More details have emerged after pictures of green-spotted chicken for sale at a Bay of Plenty Pak'nSave caused disgust on social media.
The photos appeared on the internet on June 28, showing packs of 1.5-2kg chicken selling for an "extra-low" price of between $9 and $11. The chicken was stained with patches of pale green, which could be seen scattered throughout almost every piece of meat.
A spokesperson for Brinks Chicken, which supplied the meat to Foodstuffs' Tauriko Pak'nSave, said investigations have identified the cause - and it's not a food safety issue.
"When cooked, the chicken can be safely consumed," they told Newshub in a statement.
"The discolouration has been identified as an interaction between the natural flora and proteins of chicken."
The spokesperson says the company has taken "immediate action to prevent recurrence", and any customers who purchased the green chicken would be fully refunded.
- 'No enforceable industry standard': More criticism of free-range chicken farmers
- Pak'nSave named as New Zealand's cheapest supermarket
- SPCA working with Canterbury property owner to prevent more than 70 chickens being shot
What are other causes for green chicken?
Earlier on Thursday, Newshub asked meat science experts what can cause green patches in chicken like the ones seen in the images.
"Sometimes with well-grown chickens, the muscle grows faster than the rate at which oxygen can be supplied to the muscle," Massey University's Dr Nicola Schreurs said.
"This can create little pockets of muscle that are under-oxygenated and when this happens the muscle will turn green."
A spokesperson for the Ministry of Primary Industries said there are many different explanations for the discoloured chicken, including as bile or faecal matter.
Stains could also be caused by something deep in the chicken's muscle, or the product bruising, which is unlikely to cause food safety issues.
On the other end of the scale is the possibility of rotting meat - which would pose a significant food safety risk.
"Meat spoilage could cause a range of colours. In this case, an accompanying odour and sliminess would make the spoilage obvious,” the MPI spokesperson said.
Dr Schreurs said the general rule when purchasing meat is if it looks green, don't buy it.
However, if you discover your chicken is green when you whip it out to cook for dinner, she says the chicken is actually safe to eat.
"I recommend trimming out the green sections to ensure visual appeal of your chicken dish."
Dr Schreur also suggested people who have discovered their chicken is green, do a sniff test before they cook it.
"If it does not smell like fresh raw chicken - don't eat it."
Editor's note: This story was updated on Thursday evening to include the poultry supplier's investigation findings over the green chicken sighting.