Inactive dry yeast application on grapes modify Sauvignon Blanc wine aroma

Metabolic and Molecular Rearrangements of Sauvignon Blanc (Vitis vinifera L.) Berries in Response to Foliar Applications of Specific Dry Yeast

Dry yeast extracts (DYE) are applied to vineyards to improve aromatic and secondary metabolic compound content and wine quality; however, systematic information on the underpinning molecular mechanisms is lacking. This work aimed to unravel, through a systematic approach, the metabolic and molecular responses of Sauvignon Blanc berries to DYE treatments. To accomplish this, DYE spraying was performed in a commercial vineyard for two consecutive years. Berries were sampled at several time points after the treatment, and grapes were analyzed for sugars, acidity, free and bound aroma precursors, amino acids, and targeted and untargeted RNA-Seq transcriptional profiles. The results obtained indicated that the DYE treatment did not interfere with the technological ripening parameters of sugars and acidity. Some aroma precursors, including cys-3MH and GSH-3MH, responsible for the typical aromatic nuances of Sauvignon Blanc, were stimulated by the treatment during both vintages. The levels of amino acids and the global RNA-seq transcriptional profiles indicated that DYE spraying upregulated ROS homeostatic and thermotolerance genes, as well as ethylene and jasmonic acid biosynthetic genes, and activated abiotic and biotic stress responses. Overall, the data suggested that the DYE reduced berry oxidative stress through the regulation of specific subsets of metabolic and hormonal pathways.

Biochar-biofertilizer combinations enhance growth and nutrient uptake in silver maple grown in an urban soil

Declining tree health status due to pollutant impacts and nutrient imbalance is widespread in urban forests; however, chemical fertilizer use is increasingly avoided to reduce eutrophication impacts. Biochar (pyrolyzed organic waste) has been advocated as an alternative soil amendment, but biochar alone generally reduces plant N availability. The combination of biochar and either organic forms of N or Plant Growth Promoting Microbes (PGPMs) as biofertilizers may address these challenges. We examined the effects of two wood biochar types with Bacillus velezensis and an inactivated yeast (IY) biofertilizer in a three-month factorial greenhouse experiment with Acer saccharinum L. (silver maple) saplings grown in a representative urban soil. All treatments combining biochars with biofertilizers significantly increased sapling growth, with up to a 91% increase in biomass relative to controls. Growth and physiological responses were closely related to nutrient uptake patterns, with nutrient vector analyses indicating that combined biochar and biofertilizer treatments effectively addressed nutrient limitations of both macronutrients (N, P, K, Mg, Ca), and micronutrients (B, Fe, Mn, Mo, Na, S, and Zn). Biochar-biofertilizer treatments also reduced foliar concentrations of Cu, suggesting potential to mitigate toxic metal impacts common in urban forestry. We conclude that selected combinations of biochar and biofertilizers have substantial promise to address common soil limitations to tree performance in urban settings.

Review of the valorization initiatives of brewing and distilling by-products

Beer and spirits are two of the most consumed alcoholic beverages in the world, and their production generates enormous amounts of by-product materials. This ranges from spent grain, spent yeast, spent kieselguhr, trub, carbon dioxide, pot ale, and distilled gin spent botanicals. The present circular economy dynamics and increased awareness on resource use for enhanced sustainable production practices have driven changes and innovations in the management practices and utilization of these by-products. These include food product development, functional food applications, biotechnological applications, and bioactive compounds extraction. As a result, the brewing and distilling sector of the food and drinks industry is beginning to see a shift from conventional uses of by-products such as animal feed to more innovative applications. This review paper therefore explored some of these valorization initiatives and the current state of the art.

