JP7340339B2 - Method for drying animal and plant tissue-derived materials and method for producing dried products - Google Patents

Description

The present invention relates to a method for drying animal and plant tissue-derived materials and a method for producing dried products.

Drying is a widely used food processing and preservation method, along with freezing and refrigeration.

Examples of food drying methods include air drying (natural drying), hot air drying, fry drying, freeze drying, and spray drying, which require a long time or a lot of energy (Patent Document 1, Patent Document 2, Patent Documents 3).

Air-dried vegetables and fruits are known as one type of dried food. Compared to freeze-drying, it has the advantage of maintaining its crunchiness. However, due to the strong shrinkage, there are disadvantages such as poor rehydration, increased energy costs due to hot air drying, and decreased nutritional content due to heating. There was a need for a less drying method.

On the other hand, it is widely known that pulsed electric field treatment is performed on foods for the purpose of sterilizing microorganisms attached to or contained in the foods and drinks (Patent Document 4).

However, the use of pulsed electric field treatment to accelerate the drying of animal and plant tissue-derived materials such as foods has not been known to date.

JP2009-142221A JP2014-204738A Japanese Patent Application Publication No. 6-105661 Special table 2014-518083 publication

One object of the present invention is to provide a method for improving the drying efficiency of animal and plant tissue-derived materials.

The present inventors have discovered that drying efficiency can be significantly improved by performing a drying process after subjecting animal and plant tissue-derived materials to pulsed electric field treatment.

The present invention includes the following inventions.
(1) A method for drying animal and plant tissue-derived materials, which comprises performing a drying treatment on animal and plant tissue-derived materials that have been treated with a pulsed electric field.
(2) The method according to (1), wherein the animal and plant tissue-derived material is a plant tissue-derived material.
(3) The method according to (1) or (2), wherein the animal or plant tissue-derived material is food or food waste.
(4) The method according to (3), wherein the food comprises at least one selected from the group consisting of vegetables, seaweeds, and fruits.
(5) The method according to any one of (1) to (4), wherein the drying process is a hot air drying process.
(6) A method for producing a dried product of animal and plant tissue-derived materials, which includes a step of drying the animal and plant tissue-derived materials that have been treated with a pulsed electric field.
(7) A method for shortening the drying time of animal and plant tissue-derived materials, which comprises drying the animal and plant tissue-derived materials that have been treated with a pulsed electric field.

According to the present invention, it is possible to improve the drying efficiency of animal and plant tissue-derived materials such as foods. Further, according to the present invention, the drying treatment time can be shortened. Further, according to the present invention, it is possible to reduce the energy cost required for manufacturing a dried product of animal and plant tissue-derived materials. Further, according to the present invention, it is possible to reduce shrinkage in a dried product of animal and plant tissue-derived materials and improve rehydration in hot water. Further, according to the present invention, it is possible to suppress a reduction in the content of nutritional components in a dried product of animal and plant tissue-derived materials.

A circuit diagram of a capacitive energy storage type pulse generation circuit using SiC-MOSFET is shown. Figure 2 shows a schematic diagram of a plate-to-plate electrode reactor. An example of the arrangement of an animal or plant tissue to be treated (spinach) in a plate-to-plate electrode reactor is shown. A typical example of voltage and current waveforms is shown. It shows the change in the moisture content of spinach during the drying process in the pulsed electric field treated area (PEF) and the untreated area (Control). The drying speed of spinach in the drying process of the pulsed electric field treated area (PEF) and the untreated area (Control) is shown. The surface area changes of spinach leaves during the drying process in the pulsed electric field treated area (PEF) and the untreated area (Control) are shown. Fig. 2 shows the change in moisture content during the drying process in the pulsed electric field treated area (PEF) and the untreated area (Control) when the test material is basil. Fig. 2 shows the change in moisture content during the drying process in the pulsed electric field treated area (PEF) and the untreated area (Control) when the test material is an apple. FIG. 2 shows the change in moisture content during the drying process in the pulsed electric field treated area (PEF) and the untreated area (Control) when the test material is wakame seaweed. The water content changes in the drying process are shown for the post-bath water electrolytic treatment group (HW+PEF), the hot water bath only group (HW), and the non-treatment group (Control). The drying speed in the drying process is shown for the post-bath water electrolytic treatment group (HW+PEF), the hot water bath only group (HW), and the non-treatment group (Control).

According to one embodiment of the present invention, there is provided a method for drying an animal and plant tissue-derived material, which comprises drying the animal and plant tissue-derived material that has been subjected to a pulsed electric field treatment.

