BACKGROUND OF THE INVENTION

The present invention is a composition for reducing or eliminating oxidative deterioration of fats and oils. Such deterioration is often described in terms like rancid and is characterized by off odors, flavors and colors in fats or oils and products containing them. Such fat and oil containing products include foods, cosmetics, pharmaceuticals and the like.

The effects of oxygen on fats and oils over time produces results which adversely affect the quality of fats or oils and the products containing them and therefore reduces shelf life. Acceptable shelf lives of fats or oils and products containing them range from a few weeks to over a year. The reduced shelf-life restricts the amount of time the substance can be transported and stored after manufacture, thereby increasing the manufacturer's cost of distribution. Furthermore, once the consumer has purchased the product, the limited shelf-life requires rapid use before the product acquires offensive characteristics. Consumers may associate the product with its short shelf-life and may be deterred from purchasing the product in the future. There is therefore a great need to develop methods of avoiding the generation of the offensive characteristics in fats or oils and products containing them.

The production of off flavors, odors and colors in products is caused by the reaction of oxygen with the fat or oil contained in the product. Oxidation of fats and oils results in the formation of a fatty acid free radical by cleavage of a hydrogen bond on the

fatty acid chain. Oxygen then reacts with this free radical, forming a fatty acid peroxy free radical, which then reacts with other unsaturated fatty acids to yield a second fatty acid free radical and a fat hydroperoxide. The second fatty acid free radical is free to react with oxygen, which continues the oxidation cycle. The fat hydroperoxide is further oxidized by heavy metals and other radical forming agents to generate aldehydes and ketones. These aldehydes and ketones are the source of the offensive characteristics associated with oxidized fats and oils. There has been a great emphasis on preventing the formation of fatty acid free radicals, fat hydroperoxides and their secondary oxidation products which result in offensive characteristics in products containing fats or oils.

Fatty acid free radicals can be rendered less reactive by the addition of free radical quenchers, also known as antioxidants. Examples of antioxidants include carotenoids, flavonoids, BHA, BHT and tocopherols. Antioxidants react with the fatty acid free radicals, generating a fat hydroperoxide and an antioxidant radical. The antioxidant radical is much less reactive than the second fatty acid free radical otherwise produced and effectively reduces the undesirable reation rates in the oxidation cycle.

Although the reaction with the antioxidant does produce a fat hydroperoxide, further oxidation of the fat hydroperoxide is prevented by removing heavy metals from the fat or oil. Antioxidant synergists, such as citric acid, ascorbic acid, lactic acid and EDTA, sequester heavy metals by forming unreactive metal

chelates. The antioxidant synergists are added to the fat or oil with the antioxidants to prevent heavy metals from reacting with the fat hydroperoxides produced by oxidation. This prevents the fat hydroperoxides from generating secondary oxidation products 5 _. such as aldehydes and ketones. The antioxidant synergists therefore enhance the activity of the antioxidant components.

Because of the improved effect on the reduction of oxidation obtained by combining a fatty acid free radical quencher and a metal chelating antioxidant synergist, natural and synthetic 0 antioxidant compositions containing these substances have been formulated to combat the effects of oxygen on fats or oils. There is a growing trend towards the use of natural antioxidants in response to questions regarding the toxicity of synthetic antioxidants and to the growing consumer preference of products 5 derived from natural sources.

In U.S. Patent No. 5,077,069 to Chang et al., there is disclosed a natural antioxidant composition containing tocopherols, ascorbic acid, citric acid and phospholipids. The antioxidant composition of the Chang patent requires large quantities of 0 antioxidant compounds and antioxidant synergists in order for the composition to be effective. The large amounts of ingredients required, such as tocopherol which is required in an amount from 10% to 62.5% by weight of the composition, are expensive and make the composition cost-prohibitive for certain uses. 5 In European Patent No. 0 326 829 to Lόllger, another natural antioxidant composition containing tocopherols, ascorbic acid and

lecithin is described. This formulation produces an' undesirable red color in the oil to which it is added.

It is an object of the present invention, therefore, to provide a natural antioxidant composition which decreases the _ amount and rate of oxidation of fats or oils, thereby improving the quality and shelf-life of products containing these fats or oils.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a graph of peroxide values in soybean oil as a function of time.

Figure 2 is a graph of peroxide values in tallow as a function of time.

