries are grown under continental climate. This study aimed to dissect the variation in volatile compound production and transcriptome in sunlight-exposed grape berries in a dry-hot climate region and to propose the key genes related to the variation.Results: Four cluster sunlight exposure strategies, including basal leaf removal at pepper-corn size stage, leaf removal at véraison (LR-V), leaf moving at véraison (LM-V), and half-leaf removal at véraison, were implemented at the north foot of the Mt. Tianshan region of northwestern China. Various cluster exposure treatments resulted in a decline in the concentrations of norisoprenoids and monoterpenes in ripening grape berries. Bothβ-carotene and lutein, the substrates of norisoprenoid biosynthesis, were reduced by cluster sunlight exposure. K-means cluster analysis showed that some genes involved in biosynthesis such asVviTPS55,VviTPS60,VviTPS66,VviCCD4aandVviCCD4bexhibited lower expression levels in exposed berries at least at one of the tested stages. Two C6-derived esters with fruity attributes, ethyl hexanoate and hexyl acetate, were reduced markedly. In contrast, main C6 alcohol compound levels were elevated in the LR-V- and LM-V-treated grape berries, which corresponded to the up-regulated expression ofVviLOXA,VviLOXOandVviADH1in the oxylipin pathway. Most of the differentially expressed genes in the exposed and control berries were enriched to the “stress response” processes, and this transcriptome difference was accumulated as the berries matured. Besides, LR-V treatment stimulated a significant up-regulation in photosynthesis-related genes in the grape berries, which did not happen with LM-V treatment.Conclusions: Cluster sunlight exposure in dry-hot climate viticulture resulted in different volatile-targeted transcriptomic and metabolic responses from those obtained in the temperate Mediterranean or marine climate region. Therefore, a modified canopy management should be adopted to improve the aroma of grape berries.

Fruit wines have gained great interest in recent years due to the increasingly diverse demands of consumers for different fruit wines with different colors, flavors, and nutritional values. Some fruits such as blueberry and strawberry are perishable and have a short shelf life. The production of fruit wine reduces fruit losses after harvest and enhances fruit utilization. The production of fruit wine with premium quality is determined by both intrinsic (i.e., genetic background) and extrinsic factors (e.g., yeast and fermentation protocol). This article provides an updated overview on the strategies and technologies aiming to improve the quality of fruit wines. Recent progress in improving fruit wine quality by variety selection, post-harvest treatments, yeast selection, fermentation protocols, fermentation conditions, and aging technologies has been comprehensively reviewed.

The quality of raw milk is a key factor influencing the whole dairy processing chain. The richness and diversity of bacteria in raw milk affect its quality and safety. However, traditional microbial detection methods mainly depend on the known microbe culture and are often time consuming. Thus, the development of efficient ways for supervising any possible microbiological contamination is desiderated. In the current work, single-molecule real-time (SMRT) sequencing, developed by Pacific Biosciences (PacBio), was applied to acquire long reads and applied for discrimination of bacteria at species level. Forty samples of raw milk obtained from Beijing, Hebei, Inner Mongolia, Shanghai, and Guangdong in China during summer, autumn, and winter were investigated. Among 35 bacteria species identified in these samples, Acinetobacter albensis, Pseudomonas gessardii, Pseudomonas weihenstephanensis, and Rahnella inusitata were the bacteria with the highest relative abundance in the overall sample, whereas the bacteria with the highest relative abundance in raw milk samples of different origins and seasons are different. Significant differences in bacterial richness and bacterial community diversity in raw milk grouped according to different production areas and different sampling seasons were confirmed by Welch's t-test. Interestingly, the transport distance and transport time positively correlated with the relative abundance of Pseudomonas weihenstephanensis, suggesting that the content of this bacteria was expected to be a standard for evaluating the freshness of raw milk. Pathogens Bacillus cereus and Klebsiella pneumoniae were detected in most samples, indicating that the raw milk was at risk of contamination by pathogenic bacteria. Moreover, the findings of this study provide important evidence for quality and safety monitoring and biological control of raw milk.

Esters are pivotal volatile compounds that shape the floral and fruity attributes of grape berries and wine. In the case of sustainable viticultural system, understanding the formation and regulation of esters is essential for optimizing aroma quality under variable environmental conditions and reducing reliance on intensive cultivation inputs. In this review, the following aspects are comprehensively analyzed: (1) the biosynthetic pathways of esters in grape berries and wine; (2) the main environmental factors affecting ester accumulation in grape berries include light, moisture, temperature, and soil fertility; (3) the impacts of yeast strain selection, inoculation protocols, and post-fermentation processes, such as barrel aging and bottle storage, on ester composition. By integrating biochemical insights with viticultural and enological strategies, this review aims to provide references for developing sustainable approaches to regulate the esters biosynthesis and enhance the aroma quality of grapes and wine.