The strains of the genus Bacillus are well known as a causative organism of food spoilage. In order to classify Bacillus sp., gas chromatography was applied for determination of volatile compounds produced in the culture medium and statistical analysis employing cluster analysis were made. The conditions were determined as optimum for producing the volatile compounds as follows; the medium contained 0.5% yeast extract, 0.5% glucose, 1.0% tryptone, 3.66% K₂HPO₄ and 0.54% KH₂PO₄, and the cultures were grown in a 500ml volume shaker flask containing 200ml of the medium at 30°C for 24 hours with reciprocal shaking. The concentrate of volatile compounds from the culture was prepared by passing a centrifuged supernatant (200ml) through a porapak R column and eluting adsorbed compounds with ethyl ether (1.5ml). About 40-80 compounds from 3 to 300 ppb were determined by GC analysis. By employing cluster analysis, 27 samples of 9 strains in the genus Bacillus were clearly classified corresponding to their strains. Further, 6 varieties of B. subtilis were also able to be classified correctly.

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Japanese persimmo'Hiratanenashi' fruits were harvested at 4 times, 25 Sep. (just beforethe initiation of coloring), 15 Oct. (50% colored), 5 Nov. (100% colored) and 26 Nov.(overmature) in 1986. Those fruits were peeled and then sun-dryed under weather condition ateach time to study the effects of harvest maturity on the removal of astringency and someother physiological changes of the fruits during drying. (1) Fruit weight decreased moregently during drying as the fruit maturity advanced. (2) Duration of removal of astringencywas longer as the fruits more matured. It took 5, 15, 20 and 30 days for the fruits harvestedon 25 Sep., 15 Oct., 5 Nov. and 26 Nov., respectively. (3) Acetaldehyde content in fleshincreased prior to the ethanol accumulation regardless of fruit maturity, in accompany withthe decrease of soluble tannin. The more the fruits matured, the lessthe contents of thesevolatiles were accumulated. (4) Total sugar content in flesh increased during drying, although the content of sucrose gradually decreased. This was more clear as withthe earlyharvested fruits. (5) No white powder was appeared on the surface of the fruits harvested on25 Sep. during drying. There was a large difference in white powder developmentamong thefruits harvested on 26 Nov. On the surface of the fruits harvested on 15 Oct. and 5 Nov., white powder started to reveal after 20th day of drying and was developed almost all over thefruit-surface in 40th day of drying. Sugar composition of the white powder was, regardlessof maturity, fructose : glucose_??_1:4.

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In the previous paper, it was reported that addition of soybean protein inactivate trypsin inhibitor (TI) remarkably. In this paper, effects of soybean protein on thermal stability of TI was investigated. Changes of thermal stability of TI by adding soybean protein components, such as 7S, 11S and 15S, were examined first of all. As a result, TI heated with llS indicated the remarkable reduction of anti-tryptic activity and thermal stability. 11S has 2 mol of SH group in its molecule, but 7S and 15S hardly have. Accordingly, effects of the SH group on thermal stability of TI were investigated by addition of some amino acids. As a result, only addition of cysteine showed the same effect as the addition of llS. When llS and cysteine were added to TI after modification of the SH with p-chloro-mercuribenzoate (PCMB), and heated, remarkable inactivation of TI was not observed. When TI was heated with PCMB, the absorbancy at 250nm (mercaptide) increasedremarkably. This indicates the reduction of SS bonds in TI molecule, and also suggests that the heat inactivation of TI was due to the exchange reduction of the SH and SS between llS and TI. For above reasons, effects of llS on thermal stability of TI fractions obtained from chinese soybean were compared. TI activities were declined 30-60% with llS against the remaining activities without 11S.

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In our study, Trypsin Inhibitor (TI) was inactivated remarkably by heating with soybean llS protein (11S). Then, denaturation of TI by heating was investigated as a change of the affinity of TI for trypsin. That is, the value of TI activity which made half the affinity of trypsin for the substrate was obtained by the plot of Lineweaver-Burk (defined as Kt), and the Kt of each TI was compared. The Kt of each TI obtained by DEAE-cellulose was about 15-100unit, and these values changed little after heating at 100°C for 15min.. However, when TI was heated with llS, the value of Kt increased 1.5-5 times and the affinity of TI for trypsin declined remarkably. Since it was presumed that the Kt of TI in soybean products changed because TI in soybean products received heat treatment with llS during processing, the Kt of TI in soybean products was measured, and the TI was investigated. As a result, the Kt of TI in Tonyu was 30 units but that of TI in the other soybean products was unmeasurable, because no effects of TI on Km value was seen when TI was added up to 500 units. Following this, TI in soybean products was added to the reaction mixture of trypsin and a substrate to investigate the ability of TI to compete with the substrate for trypsin. As a result, the reaction between trypsin and the substrate immediately stopped by adding TI in Tonyu, but the other soybean products showed no effects for this reaction. The above results indicate that TI in almost all soybean products, while having remaining the anti-tryptic activity, remarkably reduced its affinity for trypsin by heating with llS and practically had no effect on trypsin activity.

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The pasteurization at 55°C in the presence of 1% glycine (Gly), 2% sodium chloride(NaC1)and 2% ethyl alcohol (EtOH) was investigated as a basic experiment on manu facture of the foods cooked at low temperature. (1) Salmonella typhimurium grew in the presence of three chemicals, Gly, NaCl and EtOH. Moreover, the cells survived after 30min of heating at 55°C with Gly and NaCl. However, heating over 20min at 55°C with three chemicals was highly lethal to the cells. (2) The materials which show absorbance at 260nm were released from S. typhimurium during incubation when the cell suspension containing Gly or/and NaCl was incubated for 30min at 55°C. Contrarilly, the addition of EtOH to the suspension inhibited the release of cell materials under the same conditions. From these results, it was suggested that the death of the cells was not accompanied by the loss of 260nm absorbing materials. (3) Heating for 30min at 55°C acted bactericidally on Proteus vulgaris, Aeromonas hyldrophila, Saccharomyces cerevisiae and Kluyveromyces fragilis. The growth of Bacillus subtilis and Escherichia coli was observed under the same conditions. (4)Though heating for 30min at 55°C in the presence of Gly and NaCl inhibited the growth of E.coli, the action was bacteriostatic. However, the action was bactericidal against E. coli when the cells were heated under the same conditions in the presence of three chemicals. (5) The growth of B. subtilis was inhibited by heating for 30min at 55°C in the presence of Gly, or Gly and EtOH. However, the viable cells were observed in the culture. The viable cells may be the spores since B. subtilis is a sporeformer and their spore is exceedin gly resistant to heat or chemicals. These results suggest that the pasteurization of foods may be achieved at 55°C in the presence of Gly, NaCl and EtOH.

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