Individual and combined effects of pomegranate extract and ultrasonic treatments on kiwifruit juice quality parameters

Abstract

The objectives of this study were to report the effectiveness of ultrasound and pomegranate extract, individually and combined, on kiwifruit juice quality attributes. Fruit juices were treated with 180 μg/mL pomegranate extract and sonicated for 10 and 30 min (180 W, 40 kHz). Microbial populations, ascorbic acid retention, sensory attributes and color parameters were evaluated through refrigerated storage. By the end of storage, individual ultrasound treatments were able to reduce yeast and molds counts compared with that in control. Furthermore, combined treatments of ultrasound and pomegranate extract showed synergism, with higher reductions on yeast and molds. None of the treatments were able to increase the ascorbic acid retention through storage time. Color parameters evaluated showed that the treatments applied had significant differences from that of control. At Day 2, the treatments showed an improvement in color, with total color difference (ΔE) lower than that of untreated sample, indicating less color difference from fresh kiwifruit juice. Sensory attributes were not significantly affected by the treatments. However, a significant effect of storage time was perceived by the panelists, with a decrease in overall visual quality score throughout time, indicating the end of shelf-life of the product at Day 7 of refrigerated storage. Practical Applications: Ultrasonic processing technology and the application of natural antimicrobials are continuously being explored as alternatives to traditional thermal treatments in the food industry. It is necessary to study the impact of these technologies both individually and combined, in terms of microbiological stability and quality preservation. In practice, it is important to not only decrease the microbial growth on food products, but also minimize the loss of their nutritional and sensory attributes. This study suggests some processing and preservation conditions for kiwifruit juice, demonstrating the potential use of ultrasound in combination with the application of pomegranate extract as a biopreservative. This hurdle technology could be easily introduced in the fruit and vegetable juice industry, replacing thermal treatments that compromise the nutritional and sensory quality of the final product.