Advances in yeast autolysis technology - a faster and safer new bioprocess

Abstract The yeast autolysis process - an endogenous and irreversible lytic event, which occurs in cells caused by the action of intracellular enzymes, proteases and carbohydrases - is a well-known and an economic process, however, there is a constant risk of serious microbial contamination since there are many nutrients in the broth and this process is slow, favoring the growing of pathogens. The present work comes up with an attempt to accelerate the autolysis of Saccharomyces cerevisiae with focus on the high yield of yeast extract production through a fast, economic and simple technology. The proposed strategy is based on decreasing the pH of the yeast suspension at the beginning of autolysis through an acid shock to activate the cell autolytic system under stressful conditions of temperature and pH. The influence of cell concentration, temperature, time and acid shock at the beginning of the autolysis on yeast extract yields were studied. The best yields of proteins and total solids were observed for autolysis treated with acid shock (H2SO4 10 µL/g of dried yeast and final pH 4.4) at 60 °C (36, 84% of protein and 48, 47% of total solids extracted) and gradual increase of temperature 45 to 60 °C (41.20% of protein and 58.48% of total solids extracted). The shock could increase the speed of the process since the control reached about 30% of extract at 60 °C and the same experiment, however, with acid shock reached more than 43% in 12 h. When considering time in an industrial scale, it could be noted that the time was very important for the productivity as well as avoiding risk of pathogen contamination in autolysis. These results were very relevant for industrial purposes in the production of yeast extract, autolyzed yeast and glucan and mannan.

Effect of pre-harvest inactivated yeast treatment on the anthocyanin content and quality of table grapes

Due to the global warming, more and more often the red-pink grape varieties grown in the Mediterranean basin reveal an insufficient accumulation of anthocyanins and thus a scarce coloration. Nowadays, this is becoming an important technological issue, which may result in the reduction of the fresh market value of table grape. This study aimed at assessing the effect of the pre-harvest treatment by specific inactivated yeasts (YE) on the qualitative parameters and anthocyanin pattern of three red table grape varieties, which typically present poor and/or incomplete coloration during warm years. An increment of anthocyanins level up to almost seven folds corresponding to an improvement of red skin appearance was observed in all the treated table grapes, which was preserved after cold storage, too. While, no significant influence on chemical composition and berry texture and dimensions was found, meaning that YE did not cause appreciable taste changes in grapes.

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.

How Pre-Harvest Inactivated Yeast Treatment May Influence the Norisoprenoid Aroma Potential in Wine Grapes

Carotenoids are important secondary metabolites in wine grapes and play a key role as potential precursors of aroma compounds (i.e., C13-norisoprenoids), which have a high sensorial impact in wines. There is scarce information about the influence of pre-harvest inactivated yeast treatment on the norisoprenoid aroma potential of grapes. Thus, this work aimed to study the effect of the foliar application of yeast extracts (YE) to Negro Amaro and Primitivo grapevines on the carotenoid content during grape ripening and the difference between the resulting véraison and maturity (ΔC). The results showed that β-carotene and (allE)-lutein were the most abundant carotenoids in all samples, ranging from 60% to 70% of total compounds. Their levels, as well as those of violaxanthin, (9′Z)-neoxanthin, and 5,6-epoxylutein, decreased during ripening. This was especially observed in treated grapes, with ΔC values from 2.6 to 4.2-fold higher than in untreated grapes. Besides this, a principal components analysis (PCA) demonstrated that lutein, β-carotene, and violaxanthin and (9′Z)-neoxanthin derivatives principally characterized Negro Amaro and Primitivo, respectively. Thereby, the YE treatment has proved to be effective in improving the C13-norisoprenoid aroma potentiality of Negro Amaro and Primitivo, which are fundamental cultivars in the context of Italian wine production.

Effect of Different Yeast Strains and Temperature of Fermentation on Basic Enological Parameters, Polyphenols and Volatile Compounds of Aurore White Wine

The aim of this study was to investigate the content of phenolics by Ultra Performance Liquid Chromatography–Photodiode Array (UPLC–PDA), and volatile compounds by Gas Chromatography–Mass Spectroscopy (GC–MS), antioxidant capacity by 2,2′-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) radical cation (ABTS^•+) and ferric-reducing antioxidant power (FRAP) assay, and color of Comission Internationale de l’Eclairage system (CIE) L*a*b* cv. Aurora white wine depending on fermentation conditions (a temperature of 12 °C vs. 20 °C and type of natural and commercial yeast (Saccharomyces cerevisiae vs. Saccharomyces bayanus)). The final wine differed in the content of total phenolic compounds (201.0–287.2 mg/L), except for the variants fermented at 20 °C with S. cerevisiae (321.9 and 329.4 mg/L for S. cerevisiae as Challenge Aroma White and SIHA^® Cryaroma type, respectively). A decrease in antioxidant activity ranging from 43.3% to 65.4% (ABTS and FRAP assay) in the matured wine vs. must was demonstrated. S. cerevisiae wine was also characterized by the highest content of total volatile compounds (3.7–4.2 mg/L vs. 1.3 mg/L in the must). In general, the wine obtained with S. cerevisiae had higher alcohol content, antioxidant capacity, and was richer in polyphenolic and volatile compounds.

