KR101348977B1 - Drying method for dried persimons - Google Patents

Abstract

The present invention relates to a method of drying dried persimmon by freeze-temperature drying, which periodically repeats the step of drying at room temperature and the cooling step at subzero temperature above the freezing point of persimmon, and reduces the drying time by 5 times compared to the conventional natural drying method. This also eliminates the need for sulfur fumigation, and the dried persimmon produced by the natural drying method is similar to the sweetness and flavor and color of the dried persimmon, but has a thin shell thickness and a dried persimmon that can produce dried persimmons with excellent quality. In addition, the 'extra' grade Daebongsi, which was difficult to produce persimmons, also makes it possible to produce persimmons.

Description

Freezing Drying Method of Dried Persimmons {Drying method for dried persimons}

The present invention relates to a method of drying persimmon, and more particularly, to a method of drying persimmon by freeze-temperature drying, which periodically repeats a room temperature drying step and a cooling step at subzero temperature above the freezing point of persimmon.

Persimmons harvested before the softening of fruit in late October or early November are divided into sweet persimmon and persimmon persimmon, and persimmon persimmon is sold as raw persimmon, annual and dried persimmon (semi-dry and dry). According to the management performance analysis data for each use type of persimmon persimmon reported by Sangju Persimmon Test Center of Gyeongsangbuk-do Agricultural Research and Development Institute, raw persimmons are processed into dried persimmons, resulting in an increase in economics by 1.87, 1.36, and 1.62 times, respectively, during the annual sales. 0.97%, 0.94%, and 0.62% reported lower performance than raw sales. Therefore, persimmon farmers and organizations of persimmon persimmon processing technology is a very important task to determine the performance of the year.

Currently, the method of manufacturing dried persimmons is done by ripening the harvested persimmons for a certain period of time, then peeling, pinching, sulfur fumigation, and drying them in nature. The commerciality of the dried persimmons is dried along with the quality of the raw persimmons. It is determined by the work.

In general, the drying of dried persimmons is carried out at the dry field, which is two stories high for natural ventilation. The quality and success of dried persimmons in the drying process are determined by ventilation and humidity. If weak, tissue softening can lead to falling fruits, leading to high economic losses. In the early stages of natural drying, when the outside humidity becomes wet due to rainfall and snowfall, there are many cases in which economic loss is caused by the occurrence of mold, falling, and browning, and each farm has its own methods for effective dehumidification. I'm looking for a situation.

In addition, dried persimmons start in mid-November and begin in early January or 45 to 60 days before snowy season. Such a long time natural drying method was difficult to control the timely shipment of sulfur fumigation to prevent discoloration and decay of dried persimmons during drying, temperature changes and aging. In particular, in Daebong City, the large size and sweetness are high, but the 'extra' grade Daebong has high damages due to excess weight, and the drying speed is also slower than general Daebong. It was shipped as a new year with a lower value added than dried persimmon or processed into persimmon dried persimmons. Above all, Daebong, which has a heavy weight than ordinary persimmons, had a long drying time, making it difficult to ship according to the end of the year or New Year.

According to the invention of the conventional method of drying persimmons, the invention of Korean Patent No.0503971, "Dehumidification drying method and drying apparatus of persimmon", fumigated the skin with sulfur dioxide, and then air-washed and aged at 34 ° C for 12 hours, followed by 18 After low temperature dehumidification at 24 ° C. for 24 hours, and further aging at 2 ° C., the temperature is constant at 8 to 18 ° C. for low temperature dehumidification for 96 hours. Enzymatic browning is promoted due to the problem that the color of the dried persimmon, the continuous drying is made at a constant temperature, the shell of the dried persimmon was thick, there was a problem that the drying efficiency is not high.

In addition, the invention of Korean Patent No. 0584878, "Method and apparatus for manufacturing dried persimmon by reduced pressure cold air drying method", dried under reduced pressure cold wind for 2 to 5 days at 5 to 10 ℃, and aged at low temperature for 0 to 5 ℃ for 1 to 2 days , And then dried under reduced pressure cold air at 5 to 20 ° C. for 2 to 5 days and matured at room temperature for 1 to 2 days, and then dried at 5 to 20 ° C. for 2 to 5 days under reduced pressure cold air and at 15 to 20 ° C. for 1 to 2 days. By the low temperature aging, drying is performed only at the temperature of the image, unlike the natural drying method, which is dried by subtracting from the freezing and the image.There is no peculiar flavor of sweet persimmon. There was no limit.

In addition, the invention of "Dried persimmon drying method" of Korean Patent No. 0646578, after drying and aging for 20 to 26 hours at 10 to 50 ℃ in a dry aging room, transfer the persimmon to a low-temperature storage for 20 to 26 hours at 0 to 5 ℃ After repeating the sweating process 4 to 5 times, rapid freeze-drying for 10 minutes from -50 ℃ to-10 ℃, transfer the persimmon from the drying mature room to the low temperature freezer, low temperature freezer to the rapid freeze drying device This is not possible in a cork- or persimmon dried persimmon production facility, and the sweating process at 0 to 5 ° C. is too long, leading to a decrease in drying efficiency and an expensive freeze-dryer. Also, at a drying temperature of 45 ° C., enzymatic browning is required. There was also a problem in that this occurred most.

