A RESEARCH NOTE - RENNET-CLOTTING PROPERTIES AND STARTER ACTIVITY ON MILK ACIDIFIED WITH CARBON-DIOXIDE

The influence of acidification with CO2 on starter activity, rennet cl otting properties, and cheese yield have been studied. Results obtaine d with lactic acid-treated milk were compared with those obtained with CO2-treated milks. CO2-treated samples showed lower acidification by starter than lactic acid-treated samples. The higher final pH values f ound in CO2-treated samples could be attributed to reduced starter met abolic activity. Heat treatments to 60 or 70-degrees-C for 30 min did not influence coagulation time by rennet. Acidification produced a dec rease of coagulation time, which was more pronounced on samples treate d with lactic acid. Cheese yield was influenced by the growth of psych rotrophic bacteria during storage of milk.