(Materials derived from animal and plant tissues)
Animal and plant tissue-derived materials refer to materials that can be obtained from animal tissues or plant tissues, and include specimens (whole plants, etc.), materials, or fractions. The animal or plant tissue-derived material is preferably a solid or semi-solid structure. Animal and plant tissues can be obtained by cutting all or part of desired tissues constituting animals and plants.

The animal or plant tissue-derived material is preferably a cell-containing tissue sample obtained from an animal tissue or a plant tissue. Although not bound by theory, when a pulsed electric field is applied to a cell-containing tissue sample, a potential difference is created between the outside and outside of the cell membrane, and the cell membrane is compressed by Maxwellian stress, resulting in destruction of the cell membrane, and the water inside the cells is dried. It is thought that it can be removed more efficiently.

According to one embodiment of the invention, the animal or plant tissue derived material is food or food waste.

Foods include, but are not limited to, vegetables including leafy vegetables such as spinach and cabbage, root vegetables such as radish and carrots, fruits such as oranges and acerola, grains such as soybeans, rice, wheat, and corn, seaweed, and kelp. Examples include seaweeds that form fruiting bodies such as shiitake mushrooms and king oyster mushrooms, meats such as beef, pork, and chicken, and seafood such as salmon, sardines, scallops, and freshwater clams, but preferably vegetables and seaweeds. Or fruits. Suitable examples of foods include, in addition to individual food materials, mixtures thereof, processed products obtained by cutting, freezing, crushing, re-molding, etc. foods, and cooked products obtained by heating, steaming, etc. In addition, food waste is not particularly limited as long as it is derived from animal and plant tissue discarded during the process of food production and consumption, such as discarded food, inedible parts of animal or plant tissue, tea leaves, etc. can be mentioned.

(Pulsed electric field treatment)
According to one embodiment, in the method of the invention, a pulsed electric field treated animal or plant tissue derived material is provided. Pulsed electric field treatment can be performed by placing the animal and plant tissue-derived material between electrodes and applying a voltage between the electrodes in a pulsed manner.

In the pulsed electric field treatment, it is preferable to adjust the amount of energy applied to the animal and plant tissue-derived material by appropriately adjusting the voltage, pulse width, frequency, etc., depending on the properties of the animal and plant tissue-derived material and the desired drying state.

The range of energy applied to animal and plant tissue-derived materials in pulsed electric field treatment is preferably 1 J/g to 1 kJ/g.

In the pulsed electric field treatment, the range of the pulsed electric field is not particularly limited, but is, for example, 0.1 to 10 kV/cm. It is preferable to set the range of the pulsed electric field to 10 kV/cm or less from the viewpoint of avoiding discharge.

In pulsed electric field processing, the pulse frequency range is preferably 1 to 10 kHz from the viewpoint of adjusting the processing time to an appropriate range.

In pulsed electric field treatment, the pulse width range is preferably 100 ns to 10 μs.

The duration of the pulsed electric field treatment may be set as appropriate depending on the properties of the material derived from animal and plant tissue, the energy to be applied, etc., but for example, it is 1 minute or more, preferably 5 to 30 minutes, more preferably 5 minutes. ~20 minutes.

Pulsed electric field treatment of animal and plant tissue-derived materials is performed by placing the animal and plant tissue-derived material between electrodes, but it can also be performed with the space between the electrodes filled with a solution such as water. Examples of the environment in which the pulsed electric field treatment is performed include a closed environment under an atmospheric atmosphere. Further, the pulsed electric field treatment can be performed, for example, at room temperature.

(drying process)
According to one embodiment, after performing the pulsed electric field treatment, the animal and plant tissue-derived material subjected to the pulsed electric field treatment is subjected to a drying treatment. Performing the drying treatment after the pulsed electric field treatment is advantageous in significantly shortening the drying time compared to the case without the pulsed electric field treatment.

The drying method is not particularly limited, and includes natural drying methods such as sun drying, and artificial drying methods such as hot air drying, heat drying, fry drying, and freeze drying, preferably hot air drying. The power required for pulsed electric field treatment can be much smaller than the power required for the artificial drying method described above, so combining pulsed electric field treatment and the artificial drying method described above can reduce the power required for drying. It is also advantageous to do so. In addition, when carrying out the drying treatment, reduced pressure treatment, microwave irradiation, etc. may be used in combination.

The drying time may be determined as appropriate depending on the selected drying method, the type of animal or plant tissue-derived material, the desired drying state, and the like. In the case of a natural drying method, for example, half a day to several days, and in the case of an artificial drying method, for example, from 1 minute to 1 day, preferably from 30 minutes to 6 hours, more preferably from 30 minutes to 3 days. It's time.

