Mushrooms Grades and Standards

Grades of Mushrooms

  1. U.S. No. 1 consists of fresh mushrooms of similar varietal characteristics which are mature, at least fairly well shaped, well trimmed, free from open veils, disease, spots, insect injury, and decay, and from damage by any cause.
    1. Size. Size is specified in terms of diameter and unless otherwise specified meets the requirements of one of the following size classifications:
      1. Small to medium -- up to 1-5/8 inches in diameter;
      2. Large -- over 1-5/8 inches in diameter.
    2. Tolerances. In order to allow for variations incident to proper grading and handling the following tolerances, by weight, are provided as specified:
      1. At shipping point.2 5 percent for mushrooms in any lot which fail to meet the requirements of this grade, but not more than one-fifth of this amount or 1 percent shall be allowed for mushrooms affected by disease, spots, or decay.
      2. En route or at destination. 10 percent for mushrooms in any lot which have open veils. 5 percent for mushrooms in any lot which fail to meet the remaining requirements of this grade, but not more than one-fifth of this latter amount or 1 percent shall be allowed for mushrooms affected by disease, spots, or decay.
      3. For off-size. Ten percent for mushrooms in any lot which fail to meet the specified size requirements.
  2. U.S. No. 2. The requirements for this grade are the same as for U.S. No. 1 except for a greater tolerance for open veils and a larger tolerance for defects.
    1. Size. Size is specified in terms of diameter and unless otherwise specified meets the requirements of one of the following size classifications:
      1. Small to medium -- up to 1-5/8 inches in diameter;
      2. Large -- over 1-5/8 inches in diameter.
    2. Tolerances. In order to allow for variations incident to proper grading and handling the following tolerances, by weight, are provided as specified:
      1. At shipping point.2 Ten percent for mushrooms in any lot which have open veils. Ten percent for mushrooms in any lot which fail to meet the remaining requirements of this grade, but not more than one-tenth of this latter amount or 1 percent shall be allowed for mushrooms affected by disease, spots, or decay.
      2. En route or at destination. 25 percent for mushrooms in any lot which have open veils. 10 percent for mushrooms in any lot which fail to meet the remaining requirements of this grade, but not more than one-tenth of this latter amount or 1 percent shall be allowed for mushrooms affected by disease, spots, or decay.
      3. For off-size. 10 percent for mushrooms in any lot which fail to meet the specified size requirements. 

Visual Aids

Visual Aids may be found in the Official Inventory of Inspection Aids (pdf)

Detailed standards, Inspection Instructions & Other Resources: