Team:Gifu/Description

Back ground

In gifu prefecture, there are many rivers that are called “clear river”. The water coming from the streams is famous for its good quality and good deliciousness. Therefore, it is natural that the development of sake brewing. However, there is a trouble which is called “an act of God” in the process of sake brewing. This is the phenomenon of “Hiochi”. Now the risk of Hiochi has generally decreased by the complete control, the measurement of Hiochi. However, in the current sake market, the popularity of Namazake is increasing. Namazake have not passed the step of Hiire, pastuerization. Hence, Namazake have not been sterilized by heating. The taste of Namazake is fresh and delicate and the smell is pretty good. Also, there remains a feeling of sparkling. However, simply because Namazake have not been done “Hiire”, there may occur “Hiochi” after being opened the bottle when people store at home. So, we plan to make a biosensor which detects the causative bacteria of Hiochi.

what is sake?

Sake is a kind of fermented liquor and produced by three kinds of bacterial co-cultivate. Most sake is made from rice, water and rice Koji. At first glance, you might think sake is so simple and modest. However, while we refer to them all as sake, there are large varieties of sake like wine and beer. Sake is classified by criteria which is defined by Japanese national tax agency. The sake is distinguished by the following four criteria, what is used for, how much is the ratio of rice polishing, how much ratio of the Koji rice is and what smell is it. According to Japanese national tax agency, rice polishing ratio refers the ratio of weight of white rice to brown rice. Koji rice refers to white rice used for manufacturing rice Koji. Also, rice Koji is bred the Koji to white rice and can glycosylate starch of sake rice. Now you know, sake is not simple and modest but luxury.

History of Sake

According to “Harimanokuni Fudoki ”(records of the culture and geography of the Harima province) , there has been clearly described about the oldest sake which was made from rice(A.C.700). After reaching the culture of rice cultivation from Mainland China, people started to make sake mainly using rice. Sake brewing was started as a part of offerings that is dedicated to a god. As a part of offerings, the sake was made by the first rice of the year. At that time, people make sake by the way which is called “Kuchikami”( =mouth chewed). By chewing the heated crops, amylase contained in saliva converts starch into sugar. After that, wild yeast ferments sugar into alcohol. In Japan, people say “Kamosu”(=ferment at the process of brewing sake). It is said that the word of “Kamosu” came from “Kamu”(=chewing). After this era, according to some historical literature, the culture of sake brewing spreaded to the whole country. However, in those days, sake was high viscosity because the proportion of water in sake is low. Therefore, people ate sake with chopsticks. Early in the Nara period(710~794), brewers started to use the brewing method of using rice Koji. The way of sake brewing was the same as modern and there has been applied a lot of kinds of sake in Heian period. At that time, the sake was yet cloudy sake. From this period, “Sobosyu”(=sake produced by monks) started to develop till Japan government banned making sake by monks. The quality of “Sobosyu” was told to be high and their sake was so precious. During middle ages, when commerce became more prosperous, the economical value of sake as a kind of goods is equal to rice. And in this era, there were three breakthrough renovation. First, it made a dramatically quality improvement to use white rice for both steamed rice and Koji. This is called “Moroshiro”. Using this way, brewers can make sake with high clarity. Second, brewers realized that making sake at winter, it took a little longer time, but they can produce pretty good quality of sake. Third, they made it possible to control the fermentation process by “Dankake”. “Dankake” is a kind of ingenuity. When they prepared, they added steamed rice and Koji rice and water in some steps. By doing this, they could increase the quantity of acid in stages. Furthermore controlling their fermentation process they became to supply stable quality sake. In this way, mainstream of sake migrated from cloudy sake into clarified sake. In Edo period, some of innovative processing technology had developed. Here are some examples. To begin with, we will introduce the technology of “Hiire”(=pasteurization) which is most related to our team project. Pasteurization is a way to raise preserving property. Another technology is the allegation medial of adding alcohol. These two technologies are means to avoid the risk of “Hiochi”. And from this period, sake became popular among common people because sake began to carry-out to whole Japan by ships. Though the innovative processing technology had developed, “Hiire” is not a complete measure to prevent “Hiochi”. So, there were many large scale of decays in Meiji period. In 1904, Japan government established the National Research Institute of Brewing. NRIB was made in order to study yeast for seishu and improve brewing way. In NRIB, Kamajiro Eda who is a head of NRIB invented “Sokujyomoto”. “Sokujyomoto ” is sake mush which is used for fast brewing method by adding enzyme. Also he had improved the method of “Hiire”. Brewers do “Hiire” after they bottled their sake. In the early of Showa period, the new yeast which can make good smell such as the sixth yeast was picked, isolated and pure-cultured. And by the time, most of the devices for measuring has appeared. During the W.W.Ⅱ, the production of sake declined because of rice shortage. After the war, reconstruction of sake brewers started every places.

The phenomenon of “Hiochi”

Growing of Hiochi bacteria in sake and bacterial pollution of seishu is called Hiochi. After the phenomenon of “Hiochi” , seishu became cloudy and take on peculiar odor by producing acid inside of it. Hiochi bacteria is high resistant to alcohol so they can grow in seishu. Hiochi bacteria can be separated to hetero type and homo type by the style of fermentation. Furthermore, they can be classified by whether they need mevalonic acid when they grow. Hiochi bacteria are a kind of Lactic acid bacteria and cannot grow except for sake because they need mevalonic acid produced by Koji for living.

Description

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