The effect of three levels of ascorbic acid on diacetyl and acid production by two mixed-strain cultures was investigated. Each culture was grown in nonfat dry milk reconstituted to 11% total solids with 0.1% added sodium citrate. Ascorbic acid concentrations in the milk were 0, 0.10, and 0.25%. Stimulation of diacetyl production was observed at both concentrations of ascorbic acid. The stimulatory effect of ascorbic acid at both concentrations was approximately the same for each culture. Diacetyl production was initiated earlier in samples containing ascorbic acid. Ascorbic acid did not stimulate acid production.
1Present address: Department of Food Science and Technology, University of Nebraska, Lincoln, Nebraska 68583, Technical Article No. TA-14412 of the Texas Agricultural Experiment Station.