Microbiology and biochemistry of Fossa (pit) cheese

A microbiological and biochemical characterization of the Fossa (pit) chees e is reported. The cheeses analysed showed differences for the protocol of production and type of cheese-milk used (bovine or ovine), The total number of mesophilic bacteria and the number of specific microbial groups differe d among the cheeses. Lactococci used as starters were found at very low num bers. Non-starter lactic acid bacteria (NSLAB) such as Lactobacillus planta rum, Lb, curvatus and Lb. paracasei subsp. paracasei were found at high num bers (5.8-7.8 log cfu g(-1)). Cheeses produced from pasteurized or raw milk s and using lactococci as starters or not showed similar microbiological an d biochemical characteristics. High concentrations of NaCl-in-moisture (ca, 11.5%) and a low value of a(w) (ca. 0.850) negatively influenced the micro bial content and proteolysis, The ratio pH 4.6-soluble N/total N (23.6-39.1 %) and the concentration of free amino acids (11.37-41.06 mg g(-1)) were ve ry high and varied with cheeses, Fossa cheeses which contained the highest number of NSLAB also had the highest concentration of amino acids. The prin cipal amino acids were glutamic acid, valine, leucine and lysine, Urea-PAGE electrophoresis of the pH 4.6 insoluble and soluble fractions differentiat ed the cheeses. Apart from the variations in the protocol of production, th e RP-HPLC of the ethanol-soluble fraction showed a peptide profile which wa s common to all the cheeses, Especially cheeses which had the highest conce ntrations of free amino acids and the highest number of NSLAB, also contain ed the highest aminopeptidase, dipeptidase and iminopeptidase activities. F ossa cheeses also showed a moderate lipolysis which varied among the sample s: total free fatty acids ranged from 578 to 1676 mg kg(-1). The highest co ncentrations were found independently of the milk used. The principal fatty acids were butyric, caproic, palmitic and oleic acids. Sensory evaluation of the Foss cheeses showed differences especially related to the extent of proteolysis. (C) 2000 Elsevier Science Ltd. All rights reserved.