In addition, Korean Patent Publication No. 2010-0007190 discloses that the skin is dried, frozen for 18 to 24 hours, and dried at 10 to 20 ° C. for 7 to 10 days, and the breakage of the cell wall occurs during the freezing process to promote browning of dried persimmons. It can be, and dried for a long time at a certain temperature, the thickness of the dried persimmon after a certain period of time, the drying efficiency is lowered, the flavor is removed, there was a problem that the flavor is monotonous.

In order to shorten the drying period of dried persimmon as described above, mechanical drying methods or apparatuses such as hot air drying or cold air drying have been developed. However, only the shortening between the dryers has been achieved. In terms of sugar content, sugar content, etc., inferior to conventional ones, it has not been a direct solution for dried persimmon farmers. Due to these quality problems, dried persimmons produced by conventional methods are sold at a higher price than dried persimmons by mechanical drying methods, and even though many dried persimmon dryers are developed, it is also the reason why farmers or farmers' groups adhere to the conventional methods.

The present inventors shorten the drying time by five times compared to the conventional natural drying method through the freeze-temperature drying method which periodically repeats the room temperature drying step and the cooling step at subzero temperature above the freezing point of persimmon, and thus sulfur fumigation It does not need to be treated, and the dried persimmon produced by the natural drying method is similar in sweetness and color, but the thickness of the shell is thin, and excellent quality dried persimmon with reduced external wrinkles can be produced. Daebongsi of the extra-large grade was also found to be able to manufacture with persimmon completed the present invention.

An object of the present invention is to provide a drying method of dried persimmon, which is similar in quality to the dried persimmon produced by the natural drying method, but with a shorter drying time than the conventional natural drying method.

Dried persimmon drying method of the present invention, the persimmon loading step of loading the peeled persimmon in a drying apparatus having a freezer; Drying the peeled persimmons at 1 ° C. to 30 ° C .; A cooling step of cooling the internal temperature of the dried persimmon to a range of at least 0 ° C. or more and below freezing point; And repeating the drying cycle for 5 to 14 times using the drying step and the cooling step as one drying cycle.

In the dried persimmon drying method of the present invention, the drying temperature of the drying step is characterized in that 15 ℃ to 25 ℃.

In the dried persimmon drying method of the present invention, the drying time of the drying step is characterized in that 12 hours to 24 hours.

In the dried persimmon drying method of the present invention, the cooling step is characterized in that the internal temperature of the persimmon is-8 ℃ to-1 ℃.

In the dried persimmon drying method of the present invention, the cooling step is characterized in that the internal temperature of the persimmon is-6.4 ℃ to-1 ℃.

In the dried persimmon drying method of the present invention, the internal cooling temperature of the drying apparatus of the cooling step is-2 ° C to-15 ° C.

In the dried persimmon drying method of the present invention, the internal cooling temperature of the drying apparatus of the cooling step is-5 ° C to-10 ° C.

In the dried persimmon drying method of the present invention, the cooling time of the cooling step is characterized in that 3 to 10 hours.

In the dried persimmon drying method of the present invention, the drying cycle is repeated for 5 to 14 days.

In the dried persimmon drying method of the present invention, the wind speed of the drying step and the cooling step is characterized in that from 0.5 m / s to 6 m / s.

In the dried persimmon drying method of the present invention, the raw persimmon is characterized in that the large persimmon weight of 250 g to 350 g or 23 cm to 28 cm long.

In the dried persimmon drying method of the present invention, the persimmon loading step is characterized in that the skein method or dumping method.

In the dried persimmon drying method of the present invention, the method further comprises the step of aging at low temperature for 10 days to 60 days at 0 ℃ to 10 ℃ before peeling the harvested persimmon.

In addition, the dried persimmon of the present invention has a shell thickness of 0.4 ~ 0.9 mm, characterized in that dried by any one of the method of drying the dried persimmon.

The dried persimmon of the present invention is characterized in that the redness value of the Hunter color difference meter on the surface of the dried persimmon is 6 to 8.

The dried persimmon of the present invention is characterized in that it is produced from Daebong.

The present invention reduces the drying time by about five times compared to the conventional natural drying method, and thus eliminates the need for sulfur fumigation treatment. It provides a method of drying dried persimmons to produce excellent quality dried persimmons with reduced external wrinkles, and it is also possible to produce 'extra' grade Daebong, which was difficult to produce dried persimmons.

