Extraction of lactose from paneer whey using ethanol and methanol
Rajesh Ranjan Mishra, Anu Yadav, Abinash Singh, R N Shukla
In the present study, by-product paneer whey which is usually drained off in small scale dairy industry was tried for economical and rapid extraction of lactose using solvents ethanol and methanol. Effect of solvent concentration (70%, 80% and 90%), effect of initial pH adjustment (4.5, 3.5 and 2.5) at solvent to solute ratio of 90:10 (v/v) and effect of crystallization time on lactose recovery were examined. The lactose recovery of more than 90% was obtained from paneer whey in 5 hr of crystallization time at an effective ethanol concentration of 90% (v/v) whereas recovery of more than 80% was observed in case of methanol used as solvent. Conditions which were more favorable in terms of crystallized lactose yield were at pH of 4.5 than the pH of 3.5 and 2.5 which showed low recovery of lactose. Crystal size distribution (CSD) analysis has been also studied of the lactose recovered which showed that the average diameter of crystals increases on increase in crystallization time. At last residual analysis of recovered lactose suggested that residues of solvents ethanol and methanol were present within permissible limit in the sample thus we can say the recovered lactose does not contain any harmful effect of solvent and is of good quality.