Effect of sonication on the bioactive, quality and rheological characteristics of fruit smoothies

Abstract

Summary Power ultrasound was investigated as a nonthermal processing technique for fruit smoothies. Smoothies were sonicated at different amplitude levels (24.4–61.0 μm) for processing times (3–10 min). Total antioxidant capacity (TAC), total phenolics (TP), colour parameters, particle size and rheological characteristics were assessed. Sensory evaluation was conducted on selected samples for acceptability. Highest reductions in TAC ( P < 0.001) and TP ( P < 0.001) were observed at the maximum amplitude level (61.0 μm). Sonication reduced colour and rheological parameters and shortened particle size compared with fresh and thermal smoothies. However, sonicated samples received satisfactory (>3) sensory acceptability scores. Response surface methodology was applied to determine the effect of amplitude level and processing time on TP, TAC and colour parameters. A second‐order polynomial model fitted well to TP ( R 2 = 0.74) and TAC (0.79) experimental data. Lower values were obtained for colour parameters, possibly because of processing limitations. Alternatives to overcome these limitations are discussed.