The effects of natural casings treated with thyme and rosemary extracts on the quality characteristics of sausage (merguez)

The aim of the study is to evaluate the effects of natural casings treated with rosemary (B) and thyme (K) extracts before stuffing on physicochemical, chemical, microbiological and sensory attributes of fresh sausages (merguez) during 9 days in cold storage (4±1oC). Freshly prepared sausages were stuffed into the casings soaked with 1% rosemary extract (BD), 2% rosemary extract (BY), 1% thyme extract (KD), 2% thyme extract (KY), and water as a control (C). pH value of the sausages was significantly decreased by the effect of storage time and the treatment with rosemary and thyme extracts. The sausages treated with K and B had lower pH values during storage. The a* value in the sausages with rosemary and thyme extract treated natural casing was higher than those in control sausages. The thiobarbituric acid reactive substances (TBARS) value in the sausage with rosemary and thyme extracts treated natural casing was significantly (p<0.05) lower than those of control sausages during storage. The high concentration of thyme extract (0.79 mg MDA/kg) in reducing lipid oxidation was more effective than rosemary extract (0.85 mgMDA/kg) at the end of storage. Total viable counts of sausages with natural casing treated with 2% thyme extracts (6.39 log cfu/g) was significantly lower than those of sausages with K, BD, BY and KD (7.73, 6.94, 6.76 and 6.63 log cfu/g, respectively) (p<0.05). Treatment with rosemary and thyme extracts in both concentrations resulted in lower Enterobacteriaceae numbers during storage. These treatments did not negatively affect the sensory attributes of the sausages. In conclusion, the treatment with thyme and rosemary extracts before stuffing can be useful to sanitize the natural casings and to extend the shelf life of the merguez sausages during cold storage.