Late-Season Shiraz Berry Dehydration That Alters Composition and Sensory Traits of Wine

Late-season berry dehydration (LSD) is a common occurrence in Shiraz grapes, particularly those grown in hot climates. LSD results in significant yield reductions; however, the effects on wine composition and sensory characteristics are not well-documented. Wines made of 100% nonshriveled clusters (control) were related to red fruit flavors by the sensory panel, whereas wines made of 80% shriveled clusters (S-VCT) were perceived as more alcoholic and associated with dark fruit and dead/stewed fruit characters. The latter wines also resulted in higher concentrations of massoia lactone and γ-nonalactone, compounds known to contribute to prune and stewed-fruit aromas. Wines made of shriveled grapes were also characterized by an increase in C6-alcohols and a decrease in esters, whereas wine terpenoids were altered compound-specific. An increase in orange pigments and wine chemical age in S-VCT wines indicated faster oxidative aging compared to the control. LSD appeared to alter final wine composition directly but also appeared to influence yeast metabolism, potentially due to an alteration of the composition of lipids in the grape juice. This study emphasized the relevance of sorting shriveled and nonshriveled berries for final wine chemical composition and wine style.

Volatile and sensory profiling of Shiraz wine in response to alcohol management: comparison of harvest timing versus technological approaches

The aim of this study was to compare the volatile and sensory profiles of Australian Shiraz red wines produced by several methods to achieve alcohol concentrations of 10.5 and 13.5% v/v. These levels were considerably lower contents than the commercial wine (16-17% v/v) that was produced from this vineyard site. Wines were produced by: (i) harvest timing (19.3, 24 and 29.3 Brix); (ii) blending equal proportions of early harvest (19.3 Brix) and late harvest wines (29.3 Brix); and (iii) dealcoholization using reverse osmosis followed by a membrane contactor. Dealcoholization caused a significant loss of volatile compounds, particularly esters, while the blending treatment had an averaging effect on most analytes. Sensory descriptive analysis of treatments with 10.5% v/v alcohol showed that the perception of the herbaceous attribute was more intense in the early harvest wines in comparison to the dealcoholized wines, while those of dark fruit, raisin/prune, astringency and alcohol were lower. No sensory differences were found amongst the 13.5% v/v wines, except for alcohol. Sensory and compositional data were modelled by means of Common Dimension (ComDim) multi-block analysis and indicated which chemical components are important to the perceived wine sensory properties. Insights from this study will provide knowledge that may be applied to control or moderate both unripe sensory attributes in addition to a deficiency of ripe fruit aromas or mouthfeel characteristics in reduced-alcohol red wines.

Berry Shriveling Significantly Alters Shiraz (Vitis vinifera L.) Grape and Wine Chemical Composition

Berry shriveling is an often reported occurrence in the Shiraz (Vitis vinifera L.) cultivar. This study investigated the effect of berry shriveling occurring in a high yielding (18.6 ± 1.6 kg/vine) Shiraz vineyard in relation to a temporal investigation of grape and wine composition using three harvest dates. Berry shriveling resulted in delayed total soluble solids and amino acid accumulation into the berry, however differences between treatments diminished or became smaller by the third harvest date. Similarly, ethyl esters of fatty acids and higher alcohol acetates were lower in wines from shriveled berries from the first two harvests; anthocyanins were reduced in wines from shriveled berries at all harvest dates, whereas terpenes were unaltered. Wines made from shriveled berries had higher γ-nonalactone and β-damascenone concentrations. This study provides novel information on the chemical alterations of grapes and wines made from grapes affected by shriveling.