KR20090099841A - Coating agents of sweetpotato from extracts of purple sweetpotato and methods for making them - Google Patents

Abstract

PURPOSE: A surface-treating agent for sweet potato and a producing method for the same using a purple-colored sweet potato extract are provided to improve the marketability of sweet potatoes. CONSTITUTION: A surface-treating agent for sweet potato improves the storage property of sweet potato. The pH of the surface-treating agent is controlled within pH 2.0~4.0. The surface-treating agent additionally contains 5 ~ 7%(w/v) of sugar. A method for preparing the surface-treating agent comprises the following steps of: mixing a raw material of a purple-colored sweet potato and an extraction solvent and pulverizing the mixture; and filtering the mixture to obtain an extract for coating sweet potato. The raw material of the purple-colored sweet potato is dried at 60 ~ 70°C. The extraction solvent represents water or an aqueous citric acid solution containing 0.1-0.4wt% of citric acid.

Description

Coated agents of sweetpotato from extracts of purple sweetpotato and methods for making them}

 The present invention relates to a sweet potato surface treatment agent and a manufacturing method using a purple sweet potato extract, and more particularly, a method for producing a sweet potato surface treatment agent by mixing the purple sweet potato with an extraction solvent, followed by filtration and additives for heating and adjusting the pH. It relates to a method of coating the surface by immersing sweet potato in the surface treatment agent.

Recently, the quantity of sweet potatoes washed and shipped to improve the marketability is increasing. However, sweet potatoes are made of a thin, soft cork layer, which is easy to invade due to physical damage when washed by machine. In addition, when the sweet potato is washed, the surface soil that used to act as a film during the storage period after harvesting is removed to increase moisture evaporation or respiration rate, which leads to faster decomposition of sugars and nutrients, and further promotes deterioration of husk color. Degrades. Therefore, there is a need for a natural surface treatment agent that can reduce the density of bacteria attached to the surface of sweet potatoes in the washing process and at the same time improve the color and shelf life of the sweet potatoes.

Since ancient times, sweet potatoes are relatively easy to cultivate and have a very high quantity per unit area, so they have been used mainly when mixed with rice, barley, etc. when they are scarcely eaten or when they are cooked.In addition, raw sweet potatoes, sweet potatoes, sweet potatoes, malt, As a raw material for frying and industrial use, it has been used for various purposes such as starch and alcohol production.

Sweet potato is rich in carotenoids, which are predominantly vitamin A precursor of beta-carotene, and it also contains vitamins such as niacin, pantothenic acid and pyridoxine. ) It is an alkaline food that is very nutritious because it contains a lot of essential amino acids such as threonine, valine, functional dietary fiber, various oligosaccharides, and minerals such as potassium, calcium and phosphorus. In addition, sweet potatoes are more resistant to pests than other crops and resistant to pests, so they grow well without spraying pesticides during growth, and thus can be used as pollution-free natural health foods.

However, sweet potato is a high-temperature crop with a storage temperature of 12 to 15 ℃, which is susceptible to colding during the winter after harvesting, and sprouts at 18 ℃ or higher, resulting in poor quality and a low storage humidity of 85-90%. It is difficult to promote long-term storage due to difficult storage conditions, such as promoting the propagation of rot pathogens. Therefore, methods for improving the shelf life of sweet potatoes are being developed. For example, Korean Patent No. 10-0225785 discloses a method for preparing canned sweet potatoes, and Korean Patent No. 10-0435035 discloses detoxifying substances and oxidation. BACKGROUND ART Surface treatment liquids of sweet potatoes in which a reducing agent, a coloring agent, and a coloring agent are mixed are known.

In addition, since purple sweet potatoes are not visually or edible and have a dark branch color, they have a beautiful color. Therefore, research on the use of purple and brown natural pigments has been conducted. For example, Korean Registration No. 10- 0110372 discloses a method for extracting a purple sweet potato by means of alcohol extraction, a bath extraction method and an extraction method, and a method of dyeing fibers using a natural pigment extracted from a purple sweet potato is disclosed in Korean Patent No. 10-0402293. have.

