Patented Feb. 12, 1952 2,585,580

UNITED STATES PATENT OFFICE 2,585,580 STABLIZING ASCORBC; ACD WITH THO-SUGARS Jan Opplit, Prague-Nusle, Czechoslovakia, No Drawing. Application June 10, 1948, Serial No. 32,258. In Czechoslovakia June 12, 1947 8 Claims. (C. 260-344.5) 2 The present invention relates to stabilizing It is broadly known that the preservation of aScorbic acid with thio-sugars. fruit and vegetables has Such an unfavorable The aScorbic acid represents a necessary influence on the aScorbic acid content that the constituent of human food and therefore it is major part of the acid originally present is de of importance to protect the same in the various stroyed while Subsequent storage under unfavor natural and artificially prepared products against able conditions leads to an almost complete loss decomposition by suitable stabilization. The of the rest of the aScorbic acid content So that aScorbic acid, which occurs in the nature as the the health of perSons Who conSurne Such products So called vitamin C, is a relatively unstable sub in absence of any other sources of vitamin C may Stance easily oxidizable by the atmospheric air 0. be seriously impaired. Still more harm for the into dehydro-aScorbic acid, which also is unstable, health may take place if the vitamin content is and to further products of oxidation whereby the reduced in medicaments for in Such cases the physiological value of aScorbic acid as an physician relies on the patient receiving an exact antiscorbutic agent is lost. The l-aScorbic acid ly measured dose of the active Substance. C6HaO6 has the following constitution: Amongst the unfavorable influences leading to decomposition of the aScorbic acid there may be mentioned an ample contact With the atmos pheric oxygen which is unavoidable under normal H. H. E. O. O. C. conditions, higher temperatures which accelerate The ascorbic acid is a compound allied to the the oxidation, and the presence of certain ma simple Sugars having six carbon atoms in their 20 terials such as enzymes (ferments) and catalysts molecule and is characterized by a lactonic ring Which also lead to accelerated Oxidation. In the and by an endiol group -COHECOH-. This vegetable kingdon the ferments ixino Win as group accounts for the easy oxidation of a scorbic oxidases occur very frequently. These ferments acid to dehydro-aScorbic acid C6H6Os having the attack the aScorbic acid, and the most active of constitution: them is the so called ascorbinase which contains chemically combined copper. Amongst the sin OH. O. C-C-C-C-C-C- ple catalysts which speed up the oxidation of H. H. H. O. O. O. aScorbic acid there are known more particularly The last mentioned acid is also unstable, and 30 the copper compounds, while the compounds of by Splitting of the lactonic ring is converted into manganese and iron are less active. The copper 2,3-diketo-l-gulonic acid: exerts an effect already if it is present in traces of the order of 10-6 g. CH2OH-CHOH-CHOH-CO-CO-COOH On the other hand Substances are also knoWn The dehydro-aScorbic acid still may be reduced , which stabilize more or less the aScorbic acid, into aScorbic acid with relative facility also in protecting the same against oxidation also at living organisms and has antiscorbutic effect, but higher temperatures so that such substances the product of further oxidation cannot be easily represent in fact negative catalysts. Alongst converted into ascorbic acid and in any case such such substances may be mentioned e. g. the a reduction cannot take place in a living 40 sulphurous acid, hydrogen sulphide, certain Organism. So that the product is physiologically mercaptains, the cyanides , and iso-cyanides, inefficient. glutathione, methionine, cysteine, cystine, di ASCOrbic acid is contained in relatively large methyl-mercaptal-glucoses, and also highly con proportions in various natural foods, in fresh centrated Solution of Saccharose. However, these condition of the same, such as fruit, vegetables, 5 substances may not be used in the production of meat, more particularly in the muscles and liver foods or in the preparation of medicaments be of animals and in products made therefrom (such cause they either are poisonous or are unsuitable as fruit, marmalades and preserves of various for other reasons or again are not readily avail kinds, meat or liver extracts and the like). able. Synthetically prepared ascorbic acid forms a 5 In the method of treating natural products as component of various medicaments, preparations hitherto used the loss of aScorbic acid depends and injection liquids. In all the aforementioned first of all on the period of boiling and further products it is desirable to stabilize the aScorbic On other circumstances and On other properties of acid so as to retain the original physiologic value the medium, more particularly on its acidity and of the products for an indefinite period. 