Structure, technofunctionality and bioactivities of cowpea proteins - a review

Cowpea is a major protein source for millions across Africa, Asia and the Americas. Its proteins consist primarily of globulins, albumins and glutelins, while prolamins constitute a minor fraction (1-3 %). β-Sheets constitute the most prominent secondary structures (35-65 %) in cowpea proteins, followed by loops, β-turns, α-helices and random coils (32-38 %, 15-38 %, 0-16 % and 1-14 %, respectively). Glutamic acid/glutamine, aspartic acid/asparagine, phenylalanine, tyrosine, leucine, arginine and lysine constitute the majority of amino acids. Albumins exhibit the most balanced essential amino acid composition, while glutelins are distinguished by their methionine and cysteine content, matching the levels recommended for human nutrition. In addition, cowpea proteins exhibit technofunctional properties (protein solubility, water and fat holding/absorption capacities, foaming properties, emulsifying activity, emulsion stability and gelation) and bioactivities (antioxidative, antimicrobial, cardioprotective, antidiabetic, antithrombotic and apoptotic activities), which make them promising ingredients for plant-based food formulations. Traditional and novel processing methods, such as thermal processing, germination, fermentation, high-pressure processing and sonication, affect the technofunctional properties of cowpea proteins variably depending on their intensity. However, different fractions of cowpea proteins need to be investigated for their structure and technofunctionality. Additionally, the effect of different processing methods on these characteristics should also be studied.