Mayonnaises are semi-solid full-fat emulsion systems, comprised of plant-based oils as the main component (70-80%). Recently, with the ever-growing increase of the consumers’ awareness regarding the adverse effects of fat on human health, the development of low-fat or fat-free formulations has faced with a growing trend. In this line, the current study aims to produce emulsion gels based on plant-based hydrocolloids as a novel strategy in the development of low-fat mayonnaise-like products. These emulgels contain a dense network in the continuous phase, which includes oil droplets (dispersed phase). In the present study, the combination of soy protein isolate (SPI) and quince seed gum (QSG) was used to produce emulsion gels, and its application in preparation of plant-based mayonnaise (egg yolk-free) with reduced fat was eva‎luated. The structure of emulsion gels based on SPI-QSG was eva‎luated using various assessments such as appearance analysis, microscopic examination, apparent viscosity, color analysis, back extrusion assay, rheological investigations, stability analysis, and sensory eva‎luation. For the microscopic and appearance analysis of the emulsion gels, it was found that in the absence of gum in the formulation, SPI was not capable to produce emulsion gels of the desired structure. Moreover, the microstructure of the gel was completely disintegrated for the sample with pH 4.5, which was in the range of the isoelectric point of the protein. The results showed that the addition of different levels of QSG at all pH ranges could make the emulsion droplets finer and uniformly dispersed. The incorporation of the QSG at pHs 3, 4.5, and 6 led to the reduction of particle size from 8.84 ± 2.65 to 6.31 ± 1.64, 58.97 ± 2.93 to 8.11 ± 1.97, and 45.59 ± 1.7 to 9.81 ± 3.22 μm, respectively. The stackability investigations showed that increase in the QSG concentration significantly preserve the layer structures of the the stacked emulgels. The apparent viscosity investigations showed that all the produced emulgels had a shear thinning behavior, and increasing the gum concentration for all pH levels significantly increased the apparent viscosity of the samples (p < 0.05). The colorimetric analysis of the emulsion gels also displayed that the pH reduction and the gum addition caused a relative darkening of the samples. Also, it was found that for all emulgels (regardless of the pH value), increasing the amount of gum concentration from 0 to 0.9% increased the stiffness (Fmax), texture consistency (Etot), storage modulus (G′), loss modulus (G″), and stability of the emulsion gels. It is worth mentioning that G′ > G″ indicated the elastic-likd behavior of the samples. However, in non-QSG containing samples, especially the sample with pH 4.5, the increase of the frequency induced the phase transion of the emulgels. In this conditions, the adition of different gum concentrations led to the enhancement of the emulgel stability and no phase transition of the samples. The loss angle determination indicated that in absence of the gum, the increase of the system frequency resulted isn considerable reduction of stability of the semi-gel structre. The least variations in loss angle was observed for the sample with the highest gum concentration. The samples containing 0.6% gum with pH 3 and 4.5 had the highest similarity to the full-fat mayonnaise sample.

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هاجر شكرچي زاده

اميرحسين گلي , مهدي قريشي