Herb washing is the step in fresh herb processing where cut material is rinsed with clean water to remove soil, dust, insects and field contaminants before drying or further processing.
In trade practice
Washing is typically done in flume or spray systems using potable water, sometimes with a brief soak to loosen soil from dense bunches. The process must be fast to limit leaching of essential oils and water-soluble compounds that determine flavour and aroma in the dried product. After washing, excess surface water is removed by centrifuge or air knife before the herb enters the dryer, because excess moisture extends drying time and risks microbial growth. QA checks at this stage focus on visual cleanliness, water quality records and absence of foreign matter.
In a specification
A dried herb specification may require the supplier to document the washing water quality standard and confirm that surface moisture is reduced to a defined level before drying commences.