Title : Aqueous extraction of almond skin phenolics and their application as natural antioxidants in pork patties
Abstract:
The increasing volume of by-products generated by the almond industry offers valuable opportunities for upcycling, particularly given that almond skin contains 60–80% of the nut’s total phenolic compounds (Timón et al., 2022). While most previous studies have relied on organic solvents for phenolic extraction, the need for greener and food-safe methodologies remains. This study assessed the use of water as an environmentally friendly solvent to obtain phenolic extracts from four almond cultivars (Antoñeta, Guara, Soleta, Belona) and evaluated their potential as natural antioxidants in pork patties stored under modified atmosphere packaging. Aqueous extraction, performed accordint to the method described by Andrés et al. (2020) (20 mL/g, 30 °C, 60 min) produced phenolic-rich extracts with measurable antioxidant capacity, with Antoñeta showing the highest phenolic content (2.25 mg GAE/g) and a strong correlation with antioxidant activity (DPPH, r = 0.891; p < 0.01). HPLC-DAD analysis revealed isorhamnetin-3-O-rutinoside, catechin, and protocatechuic acid as the most abundant compounds. When incorporated into pork patties, the Antoñeta extract reduced weight loss during storage but did not substantially improve color stability or microbial counts. Regarding lipid oxidation, its effect was limited compared with sodium ascorbate, which consistently achieved the lowest TBARS values throughout storage (Timón et al., 2022). Overall, aqueous extraction proved viable and sustainable for recovering phenolic compounds from almond skin, though optimization of extract concentration or combined extraction techniques is needed to enhance its technological performance in meat products.
