Electrophoretic and Functional Mapping of Indica Rice Glutelin Protein Isolates

Rice glutelin protein isolates were extracted from export quality Pakistani rice varieties and their milling fractions, characterized by dry matter yield, protein content, molecular weight profile using sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and also explored the functional properties. The glutelin protein content and its dry matter yield varied significantly among rice varieties and their milling fractions. The highest dry matter yield and protein content was found in brown rice of Basmati 2000 rice variety and the lowest dry matter yield and protein content was observed in white rice of KS-282. The electrophoretic pattern showed 11 different molecular weight subunits with three major polypeptides observed at 32.1 to 34.0, 23.9 to 24.5, and 12.1 to 16.1 kDa, respectively. The overall electrophoretic profile and alpha glutelin subunits in different rice samples ranged from 12.1 to 100.9 and 32.1 to 34.0 kDa, respectively, while beta glutelin subunits ranged from 23.9 to 24.5 kDa. The variation in rice milling fractions did not show any effect on the molecular weight subunit composition of glutelin within a variety. Little is known about its functional properties, which have been shown to be variety specific. Thus, it is of importance to examine glutelin isolates from Pakistani rice varieties. The functional properties of glutelin isolates showed a non-significant effect on foaming capacity and stability within varieties, and overall it had poor foaming properties but it had good gelling properties, which may be a very promising characteristic for its use in different food applications.