Method and apparatus for suppressing after-ripening of bananas

Abstract

To provide a method and an apparatus for suppressing the after-ripening of bananas, capable of suppressing the after-ripening of the bananas and maintaining the quality of the bananas.SOLUTION: The method for suppressing after-ripening of bananas includes a step of placing bananas in a water tank, and a step of irradiating the bananas with ultrasonic waves for 2 to 7 minutes from an ultrasonic generator provided in the water tank. The device for suppressing after-ripening of bananas includes a water tank and an ultrasonic generator for irradiating the inside of the water tank with ultrasonic waves, wherein the ultrasonic generator generates ultrasonic waves having an intensity of 250 to 450W at a frequency of 40kHz.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for inhibiting the ripening of bananas and an apparatus for inhibiting the ripening of bananas. [Background technology]

[0002] Bananas are typical climacteric fruits, and as they ripen, they produce a rapid amount of ethylene, which increases respiration and changes flavor, color, and firmness. After harvest, bananas undergo ripening, during which the skin color changes from green to yellow, and at the same time the flesh softens and produces aromatic compounds, becoming edible.

[0003] Bananas are also sensitive to low temperatures, and if they are stored at low temperatures, their skin will turn brown and they will lose their marketability. For this reason, they are usually transported and stored at a medium temperature of around 13°C.

[0004] Currently, almost all bananas distributed in Japan are imported. Under the Plant Protection Act, only bananas in the ripe green stage, before ripening, are permitted to be imported into Japan. Imported bananas arrive in Japan after a one to two week shipping period. During transportation, they are stored and transported in reefer containers set at 13°C, but despite this, some bananas continue to ripen, losing their marketability and being discarded.

[0005] Imported bananas are ripened using ethylene and processed to the yellow-ripe stage before being sold. Before the ethylene treatment, bananas may need to be temporarily stored depending on demand. However, even though they are stored at around 13°C, some bananas continue to ripen. Bananas that have ripened too much are discarded before distribution due to concerns that they may be overripe when sold.

[0006] Controlled Atmosphere (CA) storage is known as one technique for suppressing the ripening of bananas. CA storage is a technique for preserving quality by suppressing the post-harvest metabolism of fruits and vegetables by maintaining a low-oxygen, high-carbon dioxide gas composition in the storage environment. Patent Document 1 discloses an automatic banana ripening process control method in which a banana ripening room is ventilated or ventilated with CO2 gas at regular intervals and then the room temperature is adjusted. However, CA storage requires the installation of a highly airtight storage room and large-scale equipment such as a CA gas generator.

[0007] In Patent Document 2, when the oxygen permeability of a package of bananas after ripening is P (cc / g / day / atm) and the storage temperature is T (℃), the oxygen permeability is 14≦T≦25 and 4.1284×P 0.8139 ≧T≧0.0028×P 3 -0.193×P 2 The method disclosed involves storing bananas at a temperature T (°C) that satisfies +4.8752×P-15.017 (Equation 1), and maintaining an oxygen concentration of 2 to 15% and a carbon dioxide concentration of 5 to 25% inside the package during storage. The method in Patent Document 2 is a technology related to packaging materials that individually package bananas after ripening, and is difficult to apply to bananas before ripening. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Application Publication No. 02-299541 [Patent Document 2] Japanese Patent Application Laid-Open No. 2000-210011 [Non-patent literature]

[0009] [Non-Patent Document 1] Hou JC, Hu YH, Hou LX, Guo KQ, Satake T. “Classification of ripening stages of bananas based on support vector machine” Int J Agric & Biol Eng, 8(6):99-103.2015 Summary of the Invention [Problem to be solved by the invention]

[0010] Even with proper temperature control, some bananas continue to ripen during import and domestic distribution, and excessively ripened bananas are forced to be discarded. Conventionally, large-scale, expensive equipment to control temperature and gas atmosphere was required to prevent bananas from ripening and maintain consistent quality.

[0011] The present invention has been made in view of the above-mentioned circumstances, and aims to solve the problem of providing a technique that can suppress the ripening of bananas and maintain their quality without requiring expensive equipment. [Means for solving the problem]

[0012] The present invention relates to a method for inhibiting banana ripening, which is characterized by comprising the steps of placing bananas in a water tank and irradiating the bananas with ultrasonic waves from an ultrasonic generator provided in the water tank for 2 to 7 minutes.

