KR102768904B1 - Composition for preventing oxidation of oil comprising onion peel extracts - Google Patents

Abstract

The present invention relates to an anti-oxidation composition for fats and oils containing an onion skin extract. By using the extract as an anti-oxidation composition for fats and oils, when the anti-oxidation composition for fats and oils containing an onion skin extract of the present invention is used, the oxidation stability of unsaturated fats and oils containing a large amount of omega-3 fatty acids is increased, and thus the storage period and shelf life can be increased.

Description

Composition for preventing oxidation of oil comprising onion peel extracts

The present invention relates to an anti-oxidation composition containing an onion skin extract.

One of the main chemical reactions of fat, which is one of the main nutrients in food, is oxidation (lipid oxidation). When fat is oxidized, various oxidation products are generated, which causes a decrease in the nutritional and sensory value of food. The most basic mechanism of lipid oxidation is autoxidation. Non-radical fat becomes a radical by external energy and reacts with oxygen, which is a diradical, and the lipid peroxy radical generated through this takes hydrogen from unsaturated fat to become lipid hydroperoxide. In the future, as lipid peroxide is decomposed, volatile substances such as low-molecular compounds such as alcohol, aldehyde, and ketone are generated, and the increase of these leads to an increase in rancidity.

Therefore, it is essential to prevent oxidation in order to store foods containing lipids for a long time. Methods for increasing the oxidation stability of foods include adding antioxidants and reducing the amount of oxidation promoters. Types of antioxidants include free radical scavengers, metal chelators, antioxidant enzymes, and reactive oxygen species scavengers such as singlet oxygen. Free radical scavengers found in nature are mainly known to have an aromatic ring structure, and many are known to be phytochemicals that have one or more hydroxy groups. Synthetic antioxidants are also used, and butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), and tert-butylhydroquinone (TBHQ) are mainly used. However, in the case of synthetic antioxidants, consumers have a negative perception of their safety, and therefore, the development of a natural antioxidant composition derived from natural substances is required. Among natural extracts for preventing oxidation of oils, green tea extract and rosemary extract have been successfully industrialized, but many other natural extracts have not been industrially successful due to their lack of significant antioxidant efficacy.

If high value-added natural antioxidants are produced using discarded natural by-products, the economic effect of cost reduction can also be achieved. The annual production of agricultural and food by-products in Korea is approximately 6,265 tons, some of which are used as livestock feed, but most are discarded (National Institute of Animal Science, 2015). Therefore, it is necessary to develop antioxidant compositions derived from natural by-products that guarantee antioxidant efficacy and stability.

Republic of Korea Publication Patent No. 10-2014-0085314 (Published on July 7, 2014)

The inventors of the present invention have made extensive research efforts to develop an antioxidant composition of oil with improved antioxidant properties while utilizing natural by-products. As a result, they have completed the present invention by elucidating that the antioxidant properties of onion skin extract are excellent, and especially, when used mixed with phospholipids, the antioxidant properties are remarkable.

Accordingly, an object of the present invention is to provide an antioxidant composition containing onion skin extract.

Another object of the present invention is to provide an anti-oxidation composition for the maintenance; and a maintenance composition containing animal oil or vegetable oil.

Another object of the present invention is to provide a method for preventing oxidation of fat, comprising the step of adding an antioxidant composition of the above-mentioned fat to a food containing the fat.

According to one aspect of the present invention, the present invention provides an antioxidant composition for fat containing an onion skin extract.

The inventors of the present invention have made extensive research efforts to develop an antioxidant composition of oil with improved antioxidant activity while utilizing natural by-products. As a result, it was found that the antioxidant activity of onion skin extract is excellent, and especially, when used mixed with phospholipids, the antioxidant activity is remarkable.

Onion (Allium cepa L.) is a perennial plant belonging to the lily family, and has a unique taste and aroma, and is one of the seasoning vegetables that is widely used not only in Korea but also around the world, along with red pepper and garlic. In addition, it has been used as a herbal medicine along with garlic since ancient times in the East, and has been widely used for fever reduction, deworming, detoxification, enteritis, and stroke treatment. Although a large amount of useful ingredients are contained in the onion skin, most research has been on the onion flesh, and research on the onion skin is insufficient.

