Potential of pressurized solvent extraction for reduction of gossypol from cottonseed meal

An attempt was made to reduce the gossypol level in cottonseed meal (CSM) using the pressurized solvent extraction (PSE) process. The effect of solvents such as acetone and isopropanol alone and their combination and the PSE conditions viz., number of passes of solvent, temperature (°C) and pressure (bar) were optimized for gossypol reduction in CSM. The significant reduction of free gossypol (FG) from 1.7 (control) to 0.05 per cent and total gossypol (TG) from 4.0 (control) to 0.5 per cent was achieved under optimized PSE process conditions [acetone and isopropanol (50: 50), seven/ten passes, 120/110°C and 100/90 bar] (P<0.05). The optimized process did not significantly affect the protein content in the sample. The maximum reduction of FG from 1.7 to 0.01 per cent which corresponds to 99.4% reduction, and TG from 4.0 to 0.05 per cent, which corresponds to 98.8% reduction, was recorded under the PSE conditions [acetone and isopropanol (50: 50), seven passes, 120°C and 90 bar] and [acetone and isopropanol (50: 50), ten passes, 110°C and 90 bar] respectively. The FG levels in the processed CSM meets the international standards (<0.05%) of the US Food and Drug Administration and UN Protein Advisory Group. Thus, the study revealed that the CSM obtained under this process has potential application in feeding ruminant and non-ruminant livestock.