KR20150050214A - Preparing method for onion peel extract - Google Patents

Abstract

The present invention provides a method for manufacturing onion skin extracts, comprising the steps of primary washing, primary drying, secondary washing, and secondary drying. The manufacturing method according to the present invention produces the onion peel extracts whose chemical residues from pesticides are reduced while their contents of functional materials are increased.

Description

TECHNICAL FIELD The present invention relates to an onion peel extract,

The present invention relates to a method for producing an onion skin extract, and more particularly, to an extraction method capable of increasing quercetin content in onion skin extract and removing pesticide residues in the extract by washing with hydrogen peroxide.

In recent years, interest in health has been increasing due to the social arrival of aging society and the improvement of income level. In addition, among the causes of death in Korea, vascular diseases including heart diseases and cerebral diseases are rapidly increasing. This is not merely a problem of blood circulation but is caused by a cardiovascular disease such as atherosclerosis, angina pectoris, cerebral infarction, will be. In order to prevent such diseases, consumers' desire for related functional food is increasing.

Onion is a perennial plant belonging to the lily family and is a representative spice widely used in the world. Among the components of the onion, compounds such as quercetin, quercitrin, rutin, flavonoid-based coloring matter and allyl propyl disulfide are contained and antioxidant activity (Hertog et al., 1993 ) Have been reported to be beneficial to health because they are effective in suppressing allergic reactions (Middleton et al., 1981), lowering cholesterol (Jain et al., 1973), and increasing blood circulation (Haldeman et al., 1987).

Onion is a food rich in polaronoids. Flavonoids are one of the pigment components distributed in the stem, root, and skin of plants, including fruits, vegetables and nuts. It is a collective name for phenolic compounds. Flavonoids are known to have antioxidants that have a physiological effect of stabilizing free radicals, as well as anti-arteriosclerosis, antimicrobial, anticancer, antiviral and antiallergic activity, with little toxicity. They are present in the free state in nature, but in most cases they exist in the form of glycosides in association with saccharides. Saccharides forming these glycosides are easily hydrolyzed by acids, alkalis, enzymes, etc., The physiological activity is known to be stronger.

Flavonoids are known to have different physiological functions depending on their structural characteristics. The flavonoids are known to have different physiological functions, such as a -OH group in the benzene ring, a double bond between 2 and 3 carbon atoms, a carbonyl group in the carbon position 4, and -OH The antioxidant activity is obtained.

The flavonoids mainly contained in onion are quercetin 4-glucoside, quercetin 4,7-diglycoside, quercetin 3, quercetin 3, 7-diglycoside, quercetin aglycone and the like, and it is contained at a level of 0.06 to 1 g per kg. However, flavonoids have higher contents in the onion skin than in edible parts of onion, and onion shells contain 10 times (2 ~ 20g / kg) more flavonoid than the edible parts and about 80% are quercetin diglycoside, It is present in the form of aglycone such as monoglycoside, quercetin aglycone. In Korea, it has been reported that it has been used as a folk remedy because it is effective for blood pressure lowering and diabetes, and it has been shown that it inhibits DNA damage and inhibits lipid peroxidation of erythrocyte membrane. The onion skin contains about 50% of many carbohydrates. The onion contains about 0.4 ~ 0.5% of dietary fiber, while the onion skin contains 25 ~ 32% of dietary fiber. Therefore, it is expected that the physiological functional activity of processed food using onion skin is higher than onion.

However, when extracts or health supplements are produced using byproducts of agricultural products, concentrated pesticides are used. Therefore, the pesticide residues contained in the byproducts of agricultural products are extracted together and are often problematic.

In order to remove pesticide residues in agricultural products, it has been reported that water-washing of spinach, sesame leaves, and biosynthetic inhibitor (CaO from shellfish) or the removal of residual pesticides by using photosensitizer / photocatalyst in crops, No studies on the safety of health functional foods have been attempted at all. The Korea Food and Drug Administration has not yet established standards for this, and when using raw materials for which pesticide residue tolerance standards are set in food circulation, (2011), but the specifications for the shell, a by-product of onion, have not yet been established.