The onion skin extract used in the composition of the present invention can be purchased or obtained by direct extraction from onion skin. The extraction can be performed after each onion skin is cut or crushed into an appropriate size.

When the onion skin extract used in the composition of the present invention is obtained by direct extraction from onion skin, various extraction solvents such as polar solvents or nonpolar solvents can be used.

Suitable polar solvents include (i) water, (ii) lower alcohols having C1 to C6 (specifically, methanol, ethanol, propanol, butanol, n-propanol, iso-propanol, n-butanol, 1-pentanol, 2-butoxyethanol or ethylene glycol), (iii) acetic acid, (iv) dimethyl formamide (DMFO) and (v) dimethylsulfoxide (DMSO). Suitable nonpolar solvents include acetone, acetonitrile, ethyl acetate, methyl acetate, fluoroalkanes, pentane, hexane, 2,2,4-trimethylpentane, decane, cyclohexane, cyclopentane, diisobutylene, 1-pentene, 1-chlorobutane, 1-chloropentane, o-xylene, diisopropyl ether, 2-chloropropane, toluene, 1-chloropropane, chlorobenzene, benzene, diethyl ether, diethyl sulfide, chloroform, dichloromethane, 1,2-dichloroethane, aniline, diethylamine, ether, carbon tetrachloride and THF (Tetrahydrofuran).

In the present invention, the onion skin extract can be used in the form of a crude extract extracted by a solvent, and can also be used after being purified to a high purity.

The term 'extract' used in this specification has the meaning commonly used in the art as a crude extract as described above, but in a broad sense, it also includes a fraction obtained by further fractionating the extract. That is, the onion skin extract includes not only a fraction obtained by using the above-described extraction solvent, but also a fraction obtained by additionally applying a purification process thereto. For example, a fraction obtained by passing the extract through an ultrafiltration membrane having a certain molecular weight cut-off value, a fraction obtained by separation by various chromatographies (designed for separation according to size, charge, hydrophobicity or affinity), and other fractions obtained through various additional purification methods are also included in the onion skin extract of the present invention. The onion skin extract used in the present invention can be manufactured into a powder state by an additional process such as reduced pressure distillation and freeze drying or spray drying.

The extraction temperature of the onion skin extract of the present invention is not particularly limited, and may be, for example, 0°C to 120°C, and specifically, 15°C to 95°C. In one embodiment of the present invention, the extraction temperature of the present invention is room temperature.

The onion skin used for extraction of the onion skin extract of the present invention may be pretreated through heating. The heating temperature for pretreatment of the onion skin may be 80°C to 250°C. Specifically, the heating temperature for the pretreatment of the onion skin is 80°C to 250°C, 80°C to 230°C, 80°C to 220°C, 80°C to 210°C, 80°C to 200°C, 100°C to 250°C, 100°C to 230°C, 100°C to 220°C, 100°C to 210°C, 100°C to 200°C, 120°C to 250°C, 120°C to 230°C, 120°C to 220°C, 120°C to 210°C, 120°C to 200°C, 130°C to 250°C, 130°C to 230°C, 130°C to 220°C, 130°C to 210°C, 130°C to It can be 200°C, 130°C to 185°C, 130°C to 170°C, 130°C to 155°C, 130°C to 140°C, 155°C to 210°C, 155°C to 200°C, 155°C to 185°C, 155°C to 170°C, 170°C to 210°C, 170°C to 200°C, 170°C to 185°C, 185°C to 210°C, or 185°C to 200°C, and most specifically 140°C, 170°C or 200°C.

