Patterns of non-starter microflora during ripening of selected South African Cheddar cheeses manufactured by the open-vat procedure

Abstract

South African Cheddar cheese from a manufacturing plant using the open-vat procedure was sampled at intervals during maturation and analysed for selected non-starter micro-organisms using microbiological culture methods. The quantities of the micro-organisms corresponded well with reports in literature. However, the yeast and mould population were higher during the earlier stages of maturation. Heterofermentative lactobacilli, coliforms, faecal coliforms and members of theEnterobacteriaceae were encountered in low or negligible numbers, indicating good manufacturing practice and a high standard of plant hygiene. Total mesophilic counts, yeasts and moulds and total acid-formers decreased during maturation while the citrate-fermenters increased. The anaerobic spore-forming bacteria decreased rapidly to undetectable levels. Marked variation in counts was observed during the first five sampling points (from the salted curd to about 2 weeks of maturation). After an initial surge and decline, the total lactobacilli, homofermentative lactobacilli and aerobic spore-formers did not show a definite increase or decrease. The various micro-organisms followed multi-phasic sum-of-exponentials, linear and exponential patterns during maturation that were expressed in terms of mathematical equations. These equations may be used as components in the development of predictive indices for the selected cheese.