Abstract
The purpose of the experiment was to attempt the isolation and identification of lactic acid bacteria content of locally fermented milk, and the feasibility of such organisms to produce diacetyl plus acetoin by single, double, and multiple combinations of identified bacteria. The following results were obtained.
An addition of 0.3 % yeast extract to broth media and to skimmed milk was useful and satisfactory.
Seven lactic acid bacteria were isolated and identified.
The activities of identified organisms were as follows: The viable cell counts ranged from 6.5 Β· 10^8^ bis 10.5 Β· 10^8^ cells/ml, culture potential acidities were 0.15β2.52%, and the time of coagulation and reduction was 16β60 h, except Leu. citrovorum which showed negative reaction.
It was advisable to use Naβcitrate with skimmed milk to confirm the positive results prior to the main experiments.
Single bacterium culture produced diacetyl plus acetoin as arange 0.79β3.50 mg/100g culture, except L. bulgaricus and L. casei.
Cultures of double bacteria combinations showed satisfactory productions of aroma materials. The range was 2.82β3.60 mg/100 g culture. Synergistic effect was notable between almost all combinations of organisms.
Multiple combination cultures showed in general abiodeteriorative effect among individual organisms of the same goup, however, some groups which were active yielded 3.6β8.36 mg/100 g aroma materials.