JP2008000117A - How to save potatoes - Google Patents

Abstract

The present invention provides a method for preserving potatoes at room temperature by suppressing the germination of harvested potatoes, without safety problems, and without requiring low-temperature storage facilities and special storage management.
A potato surface layer (skin) part is contacted with hot water at 60 ° C. to 100 ° C. for 7 seconds to 100 seconds to suppress germination, and the potato is stored at room temperature. Since it is not necessary to perform low-temperature storage as in the prior art, it is possible to save energy and save costs.
[Selection] Figure 1

Description

  The present invention relates to a method for long-term storage of harvested potatoes.

Potatoes (potatoes) begin to germinate after the dormancy period, and the quality of the tubers is consumed, resulting in a significant reduction in quality. In addition, sprouted potatoes have a significant decline in product value in terms of eating quality, such as being accompanied by a taste. For this reason, effective suppression of germination is an important issue in the long-term storage of potatoes. Low-temperature storage at 0 to 5 ° C., irradiation with cobalt 60, application of maleic hydrazide, and the like are effective for suppressing potato germination. However, low temperature storage requires special facilities such as a low temperature storage warehouse and requires energy for low temperature storage. Furthermore, an increase in reducing sugar is a problem due to low-temperature sweetening. In addition, radiation irradiation has a problem that it is difficult for consumers to accept due to an increase in food safety orientation, and maleic hydrazide is prohibited from being used due to a carcinogenic problem that has become apparent in recent years.
Therefore, at present, potatoes are stored in a cold storage warehouse, but not only do they need special facilities and consume energy to maintain the low temperature, but the harvested potatoes are stored in the cold storage warehouse. Depending on the structure of the storage facility and storage management, problems such as potato greening and germination may occur even at low temperature storage.

As one means for solving such a problem, potatoes are used by using a drying / preserving sheet having a moisture permeability of 1000 to 20000 g / m ² · day and a light blocking rate of 95% or more at a wavelength of 200 nm to 800 nm. A method of drying and storage by packaging has been proposed (see Patent Document 1 below). However, since this method requires a special sheet and requires a packaging operation, there is a problem in economy.

For these reasons, it is awaited to develop a long-term potato storage method (long-term germination suppression method) that is energy-saving, highly safe, and economical.
JP-A-6-225692

  The objective of this invention is providing the room temperature preservation | save method of the potato which can solve said subject.

  In order to achieve the above-mentioned object, the present inventors treated the potato eye tissue with hydrothermal treatment, studied the relationship between hydrothermal treatment temperature and germination at that time, and stabilized with simple hydrothermal treatment. It has been found that long-term room temperature storage is possible, and the present invention has been completed.

Thus, according to the present invention, the potato surface layer (skin) part is brought into contact with hot water at 60 ° C. to 100 ° C. to prevent germination, and then the potato is stored at room temperature. A method is provided.
In this method, it is appropriate that the germination suppression treatment time with hot water is 7 seconds to 100 seconds.
In addition, in this method, it is effective to perform germination suppression treatment by applying hot water to the portion of the eye tissue on the surface layer of potato.

  In the present invention, sprouting is effectively suppressed only by hydrothermal treatment of potatoes immediately after harvesting under specific conditions, and therefore conventional low temperature storage and special film packaging are not required. Therefore, the method of the present invention is a storage method that does not require special facilities or packaging materials, is energy-saving, and is economical and safe. For this reason, compared with the conventional method, it becomes possible to significantly reduce the cost for long-term preservation (storage) and transportation of potatoes.

  Although there is no restriction | limiting in particular in the kind and magnitude | size of a potato to which this method is applied, The thing immediately after a harvest is preferable. Since the specific gravity of the potato hardly affects the effect of the present invention, the specific gravity is a low specific gravity of 1.079 or less, a medium specific gravity of 1.080 to 1.089, or a high specific gravity of 1.090 or more. The same can be applied to this.