The extraction time of the extract of the present invention is not particularly limited and may be, for example, 10 minutes to 24 hours, and specifically, 10 minutes to 24 hours, 10 minutes to 18 hours, 10 minutes to 12 hours, 10 minutes to 9 hours, 10 minutes to 6 hours, 10 minutes to 4 hours, 10 minutes to 3 hours, 10 minutes to 2 hours, 30 minutes to 24 hours, 30 minutes to 18 hours, 30 minutes to 12 hours, 30 minutes to 9 hours, 30 minutes to 6 hours, 30 minutes to 4 hours, 30 minutes to 3 hours, 30 minutes to 2 hours, 45 minutes to 24 hours, 45 minutes to 18 hours, 45 minutes to 12 hours, 45 minutes to 9 hours, 45 minutes to 6 hours, 45 minutes to 4 hours, 45 minutes to It can be 3 hours, 45 minutes to 2 hours, 1 hour to 24 hours, 1 hour to 18 hours, 1 hour to 12 hours, 1 hour to 9 hours, 1 hour to 6 hours, 1 hour to 4 hours, 1 hour to 3 hours, or 1 hour to 2 hours, most specifically 2 hours.

The extract of the present invention can be extracted by a known natural product extraction method. For example, it can be extracted by cold extraction, hot water extraction, ultrasonic extraction, reflux cooling extraction, or heating extraction, but is not limited thereto.

In one embodiment of the present invention, the antioxidant composition of the oil may additionally contain phospholipids. Oxidation of fat occurs at the interface with moisture in the oil. Phospholipids are amphiphilic substances and are located at the interface, and if phospholipids are not sufficiently present, the added extract is less likely to be located at the interface. If phospholipids are present, the phospholipids act as a kind of guide to ensure that the added extract is located between the oil and moisture interface, and are also expected to play a role in increasing the fat solubility of the extract (Fig. 1).

In one embodiment of the present invention, the phospholipid is phosphatidylethanolamine, DMPE (bis (1, 2-dimethylphosphino) ethane), DPPE (1,2-Bis(diphenylphosphino)ethane), DSPE (1,2-Distearoyl-sn-glycero-3-phosphoethanolamine), DOPE (dioleoylphosphatidylethanolamine), phosphatidylcholine, phosphatidylinositol, DDPC (l,2-dimyristoylamido-l,2-deoxyphosphatidylcholine), phosphatidic acid, DLPC (dilauroylphosphatidylcholine), DMPC (dimyristoylphosphatidylcholine), dipalmitoyl phosphatidylcholine (DPPC), It may be at least one phospholipid selected from the group consisting of DSPC (Distearoylphosphatidylcholine), DOPC (1,2-di-oleoyl-snglycero-3-phosphocholine), POPC (1-palmitoyl-2-oleoylphosphatidylcholine), DEPC (diethyl phosphorocyanidate), Phosphatidylglycerol, DMPG (dimyristoyl phosphatidylglycerol), DPPG (dipalmitoyl-phosphatidylglycerol), DSPG (dermatan sulfate proteoglycan), POPG (1-palmitoyl-2-oleoyl-phosphatidylglycerol), Phosphatidylserine, DOPS (dioleoylphosphatidylserine), and lecithin, but is not limited thereto.

In a more specific embodiment of the present invention, the phospholipid is, but is not limited to, 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) or lecithin.

More specifically, examples of usable lecithin include plant lecithins such as soybean lecithin, canola lecithin, corn lecithin, and sunflower lecithin, and animal lecithins such as egg white lecithin, as well as crude lecithin of natural origin, or highly purified lecithin (purified lecithin) obtained by removing impurities such as neutral lipids, fatty acids, carbohydrates, proteins, inorganic salts, sterols, and pigments from crude lecithin, and also includes enzymatic lecithin that has undergone enzymatic decomposition.

In the present invention, it was confirmed that the antioxidant activity of onion skin extract increased through the addition of phospholipids, and in order to explore the possibility of practical industrialization, it was confirmed that when commercially available phospholipids were used and mixed with onion skin, a synergistic effect occurred and the antioxidant activity significantly increased.

In one embodiment of the present invention, the onion skin extract may be extracted with an organic solvent, water, or a mixed solvent thereof.

In a more specific embodiment of the present invention, the organic solvent may be selected from the group consisting of C1 to C6 lower alcohols, petroleum ether, hexane, benzene, chloroform, methylene chloride, ether, ethyl acetate, and acetone. More specifically, the organic solvent may be a C1 to C6 lower alcohol, and even more specifically, methanol or ethanol, but is not limited thereto.

