Drug – bio-affecting and body treating compositions – Preparations characterized by special physical form – Cosmetic – antiperspirant – dentifrice
Reexamination Certificate
1997-08-14
2003-07-15
Criares, Theodore J. (Department: 1617)
Drug, bio-affecting and body treating compositions
Preparations characterized by special physical form
Cosmetic, antiperspirant, dentifrice
Reexamination Certificate
active
06592880
ABSTRACT:
Method for inhibition of sorbate-induced brown discolorations in cosmetic compositions and foodstuffs, and color-stabilized formulations containing sorbate preservative.
The invention relates to a method for the preparation of color-stabilized cosmetic compositions and foodstuffs containing sorbate preservative and to these compositions themselves.
Sorbic acid (2,4-hexadienoic acid) and its salts, in particular the readily water-soluble potassium salt, have been used worldwide for many years for preserving food-stuffs. Sorbic acid is an unsaturated fatty acid which is distinguished by particular physiological tolerability. Sorbic acid is metabolized in the human body analogously to a fatty acid, is not accumulated and is classified as safe by the scientific advisory committees of the World Health Organization and of the European Union. The ADI (acceptable daily intake) value specified for sorbic acid by both committees, which can be rated as a measure of the physiological acceptability of foodstuff additives, is 0 to 25 mg/kg of body weight and day and is therefore by far the highest ADI value of all preservatives. Sorbic acid and sorbates are regarded as non-allergenic and are therefore also not mentioned in any of the known allergy databanks (for example Leatherhead Food Tolerance Data-banks Project).
The activity of sorbic acid is directed, above all, against yeasts and molds, and to a somewhat lesser extent against bacteria. The activity of sorbic acid depends on the non-dissociated content and therefore on the pH of the goods to be preserved. Because of the high pH of 4.76, sorbic acid is also suitable for preserving weakly acid goods (to pH 6.5), in contrast to other preservatives based on organic acids.
In the solid form, sorbic acid and sorbates are stable. In aqueous solution, in foodstuffs and in cosmetic compositions, however, sorbic acid is subject to oxidative influences. In particular, aldehydes and ketones, which may be the cause of off-flavors, can be formed by oxidative cleavage of the double bonds. Polymerization products of these aldehydes, like the reaction products of these aldehydes with amino acids or other primary and secondary amino groups, can also be responsible for color changes, in particular browning reactions. Such products are called Maillard products and in many cases are responsible for color changes in cosmetic compositions and foodstuffs.
The mechanism of oxidation of sorbic acid and corresponding stabilization measures have in many cases been the subject of scientific studies (Arya, S. (1980); Stability of sorbic acid in aqueous solutions. Journal Agric. Food Chem. 28, 1246-1249; Arya. S., Thakur, B. (1988): Degradation products of sorbic acid in aqueous solutions. Food Chem. 29, 41-49; Ledward, D. (1990); Stability of sorbic acid in intermediate moisture systems. Food Add. Contam. 7, 677-683; Merciadez, M., Mohammed, K., Maniere, F. (1992): Stabilized sorbic acid or salts therefore. U.S. Pat. No. 966,246, Oct. 10, 1992; Thakur, B., Singh, R., Arya, S. (1994): Chemistry of sorbates—a basic perspective. Food Rev. Intern. 10, 71-91). In the context of the abovementioned studies, attempts have been made in some cases to reduce the sorbate-induced brown discolorations and odor changes described for foodstuffs by addition of metal ions (in particular manganese) in a concentration range of 0.1-5 ppm. In addition, color stabilization of, for example, sweetener solutions also by salts of copper, zinc and cobalt has been described. The addition of these metals, which also all have a pro-oxidative action depending on the concentration, to foodstuffs seems unacceptable physiologically. The same applies to cosmetic compositions. There therefore also continues to be the need to prevent sorbate-induced brown discolorations both in foodstuffs and in cosmetic compositions.
On the basis of their good activity against micro-organisms which spoil cosmetics and their particular skin tolerability and physiological safety, sorbic acid has recently been employed increasingly for preservation of cosmetic compositions. Sorbates are the preservatives of choice for cosmetic compositions since:
they act to a particular extent against micro-organisms which spoil cosmetics (for example Pseudomonas aeruginosa)
they prevent the formation of mycotoxins in cosmetic compositions
they have a good skin and mucosa tolerability
they do not irritate the skin
they are not phototoxic
they cause no ecological problems (water pollution class 0)
On the basis of these excellent physiological data, sorbic acid has been classified as “safe” by the CIR Expert Panel, and is approved worldwide for use in cosmetic compositions.
The technological advantages of the use of sorbate in cosmetic compositions are the following:
protection from microbial contamination during storage and use
good compatibility with the raw materials of cosmetics
no inactivation by the contents of cosmetics
“synergistic” effects with other preservatives in cosmetics
high activity at pH values relevant to cosmetics
because of the favorable partition coefficient (the microbiological sensitive aqueous phase remains), particularly suitable for preserving oil-in-water emulsions
no loss of action by reaction with packaging materials
On the basis of these excellent technological properties, sorbates are employed in all cosmetic compositions (for example shampoos, shower gel, body lotion, sunscreen preparations, cleansing milk, facial lotion, self-tanning compositions, decorative cosmetics, oral hygiene products and moist tissues or moist toilet paper). However, it is known from the literature that precisely in cosmetic compositions which are stored for a relatively long time, are exposed to an oxidative influence and comprise amino components, sorbate-induced brown discolorations still lead to problems (Domsch, A. (1994): Die kosmetischen Präparate [Cosmetic Preparations], volume 2: Wassrige und tensidhaltige Formulierungen [Aqueous and surfactant-containing formulations], 4th edition, page .329, Augsburg: Verlag fur die chemische Industrie). The protective measure implemented most frequently to date is the co-use of complexing agents (EDTA or citrates), which slow down sorbate-induced brown discolorations by complexing pro-oxidative metal ions. Modifications to the perfuming are a second possibility. A delay in sorbate-induced brown discolorations can be achieved by both measures. However, the problem mentioned still remains for clear formulations in clear plastic bottles (a formulation which is currently used very often) in particular. Since the brown discolorations described are temperature-dependent, this applies in particular to cosmetic compositions exported to tropical countries.
Since sorbates, because of their antimicrobial activity, can also be used as active compounds in mouthwashes, toothpastes and cleaning compositions for dentures and these products are often available as clear formulations, the use of allantoin as an active compound (anti-inflammatory, analgesic) and an inhibitor of brown discolorations caused by sorbate in oral hygiene compositions is described (Hirohata, H., Ozawa, T. (1993): Composition for dental use. JP 5-339135). However, since they generally comprise no amino components which accelerate discoloration, oral hygiene compositions do not make too high a demand on the browning-inhibiting substance.
Since degradation products of sorbic acid formed oxidatively can react to a particular extent with foodstuff constituents of high nutritional physiology value, such as amino acids, protection of sorbic acid against oxidative changes is also of considerable relevance in nutritional physiology. Studies which describe a reactivity of sorbic acid degradation products with amino acids such as lysine or glutamic acid are available (Ledward, A. D: (1990): Stability of sorbic acid in intermediate moisture systems, Food Add. Contam. 7, 677-683).
There was thus a need for a method which enables cosmetic compositions and foodstuffs to be preserved with sorbic acid without brown coloratio
Aktiengesellschaft
Connolly Bove & Lodge & Hutz LLP
Criares Theodore J.
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