Optimization of edible oil quality through vacuum bleaching: An experimental design and analysis study

A leading cooking oil producer in Zimbabwe encountered challenges in meeting quality specifications for edible oil, particularly due to high colour and free fatty acid levels. This prompted the exploration of vacuum bleaching, as the bleaching stage significantly impacts these parameters. Controlled experiments demonstrated that vacuum bleaching effectively reduces both colour intensity and free fatty acids, achieving optimal quality for soybean oil production while minimizing bleaching earth usage to no more than 12.5 kg. Predictive modelling with Minitab software guided the system's design, resulting in a highly efficient and reliable vacuum bleaching process that meets industry standards. It was concluded that the system performs more than adequately in lowering FFA and reducing colour to within specifications.