Studies on the sterilization of seasonings. III. Heat sterilization of bacterial spores in soya sauce
Yamamoto, Y.; Kobayashi, S.; Yoshii, H.
Journal of the Japan Soy Sauce Research Institute 6(1): 19-23
1980
Document Number: 500285
Counts of spores of Bacillus subtilis, B. cereus, B. megaterium and B. natto, each added to soya sauce at 2-9 x 104/ml, did not change during 6-7 days at 30 degrees C and were not affected by ethanol at 5%, pH 4.0, or BPOB at 50 p.p.m. About 90% of spores survived heating at 80 degrees C; 30 min at 90 degrees C reduced counts from 105 to 10superscript 2/ml, and spores were eliminated after 40 min. Survival curves showed that at 87 degrees C D value ( from 10superscript 3 to 10superscript 2/ml) was 42.8 min and total death time (TDT) was 214 min; TDT for 105 spores/ml was 10 min at 100 degrees C. At 92 degrees and 87 degrees C resp. reducing pH to 4 reduced TDT from 70 and 214 min to 9.5 and 33.4 min; with ethanol at 5%, TDT was 14.3 and 46.5 min; with ethanol and reduced pH, TDT was 2.0 and 7.5 min; and with 50 p.p.m. BPOB and pH4, TDT was 5.0 and 37.0 min. TDT decreased almost linearly with decreasing pH from 4.8 to 4.0 and increasing ethanol content from 1 to 5%.