Influence of Brine Concentration, Brine Temperature, and Presalting on Early Gas Defects in Raw Milk Pasta Filata Cheese

Abstract

Thirty-one 3.8-kg blocks of Ragusano cheese were made on each of 6 d starting with a different batch of raw milk on each day. On d 1, 3, and 5, cheeses were not presalted and on d 2, 4, and 6, all cheeses were presalted. Before brine salting, one of the 31 blocks of cheese was selected at random for analysis (i.e., at d 0). The remaining 30 blocks were randomly divided into 2 batches of 15 blocks each, one group was placed in 18% brine, and the other group was placed in saturated brine. For the 15 blocks within each of the 2 brine concentrations, 5 blocks each were placed in brine tanks at 12, 15, and 18°C. Cheese blocks were sampled immediately before brine salting (d 0) and after 1, 4, 8, 16, and 24 d of brine salting. Presalting the curd with 2% added salt before stretching reduced the coliform count in the cheese by 1.41 log and resulted in a major reduction in early gas formation. Across all treatments in the present study, the average reduction in gas formation due to presalting was 75%. Reducing brine temperature had the second largest impact on reducing gas production, but did not reduce the coliform count in the cheese. Reducing brine temperature from 18 to 12°C made a larger reduction in early gas formation in cheeses that were not presalted (from 6.8 to 1.8% gas holes, respectively) than in cheeses that were presalted (from 1.9 to 0.5% gas holes, respectively). To achieve the same absolute level of gas production in the nonpre-salted cheese as was achieved in presalted cheese in combination with 18°C brine, the brine temperature for the nonpresalted cheese had to be lowered from 18 to 12°C. Reducing brine concentration, although effective at increasing the rate of salt penetration into the block, did not have any impact on coliform count and had minimal impact on reducing gas production. The condition where reducing brine concentration was able to make a reduction in gas production was for cheeses that were not presalted and brined at 18°C. Presalting is a very simple and practical approach to reducing the problem of early gas formation in combination with strategies to improve milk quality and cheese making conditions. Further work is needed to understand the impact of different levels of presalting on death of coliforms and gas production in the cheese.