Performing the drying process after the pulsed electric field treatment is advantageous in reducing the degree of heating during the drying process and shortening the time in the heated state, thereby reducing the loss of nutritional components caused by heating. . Such nutritional components include sugar, various vitamins (vitamin A, vitamin B, ascorbic acid, etc.), and the like.

Further, it is preferable to perform a drying treatment after the pulsed electric field treatment in order to reduce shrinkage of the animal and plant tissue-derived material during the drying treatment. Further, performing a drying treatment after the pulsed electric field treatment is advantageous in maintaining the form of the animal and plant tissue-derived material and shortening the time required for returning the material by immersion in hot water or the like.

According to one embodiment, a dried product of animal and plant tissue-derived material obtained by the above method is provided. Examples of such dried products include dried meat, dried vegetables, and dried fruits.

According to one embodiment, the method for drying animal and plant tissue-derived materials described above can also be advantageously used for drying food waste. So-called garbage disposal machines are widely used for home and commercial purposes, and their mechanisms include bio-methods that utilize decomposition by microorganisms, drying methods that involve hot air drying, and hybrid methods thereof. Among these, the drying method and hybrid method usually consume a large amount of energy due to heating. However, when the above-mentioned method of the present invention is used for drying garbage in a drying type or hybrid type garbage dryer, it is possible to shorten the drying processing time in garbage drying, reduce power consumption accordingly, and eliminate unpleasant odors. It is possible to effectively implement mitigation measures.

According to one embodiment, before and after the pulse electrolytic treatment step, heat treatment is performed for the purpose of blanching (enzyme deactivation), sterilization, preservation, etc., taking into consideration the desired properties, transportation, etc. of the material derived from animal and plant tissue. (boiling water immersion treatment, steaming treatment, etc.) or freezing preservation treatment may be performed.

According to one embodiment, the material derived from animal and plant tissue is preferably heat treated before the pulse electrolytic treatment step. The conditions for the heat treatment may be appropriately set depending on the required quality of the dried product of animal and plant tissue-derived materials, and the temperature is, for example, 40°C to 105°C, preferably 60 to 100°C. Further, the heat treatment time is, for example, 30 seconds to 1 hour, preferably 30 seconds to 3 minutes.

According to another embodiment, there is provided a method for producing a dried product of an animal and plant tissue-derived material, which includes a step of drying the animal and plant tissue-derived material that has been treated with a pulsed electric field. . According to another embodiment, there is provided a method for shortening the drying processing time of animal and plant tissue-derived materials, the drying processing time being characterized in that the drying processing is performed on the animal and plant tissue-derived materials that have been treated with a pulsed electric field. A method is provided to shorten the . All of the above methods can be carried out in accordance with the description of the method for drying animal and plant tissue-derived materials described above.

EXAMPLES Hereinafter, the present invention will be specifically explained based on Examples, but the present invention is not limited to these Examples.

(Pulsed electric field processing method and device)
FIG. 1 shows a circuit diagram of a capacitive energy storage type pulse generation circuit using SiC-MOSFETs. In this circuit, energy is stored in the capacitor C using a DC power supply (Pulse Electronic Engineering Co., Ltd., MODEL-600F). Then, using a microcomputer (Atmel, Atmega1248P) programmed to periodically emit pulse signals, a signal is sent to the gate of the SiC-MOSFET (TPEC) through a gate driver to perform switching. When the gate is on, the energy stored in the capacitor is transferred to the reactor, and a pulsed electric field is applied to the sample inside the reactor. The values of each element used are as follows: charging resistor R is 200 kΩ, capacitor C is 0.218 μF, and gate resistor RG is 1Ω.

FIG. 2 shows a schematic diagram of a plate-to-plate electrode reactor. H. V means high voltage. The reactor has a parallel plate electrode structure consisting of two stainless steel plate electrodes. The plate dimensions are approximately 60 ^mm2 . Further, the gap distance was set to 10 mm by installing an acrylic resin spacer so as to surround the center. The volume of the portion into which the sample is placed is 60 mL.

FIG. 3 shows an example of arrangement of a material derived from animal and plant tissues to be treated (spinach) into the reactor. As shown in the figure, the objects to be processed formed within the electrodes are stacked so that there are no gaps, and a pulsed electric field is applied. The application conditions may be, for example, an applied voltage of 3 kV, a pulse width of 1 μs, a frequency of 1 Hz, and a processing time of 15 minutes.

