ULTRAFILTRATION MEMBRANE-PERMEABILITY OF SOME MILK CONTAMINANTS

The aim of this study was to investigate the distributional behavior o f certain milk contaminants including insecticides, antibiotic and hea vy metals during ultrafiltration (UF) and diafiltration-(DF) of milk. Raw milk containing 3.0 mg Kg(-1) beta.BHC, 1.0 mg Kg(-1) lindane, 2.0 mg Kg(-1) pp DDT, 0.02 I.U. penicillin mL(-1), 1.6 mg Kg(-1) Fe, 0.4 ppm Cu, 6.5 mg Kg(-1) Zn or 0.1 mg Kg(-1) Pb was heated at 85 degrees C for 20 s and left overnight at 4 degrees C for complete adsorption o f the contaminant added. The UF-process was carried out at 50 degrees C to concentration factors (CF) of 2 and 3. The last concentrate (CF = 3) was diafiltered twice, each time using an amount of water equal to that of the retentate. The results indicated that the applied heat tr eatment (85 degrees C/20 s) caused the disappearance of about 74% of b eta BHC, 73% of lindane, 65% of ppm DDT, or 25% of the penicillin adde d. The UF-concentration of CF 2 caused further removal of about 17, 43 , 28 or 28% of these compounds, respectively, while removal at CF 3 wa s 40, 59, 46 or 35%, respectively. The permeability of Fe, Cu, Zn or P b was very low; as at CF 3 the concentrate contained about 91, 53, 91 or 63%, respectively, of these metals. The 2x diafiltration increased the reduction level to 85, 92, 84 or 44% respectively, of beta-BHC, li ndane, pp DDT or penicillin when the effect of the previous heat treat ment was included, while the final reduction levels in Fe, Cu, Zn or P b were 13, 63, 16 or 50%, respectively.