Procymidone is an organic chlorine-based pesticide used in onion cultivation. As a result of analyzing the residual amount of pesticide residues in the cultivation soil of Korea (agricultural product main production area, large-scale facility cultivation area and environment friendly agricultural product producing area, 2003) It is used in crops such as grapes, cucumbers, onions, strawberries, tomatoes, peppers (including sweet peppers), watermelon, peaches, leeks, lilies, gerberas and grass. Proximidone is a very stable compound such as hydrolysis or decomposition by microorganisms. It is reported to have a half life of 248 days (room temperature incubation, 25 ℃) and 330 days (indoor incubation, 10 ℃) It has been reported that the decomposition rate is fast at the temperature.

Therefore, it is necessary to try to approach the washing process of alkaline condition in order to reduce excessive amount remaining in the onion skin. However, since the flavonoid compound which is a functional ingredient of onion has a structural change in alkali, .

Consumer awareness survey on the quality control of agri-food products showed 39.2% of origin (34.9%), safety (34.9%) and price (10.1%) as the criteria to choose when purchasing agricultural products. (48.3%) among the harmful substances are considered to be the most dangerous factors. Therefore, in the process of extracting physiological functional ingredients from agricultural products and formulating them into health functional foods, the residual pesticides are reduced and the content of physiological functional ingredients There is a need to develop a technique for increasing the machining process.

KR 10-2013-0095121A

The present invention aims to provide an extraction method for reducing the residual pesticide and increasing the content of functional active ingredients in the extract in the method for producing an extract using an onion by-product.

The method for producing an onion skin extract according to the present invention comprises the steps of washing the onion skin and washing the onion skin; A second washing step of treating the primary dried onion skin with aqueous hydrogen peroxide (H ₂ O ₂ ) and washing with a detergent; A second drying step of drying the second washed onion skin; And an extraction step of adding an extraction solvent to the secondary structure.

Unless otherwise specified in the specification of the present invention, quercetin is a functional substance abundantly contained in vegetables and fruits, especially onions, in the form of routines, such as glycosides. The quercetin has been used as an antioxidant, which is a food additive that prevents a food from being deteriorated. However, recently, the function of oxidative damage of cells, antioxidant activity, antimicrobial activity, Interest in applications related to materials such as health functional foods and therapeutic agents is increasing.

In the specification of the present invention, the hot air drying is performed by heating the air with an electric heater, a gas burner or a heat exchanger using water vapor, blowing the air into the drying object, heating the water with hot air and evaporating, Means a drying method by forced circulation.

Hereinafter, the present invention will be described in more detail.

In the specification of the present invention, the onion skin includes all the byproducts generated in onion processing, and refers to an onion skin, specifically, an orange onion skin, and may include a stem or a root of an onion.

The onion skin can be washed and powdered to maximize the contact area with the extraction solvent to increase the extraction yield. Therefore, the step of preparing the onion skin extract of the present invention may further include a step of preparing the onion skin powder.

In the present invention, the step of washing and drying the onion skin may be performed by washing the onion skin, which is an onion by-product produced during the processing of the onion, and drying the washed onion skin.

The method of washing the onion skin can be carried out by a food material washing method commonly used in the field of food manufacturing technology, preferably by washing with a detergent.

The detergent may preferably be a detergent of the first kind. The above-mentioned one kind of cleaning agent means one kind of cleaning agent according to the Ministry of Health and Welfare, and includes all the cleaning agents that are used by people to eat and wash vegetables or fruits. Specifically, the first kind of cleaning agent is a cleaning agent having a pH of 6.0 to 10.5, a methyl alcohol content of not more than 1 mg / g, an arsenic content of not more than 0.05 ppm and a heavy metal content of not more than 1 ppm, and no fluorescent whitening agent. In the case of using the above-mentioned one-kind cleanser, the problem of heavy metals or toxic substances may not be caused in the step of pretreating the raw material for producing food extract, and the step of rinsing with water may be reduced, so that the manufacturing process can be efficiently performed.

The above-mentioned first-class detergent is not limited to the formulation and can be used. The concentration of the first detergent may be adjusted within a range that is obvious to a person skilled in the art depending on the weight of the object to be cleaned.

The primary drying step may be performed according to a drying method commonly used in the technical field of the present invention. Examples of the drying step include both blow drying, natural drying, hot air drying, high temperature drying, low temperature drying and cold air drying do.

