Quantifications of Oleocolloid Matrices Made of Whey Protein and Oleogels

Abstract

Consumer demand for high protein content and plant-based fat has necessitated novel approaches to healthy food products. In response to this need, oleogels (OG) (structured liquid oils) emerged as a possible means of not only replacing saturated and trans fats but also delivering food protein. Nevertheless, an in-depth view of the structure of networks made of OG and protein is deficient. Hence, the objective of this study is developing oleocolloid (OC) (whey protein and rice bran wax OG) and hydro-oleocolloid (HOC) (OC + water) matrices with varying protein content (2.5–7.5%) to characterize their structural properties. Thermal analysis of the matrices via differential scanning calorimetry (DSC) documented the effects of hydrophobic interactions on the protein structure and its stability. Whey protein denaturation temperature increased from 74.9 °C to 102.8 °C in the presence of high oleic soybean oil. The effects of vegetable oil on WPI structure was also verified by FTIR spectroscopy. Data analysis revealed slight structural changes of the WPI secondary structure in the hydrophobic oil medium and the α-helix and β-sheet proportion in the emulsion medium was significantly altered. Similar analysis was performed in OC and HOC networks to quantify possible interactions between protein and rice bran wax. Results indicated that the protein was denatured during the thermal and mechanical conditions required for the oleogelation process, while it did not affect the systems’ solid fat content (SFC) and polymorphic patterns of the oleogels. However, DSC analysis showed different onset of melting for OC and HOC samples due to colloidal interactions between the protein and the lipid phase. The role of these chemistry was confirmed by microscopy analyses where OC and HOC matrices displayed notably different microstructural properties. The observed differences in the structural properties between OC and HOC matrices indicate the different colloidal interactions mediated by oleogelation process and the liquid medium type (oil vs. emulsion).

Influence of Carboxymethyl Cellulose on the Stability, Rheological Property, and in-vitro Digestion of Soy Protein Isolate (SPI)-Stabilized Rice Bran Oil Emulsion

“…SPI-RBO emulsion without CMC still contained relatively large droplets than that with 0.5 wt% CMC, which indicated that RBO emulsion with 0.5 wt% CMC had undergone more thorough degradation. The reason might be that the addition of CMC, especially hydrophilic groups, such as hydroxyl and carboxyl, accelerated the adsorption rate of lipase, thus making fatty acids easier to be released ( 46 – 48 ).…”

Food-Grade Oleogels: Trends in Analysis, Characterization, and Applicability

“…In general, for all of the considered systems presented in Table 1, the structure of the formed crystals is considerably influenced by the type of oleogelator and its purity, the used oil, and the conditions for the preparation of the oleogel, such as temperature and/or cooling rate, the presence of other additives, and shear application [8]. The obtained microstructure is characteristic of the unfolding behavior of the globular proteins during the gelation process [190] Whey protein High-oleic soybean oil Polarized light microscopy Protein aggregates were observed in the microstructure Formation of whey protein aggregates is dependent on the concentration of the protein [191] White and yellow beeswax Candelilla wax Sunflower wax Monoacylglycerols…”

Application of Analytical Methods for the Comprehensive Analysis of Oleogels—A Review

“…One major drawback of FTIR is the overlapping of peaks and the mixed signals due to the complex chemical composition and similar constituents. The functional groups contained in the rice bran wax were reported to overlap with those of the protein structures, and thus it would be hard to examine protein-based foods containing wax oleogels [58]. Bioactive compounds such as carotenoid might also be hard to examine by FTIR means, since OH functional groups such as the waxes from the composition of the oleogel or oxidation by-products form peaks in the same regions.…”