JPH07203841A - Bactericidal method for physalospora piricola - Google Patents

Abstract

PURPOSE:To provide an easy and effective bactericidal method against Physalospora piricola for preventing the damage from ring spot disease in the range from fruits of pear, apple, etc., to commercial products. CONSTITUTION:After it is harvested, a fruit of pear, apple, etc., is placed in a hot water kept from 50 deg.C to 55 deg.C and warmed up until the temperature of the peel of the fruit and that of the fruit meat in a certain depth from the peel reaches at least 50 deg.C while keeping the fruit in the hot water.

Description

Detailed Description of the Invention

[0001]

It is an object of the present invention to provide a convenient and effective sterilization of ring fungus for preventing damage caused by ring disease at the commercial stage from fruits such as pears and apples susceptible to ring fungus. It is intended to provide a method.

[0002]

2. Description of the Related Art The liberalization of trade has a great influence on Japan's table culture, and even if we take a single fruit, consumers will find that various fruits of the world that are lined up in stores mixed with domestic fruits. From the inside, you can enjoy a very blessed life in which you can easily get your favorite fruit according to your taste. This phenomenon not only diversifies the tastes of consumers, but also promotes a trend toward higher quality and higher quality, and the provision of goods is becoming more severe and accurate than can be imagined at a time, so we provide goods. For the producers on the other side, it is no longer enough to simply take counter measures in terms of production price, it is important to improve varieties according to consumers' tastes, excavation of fruits with unusual eyes, commercialization etc. It has become an extremely important issue.

For Yamagata Prefecture, which is proud of the fruit tree kingdom, the above-mentioned environmental changes not only reduce the willingness of fruit tree farmers to produce, but can also lead to the collapse of farm management. Various public-private united efforts are being pursued as countermeasures against several types of fruit, including the first one. Even in the case of pears, it is the largest cultivated area in Japan (49.7% in 1991 statistics, 26.6th in Aomori prefecture 16.6%)
Are far apart. ), And intensive measures for production promotion have been devised together with cherry, San Jewel melon, Keio cherry tree, etc., and the goal is to secure more than four times the current planted area by 1997.

Pear (pear) is, as the name suggests, Japanese pear typified by varieties such as "Chojuro", "Twentieth Century", "Kosui", or "Yarley". It is a type of pear that is relative to Chinese pear, whose representative variety is
After being introduced in the early Meiji era, not only lack of cultivation technology,
The climate of Japan (I hate rain from the early summer of flowering season to summer) and the pear of the people who are familiar with Japanese pear,
Although it has a unique flavor, aroma, and texture, it has not reached the point where it can be sufficiently produced and diffused.In areas such as Yamagata and Nagano prefectures, there was little rain during the flowering season and it was an area dedicated to fruit tree production. Fortunately, production efforts have only been continued. Looking at the yields in Yamagata Prefecture, in comparison with the one during the period when production was highest before the war, in 1984 when production was the lowest, it fell to about 1/70 of the former production, and finally Heisei It has recovered to almost twice as much as the lowest time since the beginning of the era, and it is expected to continue to increase under the above-mentioned prefecture fruit tree agriculture promotion plan.

In order for the pear to become a member of one of the major fruits in our country after the establishment of this production increase system, the tastes and aromas of our environment are diversifying in recent years. It is a very favorable condition for the pear with a texture, especially for "La France" that has emerged as an improved high-grade variety because of its strong tendency, and it is very suitable for the demand from consumers in that respect. A bright outlook is predicted. However, on the contrary, the most worrisome condition is the physical property peculiar to pear, that is, this pear is
Unlike ordinary fruits that can be enjoyed immediately after harvest,
It has a huge handicap that it can not taste its unique flavor, aroma, and texture without once undergoing the process of ripening after harvesting, and that handicap cannot be overcome to make it raw. As long as it is, there is a risk that it will be worthless as a product.

[0006] Therefore, the producer is obliged to take a time to lay the fruits for a predetermined ripening period after harvesting and before shipment, but this ripening progresses to give off the aroma peculiar to pears. First, it enters the shipping stage for raw food, 2
When a fruit is exposed to temperatures above 0 ° C, Physalospora pirico, the most feared ring fungus, is suddenly feared even in pears whose disease could not be confirmed before ripening.
Once infected with this ring disease, the small round spots of light brown expand to a ring shape of brownish brown, and the edge of the lesion is Even the pear that has been able to ripen at a certain point will completely ruin its commercial value, as it becomes water-immersive and cracks and juice is released.

