Intensified recovery of lactose from whey using thermal, ultrasonic and thermosonication pretreatments

Abstract

Recovery of valuable products such as proteins and lactose from dairy industry effluents offers promise due to the value addition and reduction in the environmental concerns attributed to lowering of the biological oxygen demand based on the recovery. The current work deals with understanding the effects of application of different pre-treatment schemes as thermal, sonication (only ultrasound) and thermosonication on the recovery of lactose from paneer (cottage cheese) whey using actual commercial samples of whey procured locally. Ultrasonic horn (20 kHz) with varying power levels over the range of 100 W–250 W has been used with different levels of ultrasonic exposure for sonication and thermosonication experiments. Ultrafiltration has been subsequently used for the separation of proteins and lactose from whey followed by anti-solvent sonocrystallization of lactose using ethanol. Combined pretreatment using ultrasound and heating resulted in maximum recovery of lactose as 94.59 ± 1.26%. Detailed understanding into the effect of different pretreatment conditions allowed for maximizing the recovery of lactose. Overall present work has clearly established that pretreatment using ultrasound in combination with heating results in enhanced recovery of lactose from whey.