SUPERCRITICAL PASTEURIZATION: MICROBIOLOGICAL AND SENSORY DIVERSITIES BETWEEN FRESH AND TREATED APPLE JUICES

摘要

Recently low temperature technologies are receiving a great deal of attention as alternatives to thermal pasteurization in foodstuff stabilization. Pasteurization by means of supercritical (SC) fluids represents one of the most promising alternatives. In this study the microbiological and sensory effects on natural apple juice of SC fluids treatment, both carbon dioxide (CO_2) and nitrous oxide (N_2O), was investigated and compared to the untreated product. In a high pressure lab-scale equipment freshly squeezed apple juice was treated at 36°C and 100 bar for 10 minutes with both the gases. An almost complete microbial inactivation naturally present in the juice was achieved. The effects of the treatment on the sensory quality were evaluated by means of: 1. Discriminative analysis performed by a panel of trained judges: triangle tests were used to compare CO_2-treated and N_2O-treated juice versus fresh juice. The judges could find moderate difference between N_2O/CO_2 treated juice and the fresh one. 2. Basic chemical characterization (total solids, sugar, organic acids, polyphenols): no significant modification between N_2O/CO_2 treated juice and the untreated one.