Biocon®, an aerosol mixture of ammonium bicarbonate, sodium chloride and carbon dioxide, was examined for the effectiveness as a food preservative. Flushing the aerosol on culture media suppressed the colony formation by Escherichia coli, Pseudomonas aeruginosa, Serratia marcescens, Staphylococcus aureus, Staphylococcus epidermidis, Micrococcus luteus, Bacillus subtilis and Candida albicans. The inhibition of the growth occurred when those organisms were inoculated either before or after the flushing on agar plates. The effect was bacteriostatic and it remained active for 10 days if the media plates were sealed properly and kept at 0-4° after the flushing. The active component was proved to be NH4HCO3, which kept the reaction of the surface of agar plates between pH 8.6-9.0, most probably by maintaining a certain equilibrium among the gas-liquid state of NH4HCO3, NH3 and CO2. Biocon gave similar effects on sliced meat for 5 days without affecting taste, smell or color, if the initial contaminating bacterial number was less than 105 CFU/g. Biocon when handled properly seemed to be a harmless preservative to keep freshness of raw meats.
The most widely used indicator of the sanitary quality of oyster-growing area sea water and oysters is the coliform group of bacteria. The present study was undertaken to investigate the correlation between coliform (TC) and fecal coliforms (FC) in oyster-growing area water and oyster in Hiroshima bay. A total of 1, 116 materials including river water (72), paired samples (522) of oysters and sea water were collected and subjected to counting the coliform group during the winters from 1975 to 1984. The results obtained may be summarized as follows; 1) Between TC (X) and FC (Y), a linear least-square regression calculation gave log Y=0.779 log X-0.191 and a positive correlation of r=0.82 (p=0.01) in river water, log Y=0.732 log X-0.435 and r=0.88 (p= 0.01) in sea water and log Y=0.913 log X-0.111 and r=0.81 (p=0.01) in oysters. 2) Between TC (X) of sea water and FC (Y) of oysters, a linear gave log Y=0.668 log X+1.339 and r=0.73 (p=0.01). 3) Between FC (X) of sea water and FC (Y) of oysters, a linear gave log Y=0.785 log X+1.878 and r=0.72 (p= 0.01). 4) The FC/TC was 8.9% in river water, 10.0% in sea water, and 3.4% in oysters. The concentrating ratio of FC from sea water to oyster was 43.1 times per 100 g and 100 ml. These data suggest that the level of 70 TC MPN is equivalent to 8.4-14 MPN in sea water and TC and FC of water gave the same correlation coefficients against FC of oysters.
Viability of Vibrio parahaemolyticus at slightly acidic pH in 2% polypeptone medium with 0.1M acetate, citrate and lactate in the presence of 0.5% or 3% NaCl were examined using both agar medium of brain heart infusion (2% NaCl, pH 8.0) and BTB-teepol. The following results were obtained: (1) There are found some cases 106 cells/ml detected on BHI were not viable on BTB-teepol at all. (2) In 0.5% NaCl medium cells received acid injury stronger and more rapidly than in 3% NaCl medium. (3) At pH 5.5 acid injury occurred only by acetate or lactate, but at pH less than 5.0 citrate or HCl became injurious. (4) Lowest pH for growth were 6.5-6.8 or 6.0-6.5 with acetate, 5.8-6.0 or 5.4-5.8 with lactate, 6.0-6.3 or 5.6-5.8 with citrate and 5.2-5.4 or 5.0-5.2 with HCl (no organic acid) in 0.5% or 3% NaCl medium. These pHs for growth were almost the same as the data already reported in foods.
A mycological profile was analyzed on a total of 38 samples of commercial job's tears (Coix lachryma-jobi L. var. frumentacea Makino) and its products.The samples were composed of 25 batches of untreated grains, 9 of flour and 4 of heat treated grains. Fungal counts of untreated grains, flour and treated grains were 3-65/g (average 24/g), 31-2, 040/g (av. 112/g) and 3-41/g (av. 17/g), respectively. Among the total isolates (3, 278) from all samples, the predominant genus was Aspergillus (45.9%). Of the Aspergillus isolates, 802 (24.5% of the total isolates) were identified as the A. glaucus group (teleomorph: Eurotium). Mycotoxin-producing strains of A. flavus, A. versicolor and Penicillium citrinum were isolated from 7 samples (one batch of untreated grains and 6 of flour), 3 (one of untreated grains and 2 of flour) and 2 (flour) samples, respectively. As a result of inoculation tests with aflatoxin-producing A. flavus, sterigmatocystin-producing A. versicolor, ochratoxin-producing A. ochraceus, citrinin-producing P. citrinum, deoxynivalenol-producing Fusarium culmorum and zearalenone-producing F. graminearum, if job's tears is shown to be one of favorable substrates for the production of these mycotoxins.
The effects of 14 kinds of natural sweetners on the growth of yeast strains isolated from “tsukemono” were investigated in a synthetic medium and “fukujin-zuke” solution. Eight kinds of sweetners enhanced the growth of yeast strains in the synthetic medium, whereas the other six (D-xylose, xylitol, glycyrrhizin, stevioside, phillodulcin, and thaumatin) did not facilitate the growth of any strain. Phillodulcin and glycyrrhizin each used with saccharose were shown to give synergistic inhibitive effects on the growth of all test strains in the synthetic medium. In the “fukujinzuke” solution, phillodulcin inhibited the growth of yeast starins, the inhibitory activity being higher than that in the synthetic medium, and when used with saccharose, it gave synergistic inhibitory effects on these yeast growth.