[0013] In the method for inhibiting banana ripening of the present invention, it is preferable that the frequency of the ultrasound irradiated onto the bananas is 40 kHz.

[0014] The present invention also provides a banana ripening suppression device, which comprises a water tank and an ultrasonic generator that irradiates ultrasonic waves into the water tank. The banana ripening suppression device of the present invention is characterized in that the ultrasonic generator generates ultrasonic waves with a frequency of 40 kHz and an intensity of 250 to 450 W. [Effects of the Invention]

[0015] The ripening suppression method and ripening suppression device of the present invention suppress the ripening of bananas, making it possible to store bananas for a longer period than conventional methods. Bananas to which the ripening suppression method of the present invention has been applied can be stored at room temperature (25°C) for a longer period than conventional methods.

[0016] The method and apparatus for inhibiting banana ripening of the present invention do not require control of the gas atmosphere during ripening inhibition treatment, and therefore banana ripening can be inhibited using a simpler apparatus and method than conventional methods.

[0017] Bananas are usually washed in a washing tank immediately after harvesting. The method for inhibiting ripening of bananas of the present invention can be carried out simultaneously with this washing process. Moreover, since the ultrasonic irradiation time is as short as 2 to 7 minutes, ripening can be inhibited with almost no delay in the washing process. [Brief explanation of the drawings]

[0018] [Figure 1] FIG. 1 is a diagram showing the color index values ​​of banana peels under different ultrasonic irradiation conditions. [Figure 2] FIG. 2 is a diagram showing the color index values ​​of banana fruit skin under different ultrasonic irradiation conditions. [Figure 3] FIG. 3 shows the weight loss rate of bananas under different ultrasonic irradiation conditions. [Figure 4] FIG. 4 is a graph showing the weight loss rate of bananas under different ultrasonic irradiation conditions. [Figure 5] FIG. 5 is a photograph of a banana to which the ripening inhibition method of the present invention has been applied. [Figure 6] FIG. 6 shows preferred ultrasonic irradiation conditions for the ripening suppression method of the embodiment. [Figure 7] FIG. 7 is a schematic diagram of the ripening suppression device of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0019] The following describes the most preferred embodiment of a ripening suppression method and a ripening suppression device for bananas. Furthermore, a method for evaluating the effectiveness of the ripening suppression method of this embodiment is also described. Note that this embodiment is merely an example and is not intended to limit the scope of the claims.

[0020] [Ripening control device] FIG. 7 shows a schematic diagram of a ripening inhibition device used in the ripening inhibition method of this embodiment. The ripening inhibition device 1 comprises a water tank 11 and an ultrasonic generator 12 that irradiates ultrasonic waves into the interior of the water tank 11. The most suitable liquid to fill the water tank 11 is water. There are no particular restrictions on the water quality, and the ripening inhibition effect can be achieved using ordinary tap water or deionized water. A mesh bag or basket that does not block ultrasonic waves can be used as a means for transporting bananas into the water tank 11, holding them there for a certain period of time, and then removing them from the water tank.

[0021] [Method for suppressing ripening] The ripening suppression method of this embodiment is characterized by irradiating bananas with ultrasound for 2 to 7 minutes while they are placed in a water tank. The optimal irradiation time is strongly correlated with the intensity of the ultrasound output. However, regardless of the ultrasound output intensity, if the irradiation time is less than 2 minutes, the ripening suppression effect is very low. Similarly, regardless of the ultrasound intensity, if the irradiation time is more than 7 minutes, the ripening suppression effect is also very low.

[0022] The most preferable frequency of the irradiated ultrasonic waves is 40 kHz. The optimum conditions for irradiation time and ultrasonic intensity when irradiating ultrasonic waves with a frequency of 40 kHz will be explained in detail in the following examples.

[0023] [Method for evaluating the effect of inhibiting ripening] The ripening inhibition effect can be evaluated by the RCI value, which indicates the color index of the banana peel, and the weight loss rate.