The concentration of the organic solvent, such as the lower alcohols of C1 to C6, petroleum ether, hexane, benzene, chloroform, methylene chloride, ether, ethyl acetate, and acetone, is 1 to 100% (v/v), specifically 1 to 100% (v/v), 1 to 90% (v/v), 1 to 80% (v/v), 1 to 70% (v/v), 20 to 100% (v/v), 20 to 90% (v/v), 20 to 80% (v/v), 20 to 70% (v/v), 40 to 100% (v/v), 40 to 90% (v/v), 40 to 80% (v/v), 40 to 70% (v/v), 50 to 100% (v/v), 50 to It can be, but is not limited to, 90% (v/v), 50 to 80% (v/v), 50 to 70% (v/v), 60 to 100% (v/v), 60 to 90% (v/v), 60 to 80% (v/v), or 60 to 70% (v/v), most specifically 70% (w/w).

In one embodiment of the present invention, the weight ratio of the onion skin extract and the phospholipid may be 1:0.05 to 1:5. More specifically, 1:0.05 to 1:5, 1:0.05 to 1:4, 1:0.05 to 1:3, 1:0.05 to 1:2.5, 1:0.05 to 1:2, 1:0.075 to 1:5, 1:0.075 to 1:4, 1:0.075 to 1:3, 1:0.075 to 1:2.5, 1:0.075 to 1:2, 1:0.1 to 1:5, 1:0.1 to 1:4, 1:0.1 to 1:3, 1:0.1 to 1:2.5, 1:0.1 to 1:2, 1:0.25 to 1:5, 1:0.25 to 1:4, 1:0.25 to 1:3, 1:0.25 to 1:2.5, 1:0.25 to 1:2, 1:0.5 to 1:5, 1:0.5 to 1:4, 1:0.5 to 1:3, 1:0.5 to 1:2.5, 1:0.5 to 1:2, 1:0.75 to 1:5, 1:0.75 to 1:4, 1:0.75 to 1:3, 1:0.75 to 1:2.5, 1:0.75 to 1:2, 1:1 to 1:5, 1:1 to 1:4, 1:1 to 1:3, 1:1 to 1:2.5, 1:1 to 1:2, 1:1.5 to 1:5, 1:1.5 to 1:4, 1:1.5 to 1:3, It may be, but is not limited to, 1:1.5 to 1:2.5, 1:1.5 to 1:2, 1:1.75 to 1:5, 1:1.75 to 1:4, 1:1.75 to 1:3, 1:1.75 to 1:2.5, 1:1.75 to 1:2, 1:2 to 1:5, 1:2 to 1:4, 1:2 to 1:3, or 1:2 to 1:2.5.

According to another aspect of the present invention, the present invention provides an antioxidant composition for the maintenance; and a maintenance composition comprising animal oil or vegetable oil.

In one embodiment of the present invention, the animal oil may be, but is not limited to, fish oil, safflower oil, beef tallow, lard, oxtail oil, beef bone oil, hydrogenated beef tallow, hydrogenated oil, turtle oil, lard, beef tallow, milk oil, cod liver oil, or egg yolk oil.

In one embodiment of the present invention, the vegetable oil may be, but is not limited to, sesame oil, perilla oil, cottonseed oil, peanut oil, rapeseed oil, palm oil, palm kernel oil, palm olein oil, palm stearin oil, palm oil, jatropha oil, coconut oil, lard oil, grapeseed oil, rice bran oil, soybean oil, safflower oil, castor oil, canola oil, corn oil, olive oil, sunflower oil, pepper seed oil, nikka oil, kapok oil, brown rice oil, mixed cooking oil, or margarine.

In the case of an anti-oxidation composition containing the onion skin extract of the present invention and an oil composition containing animal oil or vegetable oil, the oxidation stability of unsaturated oil containing a large amount of omega-3 fatty acid is increased, and thus the storage period and shelf life can be increased.

According to another aspect of the present invention, the present invention provides a method for preventing oxidation of fat, comprising the step of adding an antioxidant composition of the fat to a food containing the fat.

