Microbiological study of semihard goat's cheese (Majorero)

Abstract

The development of microbial flora in industrially produced semi-hard cheese made from pasteurized goat's milk was studied during manufacture and over a 90-day ripening period. Estimates of total count, streptococci, lactobacilli, leuconostocs, coliforms, micrococci and staphylococci, Staphylococcus aureus and yeasts and moulds were carried out at various stages of the ripening process; streptococci and lactobacilli were identified by species. Initially, the total count increased rapidly, primarily as a result of the growth of mesophilic lactic streptococci mainly Streptococcus lactis and Strep, cremoris. Subsequently, both these counts stabilized or decreased. Lactobacilli increased, and by the end of the ripening period were the predominant microorganisms. Most common were Lactobacillus casei var. casei., especially at the end of storage; L. casei var. rhamnosus, L. casei var. plantarum and L. cellobiosus were also isolated. Leuconostocs were not found in any of the cheeses, and hence no eye formation took place. Coliforms, enterococci, yeasts and moulds remained below 102-103 c.f.u. g-1. Maximum levels of micrococci and staphylococci were found after 15-30 days of ripening and decreased gradually towards the end of the ripening period. Neither the milk curd, nor cheese contained Staph. aureus.