FIG. 4 shows typical voltage and current waveforms. The measured voltage and current are the voltage applied to the reactor and the current flowing into the reactor, respectively. As measuring instruments, a differential probe (Testec, TT-SI9010) was used for voltage, and a current probe (Bergoz, CT-D1.0-B) was used for current. Further, the charging voltage was adjusted so that the output waveform was a rectangular wave with a pulse width of 1 μs, and the peak value was 3 kV.

Example 1: Pulsed electric field (PEF) treatment and drying treatment of spinach (test material)
The test material was spinach from Iwate Prefecture, which was obtained from a mass retailer. After obtaining the spinach, it was stored in a refrigerator at 4°C and used within one day in consideration of quality deterioration due to freshness. A spinach leaf molded to a side of 60 mm was used as a sample to match the size of the reactor. The initial moisture content of the sample measured by the 105°C-24 hour method (Topuz et al. /LWT-Food Science and Technology 42 (2009) 1667-1673.) was 10.8 ± 0.8 (dry weight basis). Moisture content (D.B.)) (n=16).

(Pulsed electric field (PEF) treatment)
As shown in FIG. 3, a pulsed electric field was applied between the electrodes of the pulsed electric field processing device by stacking eight spinach leaves each having a side of 60 mm and stacking them without any gaps. The application conditions were an applied voltage of 3 kV, a pulse width of 1 μs, a frequency of 1 Hz, and a processing time of 15 minutes. In the untreated area, leaves shaped to a side of 60 mm and left at room temperature for the same length of time as the application time were used.

(Calculation of administered energy)
The total energy administered in the reactor was calculated by multiplying the energy administered per pulse by the total number of pulses. The formula for calculating the total input energy is shown below.
Formula (1): P=∫V・Idt×n
Parameters V, I, and n in equation (1) are the voltage applied to the reactor, the current flowing into the reactor, and the total number of pulses, respectively. The total input energy under these conditions determined using equation (1) was about 50 J.

(drying process)
Place three samples each after PEF treatment (hereinafter referred to as PEF treated area; PEF) and samples without PEF treatment (hereinafter referred to as non-treated area; Control) on a wire mesh (mesh size 1 cm on each corner), and place them inside the dryer. The sample was left standing in a hot air dryer (Yamato Scientific Co., Ltd., DKM600) set at 50°C for drying. During drying, the samples were taken out at 10-minute intervals for the first 60 minutes, and then every 30 minutes, and their mass was measured using an electronic balance, and drying was considered completed when the change in mass per 30 minutes was 0.01 g or less. In addition, the reduced mass was regarded as the evaporated water content and was converted to dry basis water content (D.B.).
Drying rate (-dM/dt) represents the amount of water evaporated per unit time. In addition, an approximate formula was obtained from the measured values using the least squares method. The approximate formula is shown below.
Formula (2): -dM/dt=aM+b
Parameters a, b, and M in equation (2) are a drying rate constant, an intercept, and a dry basis moisture content, respectively.

(Measurement of leaf area)
To measure the surface area of the leaves during drying, the sample was photographed from above when removed from the dryer, and the surface area was calculated using image analysis software (ImageJ). Note that the test in Example 1 was repeated three times.

(result)
Figure 5 shows changes in the moisture content of spinach during the drying process in the PEF-treated and untreated plots. From FIG. 5, it can be seen that the moisture content decreased over time in all treated areas. Further, the time from the start of drying until the moisture content reached equilibrium was 2 hours in the PEF treated area and 3.5 hours in the untreated area. Therefore, it has become clear that the drying time can be shortened by about 1.5 hours by performing the PEF treatment under these conditions before the hot air drying process. This shows that PEF treatment can reduce the time and cost required for drying treatment by approximately 40 to 50%.

FIG. 6 shows the drying speed of spinach during the drying process in the PEF treated area and the untreated area. From FIG. 6, it can be seen that the drying rate decreases linearly as the moisture content decreases. Further, the drying rate constant a obtained by equation (2) is 5.29×10 ⁻² in the PEF treated area and 2.90×10 ⁻² in the untreated area. From this, it can be seen that under these conditions, the drying rate constant a of the PEF treated area increases by about 1.8 times compared to the untreated area.

Figure 7 shows changes in leaf surface area during the drying process in the PEF-treated and untreated plots. From Figure 7, the leaf surface area 3.5 hours after the start of drying was 12.59 ± 0.67 mm ² in the PEF treated area and 7.32 ± 1.94 mm ² in the untreated area, and the leaf surface area in the PEF treated area was dry. It was found that the surface area of the later leaves was large.

