Influence of Ultrasound on Fresh-Cut Mango Quality Through Evaluation of Enzymatic and Oxidative Metabolism

Abstract

Ultrasound (US) was applied as a post-processing treatment on fresh-cut mangoes as a means to preserve quality and to further understand its possible physiological effects. Processed fruits were sonicated at 25 kHz for 30 min and stored for 7 days under refrigeration at 4 °C. Fruits were analyzed on treatment day (day 0) and after storage (day 7) for quality through physicochemical and chemical variables, while color and firmness were evaluated in association to physiological variables, at last, variables of oxidative/antioxidant were also analyzed. Initially (day 0), US significantly reduced soluble solids and sugar content in 15 %, although after storage (day 7), there was no difference between treatments. After storage (day 7), US-treated mango was softer, 139.34 N, than control, 241.15 N, and firmness loss was not associated to cell membrane integrity, as determined by lipid peroxidation degree, but to cell wall integrity as hydrolases pectin methylesterase and polygalacturonase were stimulated. The color attribute °Hue was affected by US and declined significantly after the storage (day 7) to 80.79, indicating darkening of tissue. Results indicate that guaiacol peroxidase was the primary cause of darkening while polyphenol oxidase activity, carotenoids, and total flavonoids could not be associated to changes in color. Constant levels of hydrogen peroxide indicate that sonication did not induce an oxidative imbalance in mangoes, and thereby, the non-enzymatic antioxidants, total antioxidant activity, and activity of antioxidant enzymes superoxide dismutase and catalase were not influenced by the US. Therefore, US affected negatively fresh-cut mangoes’ quality through deteriorating changes, and further work should be carried on to explore ultrasound under different conditions as to ensure this technology could be appropriately used at mango postharvest.