The primary drying step may be performed by a method of hot air drying, and most preferably, a method of treating a drying object by hot air at 70 to 90 ° C. When drying is carried out using the hot air of the above range, it can be effectively dried without excess loss of the functional component etc. of the drying object.

The primary drying time was different depending on the drying method, and the drying time could be adjusted within a range apparent to the ordinary artisan. For example, when drying is performed using hot air at 70 ° C to 90 ° C, it is preferable to treat the dried product with hot air for 20 to 30 hours. If the drying time is more than 30 hours, the moisture of the dried material is evaporated too much and the efficiency of the subsequent processing step is lowered. If the drying time is less than 20 hours, the moisture of the dried material can not be uniformly evaporated.

In the present invention, the second washing step includes treating the onion skin with aqueous hydrogen peroxide (H ₂ O ₂ ) and washing with a detergent.

The step of treating the onion skin with hydrogen peroxide water (H ₂ O ₂ ) includes a method of treating the onion skin with flowing hydrogen peroxide water, a method of spraying hydrogen peroxide water onto the onion skin or a method of treating the onion skin by immersing the onion skin in hydrogen peroxide water Method can be used, preferably, by a method of immersing in hydrogen peroxide water for 3 to 9 minutes, more preferably 5 to 7 minutes.

The hydrogen peroxide solution (H ₂ O ₂ ) is not limited to the concentration but may preferably be subjected to secondary washing using an aqueous solution of hydrogen peroxide in an amount of 0.1 to 0.5% (v / v) In the case of using an aqueous solution of 0.2 to 0.4% (v / v) hydrogen peroxide, the loss of the onion skin is less than that of washing once more with the detergent, and in particular, the cell walls of the onion skin are destroyed to facilitate the extraction of the functional substance contained in the onion skin Therefore, the extraction of the functional material during the extraction process can be effectively performed to produce the extract having a high content of the functional substance.

The step of washing with the detergent may be carried out in a conventional manner in the technical field of the present invention, and the detergent may preferably be a detergent. In the case of using the above-mentioned one-kind cleanser, the problem of heavy metals or toxic substances may not be caused in the step of pretreating the raw material for producing food extract, and the step of rinsing with water may be reduced, so that the manufacturing process can be efficiently performed.

The above-mentioned first-class detergent is not limited to the formulation and can be used. The concentration of the first detergent may be adjusted within a range that is obvious to a person skilled in the art depending on the weight of the object to be cleaned.

The second washing step may be carried out by removing the onion skin that has been immersed in the hydrogen peroxide solution and washing with a detergent. After the first washing, second washing is performed using hydrogen peroxide water, and onion skin extract In the case of manufacturing, hydrogen peroxide water effectively generates OH in the alkali solution, thereby inducing dissociation of hemicellulose and lignin-binding substance, which are tissue structures such as straw, thereby increasing the content of quercetin contained in the extract, The residual pesticide residues in the onion skin extract can be effectively reduced.

In the present invention, the second drying step may be performed by drying the secondarily washed onion skin, and may be carried out in accordance with a drying method commonly used in the technical field of the present invention. For example, Hot air drying, high temperature drying, low temperature drying and cold air drying.

The secondary drying step may be performed by a hot air drying method, and most preferably, a method of treating a drying object with hot air at 70 to 90 ° C. When drying is carried out using the hot air of the above range, it can be effectively dried without excess loss of the functional component etc. of the drying object.

The secondary drying time was different depending on the drying method, and the drying time could be adjusted within a range apparent to the ordinary artisan. For example, when drying is performed using hot air at 70 ° C to 90 ° C, it is preferable to treat the dried product with hot air for 20 to 30 hours. When the drying time is more than 30 hours, the moisture of the dried material is evaporated too much and the efficiency of the processing step is deteriorated later. When the drying time is less than 20 hours, the moisture of the dried material can not be uniformly evaporated.

In the present invention, the extraction step may be carried out by adding an extraction solvent to the secondary structure.

