Method for the preparation of phytosterols from tall oil pitch

Abstract

A method of preparing phytosterols from tall oil pitch containing steryl esters comprises the steps of converting the steryl esters to free phytosterols while in the pitch to produce a modified pitch containing the free phytosterols; removing light ends from the modified pitch by evaporation to produce a bottom fraction containing the free phytosterols; evaporating the bottom fraction to produce a light phase distillate containing the free phytosterols; dissolving the light phase distillate in a solvent comprising an alcohol to produce a solution containing the free phytosterols; cooling the solution to produce a slurry with the free phytosterols crystallized in the slurry; and, washing and filtering the slurry to isolate the crystallized phytosterols.

1 . A method of preparing phytosterols from tall oil pitch containing steryl esters, said method comprising the steps of: 
 (a) converting said steryl esters to free phytosterols while in said pitch to produce a modified pitch containing said free phytosterols;    (b) removing light ends from said modified pitch by evaporation to produce a bottom fraction containing said free phytosterols;    (c) evaporating said bottom fraction to produce a light phase distillate containing said free phytosterols;    (d) dissolving said light phase distillate in a solvent comprising an alcohol to produce a solution containing said free phytosterols;    (e) cooling said solution to produce a slurry with said free phytosterols crystallized in said slurry; and,    (f) washing and filtering said slurry to isolate said crystallized phytosterols.    
     
     
         2 . A method as defined in  claim 1 , wherein said modified pitch comprises less than 1% water by weight.  
     
     
         3 . A method as defined in  claim 1  or  2 , wherein said solvent comprises a low molecular weight monohydric alcohol.  
     
     
         4 . A method as defined in  claim 1  or  2 , wherein said solvent comprises a low molecular weight monohydric alcohol and water.  
     
     
         5 . A method as defined in  claim 1  or  2 , wherein said slurry is washed and filtered using a solvent like said solvent used to dissolve said light phase distillate.  
     
     
         6 . A method as defined in  claim 1 , wherein said step of converting said steryl esters to free phytosterols comprises the steps of: 
 (a) saponifying said tall oil pitch with an alkali metal base;    (b) neutralizing said saponified pitch with an acid; and,    (c) heating said neutralized pitch to remove water, the resulting pitch with such water removed defining said modified pitch.    
     
     
         7 . A method as defined in  claim 6 , wherein said alkali metal base is selected from the group consisting of: 
 (a) sodium hydroxide;    (b) potassium hydroxide;    (c) sodium hydroxide and potassium hydroxide.    
     
     
         8 . A method as defined in  claim 7 , wherein in the weight percentage of alkali metal base to tall oil pitch is in the range of 1% to 15%.  
     
     
         9 . A method as defined in  claim 7 , wherein said saponification is conducted at a temperature in the range of 100 to 250 deg. C. for a period in the range of 60 to 300 minutes.  
     
     
         10 . A method as defined in  claim 6 , wherein said acid is an organic acid.  
     
     
         11 . A method as defined in  claim 6 , wherein said acid is a mineral acid.  
     
     
         12 . A method as defined in  claim 11 , wherein said mineral acid is selected from the group consisting of: 
 (a) sulphuric acid;    (b) hydrochloric acid;    (c) phosphoric acid;    (d) a combination of acids comprising two or more of sulphuric acid, hydrochloric acid and phosphoric acid.    
     
     
         13 . A method as defined in  claim 6 , wherein said neutralization is conducted at a temperature in the range of 10 to 100 deg. C. for a period in the range of 1 to 10 hours.  
     
     
         14 . A method as defined in  claim 6 , wherein said neutralized pitch has a water phase pH in the range of 4 to 7.  
     
     
         15 . A method as defined in  claim 6 , wherein said heating step comprises heating at a temperature in the range 90 to 100 deg. C. for a time sufficient to effect the bulk disengagement of water from the organic phase.  
     
     
         16 . A method as defined in  claim 15 , wherein said heating step further comprises heating under vacuum conditions such that said modified pitch comprises less than 1% water by weight.  
     
     
         17 . A method as defined in  claim 1  or  6 , wherein said light ends are removed in a wiped film evaporator operating at a pressure in the range of 0.1 to 10 millibars and at a temperature in the range 160 to 280 deg. C.  
     
     
         18 . A method as defined in  claim 1  or  6 , wherein said bottom fraction is evaporated in a wiped film evaporator operating at a pressure in the range of 0.01 to 1.0 millibars and at a temperature in the range 180 to 300 deg. C.  
     
     
         19 . A method as defined in  claim 6 , wherein said solvent comprises a low molecular weight monohydric alcohol.  
     
     
         20 . A method as defined in  claim 6 , wherein said solvent comprises a low molecular weight monohydric alcohol and water.  
     
     
         21 . A method as defined in  claim 1  or  6  in which the crystallization of phytosterols is effected at a temperature in the range of 0 to 35 deg. C.  
     
     
         22 . A method as defined in  claim 1 , further including the step of evaporating said light phase distillate after step (c) and before step (d) to enhance the concentration of free phytosterols in said light phase distillate.  
     
     
         23 . A method as defined in  claim 22 , wherein water is added in step (d) in a proportion up to 35% by weight relative to the organic solvent phase.  
     
     
         24 . A method as defined in  claim 23 , wherein the weight ratio of solvent to distillate is between 0.3 to 2.0.  
     
     
         25 . A process according to  claim 19 ,  20  or  24  in which the alcohol is selected from: 
 (a) methanol;    (b) ethanol;    (c) 2-propanol;    (d) a combination of alcohols comprising two or more of methanol, ethanol and 2-propanol.