Method for preventing coloration of catechins and dentifrice composition

Abstract

The present invention relates to a method of suppressing coloration of catechins, which contains adding, to catechins, a water-soluble polymer forming a water-insoluble complex with catechins, as well as hydrogel particles containing a water-insoluble complex between catechins and a polymer forming a water-insoluble complex with catechins. Further, the present invention relates to a dentifrice composition containing hydrogel particles containing catechins and a polymer forming a water-insoluble complex with catechins, a binder and water.

1 . A method of suppressing coloration of catechin, which comprises adding, to the catechin, a water-soluble polymer (referred to hereinafter as polymer A) forming a water-insoluble complex with catechin. 
   
   
       2 . The suppressing method according to  claim 1 , wherein the polymer A is polyvinyl pyrrolidone. 
   
   
       3 . The suppressing method according to  claim 1  or  2 , wherein the weight-average molecular weight of the polymer A is 6000 to 3000000. 
   
   
       4 . The suppressing method according to any one of  claims 1  to  3 , wherein the polymer A is added in an amount of 1 to 4 times the weight of the catechin. 
   
   
       5 . Hydrogel particles comprising a water-insoluble complex of catechin and the polymer A defined in  claim 1 . 
   
   
       6 . The hydrogel particles according to  claim 5 , wherein the polymer A is polyvinyl pyrrolidone. 
   
   
       7 . A dentifrice composition comprising hydrogel particles comprising catechin and the polymer A defined in  claim 1 , a binder and water. 
   
   
       8 . The dentifrice composition according to  claim 7 , wherein the polymer A is polyvinyl pyrrolidone. 
   
   
       9 . The dentifrice composition according to  claim 7  or  8 , wherein the binder is at least one or more members selected from the group consisting of sodium alginate, carboxymethylcellulose sodium, carrageenan, xanthan gum, sodium polyacrylate, hydroxyethyl cellulose, hydroxypropyl cellulose, pectin, tragacanth gum, gum arabic, guar gum, karaya gum, locust bean gum, gellan gum, tamarind gum, psyllium seed gum, polyvinyl alcohol, sodium chondroitin sulfate, and a methoxy ethylene-maleic anhydride copolymer.