The method for preventing oxidation of the oil of the present invention is an invention that uses a composition for preventing oxidation of oil containing the onion skin extract of the present invention described above, and the overlapping contents therewith are cited, and are omitted to avoid complexity of the present specification.

The present invention provides an anti-oxidation composition for fat containing an onion skin extract, the anti-oxidation composition for fat, and a fat composition containing animal oil or vegetable oil, and a method for preventing oxidation of fat using the anti-oxidation composition for fat.

When the present invention is used, the oxidation stability of unsaturated fat containing a large amount of omega-3 fatty acids is increased, and thus the storage period and shelf life can be extended.

Figure 1 is a schematic diagram showing the mechanism by which antioxidant activity increases in the presence of phospholipids.
Figure 2 shows the results of DPPH (2,2-diphenyl-1-picryl hydrazyl) analysis of onion skin natural extract and phospholipid mixture. (Onion skin extract: phospholipid)
Figure 3 shows the results of ABTS (2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid)) analysis of onion skin natural extract and phospholipid mixture. (Onion skin extract: phospholipid)
Figure 4 shows the results of FRAP (Ferric Reducing Ability of Plasma) analysis of onion skin natural extract and phospholipid mixture. (Onion skin extract: phospholipid)
Figure 5a shows the results of analyzing the effect of increasing antioxidant capacity of onion skin extract in edible oil by adding commercial lecithin through CDA value. (Lecithin X: group not treated with lecithin, Lecithin O: group treated with lecithin)
Figure 5b shows the results of analyzing the effect of increasing antioxidant capacity in edible oil of onion skin extract according to the addition of commercial lecithin through p-Anisidine Value. (Lecithin X: group not treated with lecithin, Lecithin O: group treated with lecithin)

Hereinafter, the present invention will be described in more detail through examples. These examples are only intended to explain the present invention more specifically, and it will be apparent to those skilled in the art that the scope of the present invention is not limited by these examples according to the gist of the present invention.

Example

Example 1: Preparation of onion skin natural extract and analysis of distribution of major antioxidants in onion skin extract

Onion skins were heat-treated at 140℃, 170℃, and 200℃ for 1 hour, respectively, using a convection oven. 70% ethanol was added to the non-heat-treated onion skins and the samples heat-treated by the above method at a ratio of 1:20 (w/v), and extracted for 2 hours at room temperature using a vertical shaker. After that, the residue was removed by vacuum filtration using Whatman paper #2, and the residual ethanol was removed using a vacuum concentrator. After that, the samples were freeze-dried using a freeze dryer and stored in the freezer.

The distribution of major antioxidants in onion peel extracts was analyzed by GC/MS after derivatization, and the results are shown in Table 1 (OE: Onion Peel Extract extracted without heat treatment, OE140: Onion Peel Extract extracted after heat treatment at 140℃, OE170: Onion Peel Extract extracted after heat treatment at 170℃, OE200: Extracted after heat treatment at 200℃).

Retention Time (min) compound OE OE140 OE170 OE200 29.402 Pyrogallol 0.322 0.392 0.55 0.539 32.265 4-hydroxybenzoic acid
(4-Hydroxybenzoic acid) - 0.248 0.695 0.373 32.564 Phloroglucinol
(Phloroglucinol) 1.211 1.919 1.281 0.764 38.032 Vanillic acid - 0.354 0.751 0.605 40.478 Protocatechuic acid
(Protocatechuic acid) 16.794 22.782 54.534 29.177 47.427 Phloroglucinol acid 5.47 5.334 2.405 0.698 68.864 2,6-Dihydroxyacetophenone
(2,6-Dihydroxyacetophenone) 0.349 0.256 0.814 0.335 71.129 Quercetin
(Quercetin) 53.482 57.272 59.205 50.259 71.407 Isorhamnetin 3.578 3.244 4.333 3.055

As shown in Table 1, mainly quercetin and protocatechuic acid were detected in high contents, and the highest content was detected at OE170. Except for phloroglucinol, phloroglucinolic acid, 2,6-dihydroxyacetophenone, and isorhamnetin in the ethanol extract, the contents of the compounds tended to increase as the extract was heated at a higher temperature, but the contents decreased again at OE200. This difference in the degree of extraction is predicted to be due to the fact that some phytochemicals are decomposed from their precursors as the heat treatment progresses, while other phytochemicals form new physical/chemical bonds as the heat treatment progresses or are decomposed due to low thermal stability.

