Characterization of malolactic bacteria isolated from Aosta Valley wines and evidence of psychrotrophy in some strains

Energy efficiency in winemaking industry: Challenges and opportunities

The United Nations has issued a warning over the limited time for climate disaster prevention. In the last two decades, several countries have set targets to reduce fossil fuel usage and greenhouse gas emissions. These goals are tracked through the adoption of energy systems that prioritise efficiency and low-carbon alternatives, in alignment with the Sustainable Development Goals outlined by the United Nations. In the winemaking sector, the wine produced in the European Union comprised 65 % of the worldwide total from 2014 to 2018, with vineyards making up 4.7 % of its farms in 2020. Electricity is the primary source of energy used in vineries, accounting for around 90 % of the total energy consumption. The energy consumption associated with winemaking is mostly attributed to two key processes: fermentation, which accounts for 45 % to 90 % of the entire energy consumption, and bottling and storage, which contribute around 18 % of the overall energy consumption. The aim of this article is to provide an integrated review of energy efficiency in wineries through examining 144 academic publications. The selected publications cover various aspects, including sustainable energy utilisation in the wine industry, thermal performance analysis of buildings, energy efficiency assessment of systems and technologies, and the integration of renewable energy sources. A link has been established between the geographic distribution of academic publications and wine-producing countries. In relation to European publications, it is observed that research funding is associated with the energy directives of the European Union. It can also be concluded that wine customers are pushing for environmentally friendly practices. However, not everyone in the winemaking sector is moving in the same direction or at the same pace. To identify areas for improvement, winemakers must have supporting tools to manage energy use. Systems optimisation, monitoring, and accounting can be used to decrease energy consumption in winemaking processes or equipment. Progresses on sustainable energy use through greater energy efficiency and share of renewable energies in the wineries can contribute to the reduction of greenhouse gas emissions, and consequently, brings the wine industry closer to climate neutrality.

Valorisation of Bovine Sweet Whey and Sunflower Press Cake Blend through Controlled Fermentation as Platform for Innovative Food Materials

The current environmental challenge is pushing food systems towards more sustainable models of production that require reorganizing of processes by re-using side products still containing nutrients. This work aimed at valorising a mix of bovine sweet whey and sunflower press cake, through targeted fermentation. After preliminary screening based on growth rate, final pH, lactose/galactose assimilation, phytase activity, six Lactic Acid Bacteria strains (Lacticaseibacillus casei, L. paracasei (2), Lactococcus lactis, Lentilactobacillus parakefiri and Leuconostoc pseudomesenteroides) and three yeasts (Kluyveromyces lactis, K. marxianus and Torulaspora delbrueckii) were co-cultivated in pairs in microcosms (1-part ground press cake: 4-parts whey). All tested microorganisms were able to grow and acidify the blend: the LAB counts increased during the incubation (26 °C for 48 h) of +2.80 log CFU/g, whereas yeasts counts were of +1.98 log CFU/g, with significant differences among the different associations (p < 0.01). Mould counts were always <3 log CFU/g. Interestingly, the bacterial contaminants count significantly varied in samples with different pairs of strains (p < 0.001). Acidification level, acetic acid and ethanol contents were the limiting factors affecting the growth of spoilage micro-organisms. Best performances were attained in microcosms inoculated with L. lactis or L. paracasei and K. lactis or K. marxianus.

Integrative multiomics analysis of the acid stress response of Oenococcus oeni mutants at different growth stages

BACKGROUND

Acid stress is one of the most important environmental stresses that adversely affect the growth of lactic acid bacteria (LAB), such as Oenococcus oeni which was isolated from grape-berries and mainly used in wine fermentation. The aim of this paper is to comprehensively characterize the mechanisms of acid stress regulation in O. oeni and to provide a viable theoretical basis for breed and improvement of existing LAB.

METHOD

First, six O. oeni mutants with acid-sensitive (strains b2, a1, c2) and acid-tolerant (strains b1, a3, c1) phenotypes were screened from three wild-type O. oeni, and then their genome (sequencing), transcriptome and metabolome (LC-MS/MS) were examined.

RESULTS

A total of 459 genes were identified with one or more intragenic single nucleotide polymorphisms (SNPs) in these mutants, and were extensively involved in metabolism and cellular functions with a high mutation rates in purine (46%) and pyrimidine (48%) metabolic pathways. There were 210 mutated genes that cause significant changes in expression levels. In addition, 446 differentially accumulated metabolites were detected, and they were consistently detected at relatively high levels in the acid-tolerant O. oeni mutant. The levels of intracellular differentially expressed genes and differential metabolites changed with increasing culture time.

CONCLUSION

The integrative pathways analysis showed that the intracellular response associated with acid regulation differed significantly between acid-sensitive and acid-tolerant O. oeni mutants, and also changed at different growth stages.

Evaluation of Malolactic Bacteria Associated with Wines from Albariño Variety as Potential Starters: Screening for Quality and Safety

The biodiversity of lactic acid bacteria in musts and wines of Albariño variety has been studied. The identification of species was addressed through a combination of biochemical and genetic methods (API^® 50 CHL test, 16S rDNA and recA gene sequences, Amplified Ribosomal DNA Restriction Analysis -ARDRA- and 16S-26S intergenic region analysis). The results grouped the isolates into six species predominating those of the genus Lactobacillus and showing a typical biogeographical distribution. Among sixteen strains evaluated, eight of them showed malolactic activity. The study of the presence of genes hdc, odc, and tdc, along with the LC/MS-MS analysis of biogenic amines in wine, showed five strains lacking aminogenic ability. The absence of the pad gene in the above-mentioned strains discards its ability to produce volatile phenols that may adversely affect the aroma. Finally, all malolactic strains showed β-glucosidase activity so that they could contribute to enhance and differentiate the aromatic profile of Albariño wines.

Distribution of Oenococcus oeni populations in natural habitats

Oenococcus oeni is the lactic acid bacteria species most commonly encountered in wine, where it develops after the alcoholic fermentation and achieves the malolactic fermentation that is needed to improve the quality of most wines. O. oeni is abundant in the oenological environment as well as in apple cider and kombucha, whereas it is a minor species in the natural environment. Numerous studies have shown that there is a great diversity of strains in each wine region and in each product or type of wine. Recently, genomic studies have shed new light on the species diversity, population structure, and environmental distribution. They revealed that O. oeni has unique genomic features that have contributed to its fast evolution and adaptation to the enological environment. They have also unveiled the phylogenetic diversity and genomic properties of strains that develop in different regions or different products. This review explores the distribution of O. oeni and the diversity of strains in natural habitats.