The present study aimed to find the effect of thermal (heat treatment) and non-thermal (sonication) processing on the naringin and ascorbic acid content of grapefruit juice. The three-level factorial experimental design was adopted, and a two-factor interaction model was fitted to assess the effect of variables on naringin and ascorbic acid content. The variables showed a significant (P < 0.05) linear and interaction effect on responses (naringin and ascorbic acid content) for thermal and non-thermal processed grapefruit juice. The naringin and ascorbic acid content of thermally processed juice varied from 561.50 to 612.20 ppm and 32.75 to 38.20 mg/100 mL, respectively. There was a significant (P < 0.05) decrease in the naringin and ascorbic acid content of grapefruit juice due to an increase in temperature and time. In the case of sonication, the naringin and ascorbic acid content of sonication-treated juice varied from 690.30 to 737.50 ppm and 39.15 to 46.26 mg/100, respectively. The naringin and ascorbic acid content were increased significantly (P < 0.05) as a function of sonication frequency and time. The observations of the present study might be useful for citrus juice processing by adopting a suitable processing method.
Key words: grapefruit juice, naringin, ascorbic acid, sonication and thermal processing
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