1 is a graph showing the highest daily temperature in Gwangyang region from November 1 to December 31, 2010, which was provided by the Korea Meteorological Administration.
Figure 2 is a graph showing the lowest daily temperature in Gwangyang region from November 1 to December 31, 2010 provided by the Korea Meteorological Administration.
3 is a graph showing the daily average temperature of the Gwangyang region from November 1 to December 31, 2010, received from the Korea Meteorological Administration.
Figure 4 is a graph showing the activity according to the temperature of the polyphenol oxidase involved in browning of dried persimmon.
5 is a photograph showing the browning progress rate according to the change of surface color while preserving the peeled persimmon in an incubator at 20 ℃, 25 ℃ and 30 ℃, 20 ℃ on the left, 25 ℃ in the center, 30 ℃ on the right It is photograph of day 1 at the bottom, day 2 at the top, and day 3 at the top.
Figure 6 is a graph showing the weight loss rate of persimmon during drying period in Comparative Example 1.
7 is a graph showing a change in height of persimmon during drying period in Comparative Example 1.
8 is a graph showing a change in the thickness of the shell during the drying period in Comparative Example 1.
9 is a graph showing a change in sugar content during drying period in Comparative Example 1.
10 is a graph showing the change in hardness during the drying period in Comparative Example 1.
FIG. 11 is a graph illustrating a change in brightness among chromaticities in Comparative Example 1. FIG.
12 is a graph showing a change in redness of chromaticity in Comparative Example 1.
FIG. 13 is a graph showing a change in yellowness among chromaticities in Comparative Example 1. FIG.
14 shows the degree of browning of the dried persimmon of Comparative Example 1 in Experimental Example 4 until -10 ° C, -15 ° C, -20 ° C, and -25 ° C, respectively, and then dried again at 20 ° C. The upper photo was taken with the persimmon upright, and the lower photo was taken with the persimmon lying down. The left one was frozen at-10 ° C, -15 ° C, -20 ° C, and -25 ° C from the left.
FIG. 15 is a freezer adjusted to -40 ° C. after connecting a thermocouple (0.3 mm K-type) to the center of the persimmon to measure the freezing point of raw persimmon and dried persimmonized for 3 days in Comparative Example 1 Is a graph showing the temperature change of the sample at 1 minute intervals.
16 is a graph showing the weight loss rate of persimmon during drying period in Example 1.
17 is a graph showing a change in the thickness of the shell during the drying period in Example 1.
18 is a graph showing a change in sugar content during drying in Example 1.
19 is a graph showing the change in hardness during the drying period in Example 1.
20 is a graph showing the change in moisture content during the drying period in Example 1.
FIG. 21 is a graph illustrating a change in brightness among chromaticities in Example 1. FIG.
FIG. 22 is a graph showing a change in redness among chromaticities in Example 1. FIG.
FIG. 23 is a graph showing a change in yellowness among chromaticities in Example 1. FIG.

The dried persimmon drying method of the present invention is to perform a freeze-temperature drying method of periodically repeating the room temperature drying step and the cooling step at sub-zero temperature above the freezing point of the persimmon, semi-drying time after loading the peeled persimmon in the drying apparatus with a freezer Or drying takes place in one place until dryness.

Varieties of persimmons used in the production of dried persimmon of the present invention is mainly persimmon persimmon, Dungsi, Occasional, Walsh, Gojongsi, Danseong, persimmon, Seojo, Milsi, Daebongsi and the like, but not particularly limited It is preferable to apply when the size of the large peak is difficult to dry with dried persimmon, especially can also be applied to the 'extra' grade Daebong.

The size and weight of the raw persimmons used in the production of dried persimmons of the present invention do not need to be particularly limited, but the conventional natural drying method or other mechanical drying method takes a long time to dry, and the weight of the falling leaves is 250 g to 350 g or long width. This is particularly suitable when applied to large senses that are 23 cm to 28 cm in size.

In the present invention, raw persimmon may be used immediately after harvesting, but at low temperature, preferably at 0 ° C to 10 ° C, more preferably at 2 ° C to 6 ° C, at least 10 days of low temperature aging. Low temperature aging is more preferably 15 days or more, most preferably 20 days or more, it is preferable to undergo a desorption process with low temperature aging. Although the period of maximum low temperature aging does not need to be specifically limited, it is common to set it as 60 days or less, Preferably it is 40 days or less, More preferably, it is 30 days or less.

When the low temperature aging temperature exceeds the upper limit, the softening may proceed while the tissue of the raw persimmon is receded during low temperature aging, and the color of dried persimmon may be darkened by the action of browning enzyme. In addition, as the low temperature aging period increases, the drying period may be shortened and the thickness of the dried persimmon may be thinned.

Loading of the peeled persimmon in the present invention can use a conventional skein method, or it is also possible to use a coal mining method.

Dried persimmon drying method of the present invention, after loading the peeled persimmon in a drying device equipped with a freezer, drying step of drying the persimmon at 1 ℃ to 30 ℃ and the internal product temperature of the dried persimmon at least freezing point, 0 ℃ The drying cycle is repeated 5 to 14 times by refrigeration at room temperature with one cooling cycle for cooling in the following range.

