THERMAL DEATH PARAMETERS of ORANGE JUICE and EFFECT of MINIMAL HEAT TREATMENT and CARBON DIOXIDE ON SHELF-LIFE

Freshly squeezed, refrigerated orange juice has a relatively short shelf-life, which could be extended by minimal processing. D and z values of orange juice microflora were obtained using the capillary method, as well as a plate heat exchanger. the effect of low levels of CO2 on the shelf-life of the juice was also evaluated. the D60 value of typical orange juice flora was about 5 s and the z was 4–5C. A combination of minimal heat treatment (15 s at 60C) and 6 mM CO2 extended the storage life of orange juice to 35 days at 4C. Carbon dioxide flushed into a 10% headspace of 350 ml jars resulted in 6 mM dissolved CO2 in the juice at 4C. This level of CO2 extended the shelf-life of unpasteurized juice to 25 days at 4C and 10 days at 10C, as compared to 17 and 5 days without CO2, respectively. No significant difference in organoleptic evaluations was found between minimally heat treated juices with or without CO2 and fresh untreated juices without CO2 during the first week of storage.