Protein extraction from Buckwheat, Chondrus crispus, and Spelt and assessment of nutritional benefits and limitations in vitro

Consumption of plant-based proteins is increasing globally but challenges exist concerning their use as dietary proteins and ability to provide sufficient amino acids to consumers. Challenges include the anti-nutritional factors including indigestible fibre and trypsin-inhibiting polyphenols, major components of the plant cell wall, found in plant protein extracts. Extraction methods that can separate protein from anti-nutritional factors have potential to increase the nutritional value of plant protein biomass. Few studies concerning analysis of the amino acid content of plant protein extracts and how different extraction processes may improve the potential of plant proteins to satisfy dietary requirements for essential amino acids exists. In this work, three different protein extraction methods were used to generate protein extracts from the pseudo-cereal Buckwheat and cereal Spelt and the red seaweed Chondrus crispus . The methods used included ultra-sonication in water combined with ammonium sulphate-induced protein precipitation; an enzymatic extraction method using the enzymes Alcalase and Viscozyme, and an iso-electric precipitation extraction method using alkaline protein solubilization followed by acidic protein precipitation. Enzymatic extraction applied to C. crispus resulted in a protein extract yield of 50.8 ± 3.6%. Enzymatic extraction applied to Buckwheat resulted in a protein extract yield of 24.8 ± 0.4% and gave a protein extract yield of 20.8 ± 0.5% when applied to Spelt. Proteins extracted using the enzymatic method had the highest proportion of essential amino acids (EAA) in the total amino acids (Buckwheat: 44.0% ±0.1, C. crispus : 41.1% ±0.2 and Spelt: 37.5% ±0.9). The enzymatic protein extraction method applied to Buckwheat and C. crispus biomass generated proteins rich in EAA and in viable quantities, and the method holds promise for use in the generation of alternative marine and cereal protein extracts for human consumption.