Structural evolution during gelation of pea and whey proteins envisaged by time-resolved ultra-small-angle x-ray scattering (USAXS)

Journal Article · 22 December 2021 · Food Hydrocolloids

DOI: https://doi.org/10.1016/j.foodhyd.2021.107449 · OSTI ID:1840979

Chen, Da  ^[1]; Kuzmenko, Ivan ^[2]; Ilavsky, Jan  ^[3]; Pinho, Lorena ^[4]; Campanella, Osvaldo  ^[1]

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1. The Ohio State Univ., Columbus, OH (United States)
2. Argonne National Lab. (ANL), Argonne, IL (United States)
3. Univ. of Sao Paulo (Brazil)
4. The Ohio State Univ., Columbus, OH (United States); Univ. of Sao Paulo (Brazil)

Hydrogels from plant proteins commonly exhibit inferior gel strength compared to those from dairy proteins partially due to their distinct gel networks. How protein aggregates to form such networks in response to heat remains largely unknown. In this work, pea (PPI) and whey (WPI) protein isolate gels were produced at the same protein content and similar heating/cooling rate. The process was monitored using rheology, microscopy and in situ ultra-small-angle x-ray scattering (USAXS). Rheology showed an initial decrease in G' and G'' in PPI followed by a steady increase when the temperature surpassed ~60 °C whereas a much higher temperature (~80 °C) was required for WPI, both using 2 °C/min heating rate. Microscopy showed a coarse and heterogenous network in PPI, whereas for WPI, the network was finer and more continuous. In both gels, nano-sized spherical or ellipsoidal particles were present as the basic constituents. USAXS found individual protein was dominant in PPI or WPI solution at temperature below 57 °C. Their proportions decreased together with appearance of aggregates with an average R_g of 9–10 nm in PPI and 6–7 nm in WPI at higher temperature. The size of the aggregates changed slightly during further heating and cooling, but their proportions increased. Power law exponents revealed the aggregates were mass fractals for WPI and PPI gels, and they became more compact during heating. Our findings suggested formation of primary aggregates in protein gel networks is a more organized process and provided theoretical guidance for production of high protein food gels with desirable texture.

• Research Organization: Argonne National Laboratory (ANL), Argonne, IL (United States)
• Sponsoring Organization: National Institutes of Health (NIH); USDOE; USDOE Office of Science (SC)
• Grant/Contract Number: AC02-06CH11357
• OSTI ID: 1840979
• Journal Information: Food Hydrocolloids, Journal Name: Food Hydrocolloids Vol. 126; ISSN 0268-005X
• Publisher: ElsevierCopyright Statement
• Country of Publication: United States
• Language: English