fire pan; brazier
A container for holding fire or embers, used for heating or as a portable fire source.
In old houses, they used a fire pan to warm the room.
heating; applying heat
General term for applying heat to something, often in industrial or culinary contexts.
In this process, heat is applied to the material.
pasteurization
Specifically refers to pasteurization, often in the context of sake or other beverages.
Pasteurization of sake is important for preserving its quality.
殺菌 is a general term for sterilization, while 火入れ specifically means pasteurization through heating.
Compound of 火 (hi, 'fire') and 入れ (ire, 'putting in'), from the verb 入れる (ireru). The exact historical derivation of each sense is uncertain, but they all relate to introducing fire or heat.