Physicochemical and Functional Properties of Membrane-Fractionated Heat-Induced Pea Protein Aggregates

Abstract

This study was carried out to investigate the effect of heat pre-treatment of pea proteins at different pH values on the formation of functional protein aggregates. A 10% (w/v) aqueous mixture of pea protein concentrate (PPC) was adjusted to pH 3.0, 5.0, 7.0, or 9.0 followed by heating at 100°C for 30 min, cooled and centrifuged. The supernatant was sequentially passed through 30 and 50 kDa molecular weight cut-off membranes to collect the <30, 30–50, and >50 kDa fractions. The >50 kDa fractions from pH 3.0 (FT3), 5.0 (FT5), 7.0 (FT7), and 9.0 (FT9) treatments had >60% protein content in contrast to the ≤20% for the <30 and 30–50 kDa fractions. Therefore, the >50 kDa fractions were collected and then compared to the untreated PPC for some physicochemical and functional properties. Protein aggregation was confirmed as the denaturation temperature for FT3 (124.30°C), FT5 (190.66oC), FT7 (206.33oC) and FT9 (203.17oC) was significantly (p < 0.05) greater than that of PPC (74.45oC). Scanning electron microscopy showed that FT5 had a compact structure like PPC while FT3, FT7, and FT9 contained a more continuous network. In comparison to PPC, the >50 kDa fractions showed improved solubility (>60%), oil holding capacity (~100%), protein content (~7%), foam capacity (>10%), foam stability (>7%), water holding capacity (>16%) and surface hydrophobicity (~50%). Least gelation concentration of PPC (18%), FT3 (25%), FT5 (22%), FT7 (22%), and FT9 (25%) was improved to 16, 18, 20, 16, and 18%, respectively, after addition of NaCl.

Effect of Heat Treatment on Yellow Field Pea (Pisum sativum) Protein Concentrate Coupled with Membrane Ultrafiltration on Emulsification Properties of the Isolated >50 kDa Proteins

“…On the other hand, during the emulsification process, optimal unfolding of the >50 kDa proteins was achieved at the respective pH of the heat pretreatment, which will be further discussed in the following sections. The scanning electron microscope images (SEM) of the samples, as reported in our previous work [17], showed an amorphous floating mass and signs of networking and interaction within the structure of FT3, FT7, and FT9, while FT5 had a more discrete structure with lesser signs of interaction. Also, the droplets and aggregates at pH 7.0 and 9.0 were uniformly distributed, which could be a result of more efficient adsorption of the protein at the interfacial layer [35].…”

“…The protein aggregates and fractions were prepared as described by Asen and Aluko [ 17 ], and as shown in Figure 1 . Mixtures of 10% ( w / v ) dispersion of the PPC (68.6% protein content) were prepared in distilled water, adjusted to pH 3.0, 5.0, 7.0, or 9.0, sealed, and heated in a water bath at 100 °C for 30 min.…”

“…The hidden reactive groups (sulfhydryl and hydrophobic side chains) in an unfolded protein are exposed and their functionality is enhanced after heating [ 11 ]. The literature is replete with studies that have been carried out on emulsion and interfacial properties of food protein emulsifiers, such as modified soybean [ 6 ], milk [ 15 ], and pea protein at the O/W interfacial layer [ 16 ], as well as the effect of heat treatment on the functional properties of pea protein at different pH values [ 5 , 17 ]. Similarly, membrane ultrafiltration has been used to extract, fractionate, and concentrate protein solutions to produce ingredients with superior emulsification properties and protein contents [ 18 , 19 ].…”

“…Soluble aggregates are formed when proteins are heated at higher temperatures and for longer periods (e.g., at 80–100 °C for 15–30 min) to break non-covalent and/or disulfide linkages within neonatal agglomerates [ 22 ]. Ultrafiltration is a non-thermal process driven by pressure and membrane-based protein fractionation, concentration, desalting, and clarification to preserve the functionalities of isolated proteins [ 17 ]. Membrane ultrafiltration/diafiltration is the use of semi-permeable membranes to separate species in aqueous solutions, based on size, charge, or shape, through a high pressure and convection system [ 18 , 19 , 23 ].…”

Properties of Mayonnaise Enriched With Protein

“…Показано, що у емульгуванні беруть участь молекули білка та присутні більші за розміром частинки білка, які також впливають на стабільність емульсії. Визначено поверхневий заряд та розмір білкової молекули, які емульгують розбавлену емульсію (Sridharan, 2020;Asen, 2022).…”