Membrane process for premium quality expeller-pressed vegetable oils

Studies were conducted with expeller-pressed groundnut and sunflower oils i n a magnetically stirred flat membrane batch cell with five different types of nonporous polymeric composite membranes, to improve the oil quality. Th e phospholipid contents of membrane permeates of groundnut and sunflower oi ls were lower than 360 mg kg(-1). The maximum reductions in Lovibond yellow and red color values were 75.6 and 50% in groundnut oil, and 77.9 and 77.8 % in sunflower oil, respectively. The oxidation products were rejected to t he extent of 26.5-40.3%. There was an increase in tocopherol content in per meates to the extent of 34-72.2% due to preferential permeation. Negative r ejection of free fatty acids (FFA) resulted in a small increase in FFA cont ent in permeates. The results suggest that the membrane process can be used as a single-step process for the production of premium quality edible oil. However, permeate flux needs to be improved for industrial adoption. (C) 1 999 Published by Elsevier Science Ltd on behalf of the Canadian Institute o f Food Science and Technology. All rights reserved.