The extraction solvent is at least one selected from the group consisting of water and an organic solvent. The organic solvent is ethanol, a polar solvent such as an alcohol having 1 to 5 carbon atoms, ethyl acetate or acetone containing methanol, a nonpolar solvent of benzene, hexane or dichloromethane, or a mixture thereof, preferably 1 to 5 carbon atoms Lt; RTI ID = 0.0 > 5 < / RTI > of alcohol and water. The extraction step may more preferably use 40% to 60% of ethanol as an extraction solvent by adjusting the mixed solvent to a pH of 5.0 to 6.0. When the onion skin extract is prepared using the above-mentioned extraction solvent, an extract containing highly functional substances such as quercetin in the onion skin can be prepared.

The onion skin extract may be one prepared by a conventional method for producing a plant extract. More specifically, the extraction process may be carried out by adding an extraction solvent to the onion skin removed from the impurities. The extraction process may be a cold extraction method, a warm extraction method, a pressure extraction method, or an ultrasonic pulverization extraction method.

After the extraction process, the extract may be subjected to a vacuum filtration process or may be further concentrated and / or lyophilized to concentrate or remove the solvent.

Accordingly, the extract of the present invention is not limited to the formulations, but may include liquids and solids, and may be in the form of a powder, for example, a liquid mixed with an extraction solvent, or a powder obtained by concentrating or lyophilizing an extract.

The extraction temperature in the extraction step may be adjusted according to the extraction solvent within a range obvious to those skilled in the art, and is not limited to the temperature. For example, the extraction temperature may be 40 to 60 Lt; 0 > C and stirring for 2 hours to 4 hours. When the mixed solvent of 40% to 60% of ethanol and water is used as an extraction solvent by adjusting the pH to 5.0 to 6.0, the extraction can be performed at an extraction temperature of 47 to 53 ° C. In this case, the extract having a high quercetin content Can be effectively produced.

The method for producing an onion skin extract of the present invention may further comprise the step of separating the extract obtained in the extracting step by filtering the extract and the onion skin.

In addition, the method for producing an onion skin extract of the present invention may further include a step of filtrating under reduced pressure after the extraction step or the separation step.

The vacuum filtration is not limited as long as it is a vacuum filter commonly used in the technical field of the present invention. Preferably, a vacuum filtration method using a filter plate can be used. Further, the filtration plate may contain diatomaceous earth Can be preferably used. The onion skin extract, which has undergone the reduced pressure filtration using the filter paper containing the diatomaceous earth, can remove or reduce the content of the residual pesticide extracted together with the extract, thereby solving the risk of the residual pesticide which is a problem in the past.

The filter plate may contain diatomaceous earth at 0.5 g / ml to 0.8 g / ml. When the content of the diatomaceous earth is less than 0.5 g / ml, the removal effect of the residual pesticide contained in the extract is poor, and when the amount of the diatomaceous earth is more than 0.8 g / ml, the yield after extraction is reduced and other substances in the extract are caught, It is effective to perform filtration including diatomite within the above range so as to remove the extract having a high content of the functional substance including quercetin while effectively removing residual pesticide.

According to the method for producing an onion skin extract of the present invention, an extract having a high content of quercetin, flavonoid and phenol can be effectively produced while remarkably reducing the content of pesticide residues contained in the extract, And it could contribute to industrial development by securing stability.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a flowchart showing a process for producing an onion skin extract according to a washing method. FIG.
Fig. 2 is a diagram showing the HPLC analysis result (A) of the standard quercetin and the HPLC analysis result (B) of the onion skin extract of the present invention.
3 is a flow chart showing a process for producing an onion skin extract according to a filtration method.
FIG. 4 is a graph showing the results of analysis of the contents of total phenol, total flavonoid and quercetin contained in the onion skin extract according to the filtration method, wherein the abscissa represents the content (mg / g), and the vertical axis represents the treatment group according to the filtration method. The contents are shown in the unfiltered group (F1), 0.40 g of the diatomite added treatment group (F2) and 0.66 g of the diatomaceous earth added treated group (F3).
5 is a graph of a standard calibration curve of gallic acid.
Figure 6 is a quercetin standard calibration curve graph.

Hereinafter, the present invention will be described in more detail with reference to the following examples. However, the scope of the present invention is not limited by these examples in accordance with the gist of the present invention.

