Evaluation of green solvent as an environment friendly alternative for milk fat extraction from ghee residue (clarified butter sediment waste)

Abstract

Summary Ghee residue (clarified butter sediment waste) is a fat‐rich by‐product (containing 50–70% fat, weight basis) obtained during ghee (clarified butter fat) preparation. Conventionally used fat extraction methods from ghee residue (GR) are energy intensive and generates huge amount of waste water. In the present study, solvent extraction was explored for milk fat separation from GR at different extraction temperatures using green solvents, viz., ethyl acetate (EA) and di‐methyl carbonate (DMC). Changes in differential scanning calorimetry profile, fatty acid profile, dynamic rheology, FTIR spectroscopy and colour values of the solvent extracted fat were studied. Increasing the solvent extraction temperature increased the fat extraction efficacy from 45.62% to 49.22% for DMC and from 48.70% to 52.16% for EA. Considering the fat extraction efficacy, fat extraction from GR was found suitable using EA at 65°C extraction temperature. Fat extraction from GR using the selected green solvent, that is EA needed only 57% (18 000 J g−1 of GR) of energy as compared to conventional method (31 500 J g−1 of GR) with no wastewater generation.