In the present invention, germination is suppressed by treating at least the eye part of the surface layer (skin) part of potato with hot water, but the hot water treatment temperature needs to be 60 to 100 ° C. When the hydrothermal treatment temperature is less than 60 ° C., the germination suppressing effect is small.
A suitable heat treatment temperature should be appropriately selected from the above temperature range depending on the use of potato, but when sliced into potato chips, it is preferably 60 ° C. or higher and lower than 80 ° C. When the hot water treatment temperature is 80 ° C. or higher, the potato chip often browns, so the commercial value is lowered. The hot water treatment temperature when cooking and cooking is preferably around 100 ° C. This is because the texture (hardness) when cooked is affected by the hot water treatment temperature. When the potatoes after storage are cooked and eaten, when the hot water treatment temperature is 100 ° C, the texture is most By showing good texture.

As a specific method of the hot water treatment carried out in the present invention, for example,
(1) A method of spraying hot water with a watering machine only to the eyes of the surface layer (skin) of the potato,
(2) A method of spraying hot water over the entire surface of the potato,
(3) A method of immersing potatoes in a hot water bath,
Such a method is adopted.
Among these, the method (1) or (2) is preferable.

The hot water treatment time may be 7 seconds or more, and preferably 10 seconds or more. However, since there is a possibility that the potato itself will be deteriorated if it is too long, a time not exceeding 100 seconds is preferable.
It is considered possible to perform steam treatment instead of hot water treatment. In this case, the processing temperature is substantially 100 ° C. or its vicinity.

  Potatoes whose germination is suppressed by hydrothermal treatment are stored (stored) after removing moisture adhering to the surface by natural drying or ventilation drying. The storage conditions may be normal room temperature (about 10 to 25 ° C.), and it is not necessary to store at a low temperature such as 0 to 5 ° C. as in the prior art, and it is not necessary to wrap with a special film.

  Hereinafter, the storage method of the present invention will be specifically described by way of examples, but the present invention is not limited thereto.

As a sample, a baron jar from Hokkaido in 2005 was used. Since potatoes have different properties depending on their specific gravity, they are classified according to specific gravity in the ranks of low specific gravity: 1.079 or less, medium specific gravity: 1.080 to 1.089, high specific gravity: 1.090 or more, and sample conditions are aligned. In this experiment, a low specific gravity baron was used.
The surface layer (skin) part near the eyes of the baron of the sample was treated by applying hot water of 60 ° C., 70 ° C., 80 ° C., 90 ° C. and 100 ° C. for 10 seconds with a dispenser. Thereafter, each sample was stored at 20 ° C. for 60 days. In addition, about what was processed at 60 degreeC and 70 degreeC, what was processed for 30, 60, and 90 second was also stored. As a control, untreated potatoes were stored under the same conditions.

  After the above hot water treatment, the germination state of each sample (potato) stored at 20 ° C. for 60 days was confirmed. When buds of 1 mm or more emerged from the eyes, they were regarded as sprouting, and the rate of sprouting was examined. The sprouting of potatoes was suppressed at a hydrothermal treatment temperature of 60 ° C. or higher. No sprout was found during storage in the treatment. Examples of those results processed for 10 seconds are shown in FIGS.

However, the surface layer browned when the treatment temperature was increased. That is, the browning degree (color tone) of the potato surface layer treated with hot water was measured with a color difference meter (manufactured by Minolta). The result is shown in FIG. Note that the L value represents brightness, the a value, and the b value represent red and yellow chromaticities, respectively. In either case, the color becomes brighter as the numerical value increases, and on the contrary, the closer to 0, the darker the color. As is clear from FIG. 2, the color tone of the surface layer portion increases as the processing temperature increases, and the L value and b value decrease. It is clear that the higher the germination suppression effect, the greater the browning degree. It was.
In this way, the higher the hot water treatment temperature, the greater the suppression of potato sprouting, and no sprouting was observed during storage at 90 ° C. or higher, but the surface layer turned brown when the treatment temperature increased. .

