DE4041543C2 - Stabilization of ascorbic acid in strongly acidic solution - Google Patents

Description

Ascorbic acid finds a diverse application as Vitamin addition, antimicrobial or antioxidant additive to Food, pharmaceutical or cosmetic preparations, Disinfectants and cleaning agents and the like. Disadvantageous for the use which affects especially in Solutions existing tendency to decomposition. The Stability optimum lies in the range pH 5.4 (Hagers manual) and pH 6.0 (Yakuzaigaky 21, 177-180, 1961). In strongly acidic aqueous solution shows ascorbic acid after just a few weeks Storage significant decomposition.

From the literature is known the stabilizing effect of Ethanol. For example, in T'ai-wan K'o Hsueh 30, 153-159, 1976 described that ethanol has a stabilization maximum in weakly acidic solution at pH 6.0 and an addition of 20% having.

However, this is strong for many applications, especially in the acidic area insufficient. The object of the invention is therefore the stabilization of ascorbic acid in acidic solutions, especially in solutions with a pH of 2.

Surprisingly, it has been found that polyoxyethylene polyoxypropylene polymers such as Pluronic F68, Synperonic P94 or Synperonic P103 the stability of Ascorbic acid improves and the additional use of Ethanol still causes a synergistic effect. Another Surprising stability improvement was finally by achieved an addition of sodium hydrogen sulfite.

The invention is therefore a stable aqueous Ascorbic acid solution prepared from 0.1-20% ascorbic acid, 20-70% Ethanol, 5-25% polyoxyethylene-polyoxypropylene polymer and 0-0.5% sodium hydrogen sulfite.

Another object of the invention are means for Stabilization of ascorbic acid solution prepared from 20-70%  Ethanol, 5-25% polyoxyethylene-polyoxypropylene polymer and 0-0.5% Sodium bisulfite. These funds come in liquid Form for use by addition to the to be stabilized Solution.

Another object of the invention is the use of Polyoxyethylene-polyoxypropylene polymers, preferably 5-25% to Stabilization of aqueous ascorbic acid solutions. Is preferred the additional use of ethanol, preferably 20-70% based on the solution to be stabilized. Most notably preferred is the additional use of Sodium hydrogen sulfite, preferably 0.05-0.5% based on the stabilizing solution.

The following examples and tables serve for Illustrating the invention.

In Table 1, the composition of 3 is strongly acidic Solutions described only in Pluronic content and thus also differ in the water content.

As shown by ascorbic acid levels after 1 month storage + 37 ° C, + 45 ° C and + 60 ° C, the formulations B show and C lower salary decreases than the formula A. This stabilizing effect of Pluronic F68 on ascorbic acid in strongly acidic solution (pH value 2.0) increases with increasing Concentration of Pluronic too.

Table 1

Table 2 compares formulations that all contain the same content of Pluronic F68 but have different Have content of ethanol and thus also to water. After 1 Monthly storage at + 37 ° C are no differences in the Determined ascorbic acid contents.

In the storage conditions + 45 ° C and + 60 ° C also performs in These strongly acidic solutions increase the ethanol content to one Improving the stability of ascorbic acid.

Table 2

In Table 3, both the formulations A and D and F and G differ only by the addition of NaHSO ₃ . When comparing the ascorbic acid contents of the formulations A and D after 1-month storage, only a slight improvement in ascorbic acid stability can be detected by the addition of 0.2% NaHSO ₃ in the 37 ° C. and 60 ° C. pattern.

When comparing the ascorbic acid contents of formulations A and F After heat load (37 ° C, 45 ° C, and 60 ° C) shows a clear stabilization with the addition of 10% Pluronic and increasing the ethanol content.

Although the formulations F and G differ only by 0.2% NaHSO ₃ , the formulation G delivers clearly higher ascorbic acid contents under all storage conditions.

Since the addition of NaHSO ₃ alone in Formulation D gave no substantial stabilization over Formulation A, it can be concluded that only the combination of Pluronic and increased ethanol content (ie greater than 10%) with sodium bisulfite leads to the desired stabilization.

Table 3

In Table 4 is again the stability of ascorbic acid with respect to water and HCl, compared with the Recipe G. It is illustrated that anhydrous Ascorbic acid in the different storage conditions is completely stable, the addition of water and aqueous However, hydrochloric acid solution to a drastic decrease in Stability leads, whereas the inventive formula only has a low decomposition rate.

Table 4

From these analysis findings, stabilization becomes strong acidic ascorbic acid solutions have the following composition proposed:

Ascorbic acid | 0.1% -20% Ethanol 96% 20% -70% Polyoxyethylene polyoxypropylene polymer 5% -25% sodium bisulfite 0.05% -0.50% Inorganic or organic acids @ for adjusting a pH value 2.5 Purified water, ad 100%

Claims (4)

1. Stable, aqueous ascorbic acid solution, characterized in that it contains 0.1-20% ascorbic acid, 20-70% ethanol, 5-25% polyoxyethylene-polyoxypropylene polymer and 0-0.5% sodium hydrogen sulfite. 2. ascorbic acid solution according to claim 1, characterized characterized in that it contains 3.5% ascorbic acid, 50% Ethanol, 0.3% hydrochloric acid (25%), 10% polyoxy ethylene-polyoxypropylene polymer and 0.2% sodium contains hydrogen sulfite. 3. Process for the preparation of stable ascorbic acid Solutions according to claim 1 or 2, characterized gekenn characterized in that ent. 0.1-20% ascorbic ent holding aqueous solutions to a level from 20-70% ethanol, to a content of 5-25% Polyoxyethylene-polyoxypropylene polymer, up to a content of 0.5% sodium hydrogen sulfite and optionally up to a content of 0.3% salt acid (25%) added. 4. Means for carrying out the method according to Claim 3 containing ethanol, polyoxyethylene polyoxypropylene polymer, sodium hydrogen sulfite and optionally hydrochloric acid (25%).