A mushroom flush is one wave of fruiting bodies harvested from a single crop cycle, with most cultivated species producing multiple successive flushes at intervals of several days, each typically declining in yield and cap uniformity.
In trade practice
First-flush mushrooms generally deliver the highest proportion of large, well-formed caps and are most likely to meet premium grade specifications for fresh or IQF markets. Later flushes tend to produce smaller or more irregular fruiting bodies that are better suited to sliced or diced processing grades. Harvest teams record flush number alongside lot data so that QA can correlate grade mix with flush sequence. Buyers specifying a minimum cap diameter should confirm with suppliers which flushes are included in a given delivery.
In a specification
Specifications rarely mandate a specific flush number, but a contract may require that all product meets a stated minimum cap diameter and defect tolerance, which in practice limits the proportion of later-flush material that can be included.