Afuega'l Pitu cheese quality: Carbon dioxide addition to refrigerated milkin acid-coagulated cheesemaking

The suitability of milk preserved by refrigeration and CO2 addition for the manufacture of Afuega'l Pitu, a Spanish acid-coagulated short-ripened chee se, was evaluated at pilot scale using an autochthonous cheese starter. Che eses manufactured, after milk pasteurisation, from vacuum degasified refrig erated CO2-treated samples (pH 6.2) were compared with two different contro l cheeses made from pasteurised milk either fresh or refrigerated. The mult iplication and acidification capacity of lactic acid bacteria as well as th e production of volatile compounds during cheesemaking and ripening were no t affected by the previous refrigeration and CO2-treatment of raw milk nor by the residual CO2 still present in pasteurised milk after degasification and pasteurisation. Residual CO2 retarded the proteolysis although no diffe rences on proteolysis and sensory properties were detected at the optimum t ime of consumption (15 days) between cheeses made from CO2-treated milk and those made from untreated control milk. CO2-treatment effectively prevents the decrease in cheese yield caused by the microorganisms present in raw m ilk of poor microbial quality. These results support the interest of the CO 2-addition in preservation of milk for cheesemaking, specially when it has a high initial microbial load; the method can be satisfactorily used in the manufacture of Afuega'l Pitu cheese and may be extended to the production of other acid-coagulated cheeses. (C) 1999 Elsevier Science Ltd. All rights reserved.