Chirimen awa (crepe-like foam)

Chirimen awa (ちりめん泡) refers to a particular state of foam seen while sake moromi (fermentation mash) is fermenting. As fermentation progresses, the foam changes over time and takes on various forms and types. In the early stage of fermentation, "suji awa" (筋泡, streak foam) appears, looking like a few thin lines. Gradually, "mizu awa" (水泡, water foam), a white, light foam, spreads across the surface. This then changes into "iwa awa" (岩泡, rock foam), which may rise even higher. After the foam keeps building in height, the stage in which it gradually subsides is called "ochi awa" (落泡, falling foam), and afterward firm, rounded bubbles known as "tama awa" (玉泡, ball foam) remain. The chirimen awa state refers specifically to the appearance of a thin, skin-like foam on the surface of the moromi, and it can be seen as evidence of yeast activity within the mash. It looks like a thin film with a crepe-like (chirimen) texture, and it serves as an important indicator of the moromi's fermentation state and health. Observing the quality and progress of fermentation in this way is a very important part of the sake-making process.