The structure and physical state of fats are from the most important characteristics to determine the use of them in foods. Most of fats and oils have restricted application in their natural form and so it is better to modify them. Hydrogenation is a common method to improve functional characteristics of vegetable oils. However studies have showed that in this process, 10%-40% trans fatty acid would be produced. So researchers are trying to find new methods to produce solid fats without changing in fatty acid situation and making isomers. In recent years, replacing saturated fat with organogel has been examined and had idealistic results. In this study, the effect of waves on crystallization behavior and physicochemical characteristics of olive oil oleogel prepared by propolis has been studied. In the first part the effect of the parameters such as ultrasonic power, cooling time and irradiation time on hardness also oil migration of oleogel was studied using response surface methodology (RSM). Power 300(W), cooling time 5(°C) and irradiation time 120(S) were achieved as the optimum condition. In the second part the fatty acid composition, crystal structure, thermal behavior, texture, oil migration, color, acid value and peroxide value of HIU sample were compared with the control sample. The results showed that HIU has no effect on fatty acid composition and crystal structure of the oleogel. Both HIU and control samples had crystals of ?' form. Applying HIU increased the numbers of crystals while decreased their size and the oil migration changed from 5.83% to 4.25 %. Applying HIU increased the hardness of the oleogel significantly (p 0.05). This increasing in hardness and decreasing oil migration resulted from small crystals applied by HIU. HIU didn’t change acid value whereas increased peroxide value from 3.70 ( meqO 2 /kg) to 4.75(meqO 2 /kg). The results showed that using HIU can be appropriate to improve crystallization behavior and physicochemical characteristics of olive oil oleogel. Key words : Oleogel, Ultrasonic, Physicochemical Characteristics, Olive Oil
