Oilseeds beyond oil: Press cakes and meals supplying global protein requirements

Abstract Background The world's demand for animal protein is expected to double by 2050. The environmental and health concerns about its production and consumption have thus promoted the evaluation of alternative sources. Oilseed press cakes and meals represent a promising alternative, due to high levels of production globally, and because they are naturally rich in high quality protein. Scope and approach This review will provide information on the suitability of obtaining protein from the main oilseeds (soya, rapeseed/canola and sunflower). Topics covered will be chemical, protein and amino acid composition; patented and published protein extraction protocols, and the issue of antinutrients and protein digestibility. Key findings and conclusions On average, crude protein percentages are soybean (32–43.6% DW) > rapeseed/canola (25–30% DW) > sunflower (10–27% DW). Soy and rape have well balanced amino acid composition, while sunflower is deficient in lysine. Rape contains high levels of antinutrients, also present in soybean. Aqueous extraction remains the protein-enrichment technique of choice in commercial processes, although the use of salt instead of acid or alkali has been a major improvement regarding the protein quality and environmental hazards. Nevertheless, the use of physical methodologies appears as a “green” and affordable option, adequate as well to preserve proteins quality. Despite its outstanding functional and nutritional properties, soy protein allergenicity remains the main barrier for consumption, and also for rape. Sunflower protein low allergenicity and absence of antinutrients forecasts increased use.