학술논문
The effect of organic acids and sulfur dioxide on C4 compound production and [beta]-glucosidase activity of Oenococcus oeni from wines under acidic conditions
ORIGINAL RESEARCH
ORIGINAL RESEARCH
Document Type
Academic Journal
Source
International Journal of Wine Research. February 2020, p19, 9 p.
Subject
Language
English
ISSN
1179-1403
Abstract
Introduction Wine is one of the oldest products where microbiological processes contribute significantly to the final quality of the product. Malolactic fermentation (MLF) that normally occurs after the completion of [...]
The purpose of this work was to investigate the effect of l-malic and citric acids and [SO.sub.2] on two biochemical properties (diacetyl/acetoin/2,3-butanediol formation and [beta]-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.sub.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.sub.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[+ or -]0.31 mg/L, strain MS25) represented almost threefold the lowest one (2.43[+ or -]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.sub.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 [beta]-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.sub.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 [beta]-glucosidase activity levels in O. oeni strains as influenced by acidity and organic acids are of relevance for vinification decisions. Keywords: O. oeni, metabolism, enzymatic activity, aroma, wine
The purpose of this work was to investigate the effect of l-malic and citric acids and [SO.sub.2] on two biochemical properties (diacetyl/acetoin/2,3-butanediol formation and [beta]-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.sub.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.sub.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[+ or -]0.31 mg/L, strain MS25) represented almost threefold the lowest one (2.43[+ or -]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.sub.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 [beta]-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.sub.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 [beta]-glucosidase activity levels in O. oeni strains as influenced by acidity and organic acids are of relevance for vinification decisions. Keywords: O. oeni, metabolism, enzymatic activity, aroma, wine