[Example 1] Preparation of materials and production of onion skin extract

Onion peels used in this experiment were harvested from Changnyeong, Gyeongsangnam-do, Korea and used in Changnyeong Fish Nonghyup cooperative and onion processing factory after removal of impurities and contaminants.

The onion skin extract was prepared under the same treatment conditions as in Fig. Specifically, 10 kg of onion skin (A) was mixed with washing water (water) at a concentration of 0.2% (w / v) Followed by primary drying for 24 hours to obtain a dried onion skin (B). Next, the dried onion skin was divided into four treatment groups and each was subjected to a secondary washing process. (D) was sonicated for 10 minutes at 50 DEG C using an ultrasonic washing machine (Mujigae Co., Ltd., Korea), and then washed with a detergent Treated with the same condition as the treatment group (DW). The hydrogen peroxide solution and the detergent treatment group (E) were prepared by mixing the water (water) with the hydrogen peroxide solution at 0.3% (v / v). The dried onion skin was dipped for 6 minutes and then washed under the same condition as the detergent treatment group. In the hot water and the detergent treatment group (F), the onion skin (B), which had been primarily dried in hot water at 95 to 97 ° C, was immersed for 2 minutes and then rinsed under the same condition as the detergent treatment group. In the second washing step, the first washing agent was washed with water mixed with water at a concentration of 0.2% (w / v).

The onion bark of each treatment group was subjected to secondary drying for 24 hours with hot air at 80 ° C, and citric acid (manufactured by Ehwa Industrial Co., Ltd., Korea) was added to 60% (v / v) ) Was added to the second dried onion skin at a ratio of 1: 1.5 (w / v), and the mixture was stirred at 50 ° C for 3 hours to obtain an onion extract.

The extract was separated from the onion skin and the extract through a 60-100 mesh filter mesh, and the concentrate was concentrated to 1 to 1.5 Brix. The concentrate was vacuum-freeze-dried using a vacuum freeze dryer (PVTFD 10R, Ilshin, Korea) as a test material.

[Example 2] Confirmation of washing method for increasing quercetin content and reducing pesticide residue

Example 2-1. Confirmation of second washing method by confirmation of loss of onion skin

100 g of onion skin was subjected to the second washing step under the same conditions as in Example 1, and 60% ethanol was added thereto and stirred for 3 hours. The onion skin extract was lyophilized to give an onion skin extract powder, The yield was confirmed. The analytical results of the above-mentioned yields are shown in Table 1 below.

Secondary cleaning method -
(Primary washing) Cleaner (C) Ultrasonic and Cleaner (D) Hydrogen peroxide water and detergent (E) Hot water and detergent (F) Yield of onion skin extract (g) 3.74 2.76 2.79 3.33 1.65 Relative yield (% by weight) of onion skin extract 100 73.80 74.60 89.04 44.12

As shown in Table 1, the amount of onion skin extract obtained in each treatment group was 2.76 g in the detergent-treated group (C), 2.79 g in the ultrasonic and detergent-treated group (D) 3.33 g in the detergent treated group (E), and 1.65 g in the hot water and detergent treated group (F). The relative yields (w / w) of the secondary washing-treated groups were 73.80% by weight in the detergent-treated group, 74.60% by weight in the ultrasonic and detergent-treated groups, 89.04% by weight in the group and 44.12% by weight in the hydrothermal and detergent treated groups.

According to the above results, in the case of secondary washing with hot water and detergent, the onion skin was excessively collapsed due to the heat treatment, and the dissolution of the water soluble substance was easily performed, and the weight loss of the onion skin was high, Hydrogen peroxide solution and detergent. Therefore, it was confirmed that the loss of the onion skin extract can be reduced by the second washing using the hydrogen peroxide solution and the detergent.

Conduct 2-2. Identify the second washing method according to the content of quercetin

In order to confirm the content of quercetin contained in each treatment group according to the washing method, the content of quercetin was analyzed using the onion skin extract extracted under the conditions of Example 1 above.

0.02 g of the freeze-dried extract of onion skin obtained in Example 1 was dissolved in 40 ml of 60% ethanol and 5 ml of 6 N HCl, refluxed at 95 ° C for 2 hours, concentrated under reduced pressure, 50 ml, filtered through a 0.45 μm filter, and used as the test solution.

