Adsorption of Polyphenols from Almond Blanching Water by Macroporous Resin

The almond processing industry generates large volumes of effluent after the blanching process. Blanching water is one of the main by-products with a potential source of polyphenols. However, before being used or discharged, this by-product requires pretreatment. This work was aimed at paving the way toward using adsorption on XAD-7 HP macroporous resin for wastewater treatment. This promising technique could be easily scaled up and integrated into existing production lines. Adsorption was carried out with a fixed bed in counterflow, while desorption was performed by acetone in downflow. With this approach, it was possible to concentrate up to five times the phenolic content of the initial blanching water. The resulting extract was analyzed by ultraperformance liquid chromatography-mass spectrometry (UPLC-MS), identifying more than 89% procyanidins, in addition to catechin, epicatechin, and isorhamnetin-3-O-rutinoside. Applications such as spray-drying and prilling techniques were suggested to improve the efficiency of polyphenols by preserving their stability, bioactivity, and bioavailability.