The effect of organic acids and sulfur dioxide on C4 compound production and &beta;-glucosidase activity of <em>Oenococcus oeni</em> from wines under acidic conditions

Abstract

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.

Assessment of β-D-glucosidase activity and bgl gene expression of Oenococcus oeni SD-2a

“…Numerous studies had been conducted, providing evidence of the potential βG activity of O. oeni strains for flavor enhancement in wines [7,10,[14][15][16][17][18][19][20][21][22][23][24]. These studies demonstrated that possession of βG activity is widespread and extent of βG activity is strain dependent among O. oeni strains [16,21,25,26], and the enzyme activity is mainly affected by pH, temperature, sugar, and ethanol concentration [15][16][17]19,27,28].…”

“…These studies demonstrated that possession of β G activity is widespread and extent of β G activity is strain dependent among O . oeni strains [ 16 , 21 , 25 , 26 ], and the enzyme activity is mainly affected by pH, temperature, sugar, and ethanol concentration [ 15 – 17 , 19 , 27 , 28 ].…”

Production of coconut sprout wine using Saccharomyces cerevisiae and its physico-chemical analysis

“…These fruits undergo a period of fermentation where microbiological processes contribute significantly to the final quality of the product. 1 Wine usually has an alcohol content ranging between 5 to 13 percent. Wine has a flavour like fresh fruit which could be stored and transported under the existing conditions.…”

Influence of glycosides on behavior of Oenococcus oeni in wine conditions: growth, substrates and aroma compounds

“…151 Page 2 of 12 of wine (Maturano et al 2016;Tristezza et al 2016). Microbiological stability and flavor modification of wine are also outcomes of MLF with a broad range of secondary compositional changes that include amino acids and polyols metabolism, esters synthesis and glycosides hydrolysis (Bartowsky et al 2002;Liu 2002).…”

“…However, Mansfield et al (2002) reported the production of β-glycosidase enzyme in O. oeni strains, although their culture failed to hydrolyze native grape glycosides. In addition, several studies have focused on the influence of pH, temperature, sugar and ethanol content on β-d-glucosidase activities of O. oeni (Boido et al 2002;D'Incecco et al 2004;Grimaldi et al 2005a, b;Bloem et al 2008;Gagné et al 2011;Maturano et al 2016). However, data are still scarce and often contradictory.…”