2102 - Yeasts (active or inactive); other single-cell microorganisms, dead (but not including vaccines of heading 3002); prepared baking powders:

Heading 2102 encompasses yeasts, both active and inactive, as well as dead single-cell microorganisms other than vaccines. This category also includes prepared baking powders, which are specifically formulated mixtures designed to leaven dough and batters. The key criterion for inclusion here is the biological nature of the yeast and microorganisms, or their specific application in baking, distinguishing them from live animals or other food preparations.

Within the broader Section IV, which deals with miscellaneous edible preparations, Heading 2102 stands apart from categories covering live animals (Chapter 01) or more complex food products. While other headings might mention ingredients used in food production, 2102 focuses on the specific entities of yeasts and single-cell microorganisms themselves, or ready-to-use leavening agents.

The subcategories within 2102 provide further specificity. 2102.10 is reserved for active yeasts, commonly used in baking and brewing. 2102.20 covers inactive yeasts and other dead single-cell microorganisms, which might be used as nutritional supplements or in other industrial applications. Finally, 2102.30 is dedicated to prepared baking powders, highlighting their distinct composition and purpose as a chemical leavening agent.