[0024] The color index of banana peel can be evaluated using the RCI value (Ripening Color Index) disclosed in Non-Patent Document 1. The formula for calculating the RCI value is as follows: RCI value = 100 / (1 - a* / b*) Here, the a* and b* values ​​are color values ​​that can be measured using a colorimeter. The smaller the RCI value, the more the banana skin maintains its green color. Conversely, the larger the RCI value, the more ripe the banana is.

[0025] The weight loss rate can be calculated using the following formula from the weights before the start of the evaluation (before storage) and after a certain period of time has passed (after storage). Weight loss rate (%) = (weight before storage - weight after storage) / (weight before storage) x 100 The main causes of weight loss are increased respiration and decreased water content. Therefore, a smaller weight loss rate indicates that the banana's ripening process is more inhibited, while a larger weight loss rate indicates that the banana is more ripened. [Example]

[0026] As further examples embodying the present invention, Examples 1 to 14 in which a ripening inhibition device and a ripening inhibition method were applied to ripe-green bananas from the Philippines before ripening will be described with reference to the drawings. In addition, the effectiveness of the ripening inhibition method of the present invention will be confirmed by comparing with Comparative Examples 1 to 9.

[0027] The ripening suppression device 1 used in this example is equipped with a water tank 11 and an ultrasonic generator 12. The ultrasonic generator 12 used in this example is composed of an ultrasonic oscillator (WA-1200-40T, manufactured by Honda Electronics Co., Ltd.) and a vibrator. The water tank 11 is a tank with a width of 500 mm, a depth of 300 mm, and a height of 224 mm, and a vibrator can be installed inside. In this example, tap water 23 x 10 -3 m 3 The water was stored.

[0028] The bananas were placed in a metal wire basket, with five bananas per unit. The bananas in the basket were then immersed in water in a water tank 11 and irradiated with ultrasound.

[0029] In Examples 1 to 14, the ultrasonic output and ultrasonic irradiation time were variously changed to perform the step of irradiating the bananas in the water tank 11 with ultrasonic waves. The ultrasonic output was set to five levels at 50 W intervals from 250 W to 450 W. Then, for each ultrasonic output, the ultrasonic irradiation time was set to two to four levels. The conditions for the ultrasonic irradiation step for each Example are shown below. Example 1: Ultrasonic output 250W, irradiation time 5 minutes. Example 2: Ultrasonic output 250W, irradiation time 6 minutes. Example 3: Ultrasonic output 250W, irradiation time 7 minutes. Example 4: Ultrasonic output 300W, irradiation time 3 minutes. Example 5: Ultrasonic output 300W, irradiation time 4 minutes. Example 6: Ultrasonic output 300W, irradiation time 5 minutes. Example 7: Ultrasonic output 300W, irradiation time 6 minutes. Example 8: Ultrasonic output 350W, irradiation time 3 minutes. Example 9: Ultrasonic output 350W, irradiation time 4 minutes. Example 10: Ultrasonic output 350W, irradiation time 5 minutes. Example 11: Ultrasonic output 400W, irradiation time 2 minutes. Example 12: Ultrasonic output 400W, irradiation time 3 minutes. Example 13: Ultrasonic output 450W, irradiation time 2 minutes. Example 14: Ultrasonic output 450W, irradiation time 3 minutes.

[0030] In all examples, a step of irradiating five units of bananas (total of 25 fruits) with ultrasonic waves was carried out one unit at a time.

[0031] To confirm the ripening-inhibitory effect, the bananas that had been subjected to ultrasonic irradiation were placed in a plastic case and stored in an incubator at 25°C for 11 days. After 11 days of storage, the RCI value, which indicates the color index of the banana skin, of each of the 25 fruits was measured and the average value was calculated. In this example, a colorimeter (CR-20, manufactured by Konica Minolta, Inc.) was used to measure the color. In addition, the weight of each of the 25 banana fruits was measured using an electronic top-pan balance, and the weight loss rate was calculated and the average value was calculated.

