EFFECT OF THERMAL PASTEURIZATION ON THE PHYSICOCHEMICAL STABILITY AND NUTRITIONAL QUALITY OF MOROCCAN VALENCIA LATE ORANGE JUICE

A better knowledge of the effect of pasteurization on the physiochemical stability and the nutritional quality of foods processed by emerging technologies with regard to thermal traditional technology is necessary. Thus, freshly squeezed orange juice of Moroccan Valencia Late orange variety was processed by four thermal scales 65°C/30min, 77°C/1min, 88°C/15s, 92°C/30s. The pH, soluble dry matter, total acidity, Vitamin C, total polyphenols, condensed tannins and flavonoids of fresh and treated juices were evaluated. The thermal effect on total acidity and soluble dry matter, or Brix analysis showed insignificant modifications due to all pasteurization treatments. However, the pH values increased considerably for all pasteurization treatments. Furthermore, the contents of total polyphenols revealed significant increase with 88°C/15s treatment. Also, a considerable decrease of the rate of the flavonoids was observed especially with 77°C/1min and 65°C/30min treatments. Moreover, an increase in condensed tannins compared to fresh orange juice was remarkably noted, especially for the thermal scale of 88°C/15s and 65°C/30 min. During treatments, orange juice maintained the same concentration of vitamin C.