Influence of different shrinking temperatures and vacuum conditions on the ability of psychrotrophic Clostridium to cause 'blown pack' spoilage in chilled vacuum-packaged beef.

This study determined the ability of psychrotrophic Clostridium strains isolated from vacuum-packaged beefs and abattoir environments to cause 'blown-pack' spoilage of vacuum-packaged beef stored at 2 and 15 °C. The influence of shrinking temperatures (83, 84 and 87 °C) and vacuum pressure (6 and 9 mbar) on the occurrence of such spoilage as well as the effects of simulated transportation (500 km) on the integrity of packages was determined. At 15 °C and 2 °C, twelve and six strains caused 'blown-pack' spoilage, respectively. The combination of vacuum pressure (9 mbar) combined with shrinking temperature (87 °C) retarded the occurrence of spoilage. The simulated transportation under the experimental conditions did not affect the integrity of packages. More studies that assess the factors that may contribute for the occurrence of 'blown-pack' spoilage should be performed to avoid the occurrence of such spoilage during its shelf-life.

Use of a logistic model to assess spoilage by Byssochlamys fulva in clarified apple juice.

The percentage P (%) of spoiled bottles (n=40) of clarified apple juice due to Byssochlamys fulva, was modeled by using a logistic model: P = P(max)/1 + exp (k(tau-t)) where P(max) (%) the maximum percentage of spoiled bottles, k (h(-1)) a slope parameter and tau (h) the time for P=P(max)/2. Bottles of pasteurized apple juice were inoculated with B. fulva IOC 4518 ascospores for low and high initial loads, 4.8+/-2.3 ascospores/100mL and 19.3+/-4.6 ascospores/100mL respectively and incubated at 21 degrees C and 30 degrees C. P(max) was not significantly different from 100% except for a low initial load at 21 degrees C. Model parameters were estimated with a good accuracy, RMSE in the range 3.89-7.50. Then the model was used to determine the time for 10% bottles spoiled, t(10%). This time was greater at low initial loads, 57.4 and 104 h at 30 and 21 degrees C respectively, than at high initial loads 23.9 and 75.1h at 30 and 21 degrees C respectively. This study demonstrated that even at a very low initial contamination, clarified apple juice can be easily spoiled by B. fulva highlighting the importance of controlling critical control steps of fruit juice processing (i.e., fruit washing, juice filtration and pasteurization).