In addition, various techniques using the characteristics of purple sweet potato pigments have been developed and used, but no examples of using the sweet potato pigment extract for the surface treatment of sweet potatoes.

Sweet potatoes are made of a thin layer of soft cork, which is susceptible to damage even with a slight impact. Therefore, when the sweet potato is washed and shipped by machine, the severe wounds are decayed or bitten by soft mold or bacteria after 5 to 7 days.

The phenomenon is easy to appear. In addition, in the case of washed sweet potatoes, the surface soil, which used to act as a film, is removed in the washing process, thereby reducing the weight due to water evaporation, and further deteriorating the merchandise and storage properties as the reddish husk color is dark red or pale yellow.

 Therefore, the present inventors have completed the present invention by developing a sweet potato surface treatment agent using the same as a result of studying the extract of purple sweet potato. Sweet potatoes have no wax or cuticle layers like ordinary fruits, so their skins are very fragile and thin, so it is easy to penetrate and remain inside when artificial colors and chemicals are treated on the surface. Therefore, the surface treatment agent of sweet potato is preferably a natural extract that is harmless to the human body. In addition, it should be effective in enhancing the color of the shell, and it should be cheap and easy to purchase raw materials. Since the sweet potatoes are usually shipped in winter, they are susceptible to cold when immersed in the surface treatment solution for a long time, so the shorter the treatment time, the better. In addition, the surface treatment agent should be evenly coated on the surface of the sweet potato.

The present invention relates to a method for preparing sweet potato surface treatment agent using the purple sweet potato extract, when described in more detail,

It is characterized by using purple sweet potato as the raw material of surface treatment agent for improving sweet potato skin color and maintaining freshness.

In addition, the present invention is a weight ratio of the purple sweet potato raw material and water (added 0.1 ~ 0.4 wt% citric acid) dried at 60 ~ 70 ℃ when extracting the extract 1: 10 ~ 15, the extract is evenly attached to the surface, peel color Sorbitol is added 5-7% (w / v) of the extract to make the color develop vividly, and citric acid is used to adjust the pH range to 2.0-4.0 using citric acid to make the bark color bright red. The manufacturing method has its characteristics.

In addition, the present invention

The washed sweet potato is immersed in the surface treatment agent, wherein the washed sweet potato is washed with water, immersed in 50 to 80% by weight for 2 to 3 seconds, and then immersed in acidic ionized water for 10 to 30 minutes. have.

If the surface treatment agent is treated after sterilizing and washing sweet potatoes, the shelf life is extended by lowering the decay rate and weight loss rate compared to the general washed sweet potatoes. In addition, the shell color is bright red, or the unique shell color is developed, thereby increasing the merchandise, thereby increasing the satisfaction of producers, distributors, and consumers.

1 is a schematic diagram illustrating a method for preparing a sweet potato surface treatment agent using a purple sweet potato extract, which will be described in detail below.

The purple sweet potato is washed with water after removing impurities. And the purple sweet potato is dried at 60 ~ 70 ℃ using a dryer to use as a raw material. Citric acid aqueous solution which added 0.1-0.4 weight% of citric acid to water is used as an extraction solvent. The mixture is placed in a blender so that the ratio of the purple sweet potato raw material and the extraction solvent is 1:10 to 15, and the mixture is pulverized and filtered under reduced pressure to obtain an extract. An additive, preferably sorbitol, is added to the extract extracted by the above process at a concentration of 5 to 7% (w / v) of the extract. The additive is heated to 60-80 ° C. to mix well with the extract, and acid is used, preferably with citric acid to adjust the pH of the extract to have 2.0-4.0.

Figure 2 is a schematic of the surface treatment method of sweet potatoes using the surface treatment agent of sweet potatoes prepared by the above process, will be described in detail below.

The raw sweet potatoes are washed with water, immersed in 50 to 80% by weight alcohol for 2 to 3 seconds, and then immersed in acidic ionized water for 10 to 30 minutes, and then immersed for 2 to 3 seconds in the surface treatment agent of the sweet potato to coat the surface of the sweet potato. . In this case, the water generally means general water used for washing.

