In this investigation, the variation of peroxide value in water-degummed and alkali-refined soy oil during bleaching under nitrogen stream using regenerated clay was studied. Experimental results indicated that the removal efficiency of peroxide in soy oil under nitrogen stream was found to be higher than that under vacuum. The peroxide value in the oil was found to be reduced monotonically with bleaching time and the rate of reduction was increased upon increasing initial peroxide value, ratio of clay/oil, agitation speed or bleaching temperature. The rate was also found to be increased by decreasing particle size of clay. The flow rate of nitrogen stream and water content of clay, however, were found to have no influence on the removal rate. Furthermore, an empirical relationship between peroxide value and bleaching time was determined. (C) 2006 Elsevier B.V. All rights reserved.