- Most of the food which we often eat are disinfected. There are some ways of sterilization by using chemicals or heating foods. "Food irradiation" is one of them. It isn't common in Japan. However, in Europe and America, the method with X- rays, γ and β rays is used for prolonging storage life of foods or disinfecting them. Today, food irradiation is internationally used for disinfecting spices and dried vegetables. In Japan, the laws authorize the use of irradiation only to inhibit sprouting.
![mogumogu](images/じゃがばたけ.png)
- Before people pay attention to food irradiation, they used methyl bromide for sterilization in most cases. However, after it was considered as a substance which destroys ozone layers, methyl bromide has been used for a part of sterilization, such as plant quarantine. There is phosphine as a substitute of methyl bromide, but possibility that bug which can tolerate phosphine arise by using it repeatedly. Thus, people have come to pay attention to food irradiation.
○Temperature rise by irradiation is slight, so their quality and ingredient scarcely change.
Ex)Spices go bad when they are treated with heat treatment, but they hardly go bad when treated with irradiation.
○Only surface of food can be irradiated by β-rays.
○Because they don't use chemicals, there aren't any problems of environmental pollution and remnants.
○Food irradiation by γ rays has permeability, so foods, either packaged or in bulk, can be treated equally regardless of the food shape or size.
○Moreover, they can be treated a lot in succession by γ rays.
Mogumogu one point!
- Of course, food irradiation has some disadvantages.
○The cost rises because food processing method will add cost.
Ex) The increase in price for irradiated potatoes is estimated at 3 to 5 yen per kg.
○The effect of food irradiation can vary according to food ingredient. For example, there is an experiment that irradiated wheat go bad about how easily we can process noodle and bread.
![Udon](images/うどん.png)
- Please look at the pie graphs below. This is the results of the questionnaire we used to get some information from our 35 classmates, their parents and some teachers.
We asked them 3 questions which are shown below.
Most of the food which we often eat is disinfected. Some ways of sterilization are by using chemicals or heating foods up. "Food irradiation" is another way of sterilizing food, but it isn't common in Japan. However, in Europe and America, the method of using X- rays, γ and β rays is used for prolonging the storage life of foods or disinfecting them. Today, food irradiation is internationally used for disinfecting spices and dried vegetables. In Japan, the laws authorize the use of irradiation only to inhibit sprouting.
Did you know about food irradiation before the explanation?
Yes. No.
Did you know that irradiation of food is actually used?
Yes. No.
Do you want to buy irradiated potatoes?
1. There is no problem if I'm sure they are safe.
2. I absolutely don't want to buy irradiated potatoes.
3. There is no problem if the price is reasonable.
4. Other.
First, question 1 and 2 are questions to study how much people know about food irradiation. Judging from the result, only a few students seem to know about it, while almost half of the adults surveyed know that food irradiation is actually used.
Second, question 3 is a question to study what opinions people have about food irradiated.
From this result, we can see there is a big difference between students and adults. A lot of students answered, "1. There is no problem if I'm sure they are safe." They don't seem concerned about eating irradiated food. However, the number of adults who answered "2. I absolutely don't want to buy irradiated potatoes," is higher than those who answered "1. There is no problem if I'm sure they are safe." After looking at the results closely, women especially tend to answer 2. Many house wives are responsible for meals, so a lot of them reject irradiated potatoes.
We hope to be in the situation where we can choose irradiated food or not, easily. In order to do so, it needs to be understood correctly by a lot of people. All types of sterilizing technology has advantages and disadvantages. First, we should use sterilizing technology which matches each food. Second, we shouldn't have a biased idea that we should prohibit food irradiation. These factors are very important.
We think it's effective that food irradiation be used for sterilization of yukhoe and liver sashimi, which are not allowed to be eaten in Japan, for those who want to eat them again. This is actually taken into consideration.
- We examined the change of potatoes if they were irradiated and left.
We can irradiate potatoes at γ ray irradiation chamber Takasaki Advanced Radiation Research Institute, Japan Atomic Energy Agency in Gunma Prefecture.![高崎量子応用研究所](images/jquery-1.11.1.min.png)
There are walls made of lead around the irradiation chamber.![鉛の壁](images/DSC_2755.png)
Cobalt60 of irradition source is stored in pool in order to cut off γ rays.![コバルト60](images/sengen.png)
Each potato was irradiated by 100Gy, 300Gy, 1000Gy, 3000Gy.
We arranged non irradiated potatoes.
![potatobefore](images/potatobefore.png)
![potatoafter](images/potatoafter.png)
Then, we put the potatoes in a cardboard box and observed them. Therefore, irradiated potatoes didn't sprout for about 6 months. Though, when we left them for few more months, every potato, including non irradiated potatoes, grew mold.