The inhibition mode of kojic acid on mushroom, potato, apple, white shrimp, and spiny lobster polyphenol oxidase (PPO) was investigated. Using a polarographic method, kojic acid was shown to inhibit melanosis by interfering with the uptake of O2 required for enzymatic browning. Spectrophotometric and chromatographic methods demonstrated that kojic acid was capable of reducing o-quinones to diphenols to prevent the final pigment (melanin) forming. The preincubation temperature did not significantly affect (P > 0.05) PPO inhibition by kojic acid.

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: A continuous high‐pressure carbon dioxide system, run at ambient conditions, was tested on its performance in reducing both natural and inoculated microbial loads. The prototype system continuously processes orange juice with carbon dioxide (CO2) at high pressures. A central composite design was originally used to examine the variables of pressure, residence time, and CO2/juice ratio. For microbial reduction, residence time was the major factor followed by pressure. The CO2/juice ratio showed no influence on microbial load, and in this equipment, was difficult to control. The unit was able to cause a 5‐log reduction of the natural flora in spoiled juice, and could attain a 5‐log decrease in numbers of pathogenic Escherichia coli O157:H7, Salmonella typhimurium, and Listeriamonocytogenes. No viable cells of E. coli O157:H7 orS. typhimurium were cultured after the treated juices were stored at room temperature (22 °C) for 14 d. Thus, non‐thermal pathogen reduction is possible with this system.

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The Ames Salmonella/microsome assay was employed to test the mutagenicity of benzidine and its analogs using strains TA98 and TA100 in the presence and absence of Aroclor 1254-induced rat S9 mix. 3,3'-Dichlorobenzidine-2HCl and 4,4'-dinitro-2-biphenylamine were directly mutagenic to TA98, while 4,4'-dinitro-2-biphenylamine was directly mutagenic to both TA98 and TA100 in the absence of S9 mix. 2-Aminobiphenyl, 3-aminobiphenyl, and 3,3'-5,5'-tetramethylbenzidine were not mutagenic in either strains in the presence or absence of S9. In the presence of S9 mix, 4-aminobiphenyl, benzidine, 3, 3'-dichlorobenzidine-2HCl, 3,3'-dimethoxybenzidine, 3,3'-4, 4'-tetraaminobiphenyl, o-tolidine, N, N-N', N'-tetramethylbenzidine, and 4,4'-dinitro-2-biphenylamine were mutagenic to TA98; 4-aminobiphenyl, 3,3'-dichlorobenzidine-2HCl, 3, 3'-dimethoxybenzidine, and 4,4'-dinitro-2-biphenylamine were mutagenic to TA100. Physicochemical parameters of these compounds including oxidation potentials, the energy difference between the lowest unoccupied molecular orbital and the highest occupied molecular orbital, ionization potentials, dipole moment, relative partition coefficient, and basicity did not correlate with their bacterial mutagenic activities.

Polyphenoloxidase (PPO) isolated from cuticle of Western Australian lobster (Punufim cygnus) and Florida spiny lobster (Punulirus um) catalyzed oxidation of catechol and DL-B-3,4-dihydroxyphenylalanine (DL-DOPA). The PPO from Florida lobster showed a higher substrate affinity than that from Australian lobster. They both showed higher affinity for catechol than for DL-DOPA, and optimal pH stability at 7.0. The enzymes differed with respect to activation energy and thermal stability. Electrophoretic patterns using SDS-PAGE indicated PPO from Western Australian lobster had two isoforms while Florida spiny PPO had three isoforms. These results suggest variations in enzyme activity may contribute to differences in susceptibility to melanosis between the two species.

Immunoassay techniques using the highly specific and sensitive nature of immunological reactions have been developed and applied in the food industry for detecting the naturally occurring constituents, antibiotics, pesticide residues, microorganisms, and fragments of microbial constituents related to food analysis, food production, food processing, and food safety. Both polyclonal and monoclonal antibodies are employed for the development of the various immunoassay systems, including enzyme-linked immunoassay (ELISA) and radioimmunoassay (RIA). Immunoassay techniques provide complementary and/or alternate approaches in reducing the use of costly, sophisticated equipment and analysis time, but still maintaining reliability and improved sensitivity. Immunoassay techniques in their most simple forms provide excellent screening tools to detect adulteration and contaminations qualitatively. The application of immunoassay techniques contributes tremendously to the quality control and safety of our food supply.

A commercial ClO 2 -producing solution killed mostly Escherichia coli, Listeria monocytogenes Scott A and its streptomycin-resistant (Str R ) strain at 15, 10, and 7.5 ppm, respectively, while aqueous ClO 2 and chlorine achieved similar results against the tested strains at 20 and 25 ppm, respectively. Aqueous ClO 2 and the commercial solution were more effective than aqueous chlorine in killing Str R -L. monocytogenes inoculated on fish cubes (mangrove snapper) at 3.4 ϫ 10 3 or 2.4 ϫ 10 6 CFU/g, as well as in solutions washed off the cubes. Fish cubes treated with aqueous chlorine or ClO 2 contained negligible chlorine residues, while the commercial treatment samples contained chlorite and some free and combined available chlorine.