The purpose of this work was to investigate the effect of l-malic and citric acids and SO 2 on two biochemical properties (diacetyl/acetoin/2,3-butanediol formation and β-glucosidase activity) relevant to flavor development in six Oenococcus oeni strains from wines at pH 4.8 and 3.8. Cells were cultured in MRS without citrate (control medium) and combined with l-malic acid (2 g/L), citric acid (0.7 g/L), and SO 2 (80 mg/L) at pH 4.8 and 3.8. All the test strains grew at all conditions tested including in the presence of SO 2 and at initial pH 3.8, even though growth parameters were maximum in the presence of both the acids at pH 4.8. Organic acids were depleted totally regardless of the condition examined, in which degradation of l-malic acid was faster than that of citric acid. Diacetyl, acetoin, and 2,3-butanediol levels significantly varied depending on the strain for a given condition, for example, at pH 4.8 in control medium the highest value (6.55±0.31 mg/L, strain MS25) represented almost threefold the lowest one (2.43±0.22 mg/L, strain MS9). There was also variability for each strain depending on the initial pH (strains MS25, MS27, and MS48) and the presence of organic acids (all strains except MS25) but not SO 2 . In addition, among strains there was a trend toward mainly diacetyl formation (55%-75%). O. oeni MS9, MS20, and MS46 yielding adequate diacetyl levels were selected for investigating specific β-glucosidase activity and its possible cell localization. Cell suspensions of all the selected strains exhibited positive activities at both pH values which were >4.8. As observed for C4 compounds, organic acids stimulated this activity (28%-49% at pH 4.8; ~20% at pH 3.8), thus partially reverting the inhibition caused by acid stress, while SO 2 did not affect it. The use of different cell fractions (permeabilized cells, cell protoplasts, and cell extracts) associated this activity to the cell surface. Results indicated that diacetyl formation and β-glucosidase activity levels in O. oeni strains as influenced by acidity and organic acids are of relevance for vinification decisions.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.