Green, Grey and Brown Discolouration

Describe colour, boundary and timing

Record hue, intensity, depth, shape and whether the area is surface, core, ring, smear, pocket or diffuse zone. Establish when it first became visible: before curing, after fermentation, after heating, during drying, at slicing, inside an unopened package or after exposure. Compare affected and unaffected units under controlled light. Colour names vary between observers, so photographs and measurements should support rather than replace a precise physical description.

Map chemical and physical mechanisms

Brown or grey colour commonly directs attention toward pigment oxidation, oxygen exposure, light, time, temperature or failure to form or protect cured pigment. Green appearances can arise through several pigment reactions and must not be assigned automatically to one organism. Heat, pH, reductants, oxidants and local package conditions can change the same pigment system. The proposed mechanism should explain the colour's location, boundary and development over time.

Investigate microbial change as a separate hypothesis

When discolouration is progressive or accompanied by slime, gas, odour, package swelling, softening or an abnormal pH path, preserve unopened samples for competent microbiological examination. Some microbial metabolites can alter pigment, but the visible hue does not identify species or establish whether a toxin or pathogen is present. Sampling should compare the coloured zone, its boundary, normal-looking product and relevant environment while preserving chain of custody and method limits.

Reconstruct cure, heat and package exposure

Review cure calculation and distribution, pH, fermentation, product-core heating, cooling, oxygen, seal condition, film, gas mixture, storage temperature, light and time. A grey centre after cooking suggests a different path from a brown top slice under display light or a green pocket around a void. Compare package heads, rack positions, diameters, slice-stack depth and exposure history. An acceptable final average cannot erase a local abnormal trajectory.

Define affected scope before intervention

Hold units linked by raw material, cure batch, mixer or injector window, chamber position, cook load, slicer, packaging head and storage exposure. Do not open, trim, wash or repackage every unit before representative evidence is preserved. A dramatic isolated patch may be local, while a subtle top-slice fade may affect an entire display-exposed population. The scope should follow the credible mechanism rather than the most visible example.

Correct the cause and verify the relevant period

Correct formulation, distribution, hygiene, heat, cooling, oxygen barrier, sealing, light or storage according to evidence. Stronger smoke, colourants or spices only conceal the sign and may create a different product. Product disposition must address safety, legal compliance and quality separately. Verify the correction at the former fault positions and through the time in shelf life when the change previously emerged; one normal slice or one satisfactory day is not effectiveness evidence.