Study of sumac extract (Rhus coriaria L.), lactic acid and thyme oil as decontaminants for shelf life extension of refrigerated rabbit meat

Abstract

In an attempt to improve the microbiological quality and extend the shelf-life of refrigerated rabbit meat, four groups of rabbit meat from New Zealand breed were prepared, the 1^st group was untreated (control), while the other three groups were treated with lactic acid 0.5 %, thyme oil 0.5 % and water extract of sumac 8 % by dipping for 1, 1 and 10 min, respectively. Then the samples were refrigerated at 2 ± 1 °C to be periodically examined for their sensory and microbiological status. The control and treated samples showed excellent overall acceptability by panellists at zero-day of examination, off odours and tastes were noticed by the day 9, 12, 9 and 15 day of storage in control (C), lactic acid (LA), thyme oil (TO) and water extract of sumac (WES) treated groups, respectively. There was no significant differences in aerobic plate counts “APC” (at p < 0.05) between treated and untreated groups at zero and 3^rd day of examination, while at 6^th and 9^th day of refrigerated storage, the values of APC were significantly lower in LA and WES treated groups than C and TO treated groups. The APC results confirm the concept that the slowest growth rate of the total bacterial population extends the shelf life of rabbit meat. Approximately, similar pattern to that of APC was observed in the results of coliforms (MPN). The MPN values of faecal coliforms and E. coli were relatively low, which could be attributed to the preparation of rabbit samples under strict hygienic measures. The obtained results in the present study suggest that WES can be used as a decontaminant for rabbit and poultry meat at each decontamination step instead of other chemical substances which could affect the acceptability of the final product and remain some hazardous residues.

Keywords: sumac, rabbit, quality, shelf life, thyme oil, lactic acid.