Furthermore, in order to evaluate the quality of hot water-treated potatoes, potatoes stored at 20 ° C. for 50 days after hot water treatment were used to examine differences in the amount of components (starch and free sugar).
The starch and free sugar were prepared by the following extraction method. That is, 10 g of the surface layer containing the potato skin was crushed with Hiscotron, extracted with heat, and the supernatant was centrifuged and the total sugar content was reduced by the phenol-sulfuric acid method and reduced by the somogy-Nelson method. The amount of sugar was measured. The precipitate was subjected to the following treatment, and the starch content of the obtained solution was measured by the phenol / sulfuric acid method.
As a result, as shown in FIG. 3, there was no significant difference in starch content during storage by hot water treatment, but the amount of reducing sugar slightly increased in the 80 ° C. to 100 ° C. treated sample.
As mentioned above, although the big difference was not looked at by the starch content in the storage by a hot water process, the amount of reducing sugars increased a little with the hot water process sample at 80-100 degreeC.

  Next, the chip color of potatoes 60 days after storage treated with hot water at 80 ° C. to 100 ° C. was measured. The result is shown in FIG. As is clear from FIG. 4, the chip color of potato 60 days after storage at 80 ° C. to 100 ° C. with hot water decreased the L value (lightness) and increased the a value (redness). Therefore, hot water treatment at 80 ° C. or lower is suitable for potato chips.

  Furthermore, the hardness of the steamed sample was measured. Here, potatoes stored for 60 days at 20 ° C. after hot water treatment are shaped into a cylinder with a diameter of 10 mm and a height of 10 mm, boiled for 20 minutes, left in a desiccator for 1 hour, and then textured (hardened) with a Leoner. Measurement). As a result, as shown in FIG. 5, the hardness of the steamed sample was almost the same as that at the start of storage of the untreated potato in the 100 ° C. treatment, but softened as the treatment temperature was lowered. That is, the hardness of the steamed sample was almost the same as that at the start of storage of untreated potatoes at 100 ° C., but softened as the treatment temperature was lowered.

As described above, it was confirmed that sprouting was suppressed and the storability was improved by performing the hydrothermal treatment. Then, in order to elucidate the mechanism of the germination inhibitory effect, the protein extracted from the structure | tissue near the non-emergent eyes of the potato surface layer part which performed the hydrothermal treatment was used for two-dimensional electrophoresis. At this time, the sample solution was extracted as follows.
To 0.5 g of untreated and hydrothermally treated potato eyes, 10 mg of DTT and 1 ml of extraction buffer were added, crushed with a multi-bead shocker, and the supernatant obtained by centrifugation was used as the extract. 1/10 amount of 1M acrylamide solution was added to this extract, and 50 μg and 100 μg of protein amount were subjected to two-dimensional electrophoresis. The amount of protein was determined by the Lowry method, and the gel was stained by silver staining.

  As a result of two-dimensional electrophoresis, the expression of two protein spots of 33.5 kDa, pI8.3, and pI8.5 was confirmed by hydrothermal treatment, and these spots were more apparent as the treatment temperature was higher. This suggests that the above two proteins may be involved in sprouting suppression.

  According to the present invention, since germination can be effectively suppressed by simply performing a simple hot water treatment on the harvested potato, the potato can be stored and stored in a normal warehouse. For this reason, this invention can be utilized effectively in preservation | save of each field | area of production, distribution, and processing of potato.

Graph showing the relationship between germination rate and hydrothermal treatment temperature Graph showing the relationship between hot water treatment temperature and potato color (L value, a value, b value) after treatment A graph showing changes in the amount of starch, the amount of soluble total sugar and the amount of free sugar after storage at 20 ° C. for 60 days of the hot water treatment temperature and the hot water treatment temperature Graph showing the relationship between hydrothermal treatment temperature and chip color measurement results The graph which shows the texture (hardness) of the steaming sample after storing the hot water processing temperature and the hot water processing potato for 20 days at 20 degreeC. Photograph showing budding state of potatoes treated with hot water at each temperature after storage at 20 ° C for 60 days

Claims (3)

  A method for preserving potatoes, characterized in that after the surface layer (skin) portion of potato is brought into contact with hot water at 60 ° C. to 100 ° C., germination suppression treatment is performed, and then the potato is stored at room temperature.   The method for preserving potatoes according to claim 1, wherein the sprouting treatment time with hot water is 7 to 100 seconds.   The method for preserving potatoes according to claim 1 or 2, wherein the sprouting treatment is carried out by applying hot water to the part of the eye tissue on the surface layer of the potato.

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