摘要:

The influence of pH on the susceptibility of Staphylococcus aureus 196E to repeated freeze‐thaw stress was studied in 0.2 Macetate buffer (pH 3.0–7.8) and ground beef (adjusted to pH 4.2–6.3). In acetate buffer in the pH range of 4.4–7.0, repeated freeze‐thaw stress did not decrease the viability of the cells; at pH values below 4.1 and above 7.5, decrease in the viable cells was exponential with the number of freeze‐thaw cycles. In meat, S. aureus was not killed at pH values 4.3–6.3; however, at pH 4.2, death resulted from the repeated stress. Repeated freeze‐thaw cycling of foods should have little effect on the viability of S. aureus within the pH values of most foods implicated in S. aureus

ISSN:0149-6085    

DOI:10.1111/j.1745-4565.1982.tb00443.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

Poly (hexamethylene biguanide hydrochloride) (PHMB), an industrial disinfectant, was evaluated for potential use in the food industry following suggestions in the literature. A colorimetric test based on the reaction with nitro‐prusside reagent was found suitable for the dosimetry of this compound. In a bacteriological medium, at a concentration of 20 μg/ml, PHMB was inhibitory to Escherichia coli, less effective against Staphylococcus aureus, and practically ineffective against Pseudomonas aeruginosa. The bactericidal activity of PHMB was impaired in the presence of milk but little affected upon the addition of blood. Finally, in a toxicological test in vitro, PHMB was found to be toxic toward Chinese hamster cells, at doses similar to those required for antibacterial activi

ISSN:0149-6085    

DOI:10.1111/j.1745-4565.1982.tb00444.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

The toxic and mutagenic effects of gamma‐irradiated peanut meal contaminated with aflatoxin B1were studied in Salmonella typhimu‐rium strain TM 677, using forward mutation to 8‐azaguanine resistance. After treatment with 5 to 10 M‐rad gamma radiation, the contaminated peanut meal lost its toxic and mutagenic properties. Irradiation at 0.1 to 1.0 M‐rad removed 75–100% of the toxicity but not m

ISSN:0149-6085    

DOI:10.1111/j.1745-4565.1982.tb00445.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

This paper reports the levels of Pb, Cd, and Zn found in 39 individual canned foods and in samples of ground beef and sugar collected throughout the United States in fiscal years (FYs) 1980 and 1981. The foods were collected in conjunction with the Total Diet Studies program of the Food and Drug Administration (FDA), but were analyzed separately from the Total Diet samples at the FDA Kansas City District Laboratory. Before analysis, multiple‐can samples of each product type were individually composited and thoroughly homogenized with dilute nitric acid to ensure representative subsamples for analysis. Homogenized subsamples were dry‐ashed with sulfuric acid as the ashing aid and analyzed by differential pulse anodic stripping voltammetry for Pb and Cd and by atomic absorption spectroscopy for Zn. Quantitation limits were 0.02 ppm Pb, 0.002 ppm Cd, and 0.1 ppm Zn. The overall mean levels of Pb, Cd, and Zn found in the 19 canned foods that contained sufficient samples for statistical analysis were 0.19 and 0.22 ppm Pb, 0.011 and 0.008 ppm Cd, and 4.3 and 5.0 ppm Zn in FY‐80 and FY‐81, respectively. These levels are about one‐half as high as the levels found for Pb and Cd in an FDA FY‐74 survey but are about the same for Zn. The frequency and magnitude of occasionally high levels of Pb in individual samples were considerably diminished in FY‐80 and FY‐81, compared to those in FY‐74. These lower levels are probably due to improvements in canning technology, in quality control by food processors, and in the methods used for analysis. Over the next 3 years the FDA will continue this survey of individual canned foods, focusing on adult canned foods commonly eated by children, to monitor the progress of industry in reducing Pb level

ISSN:0149-6085    

DOI:10.1111/j.1745-4565.1982.tb00446.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

ISSN:0149-6085    

DOI:10.1111/j.1745-4565.1982.tb00447.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

The results obtained by a rapid Celite column extraction method for the determination of dimethylnitrosamine (DMN) in beer and ale were compared with those obtained by a more elaborate vacuum distillation method. The end determination in both cases was done by gas‐liquid chromatography using a thermal energy analyzer (TEA) detector. The two sets of results for 28 samples of beers from various countries were highly comparable. Recent survey results for both Canadian and imported beer and ales suggest a significant decrease in the levels of DMN in these beverages from that observed 2–3 years earlier. This decrease is probably due to the improvements in the malt drying techniques instituted in Canada as well as in other countr

ISSN:0149-6085    

DOI:10.1111/j.1745-4565.1982.tb00448.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

ISSN:0149-6085    

DOI:10.1111/j.1745-4565.1982.tb00449.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY