Recently, researchers from plant chemical constituents and omics research innovation team at Institute of Food Science and Technology, Chinese Academy of Agricultural Sciences, established a pH-driven co-assembly system of rice glutelin and dipotassium glycyrrhizinate, systematically elucidated the molecular mechanisms by which this natural food-medicine dual-use small molecule regulates the solubility and aggregation behavior of plant proteins. The findings were published in Food Hydrocolloids (JCR Q1, IF: 12.4). Li Ning, a PhD student, and Dr. Wang Fengzhang are the co-first authors, Prof. Tong Litao is the corresponding author.

The poor solubility of rice protein constitutes a primary constraint on its deep processing and high-value applications. While conventional modification methods such as physical, enzymatic, or chemical approaches can enhance solubility to a certain extent, they still face challenges including high energy consumption, unstable modifications or compromised protein functionality. Therefore, establishing a green, safe, controllable and efficient strategy for regulating the solubility of plant proteins has become a significant scientific challenge in the functionalisation of cereal proteins.

This study focuses on glutelin, the major poorly soluble component of rice protein, and develops a modification strategy termed “pH cycling–protein unfolding–small-molecule-assisted co-assembly” using dipotassium glycyrrhizinate, a medicinal and edible homologous compound. This strategy significantly enhances the solubility of rice protein. By combining experimental analyses with molecular dynamics simulations, the regulatory mechanism by which dipotassium glycyrrhizinate modulates the structure and aggregation behavior of rice glutelin is systematically elucidated.

The results show that under alkaline conditions, rice glutelin undergoes structural unfolding, exposing hydrophobic regions and positively charged sites, thereby providing favorable conditions for the co-assembly of dipotassium glycyrrhizinate with the protein. Dipotassium glycyrrhizinate forms stable complexes with rice glutelin through hydrophobic interactions, electrostatic attraction, and hydrogen-bond networks, and exerts a pronounced steric hindrance effect during the protein refolding process, effectively inhibiting protein self-aggregation and fundamentally improving protein solubility. Meanwhile, the particle size of rice glutelin is significantly reduced from the micrometer scale to the nanometer scale.

Overall, this study not only markedly improves the processing properties of rice protein but also provides an important theoretical basis for promoting the high-value utilization of poorly soluble plant proteins in the food industry.

This work was supported by the National Key Research and Development Program of China and the Key Task of the Central Plains Research Centre, Chinese Academy of Agricultural Sciences.

Original article link: https://doi.org/10.1016/j.foodhyd.2025.112335