Dry fractionation is an environmentally friendly and cost-effective method to separate protein fractions. While most research has focused on the structure and functional properties of pea protein isolates (PPI), the information on dry fractionated pea protein (DFPP) is limited. This study compared DFPP (protein content (PC)-50.7%, insoluble fiber-17%), to PPI (PC-80.1%, insoluble fiber-8.33%), in terms of the protein structure, solubility, and heat-induced gelation. SDS-Page, size-exclusive chromatographic, and Fourier-transform infrared spectrophotometer analysis indicated that DFPP contained the major protein components in pea, and their native structures were well maintained. Whereas for PPI, some proteins were lost during wet extraction, and partial protein unfolding and aggregation were observed. At neutral pH, DFPP showed significantly higher solubility (44.64±0.55%) than PPI (12.09±1.42%). Interestingly, DFPP showed good gelling capacity as reflected by lower gelling concentration and higher gel mechanical strength and elasticity compared to those made from PPI. The DFPP gels were twice higher in mechanical strength (7.71±0.21kPa) than that prepared from PPI at pH 7. Strong gels were also obtained for DFPP at pH 5. The gel morphology revealed phase separation between protein and polysaccharides by heating, with stick-shaped fiber (10-25μm) dispersed in the continuous protein networks. Eventually, the polysaccharides including fiber and starch helped strengthen the gel network by acting as fillers. This knowledge will help to expand the applications of DFPP as a gelling ingredient in food formulations, but also allow industry to benefit from the dietary fiber co-exist in the protein to develop healthier food products using a holistic approach.

There is growing interest in the design and fabrication of next-generation plant-based (NG-PB) foods that have physicochemical and functional properties that simulate those of traditional animal-based foods, like meat, seafood, egg, and dairy products. Many of these products can be considered as colloidal materials containing particles or polymers that determine their properties, which means that these properties can be understood using soft matter physics concepts. The rheological properties of NG-PB foods may vary widely, including low viscosity fluids (like milk), high viscosity fluids (creams), soft solids (like yogurt), and hard solids (like some cheeses). For manufacturers of NG-PB foods to mimic this broad range of products it is important to have theoretical models to identify, predict, and control the key parameters impacting their textural attributes. In this article, the theoretical models developed to describe the properties of fluid, semi-solid, and solid colloidal dispersions are described, and their potential for improving the design and fabrication of NG-PB foods is highlighted. In the future, it will be important to establish the most appropriate models for different categories of NG-PB foods and to determine their range of applications.

Oilseeds need to be exploited not only for the oil but also as a source of functional protein-rich ingredients for food. This work evaluated the physicochemical properties of the colloidal fraction resulting from wet milling of rapeseed, used as model oilseed. The extraction was conducted either at natural pH (5.7) or at alkaline pH (8.5), with or without addition of a commercial pectinase. The slurry was mixed for 4 h at room temperature, and then pressed at the same pH or after shifting to alkaline/acidic pH. The resulting extract, rich in oil and protein particles, showed differences in particle size, microstructure and composition. The oil and protein yields in the extract (in relation to the amount originally in the oilseed) ranged between 60 and 70 %, with a significant increase in protein recoveries with addition of pectinase, regardless of the pH. A protein concentrate, containing between 25 and 42 % protein on dry matter, depending on the treatment was obtained after centrifugation, together with a fiber precipitate and an oil fraction. The composition of the concentrates varied, with the highest purity found for extracts at pH 5.7, showing a nearly complete physical separation of the oleosomes by low speed centrifugation. All concentrates showed similar protein composition, as analyzed by gel electrophoresis. The amino acid composition was also similar amongst the treatments. This work evidences the critical role played by biopolymers’ interactions in forming different colloidal structures, with clear consequences on the functionality of the final ingredient.