Optimization of osmosonication pretreatment of ginger (Zingiber officinale Roscoe) using response surface methodology: Effect on antioxidant activity, enzyme inactivation, phenolic compounds, and physical properties

The study assessed the effect of sonication frequency (UF) 33-68 kHz, sucrose concentration (SC) 20-60% wt/vol, and pretreatment time (PT) 10-30 min for maximizing 1,1-diphenyl-2-picrylhydrazyl (DPPH), cupric ion reducing capacity (CUPRAC), ferric reducing antioxidant power capacity (FRAP), total phenolic content (TPC), weight reduction (WR), water loss (WL), rehydration ratio (RR) and minimizing polyphenol oxidase (PPO), and solid gain (SG) of ginger by using response surface methodology (RSM). The results revealed that osmosonication pretreatment had a significant impact on DPPH, FRAP, CUPRAC, TPC, WL, WR, RR, SG, and PPO. The optimal operating conditions to attain the best DPPH, CUPRAC, FRAP, TPC, WL, WR, RR, PPO, and SG were UF (50 kHz), SC (35% wt/vol), and PT (30 min). Based on the aforementioned conditions, the experimental outcome obtained including WL (62.97 +/- 0.85%), SG (9.06 +/- 0.04%), WR (53.98 +/- 0.18%), RR (3.09 +/- 0.02), DPPH (65.69 +/- 0.23 mgTE/g dw), FRAP (50.93 +/- 0.15 mgTE/g dw), CUPRAC (55.32 +/- 0.11 mgTE/g dw), TPC (23.96 +/- 0.35 mgGAE/g dw), and PPO (13.21 +/- 0.05%) were consisted with the predicted values and the overall desirability was 0.758. The RSM plots also revealed that the independent variables significantly enhanced the physiochemical properties of osmosonicated pretreated ginger samples. Practical applications Concerning the increasing demand for new pretreatment techniques for dehydration of ginger, osmosonication could be presented as a unique, efficient, and innovative predehydration method for the pharmaceutical, beverage, and the food industries. It application preceding to drying of agricultural crops could reduce moisture content, increase drying rate, lessen the processing time and cost, and retain the physiochemical properties of the dried product.