Effects of temperature-controlled ultrasound treatment on sensory properties, physical characteristics and antioxidant activity of cloudy apple juice

Abstract

Cloudy apple juice were subjected to ultrasound treatments at various power levels (525, 975, and 1125 W) and temperatures (50, 60, and 70 °C). The effects of temperature-controlled ultrasound treatment (TCUT) on the microbial load, color, sensory evaluation, total soluble solids, water soluble pectin (WSP), rheological properties, stability, and antioxidant activity of cloudy apple juice were investigated. Ultrasound and thermal treatment play a synergistic role in the reduction of microbial populations and could achieve microbial safety. TCUT enhanced the sensorial properties and improved the content of WSP, while reducing the particle size. TCUT significantly improved the rheological properties and suspension stability of apple juice. Moreover, the phenol content and percentage of DPPH inhibition also increased by TCUT in apple juice. The optimized TCUT conditions was at 60 °C with 1125 W power for 12min. The juice showed inactivation of microorganisms (<1 log CFU/mL), a preferable sensory property, obvious decreasing in particle size, more WSP, and better cloudy stability.