[0032] As Comparative Example 1, bananas that were simply placed in water in the water tank 11 and not irradiated with ultrasound were stored in an incubator at 25°C for 11 days, and the RCI value and weight loss rate were measured. As Comparative Examples 2 to 9, bananas were irradiated with ultrasound at the following ultrasound outputs and for the following ultrasound irradiation times. Comparative Example 2: Ultrasonic output 250W, irradiation time 4 minutes. Comparative Example 3: Ultrasonic output 250W, irradiation time 8 minutes. Comparative Example 4: Ultrasonic output 300W, irradiation time 7 minutes. Comparative Example 5: Ultrasonic output 350W, irradiation time 2 minutes. Comparative Example 6: Ultrasonic output 350W, irradiation time 6 minutes. Comparative Example 7: Ultrasonic output 400W, irradiation time 4 minutes. Comparative Example 8: Ultrasonic output 400W, irradiation time 5 minutes. Comparative Example 9: Ultrasonic output 450W, irradiation time 4 minutes.

[0033] For Comparative Examples 1 to 9, a total of 25 bananas were used in 5 units, as in the Examples. Furthermore, the bananas of Comparative Examples 1 to 9 were placed in plastic cases and stored for 11 days in the same incubator at 25°C as the bananas of the Examples. After storage, the RCI value of the peel of each of the 25 bananas was measured and the average value was calculated. Similarly, the average weight loss rate of each of the 25 bananas was calculated.

[0034] Figures 1 and 2 show the average RCI values ​​of the bananas in Examples 1 to 14 and Comparative Examples 1 to 9. Specifically, Figure 1 is a graph with ultrasound intensity (unit: W) on the horizontal axis and ultrasound irradiation time (unit: minutes) on the vertical axis, showing the average RCI values ​​of each banana at the position of the corresponding condition in Examples 1 to 14 and Comparative Examples 2 to 9. The RCI value of the banana in Comparative Example 1 is shown numerically in the upper right corner of the graph. Figure 2 is a bar graph showing the average RCI values ​​of the bananas in Examples 1 to 14 and Comparative Examples 2 to 9. It can be seen that the ultrasound irradiation conditions with smaller RCI values ​​have a greater effect of inhibiting ripening.

[0035] As shown in Figure 1, the average RCI value of the bananas in Comparative Example 1, which were not irradiated with ultrasound, was 110.8. In the graph in Figure 1, the backgrounds of Examples with RCI values ​​significantly different from those of Comparative Example 1 are shown in different colors. The RCI values ​​of all bananas in Examples 1 to 14 were significantly lower than the RCI value of Comparative Example 1, and the color of the peel remained green.

[0036] FIG. 5 shows photographs of the bananas of the Example and Comparative Example after storage in an incubator for 11 days.

[0037] Figures 3 and 4 show the average weight loss rates of bananas in Examples 1 to 14 and Comparative Examples 1 to 9. Figure 3 is a graph showing the average weight loss rate (%) of each banana at the position corresponding to the conditions in Examples 1 to 14 and Comparative Examples 2 to 9, with the horizontal axis representing ultrasonic intensity (unit: W) and the vertical axis representing ultrasonic irradiation time (unit: minutes). The weight loss rate of the banana in Comparative Example 1 is shown numerically in the upper right corner of the graph. Figure 4 is a bar graph showing the weight loss rate of the RCI values ​​of each banana in Examples 1 to 14 and Comparative Examples 2 to 9. It can be seen that the ultrasonic irradiation conditions with smaller weight loss rates have a greater effect in inhibiting ripening.

[0038] As shown in Figure 3, the weight loss rate of the bananas in Comparative Example 1, which were not exposed to ultrasound, was 2.37%. In the graph in Figure 3, the background of the values ​​for Examples that had a significant difference in weight loss rate from Comparative Example 1 is shown in different colors. The weight loss rates of all bananas in Examples 1 to 14 were significantly lower than that of Comparative Example 1, confirming the effectiveness of the ripening inhibition method applied in the Examples. Furthermore, the weight loss rates of the bananas in Comparative Examples 2 to 9 were lower than that of Comparative Example 1, confirming that a certain level of effect could be obtained even under the ultrasound irradiation conditions of Comparative Examples 2 to 9.

[0039] In the ripening suppression method of this example, the highest ripening suppression effect was obtained when irradiation was performed within a specific irradiation time range corresponding to each ultrasonic intensity. If the irradiation time is too long or too short, the ripening suppression effect decreases.

