Characterization of the high moisture extrusion of pea protein isolate from various sources

Protein-rich food has been the ever increasing demand with the growth of the world population. Animal meat protein that is provided by the traditional breeding industry will be difficult to meet human needs. Alternatively, plant protein can be expected to serve as the demand for protein, due to the higher yield and wider resources. Therefore, the plant-based meat products can be used to partially replace animal meat with plant protein using modern processing technology. It is of great significance in sustainable development, low carbon emission reduction, and nutritional demand. Among them, peas are widely used in the food industry, because of their high yield, high nutritional value, and low cost. The pea protein can be taken as the raw material in plant-based meat products using high water extrusion technology (moisture content of 40%-80%). The products are also closer to the texture quality of animal meat. However, pea protein isolate (PPI) from various sources varied greatly, in terms of both quality and functional characteristics. It is unclear on the high moisture extrusion qualities, which made it difficult to produce the pea protein in the plant-based meat substitutes. In this study, five commercial PPIs were selected to evaluate the variations, in terms of component content, particle size, solubility, gelation, and high moisture extrusion properties at 2 different cooling temperatures (65°C, and 90°C). The findings revealed that the quality and functional properties of PPI, as well as the cooling temperature, were connected to the quality of the extrudates. The PPI with high solubility (21.24%-25.51%) and strong gelation (0.84-1.14 N) was more advantageous to the fiber structure development (fibrous degree>1.5). At the lower cooling temperature, the solubility and extrudates' hardness, and chewiness were a very significant positive correlation (P<0.01), and the fibrous degree was significantly positively (P<0.05) related to the solubility, indicating that the higher solubility of protein raw material had improved the hardness, chewiness, product, and fibrous degree. At high cooling temperatures, the solubility of the springiness of the extrudate was very significant positive correlated (P<0.01), the fibrous degree was a significant positive correlation (P<0.05), the gel strength and the rigidity of the extrudate were significantly negative correlation (P<0.05), very significant positive correlation (P<0.01) on the organization, indicating the solubility and gel strength influencing the extrusion quality. Besides, the moisture, protein, fat, and ash content were not correlated with the extrudates' fibrous degree at a lower temperature, while the high temperature after the extrudates' fibrous degree was a very significant positive correlation with the moisture and protein (P<0.01), correlated with the fat (P<0.05), and the ash content was a significantly negative correlation (P<0.05). Consequently, there was a significant correlation between the content of water, protein, fat, and ash, as well as the quality of extruded materials. as the cooling temperature changed. In addition, 90℃ cooling temperature was more conducive to the increase of new covalent bonds, promoting protein aggregation. The surface hydrophobicity analysis showed that the extrusion process resulted in the increase of hydrophobic groups, and then promoted protein aggregation. The secondary structure showed that the increasing cooling temperature increased the proportion of the β-folding structure and the formation of the fiber structure. This finding can provide the theoretical basis for the selection of raw materials at the cooling and forming temperature for plant-based meat products that are prepared by high moisture extrusion technology. A strong reference can be offered for the product development and quality improvement of new plant-based meat products.