EVALUATION OF CITRIC-ACID AND GDL IN THE RECOVERY AT DIFFERENT PH LEVELS OF CLOSTRIDIUM-SPOROGENES PA-3679 SPORES SUBJECTED TO HTST TREATMENT CONDITIONS

Spores of Clostridium sporogenes PA 3679 were heated at different temp eratures (121, 126, 130 and 135 degrees C) in white asparagus puree (p H 5.8) and acidified with glucono-delta-lactone (GDL) and citric acid to pH levels of 5.5, 5.0 and 4.5. Afterwards, the spores were recovere d in MPA3679 medium in various conditions: unacidified (pH 7.5), acidi fied with GDL (500 ppm) and acidified with citric acid (500 and 250 pp m) to pH levels of 6.5, 6.0 and 5.0. The results indicated that the pH levels, concentration and type of acid used act synergistically rathe r than independently. Citric acid has a stronger inhibiting effect tha n GDL on the recovery of C. sporogenes PA 3679 spores. At the higher h eat treatments (130 and 135 degrees C) the major injury on the spores sensitize more than against the acids and low pH values.