THE EFFECTS OF TEMPERATURE AND MANGANESE ON THE NATURAL FERMENTATION OF WHOLE WHEATFLOUR

The natural fermentation (no added culture) of whole wheat flour (WWF) was studied to determine the feasibility of obtaining naturally soure d WWF. A brew (1:2, WWF:water) was incubated (10 degrees, 15 degrees, 20 degrees, 30 degrees, 35 degrees and 40 degrees C) in the presence o f 0 (control), 3, and 7 mu g Mn2+ g(-1). The fermentation was brought about by the indigenous lactic acid bacteria of the WWF. At temperatur es >30 degrees C, there was an increase and a decrease in fermentation time (t) and rate (F), respectively. The lag period (no net change in pH) of the fermentation of WWF was reduced with the increase in the f ermentation temperature and eliminated in the presence of manganese (e xcept for 40 degrees C). The presence of manganese at each temperature (except for 40 degrees C) increased F as compared with the control. T he values of t and F of the control at 30 degrees C were comparable wi th those of samples with 3 mu g Mn2+ g(-1) at 15 degrees C. Between 15 degrees and 30 degrees C a linear relationship was found between F-0. 5 and the absolute temperature, with and without added manganese. The value of T-0 was used in a model to determine the fermentation time. T he Arrhenius plots of the acid production rate showed a breakpoint at 25 degrees C for the control, and the two manganese treatments. The Q( 10) values above and below the 25 degrees C breakpoint coincided with the activation energy E(a) values. (C) 1996 Academic Press Limited