Valorising legume protein extraction side-streams: Isolation and characterisation of fibre-rich and starch-rich co-products from wet fractionation of five legumes
Ruoxin Liu, Bernadine M. Flanagan, Vishal Ratanpaul, Michael J. Gidley
Abstract
The legume protein fractionation process focuses on producing protein concentrates or isolates but generates large amounts of protein-deficient co-products. Evaluating the potential use of co-products (mainly starch and fibre) from side-streams is important for the development of economically viable processes. Traditional wet fractionation was conducted to solubilise protein from five legumes (Desi chickpea, Kabuli chickpea, lupin, mung bean and faba bean). Non-solubilised materials, and their component large (fibre-rich) and small (starch-rich) fractions were recovered. The yield, composition, and functional properties (water holding capacity, oil holding capacity, swelling power and water solubility index) of the three fractions were investigated for all five legumes. The combination of fibre and starch in the non-solubilised material influenced starch gelatinisation and functional characteristics. The relationships between composition and functional properties varied between legumes, but general correlations were found between dietary fibre content and water-/oil-holding capacity, starch content and swelling power, and protein content and water solubility index. A combination of botanical origin and chemical composition determined the promising functional properties of separated starch-rich and fibre-rich co-products of wet protein extraction for the five legumes studied. • Legume protein fractionation results in large amounts of starch/fibre-rich co-products. • High purity starch and fibre co-products obtained from wet fractionation after sieving. • Different co-products have distinct water/oil absorption and swelling properties. • Both composition and botanical origin influence co-product functional properties.