Optimization of phytochemicals production from potato peel using subcritical water: Experimental and dynamic modeling

• The S–L batch and sCW extraction at 190 °C produced extracts with similar antioxidant activity.
• pH modification of the sCW can tailor phytochemical production.
• Optimum phytochemicals release are obtained with sCW at T < 180 °C and P = 40 bar.
• Fragmentation reactions occur at T > 180 °C and P > 40 bar.
• The dynamic model showed a direct relation between reactions and pressure.

Phytochemicals were obtained from potato peel using conventional and subcritical water (sCW) extraction. The influence of process parameters on the removal of carbohydrates, phenolics and antioxidant compounds were optimized using Response Surface Factorial Design and the Taguchi method. Ethanol concentration (1–90%) and pH (3–10) were studied for the conventional extraction and static holding time (2–25 min), pressure (40–120 bar), temperature (140–260 °C), and pH (3–9) were studied for the sCW extraction. Higher amounts of phytochemicals were obtained with the sCW extraction than with the conventional extraction. The highest total carbohydrates (610 mg GE g−1 potato peel), total phenolics (20 mg GAE g−1 potato peel), and total antioxidant activity (42 mg FeSO4 g−1 potato peel) with low browning color of the extracts were obtained at 40 bar, 190 °C, and 9 min of static holding time using a flow rate of 3 mL min−1. The proposed dynamic mass transfer-reaction model fitted well the experimental data with a mean square error of 0.4 and predicted well the potato peel residual mass.

Figure optionsDownload as PowerPoint slide