CHEMICAL, TECHNO-FUNCTIONAL, AND ANTIOXIDANT PROPERTIES OF TIGERNUT (CYPERUS ESCULENTUS L.) RESIDUE FLOURS

Tigernut processing generates nutritionally-rich residue, mostly discarded as waste. This research reports for the first time the amino acid profile, phenolic profile, and pasting properties of tigernut residues. Yellow and brown tigernut residues were analysed for amino acid and phenolic profile, antioxidant, techno-functional and pasting properties. The total essential amino acids were 49 and 56% for yellow and brown tigernut residue flours, respectively. The flavonoid content and ferric reducing antioxidant property were 0.91 and 0.32 mg GAE/ g, and 3.43 and 1.41 AAE/ g for yellow and brown residue, respectively. Caffeic acid (29 – 56 mg/ 100 g), ferulic acid (39 mg/ 100 g), vanillic acid (38 mg/ 100 g), Quercetin (48 mg/ 100 g), and phenyl acetic acid (3 – 68 mg/ 100 g) occur in abundance in the residue flours. The oil absorption capacity (3.40 ml/ g), L* value (63.78), and b* value (15.61) were higher in yellow than in brown residue. Brown tigernut residue flour cooked faster (5.77 min) than yellow tigernut residue flour (6.97 min). Some essential amino acids detected were lysine, leucine, and methionine. The reports obtained in this work showed that tigernut residues have the potential to be incorporated in food due to their richness in essential amino acids, phenolic compounds, and antioxidant activity