Structures and interactions of bamboo shoot protein-shellac complexes prepared by pH-driven method

A previous study showed that the by-product of square bamboo shoot processing was rich in protein and contained many essential amino acids good for health. Bamboo shoot protein (BSP) had great potential as a naturally occurring functional protein. However, the utilization of single plant protein is limited due to its unstable degradation and reduced bio-activity in the gastrointestinal tract. Improving the stability and functional properties of BSP by complexion with other natural polymers is a potential strategy. And shellac (SHL), as a natural polymer, has good pH responsiveness and thermal stability. In this study, bamboo shoot protein-shellac (BS) complexes of different mass ratios were prepared by pH-driven method, which showed that the covalent and non-covalent interactions between the two reduced the particle size. At the ratio of 2:1 (BS-2:1), the complex generated had the smallest size of 193.97 nm, PDI of <0.20, and ζ-potential of -27.99 mV, its solution had higher stability and higher thermal tolerance. FTIR and fluorescence intensity further demonstrated that the pH-driven method resulted in structural changes of BSP and SHL, promoted inter-molecular interactions (mainly hydrophobic interactions, electrostatic interactions, and hydrogen bonding), modified the instability of BSP, and generated BS complexes with excellent physical, chemical, and functional properties. This study gives us a better understanding of BS complexes and lays the foundation for the loading of active compounds.