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This study aimed to assess the feasibility of employing cloud point extraction (CPE) as an efficient way of extracting polyphenols from peach waste (PW). Four distinct food-grade surfactants (Genapol X-080, PEG 8000, Tween 80, and lecithin) were evaluated at concentrations ranging from 2–10% w/v to determine the efficiency of the technique in two separate PW streams i.e., lye peeling waste stream (LPWS) and total wastewater stream (TWS). Low amounts (2% w/v) of surfactants in a single-step CPE were found to result in less than ~61% polyphenol recovery in LPWS and less than ~69% polyphenol recovery in the TWS, necessitating additional extraction steps. In both PW streams, the single-step polyphenol recovery was improved by 25–67% utilizing a higher amount of surfactants (5–10% w/w), leading to a statistically significant figure (p < 0.05). The CPE procedure was conducted under optimal conditions, including a temperature of 65 °C, a sodium chloride concentration of 3% w/v, a pH level of 3.5, and a surfactant concentration of 5% w/v. The polyphenol recovery was efficient when the CPE procedure was conducted twice. Tween 80 proved to be the most efficient surfactant among the four tested surfactants, achieving recoveries above 98% in both PW streams. Under optimum extraction conditions, the total polyphenol content and antiradical activity of PW extracts were evaluated. The results showed statistically significant differences (p < 0.05) between the two PW streams, with the LPWS having approximately 12 times higher polyphenol content and being more potent, achieving ~64% antiradical activity. Using the LPWS instead of the TWS is a more cost-effective and feasible option for the industry. In addition, the considerable volume of the TWS makes it challenging to handle and demands a correspondingly major amount of surfactant. Considering that Tween 80 is a low-toxicity surfactant and that the CPE method is simple, fast, cost-effective, highly accurate, and selective, the extracted polyphenols from two PW streams could be exploited as natural antioxidants to be used directly in the food industry. These findings could have major implications for the manufacturing of sustainable and naturally-derived food additives.
Giovanoudis et al. (Mon,) studied this question.