Malolactic Fermentation Ability Of Mutagenesis Of Oenococcus Oeni And Its Effect On Wine Aroma

Oenococcus oeni is the most important strain that was used to start and complete malolactic fermentation?MLF?.However,its growth and metabolism were inhibited because of low pH,high alcohol concentration and sulfur dioxide?SO₂?after alcoholic fermentation?AF?.Therefor,Oenococcus oeni should not only have good malolactic fermentation ability but also good the stress resistance.The acid-tolerant mutant b1 and acid-sensitive mutant b2 that were sceened by ion implantation mutagenesis,purification and stress enviroment training were used as the experiment materials and the effect of stress environment?pH,alcohol and L-malic acid concentration?and wine-model condition on growth,the degradation rate of L-malic and?-glyacosidase activity were researched using Oenococcus oeni SX-1b and commercial strain31-DH as control.At the same time,the malolactic fermentation potential of the mutant strains were assessed.The main results are as follows:?1?The growth of strains?SX-1b,b1,b2 and 31-DH?were inhibited by low pH?3.0?,high alcohol?14%?and L-malic acid concentration?3 g/L?,while the growth of b1 was higher than other strains under stress conditions,and the growth of b2 was higher than O.oeni SX-1b.The influence degree sequence decreasingly on strains of growth were pH,alcohol concentration and L-malic acid concentration.?2?The degradation rate of L-malic acid and?-glycosidase activity of strains were inhibited by pH and alcohol concentration.The degradation rate of L-malic acid of strains were promoted by L-malic acid,but the?-glucosidase was inhibited.The degradation rate of L-malic acid and?-glycosidase activity of the strain b1 were higher than other strains under stress conditions,but the degradation rate of L-malic acid and?-glucosidase activity of strain b2 were lower.?3?Four Oenococcus oeni SX-1b,b1,b2 and 31-DH showed good deacidification,and could complete malolactic fermentation.The malolactic fermentation efficiency of the strain b1 was higher than others,which the fermentation for 12 d was completed,the efficiency of b2was lower than others,which the fermentation for 19 d was completed.Starting malolactic fermentation by using strain b1 could improve the content that was 92361.98?g/L and variety of aroma substances that was 59 types in wine.But the content of aroma substances in wine were lower than others using strain b2,which was 78321.31?g/L.Therefore,the acid-tolerant mutant b1 was more conducive to improving the quality of wine aroma and has the potential to be the commercial starter.