Resumen de Extraction and Functional Characteristics of Brazil Nut (Bertholletia excelsa HBK) Globulin
Pushkar Singh Bora, C. M. Pinto Ramos
Proximate analysis of Brazil nut kernel showed 68.6 and 16.5% lipid and protein contents, respectively. The protein content in defatted kernel flour increased to about 46.7%. Extraction with 50 mM phosphate buffer containing 0.5 M NaCl (pH 7.2) solubilised about 81% proteins, out of which nearly 72% proteins (globulin) were recovered. Unextracted and soluble proteins accounted for 18.7 and 9.2% of total proteins, respectively. In relation to functional properties, the globulin showed pH of minimum solubility at 5.0. The globulin presented lower solubility (0.9-41.3%) in the pH range of 5.0-10.0 but above and below this pH range, there was a considerable improvement. The water and oil absorption capacities were 2.0 and 1.4 g/g globulin. The apparent viscosity of 1-3% globulin solutions at room temperature (29 °C) before and after heating at 90 °C for 15 min differed significantly. However, no significant difference was observed between apparent viscosity of unheated and heated globulin samples irrespective of their concentration. Emulsifying capacity varied with the pH, being maximum at pH 3.0 (94.5 mL/100 mg of globulin) and minimum (38.5 mL/100 mg globulin) at its isoelectric pH (5.0). Emulsion activity and stability also followed similar behaviour as that of emulsifying capacity. (A)
