Characteristics of lamb and kid artisanal liquid rennet used for traditional Feta cheese manufacture

Samples of artisanal liquid rennets originated from 20 Feta cheemaking factories located in two different regions in Greece were grouped as rennets A and B, respectively, and analyzed for their chemical composition, microbiological quality and enzymic properties. In general, the obtained results indicated a marked variability of the composition of this rennet type, independently the region of production. The average values of the physicochemical characteristics of rennet A were pH 4.74, dry matter, protein, fat and salt content 12.6%, 1.99%, 3.65% and 6.5%, respectively, while the corresponding values of rennet B were 4.71%, 18.37%, 1.5%, 3.22% and 13.46%. The microflora of both, rennets A and B was consisted of relatively low populations. The mean counts of total mesophilic microflora, coliforms and enterococci, expressed as log10 cfu ml−1, in rennet A were 4.86, 2.61 and 3.11, while the respective values in rennet B were 4.39, 0.42 and 2.43. No pathogen like Salmonella sp. or S. aureus was found in any rennet. With regard to enzymic characteristics, rennet A had mean milk clotting activity 14.28 International Milk Clotting Units (IMCU)/ml, chymosin activity 61.91% of the total activity and lipolytic activity 1.15 Lipase Units (LU). The respective values of rennet B were 8.91 IMCU/ml, 63.11% and 0.86 LU. It was concluded that, no matter the region of origin, the total quality of the artisanal rennet used in Feta cheese is acceptable.