Unfortunately, recently, in order to allow all the fruits to be ripened uniformly and satisfactorily, a pre-cooling box has been installed either at the producers themselves or at a fruit collection site such as an agricultural cooperative. , Before ripening, at a predetermined temperature for a predetermined time (varies depending on the variety, but in "La France", 5
After pre-cooling the harvested pears for 10 days), after the ripening is completed, the pear is stored specially until shipment or shipment. It is almost impossible to confirm the appearance of ring spot disease before ripening, especially in the pre-cooling stage. There is also a risk that disease germs will spread.

[0008] Therefore, naturally, the production farmer is inevitably extremely nervous in the countermeasure against the disease of ring spot disease, and the infectious source formed in the branch trunk is scraped off and a prescribed drug is applied to reduce the bacterial density. It is necessary to incinerate the diseased stems that have been pruned or shaved, or to incinerate the bark that has been shaved, and to apply the drug even during the dormant wintering period. While focusing on spraying chemicals, put a bag on the growing fruit to isolate it from the spread infection of ring fungus, and also take sufficient time to ripen it at low temperature as much as possible. The actual situation is to prevent infection and disease from ring rots as much as possible.

According to the present invention, in addition to the above situation,
Basically, considering the limit of control by chemical spraying of fruit growth period and the legal regulation for pesticide sterilization on fruits after harvest, fruits such as pears and apples susceptible to ring spot disease,
How easily and without effectively degrading the quality of the fruit as an effective measure against ring disease, or killing the ring fungus from the fruit that has been sick, to other fruits It was possible to confirm an extremely effective sterilization method while continuing to search for a sterilization method that can prevent infection or irradiate various angles such as electromagnetic waves such as ultraviolet rays and infrared rays. And
The sterilization method will be described in detail below.

The method for sterilizing ring fungus of the present invention is basically realized by the following constitution. That is, after harvesting, the fruit is kept immersed in hot water kept in the range of 50 to 55 ° C. until the skin temperature of the fruit and the flesh temperature of a predetermined thickness portion from the skin reach at least 50 ° C. or more. As a result, it is a method for sterilizing ring fungus, which attaches to, hides in fruit, or kills the ring fungus that has caused the disease.

As the fruits, all fruits such as pears and apples which are susceptible to ring spot disease are targeted. In particular,
For apples, "Golden Delicious" and "Muttsu",
The target fruits are "tamarin", "Toko", "Fuji", "Indo", and "Kunimitsu".
Or “new”, “Kikusui”, etc.
In addition to "Bartlett," varieties such as "La France", which has recently attracted attention and is the main variety in Yamagata Prefecture, are targeted. The most effective temperature range for sterilization is that although some deviations are recognized due to the difference in these fruits, the quality of the fruit actually deteriorates, for example, the so-called “burned” phenomenon due to heat, which causes the fruit epidermis to brown, and the softening phenomenon of the flesh. It is recognized that the bactericidal effect of the ring fungus that is possible by avoiding the above is that the practice of the bactericidal method of the present invention effectively acts on all fruits affected by the ring disease.

[0012] As is clear from the following experimental results, hot water is effective in sterilizing ring fungus and has a temperature range that does not deteriorate the quality of the target fruit. Since a temperature range of 50 ° C to 55 ° C, which has not been confirmed until now, was discovered for the first time in the present invention, a constant temperature water tank capable of heating and adjusting distilled water within this temperature range (all fruits can be immersed) If so, the structure is not particularly limited.), The epidermis of the fruit is firm, and the temperature of the flesh part, which is the maximum possible thickness of the ring fungus in the epidermis, is latent. , At least 50
℃, optimally, until the minimum value of the temperature range effective for sterilization determined by the conditions of the fruit is reached, it is possible to continue the heating adjustment of the constant temperature water tank, within the above temperature range. You have to make sure it's accurate.

The above-mentioned time required for soaking the fruit naturally depends largely on the individual temperature of the target fruit, so that the outdoor temperature at the harvest stage is low and the individual temperature is low. In addition, before immersing in hot water in a constant temperature water tank, by preliminarily preheating all fruits to be immersed by appropriate means such as steam, it is possible to carry out the sterilization method according to the present invention. It is extremely effective in making the sterilization method of (3) effective.

