Microbial and Nutritional Stability of Pineapple Juice during Storage: Effect of Harmonized Thermal Pasteurization Technologies

The effect of one or two thermal treatments during pineapple juice production was evaluated on pH, vitamin C and microbiological evolution of 6 categories of juice during 12 months of storage. Three pasteurization temperatures (75°C, 80°C, 85°C) combined with one (1T) or two (2T) thermal treatments defined the juice category. Storage test consisted of green-glass bottled juices packaged in closed boxes, kept at ambient temperature. Analyses were performed each 4 months from production date (0 month). As results, the juices pH was 3.90 - 4.14 after production and no significant variation (p ≥ 0.05) occurred during storage, except for juices 80°C, 1T and 80°C, 2T at 12 month. The microbiological quality of all juices after production revealed conformity with standards. Enterobacteria and lactic acid bacteria were totally absent all the time. Mesophilic bacteria and yeasts and moulds counts generally decreased in each juice during storage. The initial vitamin C content significantly (p<0.05) varied from 4.52 to 23.48 mg/100ml in the juices and so decreased through storage. Juices pasteurized at 75°C contained more initial vitamin C but their content was quickly lost. Vitamin C was more stable in the most thermally treated pineapple juices throughout storage, especially in juice 85°C, 2T.