Consumer awareness about the importance of diet on human health has always been increasing. Lipids are one of the essential food components of human diet and food products and a suitable source of energy and solvent for some important nutrients such as fat-soluble vitamins and bioactive compounds. Due to the high amount of saturated or trans fatty acids in solid lipids and its adverse effects on health, a new method called oleogel production to create a structure in liquid oils, which can be used as a substitute for solid fat without changing the chemical nature of the oil provides; Is taken into consideration. In this case, the liquid oil is trapped in the three-dimensional network of biopolymer and shows quasi-solid properties. The purpose of this study is to investigate the possibility of producing oleogel by foaming method using tragacanth and whey protein biopolymers and the effect of adding beeswax and glycerolmonostearate on its physicochemical properties. The present research was carried out in two parts; In the first part, solutions with different concentrations of tragacanth gum (0, 0.25 and 0.5%) and whey protein concentrate (1, 2 and 4%) were prepared and their physical properties were investigated. Next, the porous structure of the cryogel was formed by freeze drying and the physical properties of the cryogels were also eva‎luated in different concentrations of these two biopolymers. The results showed that the presence of tragacanth as a thickening agent significantly increased the viscosity of the solution and increased the stability of the foam, while it had no effect on the increase in the volume of the produced foam, and the increase in the volume of the foam was caused by the presence of whey protein concentrate. Also, the findings showed that increasing the concentration of biopolymers and the amount of dry matter increased the density of the cryogel network and decreased the percentage of moisture absorption. Investigating the oil absorption capacity of cryogels showed that the presence of tragacanth and the network density can be effective on the oil absorption of the samples, so that the samples containing 0.5% tragacanth and 2% whey protein showed the highest amount of oil absorption. In the second part, the sample containing 0.5% of tragacanth gum and 1% of whey protein concentrate with 1% of beeswax and 2% monoglyceride was selected as the best oleogel and for performing additional tests of microstructure, colorimetry, infrared spectroscopy, X-ray diffraction, rheology, percentage of oil entrapment, hardness , differential scanning calorimetry was investigated at different temperatures was investigated. The results of microstructure analysis, spectroscopy and X-ray diffraction showed that hydrogen and van der Waals bonds are effective in forming the semi-crystalline oleogel network. Also, the desired oleogel showed the ability to restore the structure and maintain the appropriate gel strength, and the oleogel network was able to reduce the oxidation rate of edible oil during 35 days of storage. Based on the obtained results, tragacanth oleogel and whey protein together with beeswax and glycerolmonostearate can be used as a suitable substitute for solid fat in food products.

مهدي كديور

مهدي كديور , عباس پاكدل