Identification of the potential inhibitors of malolactic fermentation in wines

The pH adjustment of Vitis amurensis dry red wine revealed the evolution of organic acids, volatomics, and sensory quality during winemaking

To produce quality dry red wines with high-acidity grapes of Vitis amurensis, an experiment was designed to adjust pH during winemaking by adding KHCO3 at two time points and two pH levels in conjunction with malolactic fermentation (MLF). The organic acids and volatiles were detected by HPLC and GC-MS separately, combing with the color characteristic and sensory evaluation, we investigated the quality of V.amurensis wines under pH adjustment. Results showed that the pH adjustment weakened the wine color slightly but helped to initiate MLF. The low pH value of alcoholic fermentation favored the development of esters and higher alcohols. Higher pH levels promoted a sufficient MLF and enhanced the global aroma levels by 1.14-1.25 times, which led to higher sensory scores. In conclusion, KHCO3 addition and MLF improved the quality of V. amurensis dry red wines, chemical addition after alcoholic fermentation was more effective for cold regions.

Exploring the diversity of bacteriophage specific to Oenococcus oeni and Lactobacillus spp and their role in wine production

The widespread existence of bacteriophage has been of great interest to the biological research community and ongoing investigations continue to explore their diversity and role. They have also attracted attention and in-depth research in connection to fermented food processing, in particular from the dairy and wine industries. Bacteriophage, mostly oenophage, may in fact be a 'double edged sword' for winemakers: whilst they have been implicated as a causal agent of difficulties with malolactic fermentation (although not proven), they are also beginning to be considered as alternatives to using sulphur dioxide to prevent wine spoilage. Investigation and characterisation of oenophage of Oenococcus oeni, the main species used in winemaking, are still limited compared to lactococcal bacteriophage of Lactococcus lactis and Lactiplantibacillus plantarum (formally Lactobacillus plantarum), the drivers of most fermented dairy products. Interestingly, these strains are also being used or considered for use in winemaking. In this review, the genetic diversity and life cycle of phage, together with the debate on the consequent impact of phage predation in wine, and potential control strategies are discussed. KEY POINTS: • Bacteriophage detected in wine are diverse. • Many lysogenic bacteriophage are found in wine bacteria. • Phage impact on winemaking can depend on the stage of the winemaking process. • Bacteriophage as potential antimicrobial agents against spoilage organisms.