Was by using a HPLC system (Hewlett Packard 1100 series, USA) analyzing whether or not to include quercetin, a column for analysis was performed using a _{ZORBAX C 18 (4.6 × 150 mm} , 5 ㎛, XDB-C 18, Hewlett Packard, USA), In the mobile phase, water (5% acetic acid): acetonitrile (40%: 30%: 30%) was detected with PDA (370 nm), moving speed of 1.0 ml / min, injection volume and 20 μl And the presence or content of quercetin in each treatment group was confirmed.

The results of confirming the presence of the quercetin are shown in FIG. 2, and the contents of quercetin are shown in Table 2.

Secondary cleaning method -
(Primary washing) Cleaner (C) Ultrasonic and Cleaner (D) Hydrogen peroxide water and detergent (E) Hot water and detergent (F) Yield of onion skin extract (g) 3.74 2.76 2.79 3.33 1.65 Relative yield of onion skin extract 100 73.80 74.60 89.04 44.12 Quercetin content (mg / g) 295.75 + - 6.43 325.31 + - 7.75 329.22 + - 2.43 321.48 ± 1.26 311.61 ± 2.91 Total quercetin content (mg / g) 1105.51 897.88 918.55 1070.53 514.16 Total quercetin (%) 100 81.22 83.09 96.84 46.51

As shown in FIG. 2, the extract of the present invention showed the same peak point as HPLC of standard quercetin, confirming that quercetin was contained in the onion skin extract extracted by the above method. As a result, quercetin was detected as a representative functional substance And the effect experiment was performed according to the extraction method.

As shown in Table 2 above, it was confirmed that the yield of the extract powder obtained from the onion skin was highest in the hydrogen peroxide solution and the detergent-treated group (E) in the second washing step. In particular, there was not much loss in yield compared with the rough treatment group only in the first washing step. The quercetin content of the onion skin after each washing step was 295.75 mg / g for the first washing (B), 325.32 mg / g for the second washing (C), and ultrasonic and detergent (D) 329.33 mg / g, hydrogen peroxide water and detergent treated group (E) 321.48 mg / g, and hydrothermal and detergent treated group (F) 311.61 mg / g.

The increase in the quercetin content of the second wash group compared to the first wash group (B) was due to the removal of some water-soluble substances through the second wash process, and the quercetin content in the onion skin extract was relatively increased Respectively.

According to the above Table 2, the quercetin content per 1 g of the ultrasonic and detergent extract (D) is the highest, but when judged together with the yield of the powder extracted from the onion skin of Example 2-1, The amount of quercetin extracted was 1070.53 mg / g in the hydrogen peroxide solution and the detergent treatment group (E), which was higher than the ultrasonic and detergent treatment group (D). The quercetin content of each of the secondary washing treatment groups treated with the primary washing only was 81.22% by weight of the cleaning agent treatment group (C), 83.09% by weight of the ultrasonic cleaning agent treatment group (D) Of the onion skin before treatment and 96.84% by weight of the cleaning agent treatment group (E) and 46.51% by weight of the hydrothermal and cleansing agent treatment group (F) It was confirmed that this is a washing method capable of obtaining a skin extract.

Examples 2-3. Identification of cleaning methods according to residual pesticides

100 ml of acetonitrile was added to 50 g of the onion skin extract obtained in Example 1 in order to establish a washing method capable of reducing the residual pesticide, and then the mixture was homogenized in a homogenizer (WiseTis (R) Homogenizer And homogenized at 5,000 rpm for 3 minutes. After filtration under reduced pressure, the filtrate and 10 g to 15 g of sodium chloride were placed in a 150 ml separating bottle. The stopper was capped and shaken for 1 minute and left to stand for about 1 hour to separate the acetonitrile layer and the water layer. For GC analysis, 10 ml of the acetonitrile layer as the supernatant was taken and concentrated under reduced pressure. The residue was redissolved in 1 ml of n-hexane containing 20% acetone. The redissolved sample was added to the top of a pre-activated Sep-Pak (Florisil cartridge, Waters, USA) and the sample was eluted with 8 ml of 20% acetone-containing n-hexane and received in the same test tube. The eluate was concentrated to a fine concentration and then redissolved in 1 ml of n-hexane containing 20% acetone to use as an analytical sample. Conditions for measuring the residual amount of procymidon in onion skin extract were as shown in Table 3 below. Table 4 shows the results.

