Timing of inoculation of Oenococcus oeni and Lactobacillus plantarum in mixed malo-lactic culture along with compatible native yeast influences the polyphenolic, volatile and sensory profile of the Shiraz wines

Enhancing blueberry wine quality and antioxidant capacity through mixed fermentation with S. cerevisiae and O. oeni

This study investigates the impact of O. oeni on the quality of blueberry wine, employing various analytical methods to determine parameters such as alcohol content, antioxidant capacity, organic acids, amino acids, and volatile components. The results demonstrated that co-inoculation with O. oeni significantly decreased the titratable acidity of blueberry wine. Among the organic acids, the malic acid content of ST and SE groups decreased by (26.24 ± 1.24)% and (35.75 ± 4.02)%, respectively. The main consumed amino acids were aspartate, lysine, and arginine after co-inoculation with O. oeni. Additionally, co-inoculation with O. oeni significantly increased the content of medium-chain fatty acid ethyl esters, especially isoamyl acetate content. The antioxidant capacity of blueberry wine was significantly enhanced by co-inoculation with O. oeni, particularly in terms of measurement of 1,1-diphenyl-2-picryl-hydrazyl (DPPH) clearance. The findings of this study provide a solid basis for improving the quality of blueberry wine and promoting the growth of blueberry wine industry.

Research on microbial diversity and nutritional flavor formation of Xianju wheat paste

BACKGROUND

Xianju wheat paste, a traditional condiment in Hubei Province, China, possesses nutritional value and a distinctive taste profile. Nevertheless, there remains a dearth of comprehensive comprehension regarding the intricate interplay between the microbial population and its nutritional profile in Xianju wheat paste.

RESULTS

It was determined that Xianju wheat paste harbors predominant microbial genera such as Bacillus, Staphylococcus and Aspergillus. The findings from high-throughput sequencing analysis revealed the presence of 11 bacterial genera in Xianju wheat paste, with relative abundances exceeding 1%. These genera included Bacillus, Staphylococcus, Brevibacterium, Lactobacillus, Allorhizobium-Neorhizobium-Pararhizobium-Rhizobium, Enterobacteriaceae, Pantoea, Brachybacterium, Klebsiella, Escherichia-Shigella and Ochrobactrum. Furthermore, six fungal genera were identified with relative abundances greater than 1%, specifically Aspergillus, Zygosaccharomyces, Cutaneotrichosporon, Candida, Millerozyma and Rhizopus. The correlation analysis indicated a significant impact of the microbial community and nutritional flavor on the second phase of fermentation in Xianju wheat paste. The predominant bacterium Bacillus in Xianju wheat paste facilitated the production of free amino acids, whereas Staphylococcus exhibited a negative correlation with free amino acid levels. The quantity of volatile compounds in Xianju wheat paste progressively increased during fermentation, with the presence of typical aroma compounds 4-vinyl-2-methoxyphenol significantly associated with Bacillus. This indicated Bacillus notably enhanced the production of aromatic substances. Furthermore, a strong correlation was observed between Staphylococcus and the 18 volatile organic compounds, highlighting their substantial contribution to these aroma compounds.

CONCLUSION

This research indicates that the presence of microbial communities significantly contributes to the development of the nutritional flavor profile in Xianju wheat paste. © 2024 Society of Chemical Industry.

Lactiplantibacillus plantarum exerts strain-specific effects on malolactic fermentation, antioxidant activity, and aroma profile of apple cider

This study aimed to investigate the impact of different strains of Lactiplantibacillus plantarum on malolactic fermentation (MLF), antioxidant activity, and aroma of ciders. A commercial strain of Saccharomyces cerevisiae and six indigenous L. plantarum strains were co-inoculated into apple juice to induce simultaneous alcoholic fermentation (AF) and MLF. The findings indicated that despite belonging to the same species, the different L. plantarum strains significantly differed (p < 0.05) in terms of antioxidant activity and aroma compounds in the ciders. MLF induced by L. plantarum resulted in the substantial consumption of malic acid and increased levels of lactic acid in the ciders, with strain-specific effects observed, particularly with L. plantarum SCFF284. In addition, ciders produced from mixed fermentations exhibited higher levels of antioxidant activity than those from pure S. cerevisiae fermentation (p < 0.05), especially for LAM284. Furthermore, ciders produced from mixed fermentations exhibited higher levels of aroma compounds, such as ethyl acetate and isoamyl alcohol, and also received higher sensory scores compared to ciders produced through pure S. cerevisiae fermentation (p < 0.05). These results highlight the effectiveness of MLF induced by L. plantarum in enhancing the antioxidant activity and aroma profile of ciders.