[0040] Furthermore, the stronger the ultrasonic intensity, the more effective the ripening inhibitory effect can be seen with a shorter irradiation time. In other words, there is a negative correlation between ultrasonic intensity and irradiation time as the ultrasonic irradiation conditions for obtaining the ripening inhibitory effect.

[0041] The bananas obtained in Comparative Example 8 (ultrasonic output 400 W, irradiation time 5 minutes) showed the same ripening inhibitory effect as the Examples in both RCI value and weight loss rate. However, Comparative Example 7, which used ultrasonic irradiation for a shorter period of time (ultrasonic output 400 W, irradiation time 4 minutes), showed a lower ripening inhibitory effect, so the results of Comparative Example 8 were deemed to be peculiar. The ultrasonic irradiation conditions of Comparative Examples 7 and 8 were excluded from the consideration of suitable conditions for ripening inhibition.

[0042] Figure 6 shows a graph of estimated upper and lower limit values ​​of the ultrasonic irradiation conditions for which a ripening effect was confirmed in this example. The estimation was performed based on the ultrasonic irradiation conditions of Examples 1 to 14 and Comparative Examples 1 to 9. The maximum value of the irradiation condition is the longest irradiation time for which a ripening inhibitory effect was confirmed for each ultrasonic output. The minimum value of the irradiation condition is the shortest irradiation time for which a ripening inhibitory effect was confirmed for each ultrasonic output. Furthermore, the values ​​obtained by linear approximation of the maximum and minimum values ​​are shown with dashed lines.

[0043] The approximate maximum value of the irradiation time t is expressed by the following formula using the ultrasonic intensity W: t=-0.022 × W + 12.5 The approximate minimum value of the irradiation time t is expressed by the following formula using the ultrasonic intensity W: t=-0.014 × W + 7.9

[0044] The maximum and minimum values ​​of the ultrasonic irradiation conditions described above are values ​​obtained based on the configuration of the ripening suppression device 1 used in this example. However, even if the size of the ripening suppression device 1 is changed, it is thought that there is a negative correlation between the ultrasonic intensity and the irradiation time for the ultrasonic irradiation conditions that provide the ripening suppression effect.

[0045] In this study, differences emerged between the presence or absence of a ripening-inhibitory effect when evaluating the ripening-inhibitory effect using the RCI value and when evaluating the ripening-inhibitory effect using the weight loss rate. When evaluated using the weight loss rate, the ripening-inhibitory effect was also confirmed for the ultrasonic irradiation conditions in the comparative example. In this study, only cases where the effect was clear in both the RCI value and the weight loss rate were used as examples. However, which evaluation item is used to determine the optimal conditions for the ripening-inhibitory method can be changed as appropriate depending on the type of banana and distribution method used for the evaluation.

[0046] The method and device for inhibiting banana ripening of the present invention have been described above based on the examples, but the configuration of the method and device for inhibiting ripening can be modified as appropriate. For example, the size of the water tank is not limited to that of the examples, and it is possible to use a larger water tank and increase the ultrasonic intensity to process a large number of bananas simultaneously. Furthermore, the frequency of the ultrasonic waves can be modified as appropriate within a range that does not adversely affect the banana tissue. [Industrial Applicability]

[0047] The method and device for inhibiting ripening of bananas according to the present invention can be applied to any other fruits and vegetables in addition to bananas. [Explanation of symbols]

[0048] 1 Ripening control device 11 Aquarium 12 Ultrasonic generator

Claims

1. placing bananas in a water tank; a step of irradiating the bananas with ultrasonic waves from an ultrasonic generator installed in the water tank for 2 to 7 minutes; This method inhibits banana ripening.

2. 2. The method for inhibiting banana ripening according to claim 1, wherein the frequency of the ultrasound irradiated to the banana is 40 kHz.

3. Aquarium and an ultrasonic generator that irradiates ultrasonic waves into the inside of the water tank; The apparatus for inhibiting banana ripening is characterized in that the ultrasonic generator generates ultrasonic waves having a frequency of 40 kHz and an intensity of 250 to 450 W.

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