Ultrasound in orange sweet potato juice: Bioactive compounds, antioxidant activity, and enzymatic inactivation

Abstract

Orange flesh sweet potato contains bioactive compounds which have nutritional and health-protective values. The aim of this investigation was to evaluate the impact of ultrasound treatment in orange sweet potato juice on physicochemical parameters, β-carotene, total phenolic, antioxidant activity (ORAC and ferric thiocyanate), polyphenol oxidase, and peroxidase activity. The juice was sonicated for 2, 4, 6, 8, and 10 min, with ultrasonic intensity of 0.24 and 0.66 W cm−2. The sonicated juice showed an increase of β-carotene content (57%) and a decrease in the percentage of total polyphenol content with values between 4.88 and 14.25%. The antioxidant activity by ORAC was 29.55 µmol TROLOX equivalent mL−1 and the inhibition of linoleic acid oxidation was higher than 94%. Ultrasound treatment showed inactivation of 28.38 and 46.28% for polyphenol oxidase and peroxidase, respectively. Ultrasound technology allowed the achievement of a sweet potato quality juice without compromising the retention of antioxidant compounds. Practical applications Orange fresh sweet potato has minimal industrialization in México. In general there is lack of knowledge about the functional properties that this product may have. This research presents a preprocessing option for the sweet potato that allows the greater extraction and conservation of its bioactive components, such as β-carotene. Likewise, the potential benefit of sweet potato juice can be obtained by combining it with other juices to increase its palatability and to develop more functional and nutritious products. Once combined the juices they should be subjected to a thermal processing to inactivate enzymes and to extend the shelf life.