Existence of Spore Forming Bacteria in Raw Milk

Abstract

Heat processing techniques are used to destroy problematic microorganisms present in the raw milk. Most of the vegetative bacterial cells are easily destroyed during the pasteurization temperature but, heat resistant spores can survive and create problems than vegetative cells affecting the shelf life, flavour and quality of fluid milk. Therefore, the present study was conducted to find out the existing population level of spore-forming bacteria in milk, to identify the best management practices to ensure low contamination of raw milk under the present situation. Thirty farmers were randomly selected from extensive, semi - intensive and intensive systems according to their management practices. From each category, ten farmers were selected from Polonnaruwa, Medirigiriya and Katuwanwila chilling center areas, that belong to Milco (Pvt) Ltd. Samples were collected at the point of milking. All samples were analysed for mesophilic, psychotropic and proteolytic spore forming bacteria. Results were analyzed using.one-way ANOVA. Mean psychotropic, mesophilic and proteolytic spore count of raw milk samples at farmer level were 2.38, 2.93 and 2.47 log1 0 cfu/ml, respectively. Spore forming bacterialcountswere significantly different (p<0.05) in extensive and semi intensive systems from intensive system. Main findings suggest that due to the routine management practices applied in extensive and semi-intensive dairy farming in Polonnaruwa area systems appear to cause high level of contamination of raw milk especially with problematic psychotropic, mesophilic and proteolytic spore forming bacteria.