Synthesis of Nano-Scale Biopolymer Particles from Legume Protein Isolates and Carrageenan

Food proteins and polysaccharides can be used for the synthesis of nano-scale biopolymer particles with potential applications in the fields of food and pharmaceuticals. This study focuses on utilizing legume proteins for the production of biopolymer particles via regulation of their electrostatic interactions with carrageenan.

Protein isolates were obtained from mung bean (Vigna radiata), cowpea (Vigna unguiculata) and black gram (Vigna mungo) and their protein profiles were determined. Next, these isolates were allowed to interact with carrageenan at pH=5.0-7.0 to determine optimum conditions for obtaining nano-scale biopolymer particles. Selected biopolymer mixtures were then subjected to a heat treatment (85 °C for 20 min) to enhance the interactions among biopolymers.

Nano-scale biopolymer complexes were obtained at pH=6.5. They were roughly spherical in shape with a majority having a diameter in the range of approx. 100-150 nm. Heating of the biopolymer mixtures increased the diameter of the biopolymer particles by approx. 2.5-fold. In addition, their negative surface charge was increased, stabilizing them against aggregation over a broader pH range (4.0-7.0), enhancing their potential to be utilized in food matrices.

This study reports the applicability of mung bean, cowpea and black gram proteins for the synthesis of stable biopolymer particles. These biopolymer particles can be potentially used for the encapsulation and delivery of bioactive components.