5 finally on the period of storing (ageing) of the 2,585,580 3. 4. preserves. With a boiling period of 15 minutes simple sugar components. Examples of Such the content of vitamin C will be reduced in the thio-Sugars are the thio-glucose average to 75% and with a boiling period of 90 minutes it will be reduced down to 15% of the CH2OH (CHOH)4CSH original value. Immediately after the completion is or, according to more recent findings of research of the boiling process a loss of about 50% of the CH2OHCH (CHOH)3CHSH ascorbic acid content in the average is to be expected, but these losses vary within large. limits O in any particular case. ithio-fructose CH2OHCCHOH)3CSCH2OH, thio in highly acid medium (lemon or currant juice) is maltose C12H22O10S. It is also possible to use the oxidation of a scorbic acid proceeds at a rela ...the acetylated derivatives of the thio-SugarS. tively low speed and also the losses due to ageing Such derivatives are obtained by the acetylation are low. The natural acidity of fruit juices, of the CH-groups, that is by substitution of the expressed in pH-units, amounts to 4.5-6.5. Due group COCN3 for hydrogen. to the ageing of the preserves 'Subsequent to By further investigation of the thio-sugars it their preparation in the usual Way, the aScorbic has been found that a particularly Suitable sta acid content continuously decreases further So bilizer is the diglucosyl disulphide . that after 6 to 12 months the aScorbic acid content CH2OH (CHOH)4CS.S.C (CHOH)4CH2OH. is reduced in very favorable cases to 20 Or i0% of the original value, while in some unfavorable cases 24 Or, according to more recent findings of research the ascorbic acid may completely disappear. In O-Hi creased temperature, more ample contact with the air and the presence of catalysts impair the chocolai ageing characteristics of preserves. CHOHCH (CHOH)3CHS In neutral and especially in alkaline medium 25 O the oxidation of the aScorbic acid takes place which is obtained as an intermediate product in very rapidly, and this applies also to the loss due the preparation of thio-glucose and which by to ageing so that within three weeks the aScorbic reduction and splitting may be converted to acid completely disappears from such preserves. thio-glucose. The diglucosyl disulphide is still The decomposition of ascorbic acid is also ac 30 more advantageous than the thio-sugars in the celerated by the presence of copper and iron When stabilization of C-Vitainin. making the preserves in copper or iron vessels, The amount of Sulphur Sugar derivatives re because these two metals act as oxidation cata quired for the stabilization depends, on the one lystS. hand, on the amount of aScorbic acid to be Sta An object of the present invention is to provide 85 bilized and, on the other hand, on the concen a method of stabilizing and -a stabilizer for the tration of the ascorbic acid in the Solution under aScorbic acid (vitamin C) in natural and arti treatinent. A larger amount of aScorbic acid ficially prepared products for human food and requires a correspondingly larger amount of Sta also in medicaments, various preparations, in bilizer. However, with increasing dilution of the jection solutions, etc. The new method and Sta 40 ascorbic acid the required amount of stabilizer bilizer are suitable in the first place for fruit and increases too, so that the more dilute the Solu vegetables preserved and prepared in any desired tions of C-Vitamin are, the larger is the required manner, for fruit juices, jams, marmalades, com proportion of Stabilizer. potes, for the preservation of meat, liver, other If thio-sugars are used for the stabilization, organs of the animal body and for extracts made 45 an amount of the order of at least 1% calculated therefron. on the ascorbic acid present Will be required. In As Stabilizers there may be used in the first connection with diglucosyl disulphide it has been place the Various Sulfur derivatives of Sugars found that a still lower amount is required than Such as e. g. Sulpho-ureides of the SugarS, thio With the use of other thio-Sugars, an amount of acetyl derivatives of the sugars, thio-amino 5) the Order of at east, 0.4% of the amount of aSCOr Sugars, etc. The Sugar Sulpho-ureides are chair bic acid present being Suificient. The above acterized by the group minimum proportions of Stabilizer are valid for N at least 1% concentrations. Of C-Vitamin (1 gram -s-C/ of C-Vitamin in 100 grains of Solution). If the -S S5 C-Vitamin Solutions are more diluted, it may be NE necessary to add relatively larger proportions of stabilizer, so that the addition of stabilizer may or by the group -N-CS-NH2 which are united reach under certain conditions an amount of the ...to a residue (a radical) of Some simple Sugar, Order of the an Ount of C-Vitamin present. such as glucose or fructose, e.g. the glucose Sull 60 The natural juices and