SHELF-LIFE AND MICROBIAL GROWTH KINETICS OF FRESH CITRUS JUICES: SHAMOUTI ORANGE

The paper deals with the shelf-life and endogenous microbial growth kinetics of freshly squeezed unpasteurized Shamouti orange juice. Microbial and organoleptic data was evaluated for seven temperatures (range of 2.0 to 14°C). Microbial lag-time was more sensitive to temperature change in the lower range (E _a = 42.4 Kcal/mol). The effect of temperature on growth rate was quite moderate in the lower range but in the order of 12.1 Kcal/mol at the upper end. Organoleptic data kinetics indicated that unpasteurized Shamouti juice can maintain its initial quality for 4 days if kept a 2°C and about 2 days if kept at 7°C. The kinetics data (both microbial and taste) was used successfully for the prediction of microbial growth and for taste deterioration under variable time-temperature conditions (i.e., simulation of cold chain path).