Fruit Juices as a Valuable Ingredient in Isotonic Drinks

The growing interest in isotonic drinks translates into the need to develop formulations based on natural raw materials, which limit the use of synthetic additives while simultaneously increasing the bioactive value and sensory appeal of the products. The aim of this study was to develop innovative formulations for isotonic drinks based on natural fruit juices and to evaluate their physicochemical properties and sensory acceptance. Formulations containing 10-15% (v/v) fruit juice, with the addition of salt (0.13 g/100 mL) and organic sugar, were prepared, taking care to maintain osmolality within the range of 270-330 mOsm/kg. The 10 most appealing variants were selected and subjected to sensory analysis using the QDA; physicochemical analyses, including the determination of total polyphenol content (TP) and the DPPH free radical scavenging capacity; and the measurement of color parameters in the CIE Lab system. All the drinks analyzed received positive ratings in the sensory test (average acceptability scores ranging from 6.9 to 8.1). Physicochemical analyses revealed that the drinks had significant antioxidant activity: polyphenol content ranged from 46 mg to nearly 170 mg GAE/100 mL, whilst DPPH free radical scavenging capacity ranged from 45% to nearly 90%. We found that the use of fruit juices makes it possible to create isotonic drinks which not only effectively rehydrate, but also provide valuable antioxidant compounds.