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ARS Home » Plains Area » Fargo, North Dakota » Edward T. Schafer Agricultural Research Center » Cereal Crops Research » Research » Publications at this Location » Publication #362465

Research Project: Enhancement of Hard Spring Wheat, Durum, and Oat Quality

Location: Cereal Crops Research

Title: Phase behavior and complex coacervation of concentrated pea protein isolate - beet pectin solution

item LAN, YANG - North Dakota State University
item Ohm, Jae-Bom
item CHEN, BINGCAN - North Dakota State University
item RAO, JIAJIA - North Dakota State University

Submitted to: Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/14/2019
Publication Date: 9/30/2019
Citation: Lan, Y., Ohm, J., Chen, B., Rao, J. 2019. Phase behavior and complex coacervation of concentrated pea protein isolate - beet pectin solution. Food Chemistry. 307:125536.

Interpretive Summary: When protein and polysaccharides are mixed in a solution they bind to form a complex. The characteristics of the protein-polysaccharide complex influences its application in products for the food and pharmaceutical industries. The optimum pH (acidic or basic nature) of a solution at which protein-polysaccharide complex formation occurs is a particularly important factor in controlling complex formation. We performed research to characterize the complex formed between pea protein isolate (PPI) and sugar beet pectin (SBP). We investigated the influence of pH and the ratio of PPI and SBP on the property of the PPI-SPB complex. We also determined the optimum pH value for the formation of the PPI and SBP complex. The information obtained from this research will contribute to the use of PPI–SBP complexes in food and pharmaceutical applications, especially for the encapsulation of food or pharmaceutical ingredients prior to packaging.

Technical Abstract: Turbidity and light scattering measurements are generally used to follow the coacervation in protein/polysaccharide colloid solutions at a low concentration. We propose the state of macromolecular assembly of complex coacervates formed between concentrated pea protein isolate (PPI) and sugar beet pectin (SBP) can be characterized by phase diagram in conjunction with zeta potential and viscoelastic measurements. The effects of pH (7–2) and PPI to SBP mixing ratios (1:1–20:1) on coacervates formation were investigated by phase diagram, zeta potential, rheological, and phase composition analysis. Isothermal titration calorimetry was employed to understand the thermodynamic behavior and non-covalent bonding of coacervates. Scanning electron microscopy together with Fourier transform infrared spectroscopy was used to elucidate the difference in microstructure of coacervates at characteristic pH values. We demonstrate that phase diagram can explicitly identify the three characteristic pH values (pHf1, pHopt, and pHf2) at which recognizable transitions take place in concentrated colloids solutions. The mixing ratio dependent of pHf1 increased to pH 5.5 as PPI–SBP mixing ratio increased to 20:1. The pHopt, a particular important factor in the application area for microencapsulation, was recognized at the net charge neutrality or the highest storage modulus of the mixed colloids solutions.