3301.29.51.28 - Of onion

This classification, HTS Code 3301.29.51.28, specifically designates essential oils derived from onions. These are concentrated aromatic substances extracted from the *Allium cepa* plant, often obtained through distillation or other extraction methods. The primary characteristic is their distinct onion aroma and flavor profile, which dictates their use in various applications, predominantly within the food and fragrance industries as flavoring agents or scent components.

While sharing the broader classification of "Other essential oils other than those of citrus fruit," this subcategory is distinct from its siblings which represent essential oils from anise, caraway, cassia, cedarwood, citronella, and numerous other botanical sources. The defining factor for this category is the specific botanical origin – the onion. Each sibling category, and indeed the broader "Other" categories, are differentiated by the unique chemical composition and sensory properties imparted by their respective plant sources.

As this is a leaf node within the HTS, there are no further subcategories. The classification of essential oils of onion is at its most specific level, indicating that any essential oil derived from this particular plant falls under this designation, provided it meets the general criteria for essential oils under Chapter 33. Further distinctions, if any, would typically rely on the purity, processing method, or specific concentration, but these are not further subdivided at this HTS code level.