The drying temperature of the drying step is 1 ℃ to 30 ℃, preferably 15 ℃ to 25 ℃, more preferably 17 ℃ to 22 ℃. When the temperature of the drying process exceeds the upper limit, the enzyme activity of the polyphenol oxidase is increased to promote the browning of the dried persimmon, so that the color of the dried persimmon is darkened. When the temperature is lower than the lower limit, the drying efficiency is low due to the low temperature and high humidity. This makes it difficult to obtain dried persimmons of desired moisture content within the desired time.

The drying time of the drying step is 12 to 24 hours, preferably 18 to 20 hours. If the drying time is too short, it is difficult to obtain the desired weight reduction rate and water content, and if too long, the flavor of the dried persimmon may be lowered.

The internal temperature of the persimmon of the cooling step is at least the freezing point, below 0 ° C, preferably -8 ° C to -1 ° C, more preferably -6.4 ° C to -1 ° C.

In the present invention, the lowest freezing point refers to the lowest temperature just before the freezing of raw material persimmon or drying process is overcooled, and the freezing point of the persimmon is affected by the moisture content of persimmon, etc. As is carried out, the moisture content of the persimmon is gradually reduced, thus lowering the freezing point of the persimmon. Therefore, it is preferable that the cooling temperature is gradually or stepwise lowered as the freezing variable temperature drying of the present invention is performed. Therefore, the cooling temperature is preferably set so that the internal product temperature of persimmon is from -1 ° C to -2.9 ° C, preferably -1 ° C to -2.5 ° C from one drying cycle to three to four drying cycles. The cooling temperature is set so that the internal temperature of the persimmon is from -1 ° C to -6.4 ° C, preferably -1.5 ° C to -5 ° C from the time of drying cycle 6 to 7 times, and from 7 to 8 drying cycles. The cooling temperature is set so that the internal product temperature of the mixture is -1 ° C to -10 ° C, preferably -2 ° C to -8 ° C.

For example, the persimmon internal temperature of persimmon is set to -2.5 ° C for 1 to 3 drying cycles, and the persimmon internal temperature of persimmon is set to -5 ° C for 4 to 6 drying cycles, and 7 times After the drying cycle, the internal temperature of the persimmon can be set to a cooling temperature of-8 ° C, and the cooling temperature of the drying apparatus is set so that the internal temperature of persimmon is -1 ° C to -2.5 ° C. Can also be set.

In the present invention, the conventional room temperature drying method is to continue drying at room temperature and low temperature, so that only the thickness of the dried persimmon becomes thicker, the drying efficiency is lowered, and in order to overcome the limitation that the flavor of the dried persimmon achieved in the natural drying method is lost. By cooling raw persimmons or persimmons which are continuously dried and softened or semi-simulated to a temperature just before freezing, microcrystals are formed in the persimmon tissues, thereby relaxing the cell walls of the persimmons, thereby releasing sugar in the tissues, While redizing the surface, it was possible to achieve a flavor similar to the natural drying method.

However, once outside the cooling temperature range set in the present invention, the persimmon tissue is frozen for a long time at a temperature below the minimum freezing point, and then the temperature of the persimmon is frozen again, the ice crystals once formed in the frozen tissue thaw once the cell walls are thawed. In this case, the tissue is receded and the persimmon installed in the cradle, such as skein, is dropped, or the tissue is destroyed, and the browning enzyme called polyphenol oxidase present in the cytoplasm reacts with the phenolic component separated from the vacuole and the browning action. This is accelerated and the fall of the merchandise such as darkening the surface color occurs.

In the cooling step, the internal temperature of the persimmon is a major factor in determining the quality, and the internal temperature of the drying apparatus having a freezer is adjusted according to the capacity, temperature, and air volume of the freezer to adjust the internal temperature of the persimmon in the above range. The optimal condition can be selected.

However, in order to adjust the internal product temperature of the persimmon in the above range, in order to easily adjust to a temperature below the minimum freezing point, the internal temperature of the drying apparatus with a freezer is -2 ° C to -15 ° C, preferably- The temperature is adjusted to 5 ° C to -10 ° C and the cooling time is maintained for 3 to 10 hours. If the internal temperature of the dryer equipped with the freezer is set to -2 ℃ to -8 ℃, even if the cooling time is more than 10 hours, the temperature does not decrease below the minimum freezing point of persimmon, but considering the energy cost required for cooling It is preferable to cool in the range of 3 to 10 hours, and at -8 ° C to -15 ° C for 3 to 8 hours, preferably 3 to 6 hours in the initial drying cycle.

One drying cycle consisting of the drying step and the cooling step allows the next cycle to proceed every 20 to 28 hours, preferably 1 day.

The dried persimmon drying method of the present invention repeats one drying cycle 5 to 14 times, preferably 6 to 12 times, more preferably 7 to 10 times. In addition, the duration of the drying cycle consisting of the drying step and the cooling step of the present invention is 4 to 14 days, preferably 6 to 12 days, more preferably 7 to 10 days. However, when the raw persimmon weight is 250 g to 350 g or a large persimmon having a long width of 23 cm to 28 cm or a large size of 'extra' grade, it is preferable to dry for 10 to 14 days. The drying cycle can be adjusted depending on whether the dried persimmons in the desired final product form are semi-dry or dry, typically having a water content of 45-50 wt%. Dried persimmon drying according to the method of the present invention is a drying period is significantly shortened compared to dried persimmon dried by the conventional conventional natural drying method for 50 days to 60 days.

