Complex Coacervation and Precipitation Between Soluble Pea Proteins and Apple Pectin

Complex formation (leading to either coacervation or precipitation) offers a tool to generate plant-based novel food structures and textures. This study investigated the formation of complexes between soluble pea proteins and apple pectin upon varying the protein-to-pectin ratio (r = 2:1 to 10:1), pH (3-7), and temperature (25 and 85 degrees C) with a total biopolymer concentration set to 1% (w/w). The results showed that predominantly soluble biopolymer complexes were formed at pH 5, and at low ratio (r = 2:1), whereas lowering the pH to more acidic condition, and to higher ratios (r = 4:1-10:1) induced the formation of more insoluble biopolymer complexes. In general, the mean particle sizes of the biopolymer complexes ranged between approximately 20 and 100 mu m. Upon heating to 85 degrees C, the amount of insoluble biopolymer complexes increased at pH 3-5 at all ratios, except at r = 2:1. In addition, the complex sizes became somewhat larger at r = 2:1 to 6:1 upon heat treatment, whereas only trivial size changes were observed at higher ratios (r = 8:1 to 10:1). Overall, electrostatic and hydrophobic interactions played a major role in the complex formation between the soluble pea proteins and apple pectin. These findings are important for designing solely plant-based food structures.

Automated summary

This study investigated the formation of complexes between soluble pea proteins and apple pectin. The results showed that predominantly soluble biopolymer complexes were formed at pH 5 and low ratio, while more insoluble complexes were formed at lower pH and higher ratios. The particle sizes of the complexes ranged between 20 and 100 μm. Heating increased the amount of insoluble complexes at acidic conditions, but had minimal effect on the size of complexes at higher ratios. Electrostatic and hydrophobic interactions played a major role in the complex formation.