Mochi is one of Japan's oldest foods — mochitsuki (rice pounding ceremony) is documented from before the Nara period; the kagami mochi New Year offering dates to the Heian period; the mochitsuki ceremony (performed publicly at New Year's time) is one of Japan's most ancient communal food traditions with deep Shinto associations; the modern mochi machine (mochi-tsuki-ki) appeared in the 1950s and democratised fresh mochi production outside of the ceremonial context
Mochi (餅 — rice cake) is produced by pounding glutinous short-grain rice (mochigome — a specific high-amylopectin variety) until the individual grains disappear and the mass becomes a unified, elastic, translucent paste. The traditional method (usu-kine — 'mortar and pestle' method) uses a large stone or wooden mortar (usu) and heavy wooden mallet (kine) — the pounding is performed by one person while another turns and wets the rice mass between blows; this requires extreme synchronisation and trust. The physics: the pounding converts the gelatinised starch granules from separate entities into a unified network of amylopectin chains (a polysaccharide that forms the characteristically elastic, stretchy gel of mochi). The result is nothing like pounded regular rice — glutinous rice's high amylopectin content (versus regular rice's higher amylose content) is what enables this gel transformation. Temperature is critical: the mochi becomes too stiff to form if it cools below 50°C; working quickly with wet, warm hands is essential. Traditional mochi is made twice yearly in Japan: New Year's (kagami mochi, 'mirror rice cake' — two round mochi stacked with a mandarin on top as a New Year's decoration and offering), and Hinamatsuri (Doll's Festival in March) when hishi-mochi (diamond-shaped pink-white-green layered mochi) are made.
Fresh mochi's flavour is almost entirely textural — the elastic stretch and the specific resistance of the amylopectin gel under tooth pressure; the flavour is of cooked glutinous rice with a clean sweetness from the sugar produced by gelatinised starch; this textural-primary flavour profile means mochi is endlessly compatible with strongly flavoured accompaniments (anko's sweetness, kinako's nuttiness, kurogoma's intensity, mitarashi sauce's soy-sweet caramel) without competing — it is a flavour carrier and textural centrepiece simultaneously
Mochigome (glutinous rice, high amylopectin) is the only suitable variety — regular rice cannot produce mochi's elastic texture; the pounding temperature window is narrow (50–65°C); wet hands and wet surfaces prevent sticking; the mass is uniform when all grain boundaries are invisible (approximately 500 pounds of pounding for a 1kg batch in the traditional method); modern mochi machines compress this to 10 minutes; fresh mochi is categorically superior to dried mochi in texture and flavour.
Microwave mochi (home technique): rinse and soak mochigome overnight; drain; microwave on highest setting in 2-minute intervals for 8–10 minutes total, stirring between each interval; the mass should be sticky, translucent, and pulling away from the bowl cleanly; wet hands form the mochi quickly before it cools; daifuku mochi (bean jam mochi): form warm mochi around a ball of anko, seal the edges; roll in katakuriko (potato starch) to prevent sticking; the starch coating on the surface is temporary — it absorbs back into the mochi within hours, making day-of-making the only acceptable service window.
Using regular short-grain rice instead of mochigome (produces paste, not elastic mochi); insufficient pounding (grains remain partially intact, producing grainy texture); allowing the mass to cool below 50°C before shaping (becomes too stiff and tears under hand pressure); not wetting surfaces and hands thoroughly (mochi tears and sticks).
Tsuji, Shizuo — Japanese Cooking: A Simple Art; Shimbo, Hiroko — The Japanese Kitchen