When the number of times of repeating or performing the drying cycle exceeds the upper limit, the thickness of the dried persimmon shell becomes thick and the dried persimmon is made of a hard texture. When the drying cycle is less than the lower limit, a sufficient weight reduction rate cannot be obtained.

The wind speed of the drying step and the cooling step of the present invention is 0.5 m / s to 6 m / s, it is advantageous to lower the wind speed in the initial drying cycle, and to increase the wind speed in the later drying cycle. The criteria for dividing the initial and late drying cycles may vary depending on the type, weight, drying and cooling temperature and time of the persimmon, but when the persimmon weight loss rate is 30 to 50% or as soft as the year, When the content reaches 55 to 75% by weight, from one drying cycle to three to six drying cycles, preferably from four to five drying cycles, is the initial drying cycle, after which it can be divided into late drying cycles. .

The wind speed of the initial drying cycle is 0.5 m / s to 3 m / s, preferably 1 m / s to 2 m / s, when the upper limit is exceeded, only the surface of the persimmon is rapidly dried, the shell is thickened, As the drying cycle is repeated, the drying efficiency is rather rapidly lowered, and below the lower limit, drying may be insufficient.

The wind speed of the late drying cycle is from 2 m / s to 6 m / s, preferably from 3 m / s to 5 m / s, and is usually set at a speed of 1.5 to 3 times that of the initial drying cycle. The wind speed above the lower limit is because a higher wind speed is required to dry the persimmon once the surface has been dried.

The dried persimmon prepared by the method of the present invention has a shell thickness of 0.4 to 0.9 mm, preferably 0.5 to 0.8 mm, and the thickness of the dried persimmon produced by the conventional natural drying method is usually 1.1 to 1.6 mm. Lowered by about%, the texture of chewing is soft and suitable for rich sweetness. There is no significant difference between the brightness (L) value and the yellowness (b) value of the Hunter color difference meter, but the redness (b) value is 6-8. As a red color as compared to the dried persimmon prepared by the conventional natural drying method, the preference is higher in color.

In order to implement the method of the present invention, as a drying device capable of maintaining a uniform air flow distribution and speed in a drying chamber, any drying device capable of generating a hot air up to 40 ° C and a freezer that can cool down to -15 ° C is limited. Can be used without

One embodiment of the drying apparatus with a freezer of the present invention includes a drying chamber of a constant volume on which the peeled persimmon is loaded; Blowing fan for discharging the cooled air to cool the internal temperature of the air or persimmon temperature controlled from 1 ° C to 30 ° C above the minimum freezing point, below 0 ° C above the drying chamber, discharged from the blowing fan to dry the chamber A freeze dryer including a differential pressure fan for sucking air circulated from the lower part of the drying chamber, and a heat exchange condensing device for cooling the air sucked from the differential pressure fan; And a controller for controlling a drying cycle including any one or more of a drying temperature, time, humidity, and air volume in the drying chamber.

Hereinafter, the present invention will be described more specifically with reference to the following examples. However, the following examples are provided only to aid understanding of the present invention, and the scope of the present invention is not limited to the following examples.

Experimental Example  1: Environmental investigation of dried persimmon

Dried persimmon cultivation environment in Jinsang-myeon, Gwangyang-si, Jeonnam, was investigated. The survey period was received from the Korea Meteorological Administration for the hourly temperature change of Gwangyang region from November 1 to December 31, which includes the persimmon production period of Daebong-si, and the daily maximum temperature (Figure 1), minimum temperature (Figure 2) and average The temperature (Fig. 3) was obtained, and the maximum, minimum and average temperatures for each period, and average, maximum and minimum temperatures for November and December are shown in Table 1.

division Maximum temperature by period
(℃) Minimum temperature by period
(℃) Average temperature by period
(℃) November
(℃) December
(℃) Daily average temperature 14.27
(11/7) -3.78
(12/6) 5.97 8.87 3.17 Maximum daily temperature 21.5
(11/13) 0.5
(12/6) 11.90 21.5
(11/13) 17.7
(12/10) Minimum daily temperature 11.5
(11/7) -8.1
(12/7) 0.86 -4.9
(11/20) -8.1
(12/7)

The maximum temperature of the dried persimmon production expected period was 21.5 ℃, the minimum temperature was -8.1 ℃ and the total average temperature was investigated to 5.97 ℃, which was used as a reference for setting the drying and cooling temperature in the present invention.

Experimental Example  2: Determination of the maximum drying temperature for drying persimmons

The browning of the surface color during drying of the peeled persimmon occurs when the polyphenol oxidase is combined with phenolic components such as tannin, and the enzymatic browning is greatly affected by temperature.