GC Agilent 7890A Column DB-5 (30 m x 0.25 mm I.D., 0.25 m) Inlet Temperature: 250 ° C, split mode (30: 1) Detector GC-ECD Temperature: 320 ° C, Make up (N ₂ ): 60 ml / min Oven (1 minute hold) → 10 ° C / min → 220 ° C → 5 ° C / min → 240 ° C → 10 ° C / min → 300 ° C (12 min hold)

Residual pesticide Secondary cleaning method A B C D E F Prosidone
(mg / kg) 217.81 ± 12.57 133.46 ± 3.93 128.47 + - 10.29 133.67 ± 21.71 128.01 + - 0.93 131.52 + - 7.05

As shown in Table 4, it was confirmed that the onion bark extract had a prosidone reduction effect of about 58.77% to 61.37% as compared with the non-washed group (A). In particular, the treatment group (E) treated with hydrogen peroxide and the second cleaning agent showed a half-pesticide removal effect as compared with the non-washed treatment group (A), thus having the best residual pesticide removal effect.

[Example 3] Confirmation of the filtration method according to the quercetin yield and residual pesticide reduction effect of the onion skin extract

For the filtration method in which the quercetin content in the onion skin extract and the residual pesticide content can be lowered, the hydrogen peroxide water and the extract of the detergent-treated group extracted according to the conditions of Example 1 were subjected to the filtration process in the non- ), A treatment group (F2) containing diatomaceous earth (0.4 g) in a filter plate (ml), and a treatment group (F3) containing diatomaceous earth (0.66 g) in a filter plate (ml) The extracts of each filtration group were concentrated under reduced pressure and then lyophilized to prepare an onion skin extract powder.

Example 3-1. Identification of filtration method according to functional ingredient content in onion skin extract

In order to confirm the yield of the onion skin extract according to the filtration method, the filtration process according to each treatment group was carried out on 100 g of the untreated onion skin, and the extracts of the hydrogen peroxide water and the detergent treatment group extracted according to the conditions of Example 1 The yield, relative yield (%, w / w), quercetin content (mg / g), total quercetin content (mg / g) and relative total quercetin content (%, w / w) of the obtained onion skin extract were measured. The analysis of quercetin was carried out in the same manner as in Example 2, and the results are shown in Table 5 and FIG.

In order to measure the total phenol content, 0.1 g of onion skin extract was dissolved in dimethyl sulfoxide (DMSO) to give a test solution of 200 ppm. 125 μL of the sample was mixed with 0.5 mL of distilled water, 125 μL of Folin-Ciocalteu reagent was added, and the mixture was allowed to stand for 6 minutes. 1.25 mL of 7% sodium carbonate was added to the mixture, and the mixture was adjusted to distilled water to a final volume of 3 mL. The mixture was allowed to stand at room temperature for 90 minutes and irradiated with a UV / visible spectrophotometer (Shimadzu, Serial No. A10934101307, The absorbance was measured. At this time, the content of the total polyphenol compound was determined from a standard calibration curve (FIG. 5) prepared using gallic acid (Sigma Co., USA), and the result is shown in FIG. 4

To determine total flavonoid content, 0.1 g of onion skin extract was dissolved in 40 mL of 90% ethanol and centrifuged at 3,000 rpm for 10 minutes. The supernatant was taken and the residue was extracted three times with 80% ethanol repeatedly, and the solution was adjusted to 100 mL as the test solution. Take 0.5 mL of the test solution and add 1.5 mL of ethanol, 0.1 mL of 10% aluminum nitrate [Al (NO ₃ ) _{3 ·} 9H ₂ O], 0.1 mL of 1 M potassium acetate (CH ₃ COOK) and 2.8 mL of distilled water, After leaving for 40 minutes, the flavonoid content was measured at 415 nm using a UV / visible spectrophotometer (Shimadzu, Serial No. A10934101307, Tokyo, Japan). At this time, the content of total flavonoid was determined from a standard calibration curve (FIG. 6) prepared using quercetin (Sigma Co., St Louis MO, USA). The results are shown in FIG.

