Exploring Ultrasound-Induced Changes on Bioactive Content and Color Properties of Sour Cherry Juice Involving Insights From Image Processing Analysis

Abstract

Thermal processing can intensify the degradation of beneficial compounds in fruit juices produced from concentrate, which underwent prior evaporation, leading to duplicated processing and likely increased quality deterioration. This study aims to (i) investigate the potential of ultrasound (US) to retain bioactive compounds and quality of sour cherry juice (SCJ) produced from concentrate and (ii) involve insights from digital image processing (IP) to evaluate color attributes of processed SCJs. US was optimized considering amplitude (60%–100%) and time (2–15 min) as independent variables, maximizing total anthocyanin content (TAC) and total phenolic content (TPC) at 67% amplitude for 7 min. Process-dependent changes in TAC, TPC, antioxidant activity, and color were compared for optimal US and conventional thermal (90°C for 1 min) treatments. US maintained similar TAC to untreated SCJ (160.4 mg/L); however, thermal processing reduced TAC to 154.4 mg/L (p < 0.05). TPC (417.89 mg/100 mL) significantly decreased by both treatments, while antioxidant activity remained stable. IP technology and conventional colorimetric methods were used to evaluate color properties. The two methods showed differing results on color properties, with IP suggesting an increase in redness and yellowness while colorimetric analysis suggests a reduction after processing. This study highlights the evaluation of the process-induced changes for better preservation of bioactive content and quality of fruit juices as well as establishes a baseline for evaluating the quality of nonthermally processed fruit juices through computer vision-based techniques.