Example 2: Preparation of onion skin natural extract and phospholipid mixture

Dioleoylphosphatidylcholine (1,2-dioleoyl-sn-glycero-3-phosphocholine, DOPC), a type of phospholipid, was mixed with onion skin extract (OE200) that was heat-treated at 200°C in Example 1 and then extracted with 70% ethanol. The onion skin extract and DOPC were mixed in weight ratios of 1:0.1, 1:0.5, 1:1, and 1:2 (w/w).

Example 3: DPPH (2,2-diphenyl-1-picryl hydrazyl) analysis of onion skin natural extract and phospholipid mixture

The antioxidant activity of onion peel natural extract and phospholipid mixture according to the mixing ratio was evaluated using DPPH (2,2-diphenyl-1-picryl hydrazyl) analysis.

The onion skin extract and phospholipid mixture prepared in Example 2 were each dispersed in methanol to prepare samples. 0.25 mL of the sample was added to 0.75 mL of 0.1 mM DPPH solution, vortexed for 10 seconds, and reacted in a dark room for 30 minutes. The absorbance was measured at 517 nm using a UV/VIS spectrophotometer (Jenesis 10UV, Thermo, Waltham, USA). A standard curve was drawn using 0 mM, 0.25 mM, 0.5 mM, and 1 mM ascorbic acid as standard solutions under the same conditions, and the values were converted to mM ascorbic acid equivalent. All experiments were repeated three times, and the results were calculated as the average values, and the results are shown in Fig. 2.

As shown in Fig. 2, it was found that the antioxidant activity significantly increased in all samples to which DOPC was added compared to when DOPC was not added. When DOPC was mixed in a ratio corresponding to 0.1, or 10%, of the onion skin extract, the antioxidant activity increased by more than 70%, showing the highest increase in antioxidant activity. When the ratio of DOPC increased beyond that, the antioxidant activity tended to decrease, but when added in a ratio of 1:2, it was observed to significantly increase again.

Example 4: ABTS (2,2’-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid)) analysis of onion skin natural extract and phospholipid mixture

The antioxidant activity of onion peel natural extract and phospholipid mixture according to the mixing ratio was evaluated using ABTS (2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid)) analysis.

The onion skin extract and phospholipid mixture prepared in Example 2 were each dispersed in ethanol to prepare samples. 7 mM ABTS aqueous solution and 2.45 mM potassium persulfate were mixed in a 1:1 ratio and left at room temperature in the dark for 15 hours to form ABTS radicals. The ABTS radical cation was diluted with ethanol so that the absorbance was 0.700 (±0.050) at 734 nm using a UV/VIS spectrophotometer. 1.9 ml of the diluted ABTS radical cation solution and 0.05 ml of the prepared sample were mixed, vortexed for 10 seconds, left to stand at room temperature in the dark for 6 minutes, and the absorbance was measured at 734 nm. A standard curve was drawn using ascorbic acid as a standard substance, and the values were converted to mM ascorbic acid equivalent. All experiments were repeated three times, and the results were calculated as the average, and the results are shown in Figure 3.

As shown in Fig. 3, up to a 1:0.5 ratio, the antioxidant activity increased as the DOPC ratio increased, but when the DOPC ratio increased beyond that, the antioxidant activity actually decreased, and in the 1:2 sample, the activity was found to be low to the extent that there was no significant difference from the 1:0 sample.

Example 5: FRAP (Ferric Reducing Ability of Plasma) Analysis of Onion Skin Natural Extract and Phospholipid Mixture

The antioxidant activity of onion peel natural extract and phospholipid mixture according to the mixing ratio was evaluated using FRAP (Ferric Reducing Ability of Plasma) analysis.

