Microwave-assisted bleaching of vegetable oils

In this thesis, sunflower oil and olive pomace oil were bleached by using microwave technique which is a novel bleaching method. In the first part of the thesis, the effect of bleaching parameters on the bleaching quality was investigated. Response surface methodology was employed to optimize the effect of microwave power, bleaching time and amount of clay for both oils. Optimum conditions obtained for microwave-assisted bleaching were 80-102 W, 8-20.07 min and 0.4-4.15% of clay for sunflower oil and pomace oil, respectively. Physical and chemical properties of both oil type investigated were sterol composition, acid value, oxidation parameters (PV, AV, Totox, K232 and K270), color parameters (chroma and hue angle values), chlorophyll, carotenoid- tocopherol content and harmful components such as PAHs. In the second part of the thesis, the quality of microwave assisted bleached oils was compared with industrially bleached oils obtained from same batch. In the third part of the thesis, the repetitive use of bleaching clay was examined at the end of the microwave assisted bleaching of sunflower oil, which is important because it reduces the production cost of oil and environmental pollution. According to the findings, microwave bleaching was found advantageous with a 50%-17% and 73%-83% reduction in the amount of clay usage and bleaching time for sunflower oil and olive pomace oil, respectively. The results of this thesis indicated that, promising bleaching quality was obtained by microwave assisted method when compared to the industrial method. So, it has been concluded that microwave bleaching could be an alternative and advantageous method for the bleaching of vegetable oils.