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Antimicrobial effects of curcumin against L. monocytogenes, S. aureus, S. typhimurium and E. coli O157:H7 pathogens in minced meat.

The aim of this study was to determine the antimicrobial efficacy of curcumin, one of the active components of the Curcuma longa (turmeric) plant, against food pathogens in a minced meat medium. Salmonella Typhimurium ATCC 14028, Listeria monocytogenes ATCC 7644, Escherichia coli O157:H7 ATCC 33150 and S. aureus ATCC 25923 strains were used as food pathogens. Minimum inhibitory concentrations (MICs) were determined using the macrodilution method. MIC values for curcumin were found to be 125 μg/ml for L. monocytogenes and S. aureus, and 250 μg/ml for S. Typhimurium and E. coli O157:H7. Food pathogens were added to the minced meat at 104 CFU/g (including the control group) and curcumin at doses of 0.5%, 1% and 2% (except the control). The curcumin-supplemented minced meat and control were analysed 0–7 days later. At the end of seven days, it was seen that the 2% dose of curcumin had lowered L. monocytogenes and S. aureus counts by approximately 3 log CFU/g, and E. coli O157:H7 and S. Typhimurium counts by approximately 2 log CFU/g; the 1% dose had lowered L. monocytogenes, S. aureus, E. coli O157:H7 and S. Typhimurium counts by approximately 2 log CFU/g; and that the 0.5% curcumin dose had lowered L. monocytogenes and S. aureus count by approximately 2 log CFU/g, and E. coli O157:H7 and S. Typhimurium count by approximately 1 log CFU/g. Changes in bacterial counts were found to be statistically significant (P ≤ 0.05). It was observed that antibacterial effect increased in direct proportion to dose, while sensory approval decreased. In this study, 0.5% and 1% curcumin doses were determined to be sensorily acceptable. It was concluded that, in view of the scientific benefits and antimicrobial efficacy of curcumin, it may be used instead of, or in smaller doses together with preservative additives in foods where colour change is not important.

Effects of different packaging techniques on the microbiological and physicochemical properties of coated pumpkin slices

In this study the effects of zein film coating along with benzoic acid on the quality of sliced pumpkin samples, which were packaged with different techniques were investigated. The samples were allocated into different groups and were treated with different processes. Following processing, the samples were stored at +4 °C for twenty days. Physicochemical and microbiological analyses were carried out on the samples once every five days during the storage period. According to color analysis, the L* value was observed to have significantly decreased in the processed and packaged samples in comparison with the control group. Besides, a* and b* values increased in all groups. It was determined that zein film alone did not exhibit the expected effectiveness against moisture loss in the samples. According to the results of microbiological analysis, a final decrease at approximately 1.00 log level was determined in total count of mesophilic aerobic bacteria (TMAB) in the group which was vacuum packaged in PVDC with zein coating when compared with the initial TMAB. Furthermore, no molding occurred in zein-coated group on the last day of the storage period, while massive mold growth was noted in the group which was packaged without any pretreatment procedure.