Hereinafter, the present invention will be described in more detail with reference to Examples. However, the following examples do not limit the scope of the present invention.

Example  1: sterilization effect according to washing method

Washed sweet potatoes may promote the generation of decay microorganisms through physical damage to the epidermal tissue during mechanical cleaning. Acidic ionized water is reported to have a sterilizing effect without being a general chemical, and the alcohol obtained by fermenting starch has the bactericidal effect as ethanol as its main ingredient and is harmful to humans or there is no possibility of remaining. After the general water washing (A) and the general water washing (B), after the general water washing (B), instantaneous immersion in alcohol and then immersed in acidic water for 20 minutes (C) to measure the total bacteria and mold water. The results are shown in Table 1 below.

Treatment method Total bacterial count (CFU / g) Reduction Rate (%) Mold (CFU / g) % Reduction General water washing (A) 2.30 × 10 ⁴ ± 1.21 - 20.5 × 10 ³ ± 2.14 - General water washing + 10 minutes immersion in acidic water (B1) 2.12 × 10 ⁴ ± 3.24 7.9 2.56 × 10 ³ ± 4.50 87.5 General water washing + 20 minutes immersion in acidic water (B2) 2.05 × 10 ⁴ ± 1.03 10.9 1.87 × 10 ³ ± 2.35 90.9 General water washing + 30 minutes immersion in acidic ionized water (B3) 1.98 × 10 ⁴ ± 2.25 14.0 1.36 × 10 ³ ± 1.16 93.4 General water washing + 50% alcohol instant immersion + 20 minutes immersion in acidic water (C1) 11.06 × 10 ³ ± 4.10 52.0 3.01 × 10 ¹ ± 2.45 99.8 General water washing + 60% spirit dip immersion + 20 minutes immersion in acidic water (C2) 9.14 × 10 ³ ± 0.03 60.2 2.89 × 10 ¹ ± 5.89 99.9 General water washing + 80% spirit dip immersion + 20 minutes immersion in acidic water (C3) 5.27 × 10 ³ ± 2.36 7.1 1.26 × 10 ¹ ± 3.21 99.9

In the case of the treatment (B), the total bacterial count was reduced by 7.9 to 14.0% and the fungus was reduced by 87.5 to 93.4% compared to (A). In the case of (C) treatment, the total bacterial count was reduced by 7.1 to 60.2%, and the fungus was reduced by 99% compared to (A), showing the best bactericidal effect.

Example  2 : Surface treatment agent  Raw material selection and extraction method

To select purple-based surface treatment raw materials from plants, we used chichi, beet, and purple sweet potato. Since the boric siconin pigment is water-soluble, turnip betaine and purple sweet potato anthocyanin pigment are water soluble, they are extracted using ethanol in consideration of the medium polarity and edible so that the pigments of all samples can be extracted. To 100 g of each raw material, 1,000 ml of a 70% solvent 70% ethanol aqueous solution was added, and the absorbance was measured by filtering with filter paper (Whatman No. 1). As a result, the absorbance of the purple sweet potato extract was the highest. (Figure 4)

In addition, 1,000 g of aqueous 70% ethanol solution was added to 100 g of raw, turnip, and purple sweet potato raw materials, followed by extraction. The supernatant was concentrated under reduced pressure, and then lyophilized to obtain crude pigment. As a result of comparing the crude pigment yield, the purple sweet potato showed the highest yield (2.2%) compared to the 2.2% of the chives and 2.6% of the turnips. (Figure 5)

As a result of the experiments of FIGS. 4 and 5, the sweet potato having the highest absorbance and pigment yield was selected as a raw material. In order to improve the efficiency of pigment extraction from purple sweet potatoes, the lower the content, the higher the absorbance. Among them, the absorbance of ethanol 0% (distilled water) was the highest, and when 0.1 ~ 0.4% by weight citric acid was added The absorbance rose to 1.8 to 2.4 times. Therefore, the solvent for pigment | dye extraction shall add 0.1-0.4 weight% citric acid to water. Table 2 shows the absorbance of the dye according to the ethanol concentration.

