Effect of elevated ripening temperatures on the microflora of Cheddar cheese

Abstract

Summary: Changes in the composition of the microflora in Cheddar cheese ripened at elevated temperatures were examined. Cheeses were stored under the following ripening conditions: (i) control, 8°C for 32 weeks; (ii) 15°C, (iii) 17·5°C or (iv) 20°C, all for 8 weeks, then followed by 8°C for 24 weeks; (v) 15°C, (vi) 17·5°C or (vii) 20°C, all for 32 weeks. Generally, the total bacteria, lactic acid bacteria, lactobacilli and ‘undesirable lactobacilli’ (producing off flavours and CO₂) counts in cheeses stored above 8°C were higher than in the control cheese. This effect seemed to be dependent on continued storage at the elevated temperature. Streptococcal counts rose slightly during ripening at elevated temperatures and fell slightly during ripening at the control temperature. Numbers of non-lactic acid bacteria were unaffected by elevated storage temperatures. In the only treatments where off flavours developed (17·5°C for 32 weeks, 20°C for 16 weeks or more) there was no apparent relationship between any bacterial group and the off flavours.