Effect of Minimal Processing Versus Thermal Processing on the Quality Characteristics of Grapefruit Juice

Authors

1 Food Science and Technology Department, Faculty of Agriculture, Al-Azhar University, Cairo, Egypt.

2 Department of plant production, Desert Research Centre, Cairo, Egypt

Abstract

This study was carried out to evaluate the effect of using ultraviolet (UV), ultrasound (UV) with orange peel extract (OPE) combined treatments as novel minimal processing techniques vs. thermal processing on the physiochemical, microbiological and sensorial characteristics of grapefruit juice. Grapefruit juice samples were untreated (control), thermally processed (at 90◦C for 5 min) and minimally processed at four combinations (sonicated by using 35 kHz frequency at 25◦C for 15 and 30 min. / UV treated by using UV dose 3.525 J/m2 at 25◦C for 15 and 30 min. / 250 µl orange peel extract). The results showed that thermal and minimal processing of grapefruit juice did not affect its physiochemical characteristics. The degradation of ascorbic acid for minimally processed juice was lower (11.11- 20.5%) than that occurred by thermal processing (63.8%). The extractability of carotenoids and polyphenols of minimally processed juice sample was significantly increased (p < 0.05) as compared to control and thermal processed juice samples which contain the lowest carotenoid and polyphenol contents, this was reflected in recording the highest antioxidant capacity for minimally processed samples. Thermal and minimal processing exhibited noticeable reduction in microbial load as compared to control. Also, the minimally processed samples had lower sensory scores than control but higher than that of thermally processed sample. Results obtained support the use of minimal processing technique to preserve grapefruit juice with keeping their quality characteristics.

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