Search

Unlabelled: Different wine varieties, including some with low pH, were studied to determine the ability to grow and produce secondary metabolites of a previously selected autochthonous Oenococcus oeni strain (C22L9), compared with a commercial strain. Monitoring of malolactic fermentation (MLF) was carried out by microbiological and chemical analysis of wines. The concentration of some major volatile compounds and biogenic amines in wines before and after malolactic fermentation was also determined. The results showed major differences in MLF duration both between wines and strains, although the differences between strains were slight for most of the analyzed compounds. Statistically significant differences in citric acid degradation were found in all wine varieties and it was confirmed that O. oeni C22L9 is a poor degrader of citric acid; this means that MLF can be prolonged without the risk of producing high concentrations of diacetyl and acetoin. Sensory analysis of wines after MLF showed similar characteristics in wines from both strains. This study thus shows that O. oeni C22L9 possesses even better sensory and fermentation properties than the commercial strain and can be used in wines with different characteristics, which makes it highly valuable for industrial use., Practical Application: The increasingly use of grape varieties of low pH in winemaking and the higher alcohol content of wines, as a consequence of the climatic change, make interesting the study of the behavior during MLF of O. oeni strains in order to determine their ability to grow, when growth conditions are not optimal, and to produce secondary metabolites. A comparative study was conducted using an autochthonous O. oeni strain (C22L9) and a commercial O. oeni strain and 4 wine varieties., (© 2012 Institute of Food Technologists®)

Craft beer because of its fresh flavor, unique taste, and rich nutrition is becoming more popular to consumers. Compared with industry beer, craft beer is often nonfiltered and nonpasteurized, for this reason, it has a short shelf life and is more susceptible to microbial spoilage, which may cause the quality deterioration of craft beer and the formation of biogenic amine as a harmful factor for consumer's health. In this study, the 23 beer-spoilage bacteria were isolated from craft beer, which were identified as 15 Lactobacillus (L.) brevis, 3 L. plantarum, 1 L. parabuchneri, 2 L. paracasei, and 2 Pediococcus damnosus. Among 23 beer-spoilage isolates, 20 representatives were able to form tyramine, histamine, putrescine, cadaverine, and/or tryptamine in MRS broth. The nine Lactobacillus strains were incubated in beer and produced tyramine, histamine, putrescine, cadaverine, and/or tryptamine during beer storage process. Logistic and Gompertz model could be adopted to respectively describe the kinetics of microorganism growth and biogenic amine formation. The relationship between the biogenic amines and biomass was simulated by Luedeking-Piret model very well, and showed that the formation of biogenic amine was mainly bacteria growth-associated in beer. These findings may be helpful for finding the preventive measures to control biogenic amine formation and for enhancing the safety of craft beer. PRACTICAL APPLICATION: The selection of the biogenic amine-producing spoilage bacteria from craft beer and the investigation their kinetics of the growth and biogenic amines production under beer environmental conditions was very helpful for finding preventive measures to eliminate or reduce biogenic amine formation and for appropriate increase in food safety., (© 2021 Institute of Food Technologists®.)