The US Department of Agriculture (USDA) classifies a range of features for canned or pouched tuna. This includes a classification of product defects.
Specimen: canned or pouched tuna
Critical product defects:
(1) true honeycombing or evidence of decomposition
(2) contaminants such as chemicals, glass, metal, animal excreta or other extraneous materials
Major product defects:
(1) objectionable flavors or odors
(2) objectionable foreign materials but not critical, such as rust, wood, hair, dirt or insect parts
(3) form, color, packing media or flavor not specified in contract
Minor defects:
(1) prominent bruises
(2) blood clot, pieces of gills, or pieces of viscera > 6.35 mm in diameter
(3) other undesirable fish parts (skin, scales, vascular tissue bones) of objectionable size