Therefore, in the present invention is shown in Figure 4 by measuring the activity of the polyphenol oxidase for each drying temperature at 5 ℃ interval in the range of 20 ℃ to 65 ℃ considered to be a drying temperature range that can be applied to dried persimmon. According to FIG. 4, the activity of the enzyme began to increase rapidly from 35 ° C., indicating the highest enzyme activity at 45 ° C. FIG. Therefore, in the present invention, 30 ℃ was determined as the maximum drying temperature for drying persimmon, it was confirmed that the difference in activity of browning enzyme is not large at room temperature below 30 ℃.

Next, while the peeled persimmon was preserved in an incubator at 20 ° C, 25 ° C and 30 ° C, the browning progress rate according to the storage days was observed as a change in surface color, and the results are shown in FIG. 5. The left side of FIG. 5 is a persimmon preserved at 20 ° C., 25 ° C., and 30 ° C. on the right side, respectively, and the lowermost part is Day 1, the upper part is Day 2, and the upper part is photograph of Day 3.

In FIG. 5, it was observed that browning began to appear on the persimmon surface of day 3 at 30 ° C. In the present invention, the preferred drying range in the room temperature drying step is 15 ° C to 25 ° C, and the most preferable drying temperature is the natural drying condition of Experimental Example 1. Similarly determined to 20 ℃.

Comparative Example  One: Room temperature drying  Production of dried persimmon by the method

Daebong-si harvested in November 2009 from Jinsang-myeon, Gwangyang-si, Jeollanam-do, Korea. The peeled persimmons were placed in a tray, placed in a dryer, and dried at a wind speed of 2 m / s and a drying cycle of 20 hours at 20 ° C. and 4 hours at 5 ° C. in one drying cycle.

Experimental Example  3: Room temperature drying  Changes in Characteristics of Dried Persimmons by Drying Method

The weight loss ratio is expressed as a percentage of the initial weight after drying with respect to the initial weight, the height is the length from the center of the faucet to the process, and the thickness of the skin is measured by vernier calipers after peeling off the pulp. It was. The weight loss rate, height, and shell thickness were treated 10 times at daily intervals during drying.

In addition, the soluble solid content was diluted 1: 1 with distilled water to a mixer and displayed as a 10-repeat average value with brix concentration using a digital sugar meter (PAL-1, Atago, Japan). The hardness was expressed as 40 measurement averages using Texture Analyser (TA-XT2, Stable Micro System, UK), and the measurement conditions were puncture test under the condition of passing 15mm at 1.0mm / s using a 2mm diameter probe. And the maximum peak value is expressed in gforce.

The surface color of the semi-arid condition was measured using a Chromameter (CR-200, Minolta Co., Osaka, Japan) calibrated with a standard white plate (L = 97.75, a = 0.49, b = 1.96), Hunter L (Lightness), a (Redness). ) And b (Yellowness) values are expressed as 20 repetition average values.

The weight reduction rate of persimmon during the drying period increased as the drying period was longer as shown in FIG. 6, but increased rapidly until the 3rd day of drying, and then the weight reduction rate began to decrease and the drying efficiency was lower than the 3rd day from the 6th day. .

As shown in FIG. 7, the height change of persimmon during drying period tended to decrease slowly after about 75% of persimmon was reduced to about 10% after 3 days of drying and then rapidly decreased to 66 mm.

The change in the thickness of the shell during the drying period tends to be slightly slowed after 4 days of drying as shown in FIG. 8, but the increase in the thickness of the shell was observed continuously during the drying process.

As shown in FIG. 9, the change in sugar content during the drying period showed that the raw persimmon, which was the initial 16 brix, increased more than twice after 6 days of drying.

As shown in FIG. 10, the change in hardness during the drying period showed little change around 210 gforce from the second to sixth days of drying, and then rapidly increased again on the eighth day.

The change in chromaticity during the drying period is shown in FIGS. 11 to 13. Immediately after peeling at Daebong, light yellow pulp tended to decrease in brightness, redness and yellowness during drying. Hunter L-value decreased from 25.0 to 26.2 after 8 days of drying, and Hunter a value of redness was 16.6 initially but decreased to 6.7. Hunter b-value also decreased from the initial value of 31.7 to 11.4 after 8 days of drying.

When the dried persimmon is produced by the room temperature drying method, the weight reduction rate is high until 3 to 4 days, and the height decreases significantly, but after 6 days, the weight reduction rate is low and the sugar content is hardly reduced. There was almost no increase of, but the increase of the shell thickness and hardness, and the brightness and redness of the surface color decreased continuously.

In addition, it took 10 days to dry the final moisture content to 47% by weight using the room temperature drying method, the thickness of the dried persimmons on the 10th was 1.31 mm thick, and almost no fragrance, unlike the conventional semi-drying, so the room temperature drying method Was not suitable to replace conventional natural drying methods.

