Improvement of pea protein gelation at reduced temperature by atmospheric cold plasma and the gelling mechanism study

Pea protein as an alternative of soy protein has attracted growing interest in food industries. However, high temperature (> 95 ?C) is required to enable heat-induced gelation and the formed gels are relatively weak. This research aimed to study the efficacy of atmospheric cold plasma (ACP) as a novel non-thermal technique to improve the gelling properties of pea protein. While native pea protein concentrate (PPC) (12 wt%) could not form gel under 90 ?C, ACP-treated PPC showed good gelling properties when heated at 70?90 ?C. The gels exhibited homogeneous three-dimensional network structure with interconnected macropores, and those prepared at 80 and 90 ?C possessed good mechanical strength and viscoelasticity, as well as high water holding capacity. The gelling mechanism was studied by monitoring pea protein structural changes during ACP treatment and gel formation process via a transmission electron microscope, a Fourier transform infrared spectrometer, and a rheometer. These results revealed that ACP treatment contributed to the formation of protein fibrillar aggregates, and significantly reduced the PPC denaturation temperature, leading to protein unfolding at reduced temperature of 80?90 ?C. ACP treatment also increased the protein surface hydrophobicity and exposed free sulfhydryl groups, which could facilitate the formation of hydrophobic interactions and disulfide bonds, leading to gels with improved mechanical properties. Moreover, hydrogen bonding could play an important role to stabilize the gel network during the gelling process. Owing to the short exposure time and energy efficiency, ACP is a promising technology to enable wide applications to pea protein as a gelling ingredient of plant protein-based food products, such as meat analogues and egg alternatives.