Ethanol concentration (% by weight) 0 10 20 30 40 60 80 ethanol 0.73 0.64 0.61 0.55 0.5 0.45 0.3 Ethanol + 0.1% Citric Acid 1.32 1.16 1.2 1.15 0.8 0.51 0.42 Ethanol + 0.2% Citric Acid 1.75 1.58 1.42 1.21 0.95 0.72 0.66 Ethanol + 0.4% Citric Acid 1.71 1.6 1.49 1.28 1.16 0.86 0.7

Example  3: raw purple potato drying method

Purple sweet potatoes, which are used as raw materials for the preparation of surface treatment liquids, are usually raw, but may be dried using a dryer. The a * value (redness) of the colorimeter was measured at different drying temperatures, and the results are shown in Table 3 below.

Drying temperature (℃) 50 60 70 80 100 Colorimeter a * ¹⁾ Value (Red) 16.5 ± 0.4 16.9 ± 0.3 16.6 ± 0.2 13.2 ± 0.4 12.4 ± 0.5

※ 1) a *: redness, the higher the value, the more redness

As a result of experiment, the drying temperature of purple sweet potato was the best for maintaining intrinsic color value. The drying speed was slow below 60 ° C., and redness was markedly lowered as the pigment faded above 70 ° C.

Example  4: Raw material concentration of sweet potato surface treatment agent

The selection of raw material as purple sweet potato is one of the main purposes of the color development of sweet potato, and as a result of treating the surface treatment liquid, an appropriate mixing ratio of raw material and water that can approach the unique color of the sweet potato is required. Redness was measured by varying the mixing ratio, and the results are shown in Table 4 below.

Usage of Extraction Solvent (Source: Water) ¹⁾ L a * ²⁾ b * No treatment 48.6 11.5 17.8 1: 5 43.5 15.1 17.7 1: 10 45.7 17.4 18.5 1: 15 46.4 17.7 19.4 1) Weight ratio of water usage (g) to 1g of purple sweet potato raw material 2) a *: Redness, the higher the value, the more red color (L is lightness, a * is redness, b * is yellowness) )

As a result of comparing the a * value representing the redness of each concentration, the weight ratio of purple sweet potato raw material and water was 1: 10 to 15.

Example  5: sweet potato Peel Color  Of extraction solution for enhancement pH  selection

Since the color of the sweet potato is usually red, the chromaticity of the surface treatment liquid should be close to red. Therefore, it is necessary to adjust the pH of the extract using the characteristic that the anthocyanin pigment is expressed in red-blue-green according to the pH. The acidity control used citric acid which is not harmful to the human body. The maximum absorption wavelength for each pH was measured, and the results are shown in Table 5 below.

pH 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 Absorption wavelength (λmax) 520 529 535 550 561 575 583 610 Visual observation Red Red Deep red Red blue Blue blue Cyan green

As a result of visual inspection of the maximum absorption wavelength and color for each pH, the maximum absorption wavelength also increased with increasing pH. The closest color to the skin color of sweet potatoes is pH 2.0 ~ 4.0.

Example  6: Color development  Selection of additives for promotion

When the purple sweet potato extract is treated with sweet potatoes, an additive is required to have a clear, glossy feel while having an adhesion effect so that the extract is evenly coated on the sweet potato surface. Among the sugars commonly used as additives in food processing, sorbitol, arabic gum, and mannitol were treated with purple sweet potato extract to examine the expression of the bark color, and the results are shown in Table 6 below.

Colorant Additive concentration (w / v%) 7% 5% 2% Sorbitol Prize Prize medium Arabic sword Prize slander medium Mannitol Ha Ha Ha

As a result, sorbitol 5 ~ 7% (w / v) treatment was the most effective for the peel color of sweet potatoes.

Example  7: Surface agent  Chromaticity by Processing Method

When washing sweet potatoes in winter, care should be taken not to leave them at low temperatures. The shorter the sweet potato surface treatment time is, the shorter the treatment time is.