Volatile Organic Compound-Based Predictive Modeling of Smoke Taint in Wine

Smoke taint in wine has become a critical issue in the wine industry due to its significant negative impact on wine quality. Data-driven approaches including univariate analysis and predictive modeling are applied to a data set containing concentrations of 20 VOCs in 48 grape samples and 56 corresponding wine samples with a taster-evaluated smoke taint index. The resulting models for predicting the smoke taint index of wines are highly predictive when using as inputs VOC concentrations after log conversion in both grapes and wines (Pearson Correlation Coefficient PCC = 0.82; R2 = 0.68) and less so when only grape VOCs are used (Pearson Correlation Coefficient PCC = 0.76; R2 = 0.56), and the classification models also show the capacity for detecting smoke-tainted wines using both wine and grape VOC concentrations (Recall = 0.76; Precision = 0.92; F1 = 0.82) or using only grape VOC concentrations (Recall = 0.74; Precision = 0.92; F1 = 0.80). The performance of the predictive model shows the possibility of predicting the smoke taint index of the wine and grape samples before fermentation. The corresponding code of data analysis and predictive modeling of smoke taint in wine is available in the Github repository (https://github.com/IBPA/smoke_taint_prediction).

Chitosan Film as a Replacement for Conventional Sulphur Dioxide Treatment of White Wines: A 1H NMR Metabolomic Study

Chitosan–genipin (Ch-Ge) films have been proposed for the replacement of sulfur dioxide (SO₂) in white wines preservation to circumvent the adverse health consequences caused by SO₂ intake. To assess the effects of different-sized Ch-Ge films (25 and 100 cm²) on wine composition compared to SO₂-treated and untreated wines, nuclear magnetic resonance metabolomics was applied. Relative to SO₂, 100 cm² films induced significant changes in the levels of organic acids, sugars, amino acids, 5-hydroxymethylfurfural, among other compounds, while 25 cm² films appeared to induce only small variations. The observed metabolite variations were proposed to arise from the mitigation of fermentative processes, electrostatic interactions between acids and the positively charged films and the promotion of Maillard and Strecker reactions. Qualitative sensory analysis showed that wines maintained overall appropriate sensory characteristics, with 100 cm² film treated wines showing slightly higher attributes. Based on these results, the possibility of using Ch-Ge films as a replacement for SO₂ treatment is discussed.

Pilot-Scale Vinification of Cabernet Sauvignon Using Combined Lactiplantibacillus plantarum and Saccharomyces cerevisiae to Achieve Wine Acidification

Insufficient acidity in grape berries from warm climate regions has been exacerbated due to global warming, thereby becoming a major concern for winemaking. The wine lactic acid bacterium Lactiplantibacillus plantarum has potential to ameliorate wine acidity by producing lactic acid from hexose metabolism, but its impact on wine compositions and sensory outcomes is not well studied. Here, we evaluated acidification and fermentation performance of indigenous L. plantarum in two inoculation regimes (i.e., reverse inoculation and co-inoculation) by conducting pilot-scale vinification using Cabernet Sauvignon with low acidity. Important parameters of the bio-acidified wines, including fermentation kinetics, basic oenological parameters, volatile and sensory profile were compared to those in wines produced by single Saccharomyces cerevisiae with/without chemical acidification. Total titratable acidity in L. plantarum wines were either comparable or significantly higher compared to the chemical acidification control. Chemical profiling reviewed remarkable differences in certain organic acids and major volatile compounds, especially an up to a five-fold, six-fold, and nine-fold increase in lactic acid, ethyl lactate and isoamyl lactate, respectively. Changes in chemical compositions of the bio-acidified wines resulted in differentiated sensory perception compared to the control wines. Except having higher scores for “wine acidity”, the flavour profile of the bio-acidified wines was shifted towards “jammy fruit” and “butter” aromas. Together, these findings highlighted the applicability of using L. plantarum to induce biological acidification along with modulation of wine flavour.

Technological Improvements on FML in the Chianti Classico Wine Production: Co-Inoculation or Sequential Inoculation?

Winemaking variables and techniques are known to affect the composition of wines. To obtain a rapid and safe fermentation course, with a reduced risk of proliferation of unwanted microbial species, frequent recourse is made to the use of selected microorganisms, which can greatly simplify the complex management of the fermentation process. In particular, selected strains of lactic acid bacteria are used, which are much more sensitive than yeasts to the operating conditions of the medium. In this regard, the overall aim of this research was to verify whether the early inoculation of homolactic acid bacteria for hexoses (Lactobacillus plantarum) carried out after 24 h, compared with that of saccharomycetes operating alcoholic fermentation, could be advantageous compared with a traditional innoculation with a different heterolactic bacterial strain for hexoses (Oenococcus oeni) operated at the end of alcoholic fermentation. The grape variety chosen was Sangiovese, the protagonist of Tuscan oenology. The evaluation focused on different aspects such as the management of winery operations, and the quality and longevity of the product; was carried out in all phases of winemaking; and analysed both from a chemical and sensory point of view.