SUMMARY OF THE INVENTION The present invention is directed to a composition for reducing oxidation of fats and oils. The composition comprises tocopherols, β-carotene, citric acid, ascorbic acid and phospholipids. The composition preferably comprises from about 0.33% to about 1.2% tocopherols by weight, from about 0.33% to about 2.4% β-carotene by weight, from about 0.33% to about 1.2% citric acid by weight, from about 33% to about 48.2% ascorbic acid by weight and from about 44% to about 66% phospholipids by weight.

The composition is suitable for use in products containing fats or oils. The composition is added to the product as a weight percent of the fat or oil in the product. Preferably, from about

0.001% to about 0.005% tocopherols, from about 0.001% to about 0.05% β-carotene, from about 0.001 to about 0.005% citric acid, from about 0.1% to about 0.2% ascorbic acid and about 0.2% phospholipid, with all values given by weight percent of the fat or 5 _. oil, are added to the fat- or oil-containing product.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides a natural antioxidant composition wherein the antioxidizing components act 0 synergistically to provide surprisingly low rates of fat and oil oxidation. The composition of the present invention comprises oxygen free radical quenchers and heavy metal chelators which act concomitantly to reduce the level of hydroperoxides formed in the fat or oil. The composition provides superior antioxidant 5 properties over conventional synthetic and natural antioxidant compositions, even when the conventional compositions are supplemented with additional radical quenchers such as β-carotene. None of the conventional antioxidant compositions are able to suppress the hydroperoxide levels as effectively and efficiently as 0 the composition of the present invention.

The composition of the present invention is used by combining it with a product containing fats or oils, adding the composition in an amount based on the weight percent of the fats or oils. The amount of the composition to be added will of course vary depending 5 on the nature of the substance to which the composition is to be added and the conditions to which the substance will be subjected

such as temperature, exposure to oxygen and shelf storage time. The composition is preferably added in an amount comprising from about 0.1% to about 5% by weight of fat or oil, although it is to be understood that greater and lesser amounts will obviously work. 5 _. More preferably, the antioxidant composition is added in an amount comprising from about 0.3% to about 0.5% by weight of fat or oil.

The composition described herein may be used to reduce oxidation of fats or oils in any product containing fats or oils such as foods, cosmetics, pharmaceuticals and the like. The 0 composition reduces oxidation in animal fats and oils such as tallow, butter, lard and fish oils, as well as in fats and oils derived from plant sources, including but not limited to margarine, soybean oil, peanut oil, corn oil, olive oil, coconut oil, palm oil, cottonseed oil, rapeseed oil, sesame oil and other similar 5 fats and oils.

The phospholipids used in the method of the present invention function as a surfactant. Preferably, the phospholipid used is lecithin, such as soybean lecithin. Soybean lecithin comprises a combination of phospholipids including phosphatidyl choline, 0 phosphatidyl inositol and phosphatidylethanolamine. Preferably, the soybean lecithin used to practice the method of the present invention comprises about 20% by weight phosphatidyl choline, about 15% by weight phosphatidylethanolamine and 20% by weight phosphatidyl inositol. 5 It is believed that soybean lecithin functions as a superior surfactant because it is capable of delivering the antioxidant

compounds to the functional site of oxidation. Phosphatidyl choline stabilizes oil-in-water emulsions and therefore aids in the dispersion of tocopherols and β-carotene. Phosphatidyl inositol and phosphatidylethanolamine stabilize water-in-oil emulsions and aid in the dispersion of citric and ascorbic acids to the functional site of oxidation.

The composition of the present invention provides excellent antioxidizing characteristics in comparison with existing antioxidant compositions such as the composition claimed in the Chang patent referred to above. The Chang composition comprises tocopherols, citric acid, ascorbic acid and phospholipids. The formulation in the Chang patent is compared to the composition of the present invention in Table 1:

Table 1 Antioxidant Compositions (percent by weight!

Chang Composition Present Composition

Tocopherols 10% - 62.5 % 0.33% - 1.2%

β-carotene -0- 0.33% - 2.4%

Citric Acid 1.5% - 20% 0.33% - 1.2%

Ascorbic Acid 1.5% - 20% 33% - 48.2%

Phospholipids 26% - 85% 44% - 66%

The composition of the present invention uses far smaller quantities of tocopherols and citric acid which greatly reduces the cost of the antioxidant composition of the present invention when compared to the composition of the Chang patent. 5 _. Although the quantity of antioxidizing components in the present invention is significantly less than that in the Chang composition, the present invention provides unexpectedly superior protection against oxidation, as shown in Example 1.

