CONTROL DEL DESARROLLO DE BACTERIAS ACIDO BUTIRICAS EN QUESO TIPO GOUDA EMPLEANDO DIFERENTES CONCENTRACIONES DE NITRATO Y TEMPERATURAS DE MADURACION

Abstract

The objective of this study was to determine the effect of the ripening temperature and sodium nitrate concentration on the growth of butyric acid bacteria (BAB) in Gouda type cheese. Cheese was manufactured with different nitrate concentrations (0 %, 0,015 %, 0,020 % and 0,030 %) and stored at three temperatures (4 °C, 10 °C or 16 °C). At time zero and after 6, 12 and 18 weeks, the Most Probable Number (MPN) of BAB was determined (Fryer and Halligan, 1976). For each storage time and temperature, three cheeses were manufactured. The experiment was repeated three times. Results showed a low spore MPN in milk, however, after 6 weeks the BAB had grown in the cheese without nitrate. A temperature of 16 °C was favorable for the growth of BAB, with MPN of >1100/g in the cheeses without nitrate. At lower temperatures, the growth of the BAB was inhibited without nitrate (MPN <10/g). Nitrate was important for the inhibition of BAB, at 16 °C, however no differences were found among the different concentrations assayed, probably due to the low initial spore count in milk. The BAB identification showed higher percentages of isolation of C. tyrobutyricum than C. butyricum and C. sporogenes. It was concluded that a ripening temperature of ≤ 10 °C was an effective barrier to inhibit the growth of BAB, even without the addition of nitrate. At 16 °C the BAB were also inhibited, when nitrate was added, however significant growth occurred in the treatment without nitrate, at this temperature.