The onion skin extract and phospholipid mixture prepared in Example 2 were each dispersed in ethanol to prepare samples. The pH of 3.6 was adjusted to 3.6 by adding acetic acid to 300 mM sodium acetate in distilled water. 20 mM FeCl3 in distilled water was prepared. 10 mM Tripyridyl triazine (TPTZ) in 40 mM HCl (10 mM TPTZ in 40 mM HCl) was prepared. The above three solutions (300 mM sodium acetate, 20 mM FeCl3, 10 mM TPTZ) were mixed in a ratio of 10:1:1 (v/v/v). The mixed solution (FRAP reagent) was stirred for 10 minutes and then equilibrated in a 37°C water bath for 10 to 15 minutes. 0.9 mL of FRAP reagent and 0.03 mL of sample were mixed, vortexed for 10 seconds, and left to stand in the dark at room temperature for 30 minutes. The absorbance was measured at 593 nm. A standard curve was drawn using ascorbic acid as a standard substance, and the values were converted to mM ascorbic acid equivalent. All experiments were repeated three times, and the results were calculated as the average value, and the results are shown in Fig. 4.

As shown in Fig. 4, the activity increased in all samples to which DOPC was added, and, as in the ABTS results, the sample with a mixing ratio of 1:0.5 showed the highest antioxidant activity.

Example 6: Analysis of the effect of increasing antioxidant capacity in edible oils of onion skin extract by adding commercial lecithin

An experiment was conducted to analyze whether the antioxidant ability of edible oil increases when lecithin is added to the onion skin extract of the present invention. Lecithin is a type of phospholipid that can be purchased commercially.

Perilla oil was dispensed in 3 g portions and oxidized for 1 hour at 180°C using a convection oven to prepare oxidized oil samples. The prepared oil samples were divided into i) a control group with no antioxidant added, ii) a group with 200 ppm of tert-butylhydroquinone (TBHQ), iii) a group treated with 200 ppm of the 70% ethanol extract (OE) of onion skin that was not heat-treated as prepared in Example 1, and iv) a group treated with 200 ppm of the 70% ethanol extract (OE200) of onion skin that was heat-treated at 200°C as prepared in Example 1. Then, each group was divided again into a group that was not treated with lecithin and a group that was treated with lecithin, and the oxidation stability was compared as follows.

The conjugated dienoic acid value (CDA) and p-AV (p-Anisidine Value) of the prepared samples were measured to evaluate the antioxidant activity of the onion skin extract with added lecithin. Specifically, the CDA value was measured using the known AOCS Ti la-64 method (after dispersing the sample in isooctane, the absorbance was measured at 233 nm using a spectrophotometer), and the p-AV was measured using the known AOCS Cd 18-90 method (after dispersing the sample in isooctane, the sample was stirred with a solution of anisidine dissolved in acetic acid, and the absorbance was measured at 350 nm using a spectrophotometer). The results are shown in Figs. 5a and 5b, respectively.

As shown in Figs. 5a and 5b, when comparing oil samples without lecithin and oil samples with lecithin, there was no significant difference in the CDA results for the control group and oil samples with tert-butylhydroquinone (TBHQ) added (Fig. 5a), but the p-AV results significantly increased, indicating a decrease in oxidation stability (Fig. 5b). On the other hand, in the case of oil samples with onion skin extract added, it was confirmed that the oxidation stability was significantly improved in both the CDA and p-AV results. Through this, it was found that the combination of onion skin extract and lecithin can improve oxidation stability.

Claims (8)

In a composition for preventing oxidation of fat containing onion skin extract and phospholipid pretreated by heat at a temperature of 100℃ to 250℃,
The above onion peel extract is extracted with a mixed solvent of water and lower alcohols of C1 to C6.
A composition for preventing oxidation of oil, wherein the weight ratio of the onion skin extract and the phospholipid is 1:0.05 to 1:5.
delete A composition for preventing oxidation of oil, wherein in claim 1, the phospholipid is dioleoylphosphatidylcholine (1,2-dioleoyl-sn-glycero-3-phosphocholine, DOPC) or lecithin.
delete delete delete An anti-oxidation composition according to any one of claims 1 to 3; and a fat composition comprising animal oil or vegetable oil.
A method for preventing oxidation of fat, comprising the step of adding an anti-oxidation composition of any one of claims 1 to 3 to a food containing fat.