Enzymatically Hydrolyzed Amaranth as a Base for Enteral Nutrition: Nutritional Characterization, Phenolic Bioaccessibility, and Physicochemical Properties

Plant-based enteral formulas represent a hypoallergenic alternative to dairy-derived products, but incorporation of underutilized pseudocereals into enteral formulas remains insufficiently characterized. This study developed a laboratory-scale prototype of a fortified beverage for enteral administration (FBEA) from the soluble fraction of Amaranthus hypochondriacus, with added pea protein isolate, safflower oil, and carbohydrate components. Sequential enzymatic treatment with α-amylase and Alcalase hydrolyzed amaranth grain flour into soluble fraction, increasing free amino acid content relative to the unhydrolyzed flour, including arginine from 0.52 to 241.39 mg kg−1, lysine from 3.91 to 129.10 mg kg−1, and glutamic acid from 103.62 to 368.54 mg kg−1. Fortification yielded a protein content of 25.46% DW, a lipid content of 24.95% DW, and an energy density of 1014 kcal L−1, consistent with isocaloric formulas, with seven essential amino acids meeting FAO/WHO/UNU reference adequacy values. In vitro digestion showed that the soluble fraction and FBEA exceeded amaranth flour in bioaccessibility of antioxidant activity and phenolic content, with FBEA achieving the highest intestinal phenolic release. The formula met ESPEN physicochemical recommendations, with osmolality at 292 mOsm kg−1 and viscosity at 51 mPa·s, and simulated tube flowability comparable to two commercial formulas. These findings indicate that enzymatically hydrolyzed amaranth shows potential as a plant-based enteral formulation prototype, though clinical suitability requires further safety, shelf-life, and tolerance data.