Split Defect of Swiss Cheese

Abstract

In a preceding paper we reported that certain strains of Propionibacterium which grow at low temperatures are able to split Swiss cheese. The metabolic characteristics of these strains differ from those of strains unable to grow and produce CO2 at low temperatures. The optimal pH for malate dehydrogenase activity of cell-free extracts of the low-temperature growing strains was 7.5, whereas it was 8.5 for strains lacking the ability to grow at low temperatures. Arrhenius plots of enzymic specific activity for lactate and malate dehydrogenases of cell-free extracts obtained from low-temperature growing strains showed greatest activities at temperatures below 10 C. At 15 C or greater, cell-free extracts of strains without low-temperature growth ability showed equal or greater lactate or malate dehydrogenase specific activities. Thus, enzymes of low-temperature growing strains showed greater capacities for activity at both lower temperatures and lower pH. These data support the hypothesis that such strains at low temperature are capable of CO2 production which creates a predisposition for Swiss cheese to split when stored at temperatures of 10 C or lower.