PHYSICAL FACTORS INFLUENCING MICROBIAL INTERACTIONS AND BIOCHEMICAL-CHANGES DURING THE BACEMAN STAGE OF INDONESIAN KECAP (SOY-SAUCE) PRODUCTION

The composition of samples taken from the baceman stage of traditional Indonesian kecap (soy sauce) production can vary greatly from batch t o batch and from manufacturer to manufacturer. This variability could be caused by physical factors such as salt concentration, temperature, dissolved oxygen tension and pH. The effect of these factors on the c hanges in microflora and biochemical composition during the baceman st age are described in this report. Salt concentration was found to have a large influence on the spoilage of the baceman. At low salt concent rations pellicle-forming yeasts were able to grow. The pellicle on the liquid surface formed by these yeasts provided an aerobic environment in which coryneform bacteria could grow. These bacteria consumed amin o acids and fermentation products like acetate and lactate, which resu lted in a rise in pH and subsequent spoilage of the baceman. An aerobi c baceman showed the same development as those with a low salt concent ration. Salt concentration as well as temperature had a large influenc e on the rate of growth of bacteria. Growth of bacteria and associated lactate and acetate production were also stimulated by a high pH, whi le growth of yeasts and ethanol and glycerol formation was better at l ow pH. Also, the production of formol nitrogen by enzymes resulting fr om the previous bungkil stage was greatly influenced by temperature an d pH, with higher temperature and pH giving rise to higher formol nitr ogen contents. The consequences of these physical factors on the produ ction of traditional Indonesian kecap are discussed.