For example, optimal activity and quality collection should be done at a time when the active ingredient is present in the greatest amount. Improvements in analysis have led to more precise harvesting of many herbs. Organoleptic analysis involves the application of sight, odor, taste, touch, and occasionally even sound, to identify the plant. Obviously, the initial sight of the plant or extract is so specific that it tends to identify itself. If this is not enough, perhaps the plant or extract has a characteristic odor or taste.
Organoleptic analysis represents the simplest, yet the most human, form of analysis.
Every plant possesses a characteristic tissue structure, which can be demonstrated through study of tissue arrangement, cell walls, and configuration when properly mounted in stains, reagents, and media. In crude plant evaluation, physical methods often are used to determine the solubility, specific gravity, melting point, water content, degree of fiber elasticity, and other physical characteristics of the herb material. The final analytical process requires more precise assays to determine quality. These techniques are invaluable in the effort to properly and fully identify herbs, as well as standardized extracts. The plant or extract can then be evaluated by various biological methods to determine pharmacological activity, potency, and toxicity.