[No. 71] Yusuke Iino

I currently work in sake production management at Takara Shuzo's Matsudo Factory. My main duties involve checking the condition of the moromi (sake mash) daily, monitoring the maturation of the unblended sake during storage, and conducting sensory evaluations (checking taste and aroma) of the final products before shipment. Looking at my profile, you might see that I'm from the Department of Biosciences and Informatics and wonder, "Why brewing after studying life sciences?"

Indeed, the Applied Cell Biology Laboratory where I belonged conducted a lot of research using anticancer drugs, and many of its graduates are active as researchers at pharmaceutical companies or in the life sciences field. Among them, a career in brewing at a sake company is undoubtedly quite unusual. However, what I learned as a student is deeply connected to my current work and has been extremely useful. Today, I would like to talk about that connection.

For the basic flow of sake brewing, please seeour company's website(laughs), but once the moromi mash is prepared and fermentation by yeast begins, the only basic way to control fermentation is by regulating the temperature of the moromi. Even when using the same rice and the same yeast, the progress of fermentation varies slightly each time, and we adjust the temperature to achieve the desired sake quality. If fermentation does not go well, a large amount of the metabolic intermediate pyruvic acid can remain in the yeast, which can cause an unpleasant odor called tsuwarikō. In the case of cooking sake, we pay special attention because metabolism using the citric acid cycle occurs in the early stages of fermentation when oxygen remains in the tank, producing organic acids that have a cooking effect.

Every day, I monitor the moromi while keeping the citric acid cycle and glycolysis in mind. I realize that brewing is a science that spans organic chemistry, biochemistry, and cell biology.

Are you familiar with the terms "kimoto-zukuri" and "yamahai-jikomi"? Both are traditional methods of cultivating yeast, and the more I learn about them, the more I am amazed by the advanced biotechnology involved.

These yeast cultivation methods skillfully induce nitrate-reducing bacteria and lactic acid bacteria to create an acidic environment where unwanted bacteria cannot grow, allowing the yeast to multiply. Then, as the yeast produces alcohol, the lactic acid bacteria also die off, making it possible to purely cultivate only the yeast.

There are countless other examples, such as the pure cultivation of koji mold in alkaline ash, and the practice of low-temperature pasteurization, known as "hi-ire," which was performed more than 200 years before Pasteur's discovery of pasteurization to prevent the deterioration of sake during storage.

This shows how brewing and microbiology have developed together.

I recently attended a brewing-related symposium where there was a very interesting presentation on sake yeast.

Sake is a brewed beverage that ferments to an extremely high alcohol concentration of over 20%, one of the highest in the world. The presentation analyzed the characteristics of sake yeast using molecular biology techniques, such as genomic comparisons with laboratory yeast and analysis of gene expression levels. It also suggested the involvement of heat shock protein genes, which were the subject of my research as a student, and I am very curious about future developments.

As someone who majored in life sciences, I can't help but want to unravel the mysteries of brewing from a molecular biology perspective.

I majored in molecular biology and now work in sake brewing. Compared to career paths like "researching anticancer drugs and joining a pharmaceutical company" or "studying zymology and joining a sake brewery," I sometimes feel that I have jumped into a somewhat different field. However, it is precisely because the field is different that I find new and interesting things, and the knowledge and ways of thinking I have learned are connected and alive in my work, as I have illustrated with various examples.

For those of you at a crossroads in your life, such as university entrance exams or job hunting, I am sure you have strong feelings and passion for what you want to do. But has your "passion" for what you want to do turned into a "preconception"? Could it be that your strong desire to "do this one thing" is actually limiting your own potential? It's great to push forward in the heart of your area of expertise, but it's also interesting to dive into a different field. Just as it has been for me, I believe that what you have cultivated up to that point will always connect and come to life.