Example I: 0 Peroxide values of antioxidant compositions with and without β-carotene in soybean oil

The composition of the present invention was added to samples of unstabilized soybean oil containing 0.2% lecithin. The composition was added as 0.005% mixed tocopherols, 0.2% ascorbic 5 acid and 0.005% citric acid, all by weight of the oil. To half the samples thus prepared was added 0.01% β-carotene.

The mixed tocopherols (Covi-Ox T-70™ from Henkel Corporation) used in this Example comprised 9-12% α-tocopherol, 1% β-tocopherol, 60% ₇ -tocopherol and 25-26% .-tocopherol. 0 The composition of the present invention as described above was compared to the antioxidant composition disclosed in Table lb of the Chang patent. The Chang composition described therein comprises 0.1% tocopherols, 0.02% ascorbic acid, 0.02% citric acid, and 0.2% lecithin, all as percent weight of the oil. To this formula was added 0.01% β-carotene for comparison with the composition of the present invention.

The improvement of the present invention over the Chang composition was observed by measuring the peroxide levels in the fat or oil over a period of time representative of a typical shelf- life. All the samples were stored at 45°C (113°F) for three weeks and the peroxide values measured as a function of time. The peroxide levels indicate the amount of fat hydroperoxide present in the fat or oil, which indicates the degree and extent of oxidation. The results obtained are summarized in Table 2.

Table 2 Peroxide values (in Meg/Kg of Antioxidant Composition Added)

Davs Present Chang Chang with Composition Composition β-carotene

0 0.25 0.38 0.25

7 0.25 2.25 0.88

14 0.05 1.12 0.50

21 0.05 1.87 1.24

Figure 1 graphically represents the results obtained in this Example. The fluctuations seen in the peroxide levels are the result of the natural regeneration of peroxides which follows a

dying sine wave pattern. Even when the antioxidant composition of the Chang patent is supplemented with β-carotene, the composition of the present invention provides far superior antioxidant activity. 5 _. Example II:

Peroxide values of antioxidant compositions in tallow The composition of the present invention also provides superior antioxidant characteristics when compared to existing antioxidant compositions conventionally used in fats such as tallow 0 or lard.

The composition of the present invention was added to 15 pounds of tallow containing 0.2% lecithin. The composition was added in the following amounts as a percent weight of the tallow: 0.001% to 0.005% mixed tocopherols, 0.001% to 0.005% β-carotene, 5 0.001% to 0.005% 30% citric acid and 0.1% to 0.2% ascorbic acid in the form of ascorbyl palmitate.

The ascorbic acid was added in the form of ascorbyl palmitate as the palmitic ester allows better mixing of the antioxidant components with the fat due to the increased hydrophobicity 0 conferred by the palmitate chain.

The mixtures of antioxidant compositions and tallow were subjected to accelerated shelf-life testing conditions at 55°C (131°F) for three weeks. These samples were compared under shelf- life testing conditions to tallow without an antioxidizing 5 treatment and tallow mixed with the commercially available antioxidant compositions Ronoxan-A™ (Roche, Inc.), Ethoxyquin™

(Monsanto Co.) and t-butyl hydroxyquinone (TBHQ) (Eastman, Inc.), each at a 0.050% concentration. The peroxide levels were measured as functions of time during this period. The results are summarized in Table 3.

Table 3 Peroxide values (in Meg/Kg of Antioxidant Composition Added)

Figure 2 shows the peroxide levels in tallow as a function of time. The results show that the method of the present invention significantly reduces the peroxide level and maintains it at a low level over extended periods of time and under conditions of stress when compared to conventional antioxidant compositions. The peroxide levels in the control sample follow a dying sine wave pattern which represents the generation and reabsorbtion of peroxides by fats. The conventional antioxidant compositions described above contain a single antioxidizing component, thereby permitting the characteristic dying sine wave pattern to be observed in the fat. The composition of the present invention provides a system of antioxidant components and antioxidant synergists which act concomitantly to prevent the generation of peroxides as observed by the elimination of the sine wave pattern.

Although the present invention has been described with reference to preferred embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention.