Kvasny Prum. 1974; 20(2): 35-41 | DOI: 10.18832/kp1974007

Propagation of psychrophylous and mucoid microorganisms in sweetened non-alcoholic beverages.Peer-reviewed article

L. ŠVORCOVÁ

The authoress presents the results of her study into the propagation of psychrophylous and mucoid microorganisms in sweetened medium under different conditions, viz. aerobic and anaerobic, in the presence of organic substances, and at various temperatures i.e. 1, 10,17 and 25°C. Propagation of microorganisms was observed irrespectively of the created conditions. Low temperatures protract the lag and phases of the propagation curves. Between the forms of curves for 25 and 17°Cis only slight difference, at 10 °Cmaximum level is reached by 2 days later, i.e. on the 7^th day of incubation, at 1°C in the period lasting from the 5th to 13^th day the number of microorganisms is by two orders lower than at higher temperatures and maximum. i.e. 10⁶ of cells is reached on the 36th day of incubation. The presence of organic substances has a certain effect at low temperatures, whereas at higher temperatures, more favourable for propagation, no marked difference can be observed. The difference between aerobic and anaerobic conditions is pronounced at1°C and10°C, since under anaerobic conditions mycelium of moulds grows very vigorously and restricts propagation of other microorganisms. Refraction and pH are under such condition slightly lower. In other samples the decrease of refraction and pH is far more rapid which is apparently due to the assimilation of sugar by psychrophylous microbes. If metabolism is allowed to run to end pH may be lower by as much as 0,9. Mould mycelium gives the medium phenolic odour, bacteria acidic odour and yeast typical odour of fermentation. Organic substances of albumin character sticking to the bottle walls may enhance propagation of microorganisms, especially at low storage temperatures. Propagation of psychrophilous microorganisms can be efficiently restricted by washing thoroughly bottles and by adhering strictly to hygienic rules in bottling plants. From the results of experiments follows that18°C cannot be accepted as an optimum storage temperature for sweetened mineral water, since propagation of microorganisms continues at lower temperatures, i.e. 17, 10 and even at1°C.
(In Czech, English summary only)

Keywords: sweetened non-alcoholic beverages, psychrophylous microorganisms, mucoid microorganisms

Published: February 1, 1974