Example 2: Pulsed electric field treatment and drying treatment of basil, apple and seaweed (test materials and test conditions)
Basil, apples, and wakame seaweed purchased from a mass retailer in Iwate Prefecture were subjected to pulsed electric field treatment and drying treatment in the same manner as in Example 1. Table 1 shows the test materials and pulsed electric field treatment conditions.

(result)
FIGS. 8A to 8C show changes in the moisture content of each test material during the drying process in the PEF treated area (PEF) and the untreated area (Control). It can be seen that for all materials, the moisture content decreased in a shorter time in the PEF treated area compared to the untreated area. This shows that the time and cost required for drying can be reduced by pre-treating various animal and plant tissues with PEF treatment.

Example 3: Combination of blanching and pulsed electric field treatment (test material and test conditions)
Spinach from Iwate Prefecture (8 g) purchased at a mass retailer was immersed in boiling water (100°C, 60 seconds), and after wiping off the moisture, pulsed electric field treatment was performed under the same conditions as in Example 1, except that the treatment time was 3 minutes. (HW+PEF district). The HW group, which was similarly immersed in boiling water and left at room temperature for 3 minutes after wiping off the moisture, and the untreated group, which was left at room temperature for the same time as the other groups, were used for comparison. The drying treatment was carried out in the same manner as in Example 1.

(result)
FIG. 9A shows the moisture content change in the drying process of each treatment area, and FIG. 9B shows the drying rate in the drying process of each treatment area. The water content in the HW + PEF group (electrolytic treatment after hot water bathing) decreased in a shorter time than in the HW group (only hot water bathing) and the untreated group (no treatment). Furthermore, it can be seen that although the drying rate decreased in all test plots as the moisture content decreased, the HW+PEF plot always showed higher values compared to the other test plots. From these results, the effect of PEF treatment was confirmed even when used in combination with blanching (boiling water immersion).

Example 4: Analysis of Nutrient Components Regarding the dried products of the PEF treated area obtained in Example 1, the residual rate of ascorbic acid, Brix sugar content and potassium was measured in comparison with the untreated case according to the following procedure (each group N =3).

Approximately 0.5 g of the dried product of the PEF treated area obtained in ascorbic acid residual ratio 1 and an untreated sample were each prepared, and the dilution ratio was adjusted to approximately 20 times with metaphosphoric acid (2%). The obtained solution was homogenized (8,000 rpm, 10 min). After homogenization, filtration was performed using filter paper, and the amount of ascorbic acid in the filtered liquid was measured using RQ Flex (Kanto Kagaku Co., Ltd.). Furthermore, the amount of ascorbic acid in the dry product of each PEF treated area was divided by that of the untreated sample to calculate the ascorbic acid residual ratio (%).

Approximately 0.15 g of dried PEF-treated samples obtained with Brix sugar content and residual potassium ratio of 1 and untreated samples were each prepared, and the dilution ratio was adjusted to approximately 120 times with distilled water. The obtained solution was homogenized (8,000 rpm, 10 min). After homogenization, filtration was performed using filter paper, and the amount of ascorbic acid in the filtered liquid was measured using RQ Flex (Kanto Kagaku Co., Ltd.). Furthermore, the amount of potassium and Brix value of the dried product in each PEF treated area were divided by those of the untreated sample to calculate the residual potassium ratio (%) and the Brix residual sugar content ratio (%).

As a result, in the dry product of the PEF treated area obtained in Example 1, the ascorbic acid residual ratio was 112.2 ± 16.1% (standard deviation), and the potassium residual ratio (%) was 96.0 ± 3. .3 (standard deviation)%, and the Brix sugar content residual ratio was 96.8±9.7 (standard deviation)%. The amount of nutritional components (ascorbic acid, potassium, sugar) was almost the same as before drying (untreated sample).

According to the present invention, the drying efficiency of animal and plant tissue-derived materials such as foods can be improved. Further, according to the present invention, it is possible to shorten the drying time of animal and plant tissue-derived materials. Further, according to the present invention, it is possible to reduce the energy cost required for manufacturing a dried product of animal and plant tissue-derived materials. INDUSTRIAL APPLICATION This invention is useful for the manufacture of various dry foods and efficient garbage disposal.

Claims (2)

A heat treatment step of heat treating solid animal and plant tissue-derived materials;
A solid method comprising a pulsed electric field treatment step of treating the heat-treated solid animal and plant tissue-derived material with a pulsed electric field, and a drying treatment step of drying the pulsed electric field-treated solid animal and plant tissue-derived material. A method for drying shaped animal and plant tissue-derived materials. The method according to claim 1 , wherein the pulsed electric field treatment step is a step of directly applying a pulsed electric field to a solid animal or plant tissue-derived material placed between electrodes of a pulsed electric field treatment device.