pulps of fruit, vegetables pho-ureide CH2OH(CHOH)4CH=N-CS-NH2. and meat, lemon, orange, currant juice, rose-hip The thio-acetyl derivatives of the Sugars contain or apricot pulp, contain in fresh condition as the group -CSCH3 which occupies the place of corbic acid in a concentration of 10 mg. to 100 mg. hydrogen in One of the hydroxyl groups in the per 00 g. Of inlaterial. in Such cases it is neces sugar molecuie. The thio-amino-sugars are char 65 Sary to use the Stabilizer in an amount of at least acterized by the terminal group -CSNH2. Other the order of the ascorbic acid present. Sulphur derivatives of Sugar which may be used The stabilization of aScorbic acid may be in as stabilizers are more particularly the so called proved if the Said Sulphur Sugar derivatives are thio-Sugars. The expression “thio-Sugars’ is admixed with alkali metal salts of the pyro used to denote. Such derivatives of the Simple or 70 phosphoric acid H4F2O, more particularly with composite sugars (glucose, fructose, maltose) the Sodiun, potassium or ammonium salts of the Which have at least one reactive oxygenatom in latter, e.g. Na2H2E2O7. The said two conponents their molecule Substituted by a Sulphur atom are mixed togetheir in amounts of the same order, in the group CO or "COH. In the case of com and the composite stabilizer thus obtained is posite thio-Sugars the sulphur atom connects the 75 added to the piroduct in which the ascorbic acid 2,585,580 5 6 is to be stabilized, in an amount of the order of add pH-regulators to the stabilizer when rela at least 2%, calculated on the amount of aSCOrbic tively sour fruit juices or sufficiently sour fruit acid present. Under certain conditions it is pos (lemons, oranges, currants) are being preserved. sible, however, to add the said fundamental sta In Such cases the acidity of the medium is main bilizing components in an amount up to 100 tained by itself within a suitable range for the times larger, i. e. in an annount of the same order stabilization and a small addition of a pH-regu as that of the ascorbic acid, without any un lator would not have any effect. favorable effect on the stabilization of the as The new stabilizers maintain in any medium, corbic acid or On the taste, flavor, appearance Or natural and artificial, the C-vitamin content and physiologic activity of the treated product. O its biological value at an almost invariable de The fact that it is possible to overdose the sta gree, even if air is caused to bubble through the bilizer without any harmful effect constitutes an material processed in cold condition, or at a high advantage in preserving and variously processing er temperature (lower than the boiling point), or fruit and other food products in households where With boiling for a period shorter than 30 minutes. it is not possible to determine exactly the content Neither is the C-vitamin content affected by the of C-Vitamin in the available raw materials, but storage of the stabilized products for a long time, only to estimate it by the aid of tables. The say several months. If the products are boiled for amount of C-vitamin, and as a consequence the a period longer than 30 minutes, the C-vitamin amount of stabilizer required, is roughly depend content is reduced to a relatively small extent ent on the Volume and weight of the fruit to be only, at most by about 30%. The loss of vitamin treated and on the kind and freshness of the depends on the duration of the boiling, the access Same. of atmospheric air and on other unfavorable In the stabilization of ascorbic acid it is of im conditions, e. g. On the presence of Catalysts portance to produce and maintain constantly a which favor the oxidation of C-Vitamin. reducing medium, the redoxy-potential having E.5 Fruit, vegetables, meat etc. boiled or preserved preferably a value within the range of 0.08–0.166 in any of the known methods retain by the effect volt; the desired result is secured by choosing of the new stabilizer in a slightly acid medium Suitable proportions for the various components their whole content of ascorbic acid for an in to be mixed. definite length of time, as it has been proved by In carrying out the invention it has been found st) numerous tests. that in place of the salts of pyro-phosphoric acid, The stabilizer in accordance with the present it is possible to make use in the stabilizer of the invention is efficient within a broad range under organic derivatives of this acid, e.g. of the ade all conditions which may occur in practice, and nosine-triphosphoric acid C10H16O13N5P3 which moreover the Stabilizer may be used with advan contains the following constituents: adenine, 3 5 tage for the stabilization of synthetic aScorbic ribose, phosphoric acid and pyrophosphoric acid. acid in medical and injection solutions. The stabilizing effect of thio-sugars and of the Stabilizers for preserving jams or the like of other