Filtration conditions F1 treated group F2 treated group F3 treated group Extract yield (g) 2.59 2.02 2.14 Relative yield (%, w / w) 100 77.98 82.63 Quercetin (mg / g) 311.05 ± 13.94 304.58 ± 1.25 312.23 + - 18.84 Total quercetin (mg / g) 805.62 615.18 668.17 Relative total quercetin (%, w / w) 100 76.36 82.94

As shown in Table 5 and FIG. 4, the content of quercetin was increased only in the case of 0.66 g of the diatomite treated group (F3) as compared with the unfiltered treated group (F1). Total quercetin content was lower than that of unfiltered group, but the yield was higher than other treatments group and total quesetetin content showed the best effect in the filtration group. Therefore, it was confirmed that the filtration of the onion skin extract resulted in an excellent effect of performing filtration under reduced pressure using 0.66 g diatomaceous earth filter plate.

As shown in FIG. 4, the total phenol content in the filtration step was 685.21 mg / g in the unfiltered group F1, 775.3 mg / g in the diatomite added group (F2) 0.40 g and 0.66 g diatomite added group (F3) of 778.48 mg / g. F3 treatment.

As shown in FIG. 4, the content of flavonoid was 3106 mg / g in diatomite added treatment group (F2) and 0.40 g of diatomite added treated group (F3) in 336.10 mg / g of unfiltered group F1, And 320.93 mg / g, respectively. The total flavonoids in each treatment group were 49.05% in F 1 treatment group, 39.98% in F 2 treatment group and 41.23% in F 3 treatment group, respectively, when the weight ratio to total phenol was observed, Of diatomite added treatment group (F3) showed the lowest loss. Optimal filtration conditions to minimize the loss of functional material were found to be 0.68g of diatomite - added filter plate.

Example 3-2. Identification of filtration method according to residual pesticide content in onion skin extract

The residual pesticide analysis was performed by pretreating the sample in the same manner as in Example 2 except that the extract of the treatment group according to the filtration process was used as a sample. As a result of analysis, the contents of three kinds of residual agricultural chemicals, procymidone, fluquinconazole and fenobucarb were determined by filtration process, and the results are shown in Table 6.

Residual pesticide (mg / kg) Filtration conditions F1 F2 F3 Procymidone 177.30 ± 0.52 165.06 ± 1.18 121.82 ± 0.80 Fluquinconazole 0.96 ± 0.01 0.88 + 0.02 0.54 ± 0.01 Fenobucarb 0.09 ± 0.01 0.13 + - 0.01 0.06 ± 0.01

As shown in Table 6, the three kinds of residual pesticides detected showed a tendency to decrease as compared with the non-filtration treatment according to the filtration process. The removal of residual pesticides by filtration process showed the best effect in the 0.66g diatomite treated group (F3) and the highest content of functional index components in the onion skin extract. The filtration process using the filter plate containing 0.66g of diatomaceous earth Was found to be a method of producing an onion skin extract having an excellent quercetin content and a remarkably reduced residual pesticide content.

Claims (6)

Washing the onion skin and primary drying;
A second washing step of treating the primary dried onion skin with aqueous hydrogen peroxide (H ₂ O ₂ ) and washing with a detergent;
A second drying step of drying the second washed onion skin; And
An extraction step of adding an extraction solvent to the secondary structure;
≪ / RTI > The method according to claim 1,
The method for producing an onion skin extract according to claim 1, further comprising a step of filtrating the extract obtained in the extracting step under reduced pressure using a filter plate containing diatomaceous earth. 3. The method according to claim 1 or 2,
Wherein the second washing step comprises immersing the onion skin in 0.1 to 0.5% (v / v) aqueous hydrogen peroxide solution for 3 minutes to 9 minutes, and washing the immersed body with a detergent. 3. The method according to claim 1 or 2,
Wherein the second drying step comprises drying the second washed onion skin with hot air at 70 캜 to 90 캜 for 20 to 30 hours. 3. The method according to claim 1 or 2,
Wherein the extraction solvent is an alcohol aqueous solution having a carbon number of 1 to 5 and a pH of 5.0 to 6.0. 3. The method of claim 2,
Wherein the filter plate comprises diatomaceous earth at 0.50 g / ml to 0.80 g / ml.

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