Part 4: Kawahara Ai’s Love for Yogurt — The Heroic Work of Lactic Acid Bacteria Makes My Heart Pound!

Kawahara Ai was so taken by the work of tiny microorganisms that she went on to earn a doctorate degree while researching lactic acid bacteria. She has had a unique career, as after graduate school, she left her research lab to become a writer, with the aim of communicating the benefits of fermented foods and how to maintain a healthy gut microbiome. We had a long conversation with Kawahara, hearing about her time as a graduate student when she was immersed in lactic acid bacteria research and about her choice fermented food that makes her restless on days she doesn’t eat it. She even shares a delicious, easy-to-make recipe.

The more you know, the more you realize how profound and full of characters the world of bacteria really is

“Despite being so tiny that you can’t see them with the naked eye, lactic acid bacteria are essential for our lives. My imagination is piqued when I think of these bacteria, so much smaller than humans, working so hard for us.”

Kawahara’s graduate school research focused on the lactic acid bacteria contained in tofu misozuke (tofu pickled in miso), a local Kumamoto staple. Tofu pickled in a bed of miso for six months is noted for taking on a mild, cheese-like umami taste and a distinctive texture.

“Tofu misozuke has superb preservation properties. It occurred to me that its excellent shelf life may be connected in some way to lactic acid bacteria. My research involved analyzing the mechanisms that govern how the lactic acid bacteria behaves at the genetic level. Because my counterparts in this research were living organisms, I grappled with them night and day regardless of the hour.”

We speak of lactic acid bacteria as if they were all the same, but the term actually refers to a huge range of bacteria. Lactic acid bacteria have as many personalities are there are varieties.

“Just like people, bacteria consume food and digest and break down the nutrients in that food. If more than half of what a bacterium produces through this metabolic process is lactic acid, then it is defined as a lactic acid bacterium. So even though we refer to them collectively as lactic acid bacteria, they produce lots of materials other than lactic acid. The lactic acid bacteria contained in tofu misozuke secrete a substance that suppresses the growth of other bacteria, and this plays a role in extending the shelf life of tofu misozuke.”

Today, yogurts and lactic acid drinks offering a range of functions are sold that contain lactic acid bacteria and bifidobacteria. The products’ functions are the result of the individuality of the type of lactic acid bacteria used. As research moves forward, the workings and actions of previously unknown bacteria will undoubtedly be uncovered.

The delicate nature of lactic acid bacteria is adorable

“Lactic acid bacteria and many other kinds of bacteria live on our hands and face and in our hair and elsewhere,” explains Kawahara.

A year has passed since Kawahara moved on from her research work, but she still sometimes has to chuckle drily when she catches herself in her old researcher habits.

“For example, when you remove the lid from a plastic bottle or a glass jar, most people set the lid down with the inner surface facing up. Until very recently, I would always set the lid down with the inner surface facing down. In the lab, you have to always place the lids of reagent and other containers facing down to prevent airborne bacteria from finding their way into the container.

“Research lab practices had unconsciously permeated my regular life. The truth is bacteria are everywhere around us, including in the air, and they do all sorts of things without us noticing. When you think about it like that, it’s really amazing.”

The most important challenge for Kawahara in her research was cultivating lactic acid bacteria, which she worked on for seemingly ages without a day off. She went to great lengths to control the temperature and watch over the bacteria beds to ensure the lactic acid bacteria had the perfect conditions to grow and thrive.

“Lactic acid bacteria are not particularly robust bacteria. They can die off even if you feed them properly. They are naturally susceptible to heat, but low temperatures are not good for them either. The trick to cultivating them is to prepare a bed rich in sugars and proteins and frequently transport them to new beds.”

When you understand the characteristics of lactic acid bacteria from this angle, you can see why it is important to eat fermented foods without heating them if possible, and to store them in clean containers where unwanted bacteria will not grow.

I can’t stop eating it because I can feel my body’s joy

Kawahara’s interest in foods that are fermented by lactic acid bacteria and other bacteria is endless. She also experiences the tangible comfort that comes from eating fermented foods every day. Her favorite fermented food is yogurt, which is readily available at any supermarket. She claims that a day without yogurt leaves her feeling restless.

Soy milk yogurt topped with frozen blueberries is a fantastic breakfast item and a great snack when you feel peckish

“Yogurt truly is a super food. It meshes well with all kinds of ingredients, and above all, it’s delicious. If I go for a few days without yogurt, I feel like I can’t calm down. I wonder if it’s because my body starts craving fermented food. I’m a simple person, so if I can have fruit and yogurt in the morning, I’m perfectly content. (laughs) I also love salads with yogurt in combination with sweet potatoes, pumpkin, taro, or other vegetables. If you use yogurt instead of mayonnaise, you can reduce the amount of fat and extend the shelf life.”

Kawahara’s current favorite is soy milk yogurt. The protein contained in soy milk firms up as the lactic acid bacteria increases its acidity. The mechanism is the same as yogurt made from cow’s milk.

“I occasionally make soy milk yogurt at home by putting soy milk and starter bacteria in my yogurt maker. You can easily buy starter bacteria at supermarkets or online.”

Simply mix 50 grams of drained yogurt with a quarter of a pumpkin that has been steamed and roughly mashed, and add raisins or walnuts to taste to make a stylish deli-style salad

Banana yogurt cake rescues your overripe bananas

Yogurt is delicious enough to eat on its own, but if you put in a little extra effort and turn it into a dessert, it will be even more satisfying. Kawahara shares her recipe for a pound cake that is surprisingly delicious just by stirring the ingredients together.

The soy milk yogurt makes the dough moist. Wrap the slices you can’t finish in plastic wrap and freeze them for later.

For the next installment, we pass the baton to Tange Megumi, a food photographer and operator of an online school for hands-on food experiences. Be sure not to miss it!