Nutritional characterization of Lupinus angustifolius flour and protein isolate as sustainable plant-based ingredients for sports supplements

The Uruguayan agricultural system seeks profitable and sustainable crops, among which Lupinus angustifolius shows remarkable adaptability. Although its current use in the country is mainly restricted to animal feed, the growing demand for sports supplements based on innovative, protein-dense plant ingredients positions this species as a promising alternative. This work aimed to characterize the flour (LF) and protein isolate (LPI) from Lupinus angustifolius seeds to assess their potential in sports supplements.

Proximate analysis of both samples was carried out according to AOAC protocols (1999), fatty acids were determined by gas chromatography following IUPAC (1987, methods 2.301 and 2.304), and amino acids were analyzed using an automatic analyzer (Biochrom30, Biochrom Ltd., UK) by ion exchange chromatography with post-column ninhydrin derivatization (Spackman et al., 1958).

The characterization of LF revealed its content comprised 35.1±0.1% protein, 40.4±0.7% dietary fiber, and 7.4±0.2% lipids. The lipid fraction was dominated by unsaturated fatty acids, mainly oleic (39.2±0.0%) and linoleic (38.0±0.1%), together with α-linolenic (3.5±0.1%). The amino acid profile showed a balanced contribution, with leucine, lysine, and isoleucine exceeding FAO recommendations; glutamate and aspartate were also present in relevant amounts for energy metabolism and muscle recovery. LF provided essential minerals (mg/100g): calcium 265.5±17.9, magnesium 185.03±8.45, potassium 841.1±96.9, iron 6.23±0.01, and zinc 2.8±0.3.

LPI presented 85.2±1.6% protein, 6.4±0.3% fiber, and 3.7±0.0% lipids. Its amino acid profile was characterized by high levels (g/100g protein) of leucine (6.28±0.80), phenylalanine (4.10±0.50), and isoleucine (3.20±0.41), all associated with muscle protein synthesis. Despite the lower lipid content, unsaturated fatty acids remained predominant.

In conclusion, LF and LPI provide high-quality proteins enriched in essential and branched-chain amino acids, together with fiber, unsaturated fatty acids, and key minerals. These attributes align with current evidence supporting amino acids as ergogenic aids, positioning lupin as a sustainable source for developing plant-based supplements aimed at enhancing performance and recovery.