After collecting kombu kelp, they are exposed to the sun light to boost the content of glutamic acid also known as an umami factor. As they have been resting in the warehouse for many years, they are aged and we can more quickly extract Dashi. We cannot say which kombu kelp quality is better. However, Japanese cooks tend to use makombu kelp which is useful and tastes mild.
Kombu kelp (glutamic acid), dried bonito (inosinic acid) and dried shiitake mushroom (guanylic acid) are the Japan’s three major ingredients rich in umami factors.
Head chef of Japanese cuisine of Tokyo Kaikan