The present disclosure is: a free polyunsaturated fatty acid-containing composition, which comprises at least one free polyunsaturated fatty acid having 20 or more carbon atoms, the content being at least 80.0% of the fatty acids in the composition, and satisfies at least one selected from a group consisting of conditions (1) and (2): (1) the content of conjugated unsaturated fatty acid is 1.0% or less of the fatty acids in the composition, and (2) the Gardner color is less than 3+; and a manufacturing method for the free polyunsaturated fatty acid-containing composition comprising the preparation of a raw material composition containing at least one polyunsaturated fatty acid having 20 or more carbon atoms, and hydrolysis of a reaction solution containing the prepared raw material composition, a lower alcohol, water and an alkali catalyst at a temperature of 10? C. or lower.

The present disclosure is: a free polyunsaturated fatty acid-containing composition, which comprises at least one free polyunsaturated fatty acid having 20 or more carbon atoms, the content being at least 80.0% of the fatty acids in the composition, and satisfies at least one selected from a group consisting of conditions (1) and (2): (1) the content of conjugated unsaturated fatty acid is 1.0% or less of the fatty acids in the composition, and (2) the Gardner color is less than 3+; and a manufacturing method for the free polyunsaturated fatty acid-containing composition comprising the preparation of a raw material composition containing at least one polyunsaturated fatty acid having 20 or more carbon atoms, and hydrolysis of a reaction solution containing the prepared raw material composition, a lower alcohol, water and an alkali catalyst at a temperature of 10? C. or lower.

The present disclosure is: a free polyunsaturated fatty acid-containing composition, which comprises at least one free polyunsaturated fatty acid having 20 or more carbon atoms, the content being at least 80.0% of the fatty acids in the composition, and satisfies at least one selected from a group consisting of conditions (1) and (2): (1) the content of conjugated unsaturated fatty acid is 1.0% or less of the fatty acids in the composition, and (2) the Gardner color is less than 3+; and a manufacturing method for the free polyunsaturated fatty acid-containing composition comprising the preparation of a raw material composition containing at least one polyunsaturated fatty acid having 20 or more carbon atoms, and hydrolysis of a reaction solution containing the prepared raw material composition, a lower alcohol, water and an alkali catalyst at a temperature of 10? C. or lower.

Processes for purifying acetic acid by distilling a process stream in a column in which acetic anhydride is formed in the lower portion of the column. The product stream withdrawn from the column comprises acetic acid, water at a concentration of no more than 0.2 wt. %, and acetic anhydride at a concentration of no more than 600 wppm. The process further comprises hydrating the acetic anhydride in the product stream to form a purified acetic acid product comprising acetic anhydride at a concentration of no more than 50 wppm.

Processes for purifying acetic acid by distilling a process stream in a column in which acetic anhydride is formed in the lower portion of the column. The product stream withdrawn from the column comprises acetic acid, water at a concentration of no more than 0.2 wt. %, and acetic anhydride at a concentration of no more than 600 wppm. The process further comprises hydrating the acetic anhydride in the product stream to form a purified acetic acid product comprising acetic anhydride at a concentration of no more than 50 wppm.

Processes for purifying acetic acid by distilling a process stream in a column in which acetic anhydride is formed in the lower portion of the column. The product stream withdrawn from the column comprises acetic acid, water at a concentration of no more than 0.2 wt. %, and acetic anhydride at a concentration of no more than 600 wppm. The process further comprises hydrating the acetic anhydride in the product stream to form a purified acetic acid product comprising acetic anhydride at a concentration of no more than 50 wppm.

Processes for purifying acetic acid by distilling a process stream in a column in which acetic anhydride is formed in the lower portion of the column. The product stream withdrawn from the column comprises acetic acid, water at a concentration of no more than 0.2 wt. %, and acetic anhydride at a concentration of no more than 600 wppm. The process further comprises hydrating the acetic anhydride in the product stream to form a purified acetic acid product comprising acetic anhydride at a concentration of no more than 50 wppm.

Processes for purifying acetic acid by distilling a process stream in a column in which acetic anhydride is formed in the lower portion of the column. The product stream withdrawn from the column comprises acetic acid, water at a concentration of no more than 0.2 wt. %, and acetic anhydride at a concentration of no more than 600 wppm. The process further comprises hydrating the acetic anhydride in the product stream to form a purified acetic acid product comprising acetic anhydride at a concentration of no more than 50 wppm.

Processes for purifying acetic acid by distilling a process stream in a column in which acetic anhydride is formed in the lower portion of the column. The product stream withdrawn from the column comprises acetic acid, water at a concentration of no more than 0.2 wt. %, and acetic anhydride at a concentration of no more than 600 wppm. The process further comprises hydrating the acetic anhydride in the product stream to form a purified acetic acid product comprising acetic anhydride at a concentration of no more than 50 wppm.

Provided is a free-polyunsaturated-fatty-acid-containing composition that has a total metal content of 0.1 ppm or less and that comprises at least one free polyunsaturated fatty acid having 20 or more carbon atoms, in an amount that is at least 80.0% of the amount of fatty acids in the composition; and a method for manufacturing a free-polyunsaturated-fatty-acid-containing composition, comprising: providing a raw material composition containing at least one polyunsaturated fatty acid having 20 or more carbon atoms; performing a hydrolysis treatment on a reaction solution prepared by combining the provided raw material composition, a lower alcohol, water having a total metal content of 0.01 ppm or less, and an alkali catalyst; and limiting the contact between the reaction composition and the metal after the hydrolysis treatment so that the product T [cm.sup.2?days] of the contact surface area [cm.sup.2] per 1 g and the contact time [days] between the composition and the metal is 100 or less.