Patent ID: 8785698
Filing Date: 2014-07-22
Classification: A23L,B01D,C07B,C07C,C11B

Abstract:
1. A method for purifying 1-menthol, comprising: providing crude mentha oil in a crystallizer, wherein the crude mentha oil is from a mint plant and comprises 1-menthol in the range of about 50% to about 95% by weight, and wherein the crude mentha oil is free of organic solvents; crystallizing 1-menthol from the crude mentha oil by gradually reducing temperature in the crystallizer from a starting temperature at which the 1-menthol is a liquid to a cooled temperature in the range of −30° C. to 25° C. at a cooling rate in the range of 0.1° C./day to 10° C./day to form 1-menthol crystals; passing a gas over the 1-menthol crystals to remove residual oil and impurities while gradually elevating the temperature in the crystallizer to a temperature in the range of 30° C. to 40° C., wherein purified 1-menthol crystals of at least 98% purity by weight are obtained; melting the purified 1-menthol crystals to remove 1-menthol from the crystallizer as a melt; and cooling the melt into a dried, solid 1-menthol product, wherein the method is performed in a closed system without human contact with the crude mentha oil or the 1-menthol.