Nitrogen extractability and functional properties of defatted Erythrina variegata flour

• Published in: Food chemistry Vol. 96; no. 2; pp. 242 - 247
• Main Authors: Jyothirmayi, T., Prabhakara Rao, P.G., Walde, S.G.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.05.2006; Elsevier
• Subjects: absorption; Biological and medical sciences; Buffer capacity; buffering capacity; chemical precipitation; crude protein; defatted foods; Erythrina variegata; extraction; flour; Foam stability; Foaming capacity; Food industries; food processing; food quality; functional properties; Fundamental and applied biological sciences. Psychology; hexane; hulling; Indian coral tree flour; liquids; nitrogen; Nitrogen extractability; oilmeals; protein content; Protein precipitability; sodium chloride; solids; water; Nitrogen extractability; Erythrina variegata; Foam stability; Protein precipitability; Buffer capacity; Foaming capacity; Stability; Foaming; Flour; Nitrogen; Properties; Protein; Foam; Quality
• ISSN: 0308-8146; 1873-7072
• DOI: 10.1016/j.foodchem.2005.02.023

Defatted Erythrina variegata flour was prepared from dehusked seed meal by hexane extraction of residual oil. The resulting flour had 403 g kg −1 of protein as compared to 282 g kg −1 in the whole seed-defatted meal. Nitrogen extractability of the defatted flour in water was not much influenced by the length of extraction period above 40 min, but an increased extraction was observed at a higher liquid to solid ratio up to a studied limit of 1:60; the optimal ratio was found to be 1:30. The minimum of 26.9% nitrogen was extracted in the pH range 3.0–4.0 and maximum of 94.8% at pH 12. Addition of sodium chloride (0.1 or 0.5 M) broadened the pH range of minimum nitrogen extractability and shifted it toward a lower pH region. At both concentrations of sodium chloride, a marked increase in nitrogen extractability, in the pH range 3.0–7.0, was observed. Precipitation of protein from an extract of pH 10.0 was maximum (85.3%) at pH 4.75. A higher buffer capacity of the flour was observed in the acidic medium (0.195 mmol HCl g −1 flour) than in alkaline medium (0.093 mmol NaOH g −1). Water absorption and oil absorption values for the whole E. variegata seed flour and the dehusked, defatted flour were 1.81, 1.43 and 1.02, 1.52 kg kg −1, respectively.