Abstract
Natto is a traditional Japanese food made from soybeans fermented by Bacillus subtilis natto. Because natto is high in protein and contains healthful bacteria, dieticians and producers have campaigned for higher consumption of natto in areas such as Kansai, where our university is located. One of the reasons for the low consumption of natto is its distinctive flavor. As a problem-solving exercise, undergraduate students attempted to make natto more marketable. Students set a goal of modifying natto flavor by adding spices to achieve flavors deemed palatable by organoleptic tests. During the exercise, they noticed that lemongrass, Cymbopogon citratus, had a flavor-masking ability that reduced the intensity of natto flavor, and they finally determined that it was a useful food additive to make natto marketable. The exercise was an active learning process that effectively induced voluntary student effort of to solve problems originating from microorganisms.