among the gallotannins suitable for use in this invention are those obtained from chinese nut gall or sumac leaves . gallotannins can be obtained from these natural materials by known means and , are also available as materials of commerce . sumac - derived gallotannin is available form omnichem s . a . ( brussels , belgium ) as tanal ™ sc gallotannin and brewtan ™ si gallotannin . gallotannin derived from chinese nut gall is available from omnichem as brewtan ™ gallotannin c and tanal ™ 02c gallotannin and from mallinkrodt ( st . louis , mo .) as tannic 4027 gallotannin . all of these gallotannins are d - glucose based and have an average molecular weight in excess of 1000 , typically between 1000 and 2000 , preferably between 1200 and 1600 and most preferably between 1250 and 1500 . the chemical structure of the gallotannin compounds of this invention is depicted by the generic structure : ## str1 ## where each r = h or ## str2 ## independently . ( i . e ., ## str3 ## are contained in each compound . naturally - derived gallotannin material will contain many different galloyl - glucoses in terms of both homologous and isometric compounds . the gallotannins described for use in this invention are able to substantially or essentially eliminate staining of nylon rugs by aqueous foodstuffs containing fd & amp ; c dyes at typical food use levels . gallotannins use levels in the foodstuff , as consumed , of 50 parts per million or below may be achieved by means of this invention . increasing the level of the gallotannins of this invention above 50 ppm does not significantly increase the anti - staining effect . if levels of gallotannins above 50 ppm are necessary , cost considerations and regulatory restrictions make the use of such materials impractical . thus materials such as the condensed tannins and tannic acids extracted from aleppo ( i . e ., turkish nut gall ) ( average molecular weight about 950 ) or tara pods ( average molecular weight about 900 ), which have been found to require levels in excess of 100 ppm to essentially eliminate staining of nylon rugs by aqueous foodstuffs containing fd & amp ; c dyes , are not suitable for use in this invention . illustrative of the gallotannins suitable for use in this invention is chinese gallotannin derived from twig galls of rhus semialata l . as reported by niakizawa and yamagishi in an article entitled &# 34 ; tannins and related compounds . part 5 . isolation and characterization of polygalloylglucoses from chinese gallotannin &# 34 ; found in j . chem . soc . perkin trans . i 1982 at pages 2963 - 68 , chinese gallotannin reportedly contains on average 8 . 3 galloyl groups per glucose molecule , has an average molecular weight of 1434 , and has been stated as being a mixture consisting mainly of penta thru dodeca - galloylglucoses which have depside galloyl group ( s ) randomly distributed at the c - 2 , c - 3 and c - 4 positions on a penta - o - galloyl - β - d - glucose core . according to niakizawa and yamagishi , the structure of chinese gallotannin is represented by the following formula : ## str4 ## and where l + m + n = a number between 0 and 7 . the relative compositions of penta thru dodecagalloylglucoses in chinese gallotannin , as analyzed by normal phase high - pressure liquid chromatography were reported to be as follows : ______________________________________ ratio (%) identified isomers______________________________________pentagalloylglucose 4 onehexagalloylglucose 12 threeheptagalloylglucose 19 fouroctagalloylglucose 25 more than eightnonagalloylglucose 20 more than ninedecagalloylglucose 13 more than sevenundecagalloylglucose 6dodecagalloylglucose 2______________________________________ illustrative of the colorants or dyes against which the gallotannin stain - inhibiting agents of this invention are effective are fd & amp ; c dyes such as brilliant blue ( fd & amp ; c blue no . 1 ), indigo disulfoacid ( fd & amp ; c blue no . 2 ), fast green fdf ( fd & amp ; c green no . 3 ), erythrosine ( fd & amp ; c red no . 3 ), ponceau sx ( fd & amp ; c red no . 4 ), allura red ( fd & amp ; c red no . 40 ), sunset yellow ( fd & amp ; c yellow no . 6 ), tartrazine ( fd & amp ; c yellow no . 5 ), orange b , and similar soluble dyes containing anionic groups . at first glance , many of these dyes appear to have very little in common from a molecular structure standpoint . there are at least two fd & amp ; c dyes which are triarylmethanes ( blue 1 and green 3 ), one indigoid ( blue 2 ), one xanthene ( red 3 ), three monoazos ( red 4 , red 40 , yellow 6 ), at least one pyrazolone ( yellow 5 , which also has a monoazo group ). certain dyes which still carry an &# 34 ; fd & amp ; c &# 34 ; designation as a kind of shorthand identification have been &# 34 ; delisted &# 34 ; and are no longer considered safe for ingestion by humans , e . g ., orange i and orange ii . the delisted dyes are of course less preferred . despite fundamental differences in structure , however , all of these dyes have at least one anionic group substituted on a benzene or naphthalene ring structure , typically for the purpose of improving water solubility . the anionic group is generally the sulfonate radical (-- so 3 - ), which can either be in salt form ( e . g ., -- so 3 na or an internal salt form ) or acid form (-- so 3 h ); most typically , the commercial form of the dye contains at least one sodium sulfonate group substituted on a benzene or naphthalene ring structure . the sulfonated benzene can be fused to a ring of the dye structure but is more typically an independent ring - directly attached to an azo group or indirectly linked to a triarylmethane structure or whatever the dye moiety happens to be . the amount of ingestible dye needed to provide deep shades of blue , yellow , green , red , purple , orange , etc ., is relatively small compared to the weight of the complete food product ( e . g ., the fully constituted food product , including aqueous diluent , if any ) and is generally in the parts - per - million ( by weight ) range . amounts less than 1000 ppm ( more typically less than about 100 ppm ), e . g ., 1 to 50 ppm are conventionally used in processed food products . other artificial additives include sweeteners , preservatives , and the like . the presence of these additives ( or of sucrose or other sugars ) appears to have no adverse effect upon the stain - inhibiting activity of the stain inhibitors used in this invention . particularly preferred colored food products for use with this invention are powdered materials which can become drinks when blended with water , e . g ., powdered soft drinks . other suitable food products could include liquid drinks , such as fruit juices , fruit drinks or carbonated beverages , gelatin gels or other dessert gels , puddings , jams , jellies , candies and the like . this invention is further described but not limited in the following examples . a series of rug staining studies were conducted to establish the relative efficacy of various commercial ( from omnichem ) tannin materials at various levels . in each case strips of alabaster - beige commercial carpet made of nylon - 6 fiber and without any stain - resist agent was immersed in a non - carbonated , cherry flavored and colored soft drink ( kool - aid ® brand powdered drink mix ). the drink was prepared following package direction by combining the package contents ( 5 . 3 grams containing 100 mg of fd & amp ; c red no . 40 ) with 200 grams of sucrose and sufficient water ( 1759 cc ) to bring the total volume to two quarts ( 1 . 9 liters ). the resulting drink contained a level of fd & amp ; c red no . 40 of 51 ppm . the carpet strips were kept immersed in the drink for one hour after which each strip was rinsed in cold tap water . before rinsing each of the strips exhibited a red appearance . after rinsing staining was evaluated by standard colorimetric techniques . the colorimeter used was the color machine ™ colorimeter ( bic / gardner , silver springs , md .) which was calibrated with white and black tiles , and with the fresh carpet produces a reading of one as the &# 34 ; a &# 34 ; value of the hunter scale . the results are show in fig1 as follows : ______________________________________tannin type ppm tannin hunter &# 34 ; a &# 34 ; value______________________________________chinese ( tanal 02c ) 0 42 . 0 10 30 . 4 30 14 . 7 50 9 . 1 100 7 . 5 200 6 . 1sumac ( tanal sc ) 0 42 . 0 10 36 . 3 30 13 . 4 50 9 . 4 100 7 . 7 200 7 . 8aleppo ( tanal 03 ) 0 42 . 0 10 41 . 0 30 30 . 1 50 21 . 7 100 10 . 1 200 6 . 6tara pod ( tannex 40 ) 0 42 . 0 10 42 . 0 30 37 . 6 50 31 . 3 100 16 . 3 200 6 . 6______________________________________ as can be established from these results sumac gallotannin with an average molecular weight of about 1380 and chinese gallotannin with an average molecular weight about 1434 are , at the 50 ppm level , about 2 . 67 times as effective in inhibiting staining as the aleppo gallotannin with an average molecular weight of about 955 . the tara pod tannin although comparable in molecular weight to the aleppo gallotannin ( 900 v . 955 ) was even less effective which is believed due to the fact that tara tannin is built around a quinnic acid core as opposed to a glucose core . additional evidence of the correlation between molecular weights of gallotannins and their stain - inhibiting properties is evidenced by fig2 . in this example , purified gallotannin fractions obtained by means of hplc column separation of commercial gallotannin material were used at a level of 25 ppm in the same fashion as the tannins of example 1 with staining study being conducted both on carpet of nylon 6 filament and carpet of nylon 6 . 6 filament . fig2 clearly shows that stain resistance increases as the number of galloyl groups in the gallotannin fractions increases . a material designated as tannic acid powder ( certified ) was obtained from fisher scientific ( fair lawn , n . j .). this material was evaluated for stain - inhibiting properties in the same manner as in example 1 . for levels of this material of zero , 10 , 25 , 50 100 and 200 ppm . the corresponding hunter &# 34 ; a &# 34 ; values were 43 . 5 , 38 . 79 . 32 . 96 , 25 . 47 , 9 . 13 and 8 . 67 . the effectiveness of this material for stain - inhibiting at 50 ppm was below that of aleppo gallotannin and above that of tara pod tannin , but significantly below that of the chinese and sumac gallotannins which are representative of the high molecular weight gallotannins of this invention . for comparison purposes this rug staining data is also included in fig1 . a cranberry - flavored , sucrose - free powdered soft drink mix was prepared by dry blending various food ingredients to produce the following compositions : ______________________________________component weight % ______________________________________citric acid 48 . 71natural and artificial flavors 22 . 51 ( fixed in carbohydrate carriers ) malic and tartaric acids 12 . 90aspartame 5 . 34cranberry juice solids 5 . 51potassium citrate 1 . 70gallotannins ( tanal ™ sc ) 0 . 51vitamin c 0 . 36artificial colors ( red 40 and blue 1 ) 1 . 24tricalcium phosphate 1 . 22 100 . 00______________________________________ when 14 . 73 grams of this composition is combined with 1 . 89l ( 2 quarts ) of water , a beverage is produced which , as compared to a comparable beverage without added gallotannins , greatly reduces the staining of nylon carpet .
selected high molecular weight gallotannins are incorporated into fd & amp ; c dye - containing foodstuffs to prevent staining of polymeric substrates such as wool or nylon rugs and clothing . gallotannins from sumac leaves and chinese nut galls are effective at levels of 50 ppm or below . this invention is useful in foodstuffs which are not subject to oxidation .