Antioxidant, quality and electronic tongue sensory parameters of thermosonicated blueberry nectar

Abstract

Abstract The effect of power ultrasound and increased temperature (thermosonication) on antioxidant capacity, color, total phenolic compounds, degree of non-enzymatic browning (NEB) and sensory properties by electronic tongue, of blueberry nectar was investigated. Samples were treated with high power ultrasound (HPU) at 50%, 75% and 100% amplitude, during treatment time of 3, 6 and 9 min at elevated temperatures. Antioxidant capacity determined by DPPH and ABTS methods shows a positive correlation between the values. It was observed that treatment time has statistically significant impact on antioxidant capacity (ABTS) of nectar. Color was the darkest and with highest levels of red and yellow in the sample treated with ultrasound at 100% amplitude for 6 min. The degree of non-enzymatic browning was highest for samples treated with ultrasound at 100% amplitude for 9 min, and total phenolic compounds concentration indirectly increased. Sensory evaluation by electronic tongue showed differences in samples. The best results of blueberry nectar were obtained for antioxidant capacity by treatment of ultrasound amplitude at 50% for 6 min and highest value of anthocyanins (50% amplitude for 3 min). The treatment at amplitude of 50% for 3 and 6 min can be considered to give the best outcome of processed blueberry nectar because of lower influence of ultrasound treatments in terms of lower oxidative deterioration, as well as influence of cavitation. Industrial relevance This paper reports possible in-line methods and significance of the research data presented towards potential industrial applications. These methods could be used for quick monitoring of thermosonication process in order to preserve fruit juice. Through those methods, food technologist could optimise and conduct thermosonication in-line (on processing plant), in the way of obtaining high value food product.