Sensory, physicochemical, microbiological and bioactive properties of red watermelon juice and yellow watermelon juice after ultrasound treatment

Watermelon (Citrullus lanatus) is important in the fruit juice industry. The aim of this study was to determine the pH, titratable acidity, Brix, color properties, lycopene, ascorbic acid, total phenolic concentration, total flavonoid concentration, antioxidant activity, hydroxy methyl furfural, sensory properties and microbial safety after ultrasound treatments (4, 8, 12 and 16 min) and the pasteurization process in red watermelon juice and yellow watermelon juice. Red watermelon juice and yellow watermelon juice samples showed no statistically significant change in Brix and titratable acidity values at the end of the treatments (p > 0.05). Improvements in lycopene, phenolic concentration, flavonoid concentration and antioxidant capacity of fresh fruit juice samples was determined with US16 (sonication for 16 min). However, ultrasound treatments led to reductions in the concentration of ascorbic acid compared to fresh juice samples. The concentration of lycopene in both fruit juice samples was found to have a negative correlation with the HMF (hydroxymethyl-furfural) concentration. Due to the current findings presented in this study, ultrasound treatments applied to fruit juices were found to be generally microbiologically safe. A better understanding of the improvement in bioactive components, provision of microbial safety and increased consumer appreciation linked to ultrasound treatment of red watermelon juice and yellow watermelon juice was provided. © 2020, Springer Science+Business Media, LLC, part of Springer Nature