Growth and colour development of some surface ripening bacteria with Debaryomyces hansenii on aseptic cheese curd

The growth of five bacteria isolated from red-smear cheeses, Brevibacterium aurantiacum, Corynebacterium casei, Corynebacterium variabile, Microbacterium gubbeenense and Staphylococcus saprophyticus in mixed cultures with Debaryomyces hansenii on aseptic model cheese curd at 10 and 14 °C was investigated. At both temperatures, C. casei and Micro. gubbeenense had a longer lag phase than C. variabile, Brevi. aurantiacum and Staph. saprophyticus. In all cultures, lactose was utilised first and was consumed more rapidly at 14 °C than at 10 °C, i.e., 6 d at 14 °C and 10 d at 10 °C. This utilisation coincided with the exponential growth of Deb. hansenii on the cheese surface. Lactate was also used as a carbon source and was totally consumed after 21 d at 14 °C and ~90% was consumed after 21 d at 10 °C regardless of the ripening culture. Small differences (<0·5 pH unit) in the surface-pH during ripening were noticeable between ripening cultures. Differences in the colour development of the mixed cultures with the yeast control were only noticeable after 15 d for Brevi. aurantiacum and after 21 d for the other bacteria. Regardless of the organisms tested, colour development and colour intensity were also greater at 14 °C than at 10 °C. This study has provided useful information on the growth and contribution to colour development of these bacteria on cheese.