CHANGES IN THE ACID-BASE BUFFERING CURVES DURING THE RIPENING OF EMMENTALER CHEESE

Buffering curves for Emmental cheese and juice expressed from cheese w ere determined at various stages of ripening. Forward and back titrati ons were performed for each sample; buffering curves for cheese calcul ated from forward and back titrations were different. When Emmental ch eese was acidified, maximum buffering occurred at approximately pH 5 w hich was probably due to solubilisation of colloidal calcium phosphate (CCP). However, when acidified Emmental cheese was back titrated, buf fering was low at pH 5 because CCP was already solubilised but strong buffering occurred at pH 6.3 due to precipitation of CCP. This suggest s that a considerable amount of calcium in Emmental cheese is in a col loidal form similar to milk. Buffering in Emmental cheese increased by approximately 16 % during maturation, mainly at pH values > 9 due to various amino acid residues becoming available for titration as a cons equence of proteolysis. The buffering curves calculated from forward a nd back titrations of juice from Emmental cheese were identical. Juice from young cheese had maximum buffering at approximately pH 4 due to lactate. During ripening buffering increased at pH 5 due probably to t he production of propionate and acetate and at pH values > 9 due to th e increased level of proteolysis end products. Approximately 46 % of t he buffering capacity of mature Emmental cheese was in the aqueous pha se (juice) and this proportion had increased by approximately 100 % du ring maturation.