Chemical composition and some functional properties of soluble fibro-protein extracts from Tunisian date palm seeds

Abstract

This study is a contribution to give value addition to date palm seeds by extracting an enriched fibro-protein fraction (DSFPE) and to examine the effect of pH on some of its functional properties. For this purpose, DSFPE was prepared from water soluble extracts of defatted Deglet Nour and Allig seeds and obtained by precipitation at pH 4.5. Then, DSFPE was examined for their proximate chemical composition. Significant differences were observed between Deglet Nour and Allig DSFPE: Carbohydrate was 64 against 58%, protein was 33 against 38%, and ash was 2 against 3%, respectively. Glutamic acid presented the largest amount, varying from 17.14% for Deglet-Nour DSFPE to 14.71% for the Allig DSFPE. The essential amino acids (lysine, leucine, threonine, methionine, valine, isoleucine and phenylalanine) were present in the DSFPE of the two studied varieties. Effect of pH on colour and some functional properties were analysed. Colour profiles of Deglet Nour and Allig water soluble extracts were affected by pH (2 to 10). Minimum protein solubility was obtained at pH 3.5 to 4.5 and the maximum at pH 10. Water holding capacity (WHC) and oil holding capacity (OHC) of Deglet Nour and Allig DSFPE were 3.50 to 4.50 g H2O g^-1 of DSFPE and 5.50 to 6.10 g oil g^-1 DSFPE respectively. Emulsion and foam proprieties were analysed at pH 7 and 10. DSFPE presented a slightly higher foam capacity (11 to 14 cm) and lower foam stability at pH 7 or 10. Emulsion capacity of DSFPE was significantly higher at pH 10 (2800 to 3000 ml oil g^-1 of protein) than those at pH 7 (2000 to 2400 ml of oil g^-1 of protein). Emulsion stability was improved with increase in pH from 7 to 10. These results suggested that the DSFPE have a good potential in food industry and can be used to improve the techno-functional quality for neutral and alkaline food applications with a high commercial value.

Keywords: Phoenix dactylifera L, date palm seed, fibre, protein, functional properties

African Journal of Biotechnology Vol. 12(10), pp. 1121-1131