Six spice essential oils (sage, rosemary, caraway, cumin, clove, and thyme) and their basic ingredients were tested for their inhibitory effect against 3 strains of Gram-negative bacteria, 4 strains of Gram-positive bacteria, one acid fast bacterium, and one yeast. Preliminary screening of antimicrobial activity of the essential oils was done using the filter paper disc agar diffusion method. The minimum inhibitory concentration for each essential oil against various micro-organisms was also measured. Very low concentrations (0.25 – 12 mg/ml) of the various essential oils were sufficient to prevent microbial growth. The data show that Gram-positive bacteria were more sensitive to the antimicrobial compounds in spices than Gram-negative. The inhibition zones of different microbial growth produced by various essential oils were similar to those produced by their basic compounds. Thyme and cumin oils possessed very strong antimicrobial activity compared with the other essential oils. There was a relationship between the chemical structures of the most abundant compounds in the essential oils under investigation and the antimicrobial activity.

Gas‐liquid chromatography was used to determine the essential oil compositions of thyme, cumin, clove, caraway, rosemary, and sage. The basic components of these oils were thymol, cumin aldehyde, eugenol, carvonc, borneol and thujonc, respectively. The antifungal potential of the oils against Aspergillus parasiticus were investigated. The essential oils caused complete inhibition of both mycelial growth and aflatoxin production. The effectiveness followed the sequence: thyme > cumin > clove > caraway > rosemary > sage. The major components of the essential oils produced an inhibitory effect at minimum inhibitory concentrations equal to those obtained with the oils.

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RESUMEN Comparación de los tratamientos por irradiación γ y microondas en los lípidos y aspectos microbiológicos del hígado de vaca.Se estudiaron los efectos de los tratamientos por irradiación γ (0, 2.5, 5 y 10 kGy) y microondas (generados en un horno a nivel bajo y de descongelación durante 0.5, 1 y 2 min) sobre la composición química y aspectos microbiológicos de las muestras de hí-gado de vaca. Los análisis químicos y microbiológicos se llevaron a cabo en hígado de vaca tratado y no tratado al inicio y durante el almacenamiento en congelador a -18 o C durante 3 meses. Los análisis químicos de los lípidos de hígado de vaca mostraron que los índices de acidez, peróxido y TBA se incrementaron ligeramente después de los tratamientos por irradiación y durante el almacenamiento en congelador (-18 o C). Por el contrario, el índice de yodo disminuyó en el hígado de vaca tratado.Los tratamientos de irradiación redujeron considerablemente el recuento de bacterias totales en hígado de vaca. El porcentaje de reducción de carga bacteriana por el hígado de vaca expuesto a microondas generados de un horno con un modo de descongelación de 2 min y después de 3 meses a -18 o C fue del 62%. La carga bacteriana por el hígado de vaca expuesto a irradiación γ a 10 kGy después de 3 meses y -18 o C disminuyó al 98%. Por lo tanto, los tratamientos de irradiación γ fueron mejores que los tratamientos por microondas para la reducción de los microorganismos asociados con el hígado de vaca. La Salmonellae no se detectó en hígado de vaca no-irradiado e irradiado a través del período de almacenamiento. PALABRAS-CLAVE: Congelador -Hígado de vaca -Lípidos -Microondas -Microorganismos -Radiación γ. SUMMARY A comparison of γ-irradiation and microwave treatments on the lipids and microbiological pattern of beef liver.The effects of γ-irradiation (0, 2.5, 5 and, 10 kGy) and microwaves (generated from an oven at low and defrost settings for 0.5, 1 and 2 min) treatments on the chemical composition and microbiological aspects of beef liver samples were studied. The chemical and microbiological analyses were performed on the non-treated and treated beef liver immediately after treatments and during frozen storage (-18 o C) for 3 months. The chemical analyses of beef liver lipids showed that acid, peroxide and TBA values were slightly increased after irradiation treatments and also during frozen storage (-18 o C). On the contrary, iodine value of the treated beef liver was decreased.Irradiation treatments remarkably reduced the total bacterial counts in beef liver. The percent reduction of bacterial load for beef liver exposed to microwaves generated from an oven at defrost mode for 2 min and after 3 months at -18 o C was 62%. The bacterial load for beef liver exposed to γ-irradiation at 10 kGy after 3 months at -18 o C was decreased by 98%. Hence, γ-irradiation treatment was far better than microwave treatment for reduction of the associated microorganisms with beef liver. Salmonellae was not detected in non-irradiated and irradiated beef liv...

Sterilized and nonsterilized wheat kernels, soybean seeds, sesame seeds, peanut and faba bean were infected byA. parasiticus. The chemical composition, aflatoxin content and fatty acid patterns of the seeds were determined. The aflatoxins B1, B2, G1 and G2 were detected, and the amounts of the unsaturated toxins (B1 and G1) were greater than the respective dihydro derivatives (B2 and G2). Sterilized seeds infected by the fungus contained greater amounts of aflatoxins than those infected without previous sterilization. the highest and lowest toxicity indices were recorded for sterilized wheat and soybeans, respectively. Sesame, peanut and soybean exhibited intermediate toxicity indices. The toxicity of the aflatoxins produced was related significantly in every instance to the carbohydrate and lipid:protein ratio, and not to the polyunsaturated fatty acids of the seeds.