sulphur derivatives of the sugars may be low consistency are prepared preferably with an still enhanced by the addition to the stabilizing addition of starch whereby the products are mixture of secondary amines of the general thickened at the same time without boiling them type RiNHR2, or amides of the general type for a long time or thickening them in any other R1CONHR2, where R1 and R2 represent aliphatic manner, e. g. by means of pectins. The stabilizer or aromatic radicals. The required amount of for the C-vitamin has at the same time the effect amines or amides in the stabilizer is of the order of preserving the boiled products. Moreover the of 1% of the amount of thio-sugars or sulphur . stabilizers may be prepared in such a way that derivatives of Sugars present in the mixture. The fruit or vegetables of low acidity are acidified by effect of these Substances resides in the stabiliza the addition of a pH-regulator, Such as citric tion of the sulphur in the thio-sugars and thus in acid. maintaining the stability of the reducing medium. The stabilizer in accordance with the present It has been found furthermore that for the invention is quite harmless to human health and stabilization of ascorbic acid it is of advantage does not affect in the least the flavor and taste to keep by means of the stabilizer the acidity of of the jams or fine compotes, and in addition the the medium within a certain range which, ex preserves retain their original natural colour. pressed in pH-units, is comprised between 4.0 and The stabilizer may be used without difficulty in 6.5. The desired effect may be obtained by the any household and may be stored in suitable addition of pH-regulators which preferably con powdered form. tain free organic poly-carboxylic or hydroxy poly-carboxylic acids, such as e. g. tartaric or Eacamples citric acid, and the respective alkali metal salts 1. A stabilizing mixture for 100 liters of nat of the said acids. 60 ural material (fruit cut to pieces, vegetables, The addition of pH-regulators in the stabiliza pressed juice) is made by dissolving: tion of aScorbic acid is necessary more particular ly in connection with artificially prepared prod 5 g. Of thio-glucose, ucts, especially with medicaments which contain 6 g. of crystalline Sodium pyro-phosphate, synthetic ascorbic acid in approximately neutral 65 35 g. of citric acid, solution, furthermore in the preservation of cer 0.5 g. of acetanilide tain sorts of fruit and vegetables (cucumbers, in 100 g. of water. The solution so obtained is melons), meat, liver and extracts made from the mixed in a suitable mixel with 100 g. of powdered latter and generally in connection with products Saccharose and with 450 g. of potato Starch until which give juices of approximately neutral reac 70 a uniformly moist powdered mixture is obtained tion. In such cases it is required to produce by which is left to dry in the air or is dried artificial means of the stabilizer a slightly acid medium ly at a moderate temperature of 40 to 50 degrees suitable for the stabilization by adding pH-regu centigrade with agitation. The aforementioned lators which maintain the acidity of the medium powdered constituents of the stabilizer may be on a predetermined value. It is not necessary to 75 mixed also in dry condition, the sugar and starch 2,585,580 7 8 being then gradually added to the stabilizing Composed of two molecules of thio-glucose con mixture proper under continuous agitation. taining in their molecule two sulfur atoms in sub 6 g. of the stabilizer so prepared in powdered Stitution for the reactive oxygen atoms in the form are used per liter of natural material, and Carbonyl groupS in an amount of at least .4% of the stabilizer is added preferably to the hot, ina the amount of aScorbic acid present. terial directly before the latter begins to boil; 2. A method of stabilizing the ascorbic acid the maSS is then thoroughly and unifornly agi in naturally occurring and artificially prepared tated and the boiling operation is effected in productS, comprising the step of adding to such the usual manner for a period as long as nec products as stabilizers diglucosyl-disulfide in an eSSalry. The just mentioned amount of stabilizer 0 amount of at least .4% of the amount of aScorbic is Sufficient to stabilize 2.5 g. or more of ascorbic acid present. acid in 1 liter of jain or the like and therefore is 3. A method of Stabilizing the aScorbic acid in Sufficient for any amount of aScorbic acid which naturally occurring and artificially prepared practically may be present in a natural naterial. products comprising the steps of adding to such The Stabilizer has at the same time a protective products as stabilizers composite thio-Sugars effect against molds and bacteria, so that it is composed of two molecules of thio-glucose con not necessary to add any of the usual preserving taining in their molecule