In order to ensure that the fruits are immersed in the hot water, there is no risk of damaging the fruit epidermis. For example, a fine mesh stainless steel mesh or the like 1-2 cm below the hot water surface. It is also extremely effective to carry out the method by placing it substantially horizontally in hot water, and in addition to all fruits immersed in hot water and the entire surface of each fruit, the temperature is evenly distributed. A structure in which hot water can be appropriately circulated in the constant temperature water tank so that the temperature distribution of the entire hot water in the constant temperature water tank is maintained as uniform as possible within the temperature range that forms the basis of the present invention, while the propagation is performed. Is adopted, or a constant-temperature water tank in the form of a water channel that quietly flows in a certain direction as a whole is realized, and a predetermined soaking time elapses while flowing through the entire length of the water channel. Combined So it is free. Less than,
Experimental results are shown and will be replaced with concrete examples.

[0015]

[Experimental results] Experiments were carried out in the Hirosaki University Faculty of Agriculture and the laboratory of the applicant of this invention using a bacterium distributed from the ring-rot disease bacterium that has been tissue-cultured at the Yamagata Horticultural Experiment Station. Flat plate culture in a petri dish with a diameter of 9 cm, culture temperature 25
Incubate in the dark at ℃. The culture composition is as follows. Composition 1 weight in 1 liter Agar 25 g Glucose 10 g Peptone 5 g Magnesium sulfate 1 g Potassium dihydrogen phosphate 0.5 g

When the fungus grows and spreads over the entire petri dish, the agar in which the ring spot fungus is propagated is cut out with a cork polar 5 mm in diameter to make a disc, which is then placed in a plastic bag. , Immerse in a constant temperature water bath adjusted to a constant temperature. The immersion temperature is 45 ° C. to 55 ° C. every 1 ° C., and the immersion time is 1 minute every 1 minute to 5 minutes. After a certain period of time, take out the discs and place 5 of these discs in another Petri dish that has been prepared in advance.
The treated section is 2 Petri dishes, and is cultured for 7 days under the same conditions as above. After culturing, the presence or absence of bacterial growth is judged from the diameter of the flora around the disc. The results are shown as the number of breeding individuals per 10 discs.

[0017]

[Table 1]

From the experimental data shown in Table 1 above, the following results are found. That is, the sterilizing effect of hot water is
Appeared after immersion at 50 ° C for 2 minutes, then at 51 ° C and 5
The bactericidal effect was recognized even at 2 ° C. for 2 minutes. 53 ° C
With the above, sterilization is surely performed. From these results, it is necessary to sterilize the ring fungus at least at 50 ° C. for 2 minutes or more, more reliably at 51 ° C. for 2 minutes or more, and more surely at 53 ° C. for 2 minutes or more. Was confirmed.

[0019]

As described above, according to the present invention, after harvesting fruits such as pears and apples susceptible to ring spot fungus, after harvesting, at a temperature not lower than that which can be found in the above experiment, and fruit quality A ring-spot bacterium that kills the ring-spot bacterium by allowing it to stand for at least 2 minutes while being immersed in hot water in a constant temperature water bath controlled to a temperature of 55 ° C. or lower so as not to drop it. Since it is a sterilization method of 1., it can be sterilized extremely easily and surely, and it can be carried out as a harmless one to the fruits after harvesting, so that it must be highly evaluated as a sterilization means.

Particularly in Yamagata Prefecture, the value of the product is impaired, as one of the fruits to be promoted is striving to make special products by focusing on the highest-class cultivar "La France" among pears. Since the sterilization method without a thing was a very important subject, the sterilization method of the present invention can sufficiently meet the expectation, and ensure the market entry as a pear with high commercial value, and many It can be said that this is an excellent invention that can exert a great deal of power in the stable supply of pears that are preferred by consumers.

[0021]

[Table 1] Effect of temperature of hot water and immersion time on sterilization of mycelium of ring fungus

Claims (3)

[Claims] 1. From the epidermis temperature and epidermis of a fruit, such as pears and apples, which are susceptible to ring spot fungus, after being harvested, while being immersed in hot water kept within a range of 50 ° C. to 55 ° C. The flesh temperature of the specified thickness is at least 50 ℃
A method for sterilizing ring fungus, which comprises killing ring fungus that adheres to, hides in fruit, or causes disease by allowing the time to reach the above. 2. After harvesting pears, 50 ° C. to 55 ° C.
By soaking for at least 2 minutes or more in hot water kept within the range, it will kill the ring fungus that adheres to, hides in the pear, or causes the disease. A method for sterilizing ring fungus, which is characterized in that 3. After harvesting pears, 52 ° C to 53 ° C
It is characterized by killing the ring fungus that adheres to, hides in, or has been infected by the pear by soaking for at least 2 minutes while being immersed in warm water kept at A method for sterilizing ring fungus.