Method for preparing a colour-stable preparation of a magnesium chlorophyllin alkali metal salt or alkali earth metal salt from natural sources of chlorophyll

A method for preparing a colour-stable preparation of a magnesium chlorophyllin alkali metal salt, said method comprising:

• (a) providing a liquid composition comprising a plant extract containing a water-insoluble magnesium chlorophyll, wherein said extract has been prepared by treating plant matter containing a water-insoluble magnesium chlorophyll with an organic solvent in which said chlorophyll is substantially soluble and chlorophyllin is substantially insoluble, wherein said composition has an oleoresin solids content of about 1% w/w to about 50% w/w and does not comprise an organic solvent in which chlorophyllin is substantially soluble;
• (b) combining an amount of a basic inorganic alkali metal salt with an amount of the liquid composition of step (a) and agitating the mixture so formed, wherein the amount of salt is sufficient to maintain a pH of equal to or greater than about 7.0 in the mixture;
• (c) incubating the mixture of step (b) under conditions sufficient to convert magnesium chlorophyll to a magnesium chlorophyllin alkali metal salt;
• (d) separating at least a portion of a first aqueous phase of the mixture of step (c) from a first water immiscible organic phase of the mixture of step (c);
• (e) combining an amount of water immiscible aliphatic glycerol ester with an amount of the first aqueous phase obtained in step (d) wherein the amount of ester added is sufficient to be capable of forming a second water immiscible organic phase which is separable from the first aqueous phase;
• (f) separating at least a portion of the first aqueous phase of the mixture of step (e) from the second water immiscible organic phase of the mixture of step (e);
• (g) adding an amount of a water miscible organic solvent in which chlorophyllin is substantially soluble to an amount of the portion of the first aqueous phase obtained in step (f) and agitating the mixture so formed, wherein the amount of organic solvent is sufficient to substantially solubilize chlorophyllin in the first aqueous phase of the mixture;
• (h) incubating the mixture of step (g) under conditions sufficient to substantially solubilize chlorophyllin in the first aqueous phase of the mixture of step (g);
• and
• (i) separating at least a portion of any solids in the mixture of step (h) from the first aqueous phase of said mixture, thereby providing an aqueous solution of said magnesium chlorophyllin alkali metal salt.