The retailers accepted their conduct was likely to mislead consumers and contravene the Australian Consumer Law (ACL).
Choice brought the issue with oregano to the regulator's attention earlier this year.
The sister organisation of the UK-based watchdog Which?, which published similar findings in 2015, found seven of 12 dried oregano samples contained other ingredients, including olive and sumac leaves.
“Consumers need to have confidence in food labels – it's simply not acceptable to be in the dark about what we're adding to our food. At the end of the day all entities along the supply chain are responsible for the authenticity and traceability of the product being sold to consumers,” it said.
Ingredients other than oregano made up between 50% and 90% of the adulterated samples.
Products in question
ACCC said the products in question were Aldi’s Stonemill brand of oregano sold only at Aldi; and the Menora brand of oregano available at IGA and independent food services in Victoria, New South Wales, Western Australia and South Australia.
The investigation identified that during 2015, Aldi made statements on the packaging of its Stonemill brand oregano product that it contained 100% oregano.
Between at least October 2015 and March 2016, Menora claimed on its oregano packaging that it contained only oregano, other than possible traces of tree nuts, peanuts, wheat, sesame seeds and soy.
Aldi and Menora also agreed to test the composition of other herb and spice products.
The regulator also resolved concerns with three other suppliers about the composition of products labelled as ‘Oregano’.
Rod Sims, ACCC chairman, said by labelling items as ‘Oregano’, Aldi and Menora represented to consumers that products contained only oregano.
“Test results provided to the ACCC identified the substantial presence of olive leaves in both Aldi and Menora’s oregano products,” he said.
“Suppliers of food products have an obligation to ensure ingredients of their products are accurately labelled and should be able to substantiate any representations made on the packaging that they approve.”
ACCC has agreed to ‘administrative resolutions’ with the smaller suppliers of “G Fresh Oregano Leaves “Mediterranean”, “Master of Spices Oregano Leaves” and “Spice & Co. Oregano Leaves”.
They must cease supply of oregano products that contain other contents and take steps to confirm authenticity of products for future supply.
In August and September 2015, Choice bought 12 different dried oregano products.
A sample from a single batch of each product was tested using Fourier Transform Infrared (FT-IR) spectroscopy and chemometric modelling.
Which? found 25% of 78 samples of dried oregano from a range of retailers contained other ingredients – most commonly myrtle and olive leaves.
The tests used mass spectrometry and were conducted by Professor Chris Elliott.