To the purple sweet potato extract, about 6% (w / v) of sorbitol was added to the surface treatment solution adjusted to pH of about 3.2. Table 7 shows.

Per treatment L a * b * 1 hour immersion 49.3 17.0 ± 0.4 17.9 Immersion (2-3 seconds) 46.6 17.4 ± 0.3 19.3

As a result, the redness was not significantly different. Therefore, the treatment time of the surface treatment agent of the present invention is suitable for instantaneous immersion in order to shorten the working time and to prevent freezing.

Experimental Example 1

Sweet potatoes have a thin layer of cork, which, when washed, can reduce weight due to evaporation of water, reduce freshness, and shorten shelf life. The surface treatment agent prepared according to the conditions of Examples 1 to 7 was treated with sweet potatoes, and then the weight loss rate according to the storage days was investigated. There was no significant difference between all treatments until 15 days after storage, but after 30 days, the weight loss rate of the surface treatment agent was 8.5% compared to 10.8% of untreated treatment (Fig. 6).

Experimental Example  2

After treating the surface treatment agent prepared according to the conditions of Examples 1 to 7 in sweet potato, and then stored in a plastic bag perforated several places in several places so as to maintain a proper humidity while keeping at room temperature to observe the mold and softness phenomenon. In the case of general cleaning, decayed sweet potatoes began to develop after 5 days, and the decay rate was 28% after 30 days. (Figure 7)

Recently, the quantity of sweet potatoes packaged or shipped in boxes is increasing, and the market for washed sweet potatoes is estimated at W100bn annually. By treating the sweet potato surface treatment agent of the present invention, it is possible to extend the shelf life by preventing freshness and decay, and the color of the shell is improved, which is expected to greatly help income.

1 is a diagram illustrating a method for preparing sweet potato surface treatment agent.

2 is a diagram illustrating a sweet potato cleaning method and a surface treatment agent treatment process.

3 shows the results of sweet potato surface treatment agent treatment.

Figure 4 shows the absorbance of the ethanol concentration of the extraction solvent.

Figure 5 shows the yield of crude pigment for each raw material.

Figure 6 shows the weight loss with or without surface treatment agent treatment according to the storage days.

Figure 7 shows the decay rate with or without the surface treatment agent treatment according to the storage days.

Claims (13)

Sweet potato surface treatment agent for improving the shelf life of sweet potatoes, characterized in that comprises a purple sweet potato extract. The sweetener surface treatment agent of Claim 1 adjusted to the range of pH 2.0-4.0. The sweetener surface treatment agent according to claim 1, which further contains a sugar at a concentration of 5 to 7% (w / v). A method of producing a sweet potato surface treatment agent by mixing the purple sweet potato raw material and the extraction solvent, and pulverized and filtered to obtain an extract capable of coating the surface of the sweet potato. The method of claim 4, wherein the purple sweet potato raw material is dried at 60 ~ 70 ℃. The method of claim 4, wherein the extraction solvent is water or citric acid aqueous solution to which 0.1 to 0.4% by weight citric acid is added.       The method for producing a sweet potato surface treatment agent according to claim 4 or 6, wherein the weight ratio of the purple sweet potato raw material to the extraction solvent is from 1:10 to 15. 5. The method of claim 4, wherein the sugar is added at a concentration of 5 to 7% (w / v). The method for producing a sweet potato surface treatment agent according to claim 8, wherein the sugar is sorbitol.       The method of claim 4 or 8, wherein the extract is a method of producing a sweet potato surface treatment agent, characterized in that adjusted to the pH 2.0 ~ 4.0 range. The sweet potato surface treatment method characterized by immersing the sweet potato in the surface treatment agent of the sweet potato of any one of claims 1 to 3.       12. The method of claim 11, wherein the washed sweet potato is washed with water, immersed in 50 to 80% by weight of alcohol, and then immersed in acidic ionized water for 10 to 30 minutes.       12. The surface treatment method of sweet potato according to claim 11, wherein the washed sweet potato is immersed in the surface treating agent of the sweet potato for 2 to 3 seconds.

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