"The difference between wholesale and retail prices on any one item fluctuates due to a number of factors including seasonality, customer demand and periodic specials," a company spokesman said.

Fairfax approached Coles after being forwarded a copy of a load sheet for the company's Manuka store dated February 29, 2016.

Coles confirmed the document, which was for produce shipped from its delivery centre at Eastern Creek to Manuka Plaza, was genuine and asked it not to be published in full as some of the information was "commercial in confidence".

Limes, which retailed at three times the wholesale price, topped the mark up table. Shipped in at an individual cost of 27 cents each, the citric flavour bombs retailed at 80 cents, a price differential of 53 cents.

Passionfruit, shipped in at .57 cents each, retailed for $1.50. This was 2.6 times the wholesale price.

Potatoes were also a good earner with the sweet gold variety selling for 2.7 times wholesale. One kilo bags costing $1.66 each were then marketed for $4.50.

Pre-mix salad kits, despite the additional handling and ingredients, weren't marked up as heavily as many standard fruit and vegetable lines. Asian salad packs, brought in wholesale at $3.04 each, hit the shelves at $5.50.

Wet pasta salad, another labour intensive offering, was offered to consumers at just over double the wholesale price of $3.57 per 800 gram container.

Sliced kale, despite being the hipster's favourite and much more popular than its distant cousin, Brussels sprouts, was not heavily marked up given its short shelf life – 175 gram packs costing $2.51 retailed for just 1.6 times that amount; $4 each.

Some products, including blueberries and plums, were offered at, or even below, the wholesale cost. Plums costing $3.07 a kilo to ship to Manuka were offered in the store for $3 a kilo.

The wholesale prices cited here are the cost of the produce by the time it had reached the distribution centre and should not be confused with farm gate prices paid to the producer.

"Gross margins do not take into account the many costs involved in bringing products to our customers," the Coles spokesman said.

"These include transport, employee remuneration, wastage and markdowns, and overheads such as rent and utility costs. Fresh products must be kept chilled and delivered quickly. Tropical fruit, such as passionfruit, must generally be airfreighted from regions much warmer than Canberra."

Because of these factors Coles's earnings before interest and tax were significantly lower than the margin on individual items.

"[Earnings] equated to 5.6 per cent of sales in the first half of the financial year," the spokesman said. "This was in line with similar retailers in Australia and around the world."

The company, which told Fairfax it had reduced the cost of the weekly shop for consumers for more than six years, cited the recently released Rural Industries Research and Development Corporation report on "From Farm To Retail – How Food Prices are Determined in Australia".

According to the report food price rises have lagged behind most other areas of consumer spending in the seven years to 2014.

"Weak consumer sentiment has led to cautionary spending on discretionary items for meals at home and reduced spending on dining out," the report said.

"There has been increased price competition between major grocery chains to be seen as providing best value prices on food and groceries.

"Australian food is generally more affordable than similar foods in other developed markets."