two sulfur atoms in sub agentS, or the addition of Such agents may be stitution for the reactive oxygen atoms and of COnSiderably reduced. also adding adenosine-triphosphoric acid for Sup The Stabilizer thickens (causes to jell) thin porting the effect of the stabilizer. juices and jams in the same way as pectin, and 4. A nethod of Stabilizing the aScorbic acid in preServes fruit and vegetables for a considerable naturally occurring and artificially prepared period in the natural colour of the same. In products comprising the steps of adding to Such the fruit or vegetables processed in this mannel, products as stabilizers composite thio-sugars the original contents of C-vitamin is preserved COmposed of tWO molecules of thio-glucose con for an indefinite period and the physiological taining in their molecule two sulfur atoms in value of the ready product remains the saias as substitution for the reactive oxygen atoms and of the value of the corresponding fresh fruit. further adding pH-regulating buffer mixtures 2. For the Stabilization of a Scorbic acid in containing a free hydroxy-polycarboxylic acid medicaments and similar preparations there is 8 and an alkali metal salt of this acid for support made use of 40 mg. of thic-glucose, 50 mg. of ing the effect of the stabilizer. Crystalline sodium pyrophosphate and 0.3 ing. 5. A Stabilizer for aScorbic acid contained in of acetanilide per 1. g. of a scorbic acid. The naturally occurring and artificially prepared pyro-phosphate may be replaced by an equal productS. Coimprising composite thio-sugars com annount of adenosine-triphosphoric acid. posed of two molecules of thio-glucose contain 3. For injection Solutions stored in sealed glass ing in their molecule two Sulfur atoms in Sub tubes a still lesser amount of stabilizer will be Stitution for the reactive oxygen atoms in the Sufficient. There is made use of 5 mg. of a mix Carbonyl group in an amount of at least .4% of ture comprising 2.3 mg. of thio-glucose and 2. the amount of a scorbic acid present. mg. of adenosine-triphosphoric acid per 100 6. A Stabilizer for the aScorbic acid contained ccm. of injection solution. The injection liquid in naturally occurring and artificially prepared in a Sealed glass tube may be sterilized at 100 productS comprising diglucosyl disulfide in an degrees centigrade for the usual period of about amount of at least .4% of the amount of a scorbic 20 minutes without any loss of ascorbic acid. acid present. 4. In 5 liters of redistilled Water there are dis 3. 7. A stabilizer for aScorbic acid contained in Solved in cold condition 500 g. of the Sodium salt natural or artificially prepared products, com of the l-aScorbic acid, the hydrogen ion con prising composite thio-sugars composed of two centration pH is adjusted to 7.0 by the addition molecules of thio-glucose containing in their of either free aScorbic acid or sodiuin bicarbonate molecule two Sulfur atons in Substitution for the and 5 g. of thio-glucose are added. The solu- : reactive oxygen atoms and adenosine-triphos tion is filled into glass tubes, in which it is phoric acid. sterilized by boiling for 20 minutes and then the 8. A stabilizer for a scorbic acid contained in glass tubes are sealed. The ascorbic acid con natural or artificially prepared products, com tent in tubes of a capacity of 5 ccm. did not prising composite thio-Sugars composed of two change, as it was proved by polarographic meas molecules of thio-glucose containing in their nol urements, even after expiration of 6 months of ecule Sulfur atons in Substitution for the reac storage of the sealed glass tubes in the usual tive oxygen atoms and pH-regulating buffer mix Way. ...tures, containing a free hydroxy-polycarboxylic 5. In 5 liters of redistilled Water there are dis acid and an alkali metal Salt of this acid. Solved in the cold 500 g. Of the Sodium salt Cf.1- 60 JAN OPPL. aScorbic acid, the hydrogen ion concentration pH is adjusted to 7.0 and 2 g. of diglucosyl disul REFERENCES CITED phide are added. The solution so obtained is The following references are of record in the filled into glass tubes where it is sterilised by file of this patent: boiling for 20 minutes and then the tubes are. 65. Sealed. The C-Vitamin content in the Solution UNITED STATES PATENTS did not change, as it was proved by polarographic Number Name Date measurements, even after expiration of six 2,395,069 Ruskin ------Feb. 19, 1946 months of storage of the sealed glass tubes in the 2,427,692 Ruskin ------Sept. 23, 1947 usual Way. 70 OTHER REFERENCES What, it clair is: - 1. A method of Stabilizing the aScorbic acid in Rosenberg: “Vitamins,' page 327, InterScience, naturally occurring and artificially prepared N. Y., 1942. products comprising the step of adding to Such Advances in Carbohydrate Chemistry, vol. 1, products as stabilizers composite thio-Sugars 75 1945. Edited by Pigman et al., pp. 134-135.