Comparative evaluation of functional properties of protein isolates from Malaysian rice varieties MRQ 76, Bario Merah Ranau and Long Pasia

Abstract

In Malaysia, a wide diversity of rice varieties is cultivated across distinct agro-ecological zones, but their protein fractions remain functionally underexplored. This comparative study evaluated the functional properties of protein isolates extracted from three Malaysian rice varieties: MRQ 76, Bario Merah Ranau, and Long Pasia. The MRQ 76 variety was obtained from the Malaysian Agricultural Research and Development Institute, while the Bario Merah Ranau and Long Pasia varieties were supplied by Mutiara Timur Rice Mill Sdn. Bhd. Protein extraction was performed using alkaline solubilization–isoelectric precipitation, and the functional properties of the protein isolates were assessed across a range of pH values. The results showed that the MRQ 76 variety exhibited the highest protein content (8.14 ± 0.03%), oil-binding capacity (239.40 ± 4.25%), and foaming stability (88.64 ± 2.75%), while the Long Pasia variety showed superior water-binding capacity (266.0 ± 5.35%) and foaming capacity (77.78 ± 3.85%). However, the protein solubility (pH 5 and 9) and emulsifying capacity (pH 4 and 7) tests showed no significant differences among the three rice varieties. The findings demonstrate variations in the influence of rice varieties on protein functionality, highlighting the MRQ 76 variety as a promising candidate for moisture-retentive food systems, while the Long Pasia variety is suitable for sparkling applications. These findings offer new insights into improving protein isolates and supporting innovation in health-oriented food products.