In the drying process by the room temperature dry-drying method, the flesh is hardened by moisture evaporation of the surface of the pulp on the third to sixth days, in particular, the third to fourth days, and a tissue such as a shell is formed. By interfering with the diffusion of moisture inside, the drying rate is delayed, deterioration of the flavor occurs due to the delay of the drying rate, and it is judged that only the surface is continuously dried and the shell becomes thick, and the first drying is performed by room temperature drying. Afterwards, the minimum cooling temperature for drying persimmon was examined to apply the method of performing image and sub-zero temperature drying.

Experimental Example  4: Quality change according to cooling temperature during drying persimmon

In Comparative Example 1, the persimmon dried for 4 days was frozen in a refrigerator at -40 ° C until the internal temperature reached -10 ° C, -15 ° C, -20 ° C, and -25 ° C, respectively, and then dried again at 20 ° C. The quality of the product was investigated.

As a result of measuring the time when the product temperature dropped by freezing the dried persimmon for 4 days, it took too long for the product temperature of the persimmon to reach the set temperature (Table 2). It was judged to be absent (FIG. 14). Therefore, it was confirmed that the cooling work below -10 ℃ during the dry drying of dried persimmon should be avoided.

division -10 ℃ -15 ℃ -20 ℃ -25 ℃ Cooling time 10 hours 51 minutes 12 hours 59 minutes 13 hours 29 minutes 13 hours 53 minutes

Experimental Example  5: raw persimmon and dried persimmon Freezing point  Measure

The freezing point of the persimmon (moisture content of 82.5% by weight) of Comparative Example 1 and dried persimmon (66% by weight of moisture) dried for 3 days in Comparative Example 1 were measured. The freezing point is shown in FIG. 15 by measuring the temperature change of the sample at 1 minute intervals in a freezer in which the temperature of the measuring cell is adjusted to -40 ° C. after connecting a thermocouple (0.3 mm K-type) to the central part. The following peak points were determined by the Beckman method, which interpreted them as freezing points. The freezing point of raw persimmon and persimmonized persimmon was measured at -2.1 ℃ and -4.2 ℃, respectively, which means that the temperature of persimmonized persimmon was lower than raw persimmon due to the freezing point drop effect.

In addition, the lowest freezing point refers to the minimum temperature just before the raw persimmon or softened persimmon is supercooled to form freezing. The minimum freezing point of the raw persimmon is -2.9 ℃ and the lowest freezing point of the softened persimmon is -6.4 ° C.

From the above experimental results, the frozen iced persimmons in Experimental Example 3 were frozen at temperatures below -10 ℃ and the frozen crystals formed at the frozen tissues. When thawing, the cell wall is destroyed. At this time, the polyphenol oxidase present in the cytoplasm is separated into the vacuoles by the tissue destruction, and the phenol component reacts to promote browning and darken the surface color.

Therefore, when the persimmonized persimmon is cooled from -6.4 ℃ to 0 ℃ above the minimum freezing point, it does not freeze in the supercooling zone immediately before the formation of ice crystals. It is not expected that if the drying proceeds further and the moisture content of the persimmon becomes lower, the quality change due to freezing of the persimmon will not occur at lower temperatures, for example -8 ° C, based on the internal temperature of the persimmon. It was expected.

Example  One: For freeze drying  Of dried persimmon

Peel the same size as that used in Comparative Example 1, and then load it into a self-made dried persimmon dryer with a drying method, and then, in one drying cycle, 20 hours at 20 ° C. and 4 hours at −5 ° C., based on the internal temperature of the dryer. After repeating the drying cycle, drying was carried out at 2 m / s (30 Hz) for 4 days, and after 4 days, the drying cycle was repeated for 18 hours at 20 ° C and 6 hours at -5 ° C. Drying was performed at 4 m / s (60 Hz).

Experimental Example  6: For freeze drying  Characteristics of Dried Persimmons During Drying

Weight loss rate, shell thickness, soluble solids, hardness, moisture content and chromaticity were measured in the same manner as in Experimental Example 3.

The weight reduction rate of persimmon during the drying period was found to increase steadily as the drying period is longer as shown in FIG.

As shown in FIG. 17, the thickness of the shell during the drying period increased thickly until the second day of drying, and gradually increased after the second day, and the thickness of the shell was only 0.54 mm until the second day.

As shown in FIG. 18, the sugar content of the drying period increased in sugar content until the 9th day of drying, which was the initial 15.5 brix.

The change in hardness during the drying period remained almost constant despite the increase in the drying period as shown in FIG. 19.

The change in moisture content during the drying period is drastically decreased after 4 to 6 days as shown in FIG. Since then it has been shown to decrease slowly.

The change in chromaticity during the drying period is shown in FIGS. 21 to 23. The light yellow flesh of the light yellow flesh immediately after peeling at Daebong decreased from 5 to 56.4 on the 2nd day after drying, and then gradually decreased to 47 even on the 9th day of drying, inhibiting the decrease in brightness due to browning. In addition, while the redness (a) slowly increased during the drying process, the yellowness (b) slowly decreased.

