THE INFLUENCE OF TEMPERATURE ON THE GROWTH LIMIT OF ACETIC BACTERIA PRESENT IN SAUVIGNON WHITE WINE WITH A CONCENTRATION OF 13% ALCOHOL PUBLISHEDCarmen Vlădulescu, Gheorghe Matei
Temperature is a determinant factor of the vital-metabolic processes of acetic bacteria. Changing wine into vinegar progresses more rapidly as the temperature is raised. Volatile acid alteration is at the beginning twice faster at 280C than at 230C and twice faster at 180C than at 230C. The scale of heating values along which starting from minimum temperature and to the maximum, the bacteria are able to perform normal vital activity, represents the area of growth temperature. Broad limits which extends the range (0 - 450C) places acetic bacteria in mesophilic microorganisms category for which the limit temperature increase is 40 - 450C. The limit temperature for thermal destruction or death ran for acetic bacteria, between 55 - 600C. The optimum temperature for growth for vital processes to take place with maximum intensity, is conventionally defined as the temperature at which cell proliferation is the most intense mode. However, this value does not coincide with that of the thermal optimum temperature for physiological activities of the cell. Maximum temperature of growth supported by acetic bacteria is the greatest heat where the biological activity is still possible, and multiplication of such micro-organisms can still be carried out. Exceeding this threshold heat affects reproductive capacity of acetic bacteria. Minimum temperature for acetic bacteria vary by species between 8 and 100C and represents the lowest heat at which cell multiplication, although very slow, can still be achieved. Theoretical the limit of development of vital processes is determined by the freezing temperature of the water. It is important to know, in oenological practice, the optimum growth temperature for the acetic acid bacteria is between 25 - 300C. In general, there were no increases in excess of bacteria colony, over 370C, but we managed to isolate several thermotolerant strains at 37 - 400C. At lower temperatures, acetic bacteria are still active even at 100C. As a result, it is difficult to draw a strict temperature range in which these bacteria can grow, the temperatures used during the wine making process seem not to affect the growth of acetic bacteria.
acetic bacteria, viable cells, white wine, temperature