Valorizing the seeds of wild berries: bioactive components and seed microstructure of the Patagonian Ribes magellanicum berries

Abstract

Wild berries represent an underutilized and sustainable food source valued by local communities for their flavor, nutritional properties, and the presence of bioactive components. Seeds are typically a by-product of berry processing that contain valuable nutrients and bioactive components, but are unexploited as a food resource. Ribes magellanicum is a wild shrub growing in Patagonia whose berries contain multiple seeds that account for around 50% of the dry weight (d.w.). Valorizing the utilization of these and other berries requires evaluating their nutritional and health potential and studying the microstructure of the fruit components. Seeds of R. magellanicum berries contained 10.8% protein and 11.6% lipids (dry basis), with a favorable 1.2-1.7 omega-6/omega-3 fatty acid ratio. Among bioactive components, the seeds contained 125-157 mg tocochromanols/100 g oil, 28.1-68.1 mg carotenoids/100 g oil; and 374.2 mg GAE/100 g of total phenolics. Antioxidant capacity measured by DPPH and ORAC was 2.1 and 4.2 (mmol TE/100 g d.w. of seed), respectively. Microstructural characterization of seeds, aimed at the selective and mild fractionation of components, was performed by X-ray micro-tomography imaging and scanning electron microscopy. The main microstructures were a mucilaginous sheath and the endosperm with cells having thick cell walls and a space for the embryo, and multiple intracellular spherical bodies 2-7 mu m in diameter, possibly deposits of proteins, lipids, and/or starch. These findings support that a comprehensive characterization of seeds from novel and underutilized plant sources is fundamental for developing mild and sustainable technologies to recover bioactive compounds and ingredients.