Experimental Example  7: For freeze drying  Dried persimmon and dried persimmon Quality comparison

The semi-dry time of 9 days of Example 1 and the semi-dry time (comparative example 2) naturally dried from November 24 to January 20 in Daebong-si in Gwangyang area were compared and the results are shown in Table 3.

division Example 1 (Day 9) Comparative Example 2 (Day 60) Weight reduction rate (%) 61.02 ± 0.83 62.77 ± 0.01 Hardness (g-force) 357.25 ± 3.15 365.31 ± 07.50 Sugar (brix) 34.53 ± 0.28 36.8 ± 0.6 Shell thickness () 0.54 + - 0.05 1.02 + 0.04 Water content (%) 59.59 ± 0.42 61.95 ± 0.10 Chromaticity L 47.20 ± 0.40 38.44 ± 0.06 Chromaticity a 6.92 ± 0.32 5.02 ± 0.70 Chromaticity b 24.53 ± 0.21 19.27 ± 0.68

The weight loss rate was about 62.77% at the time of semi-drying, and the dryness at the 9th day of Example 1 was 61.02%, and the sugar content was about 2 brixes lower than that of the natural drying, but the shell thickness was about 1/2. Levels could be reduced and had a beneficial effect on the expression of redness in the surface color. In addition, in the moisture content, the semi-drying time of Example 1 was 59.59%, and the drying rate was higher than that of about 61.95% of natural drying. In addition, the values of brightness and yellowness in hardness and surface color showed similar results.

Experimental Example  8: Sensory evaluation

In the sensory evaluation, nine panel scales were tested for shape, color, shell thickness, sweetness, bitterness, and general symbology on nine panel scales. verified by way ANOVA.

division Example 1 Comparative Example 1 (Day 8) Comparative Example 2 (Day 60) Appearance 7.89 ± 0.31 ^a 5.67 ± 0.39 ^b 7.00 ± 0.53 ^ab Outer color 8.22 ± 0.41 ^a 5.42 ± 0.57 ^b 7.00 ± 0.53 ^a flavor 7.00 ± 0.34 ^a 6.17 ± 0.37 ^a 6.50 ± 0.21 ^a Texture 6.56 ± 0.44 ^a 5.00 ± 0.24 ^b 5.50 ± 0.21 ^b Shell thickness 7.10 ± 0.56 ^a 4.17 ± 0.37 ^b 5.00 ± 0.41 ^b Comprehensive likelihood 7.64 ± 0.34 ^a 5.58 ± 0.35 ^b 6.50 ± 0.24 ^b

In appearance, Comparative Example 1 was not a high preference because of squeeze, but Example 1 exhibited a smoother appearance than Comparative Example 2, which was naturally dried, and thus the preference was rather high. In addition, the external color was dark brown and the redness was low in the dark brown, the preference was very low, but Example 1 was brighter than the comparative example 2, bright red and high redness was high preference. In the thickness and texture of the shell, Comparative Examples 1 and 2 both exceeded 1 mm, and the texture of chewing was not smooth. However, in Example 1, the thickness of the shell was very soft, which is 1/2 or less. It has been shown to enhance flavor and sweetness.

Claims (16)

Persimmon loading step of loading the peeled persimmon in a drying apparatus having a freezer;
Drying the peeled persimmons at 1 ° C. to 30 ° C. for 12 to 24 hours;
A cooling step of cooling at -2 ° C to -15 ° C for 3 to 10 hours such that the internal product temperature of the persimmon dried in the drying step is in the range of at least the freezing point and below -1 ° C; And
Drying step and the cooling step as a drying cycle repeating the drying cycle 5 to 14 times; dried persimmon drying method comprising a. The method of claim 1, wherein the drying temperature of the drying step is dried persimmon, characterized in that 15 ℃ to 25 ℃. delete The method of claim 1, wherein the cooling step dried persimmon, characterized in that the cooling of the internal product temperature of persimmon to -8 ℃ to-1 ℃. The method of claim 4, wherein the cooling step dried persimmon, characterized in that the cooling so that the internal temperature of the persimmon is -6.4 ℃ to -1 ℃. delete The method of claim 4, wherein the internal drying temperature of the drying apparatus of the cooling step is-5 ℃ to-10 ℃ dried dried method characterized in that. delete The method of claim 1, wherein the drying cycle is repeated for 5 to 14 days. The method of claim 1, wherein the wind speed of the drying step and the cooling step is dried persimmon, characterized in that from 0.5 m / s to 6 m / s. The method of drying dried persimmons according to claim 1, wherein the persimmons loaded in the loading step are large persimmons having a weight of 250 g to 350 g or a long width of 23 cm to 28 cm. The method of claim 1, wherein the persimmon loading step is dried persimmon method, characterized in that the skein method or harvesting method. The method of claim 1, wherein the dried persimmon method further comprises the step of low temperature ripening for 10 days to 60 days at 0 ℃ to 10 ℃ before peeling the harvested persimmon. delete delete delete

Images