Supermarket demands for unblemished fruit has led to a high level of waste in the tomato industry, researchers say.

A study from the University of the Sunshine Coast has found 70–84 per cent of undamaged, edible tomatoes are being left in the field because they do not meet retailers' expectations.

Environmental Science honours student Tara McKenzie said she wanted to understand where in the supply chain food waste was happening, and why.

"70 per cent of losses I found were in the field," she said.

"It was bleedingly obvious that the reason they weren't harvesting certain things … was because they weren't meeting a certain product specification."

The study investigated two supply chains originating at the same Bundaberg tomato farm — one that went to Brisbane and the other that stayed local.

Ms McKenzie said only about 45–60 per cent of the total harvestable crop reached consumers.

"At every link, from harvesting and sorting to the market floor, edible tomatoes that were slightly odd-shaped or marked, or too small or too large, were rejected," she said.

"The ability of supermarkets to impose their own specifications and reject product by the pallet, based on a single blemish, gives them considerable power over primary suppliers and wholesalers."

Tara McKenzie says the farmer involved in the study stopped growing tomatoes soon afterwards. ( Supplied: University of the Sunshine Coast )

Ms McKenzie acknowledged that the study was a snapshot of a particular time on that particular farm, during a season where oversupply of tomatoes was an issue.

But she said the drivers behind the waste applied beyond the tomato industry.

Part of a worrying trend for food security

Research fellow Lila Singh-Peterson supervised the research as part of a broad body of work studying farm systems.

"There's some really worrying trends. For example, since the 1970s we've got 30 per cent fewer farms, 40 per cent fewer farmers, 20 per cent lower areas of farmland," she said.

Between 70–84 per cent of produced tomatoes are left in the field, the researcher found. ( Supplied: University of the Sunshine Coast )

Dr Singh-Peterson said it all pointed toward a less secure future for Australian food, and she believed it would take intervention from government to reverse the trends.

"When you look at how much government support there is for farmers in different countries, in Australia it's pretty minimal," she said.

"Norway for example, about 61 per cent of their total farm income is derived from the government, because the government actually recognises that the farm is also a link to their cultural heritage, to their identity, it offers some beautiful landscapes.

"It does seem that they do value the farm for more than just its ability to produce food, which we don't seem to do in Australia."

Food diverted to charity, processors

The ABC contacted Coles, Woolworths and Aldi supermarkets for a response to the study.

In a statement a spokesman for Coles said produce that did not meet supermarket standards was often sold to food processors for use in other products.

"For instance … our sun-dried tomato supplier sources tomatoes from Queensland growers in Bowen and Bundaberg," he said.

Only about 45–60 per cent of the total harvestable crop reached consumers. ( Supplied: University of the Sunshine Coast )

The spokesman said Coles worked with farmers to have achievable standards, and also had a range of products such as 'smoothies' or kids' packs for undersized produce.

"Coles also works with food charities including SecondBite and FoodBank to divert food that might otherwise be wasted into healthy nutritious meals for those in need," he said.

"We have donated 10 million kilograms of surplus fresh food, providing over 20 million meals to community food programs since our partnership began in 2011 with SecondBite."

Also responding in a statement, a spokesman for Aldi Australia said the produce specifications were set to ensure customer needs were met.

"In 2014, we launched a new range of products within the fresh produce category that sees a larger proportion of growers' crop size utilised, where historically these items may have been sent to waste or used for juicing," he said.

"Across the country since 2015, Aldi has diverted over 6,000 tonnes of food from landfills by donating them to charitable organisations."

A spokeswoman for Woolworths said since launching an initiative to purchase slightly imperfect produce two years ago, the company had bought 78 million kilograms of these imperfect fruits, including 6.7 million kilograms of tomatoes.

"Woolworths is continually looking for new ways to work with farmers to provide fresh fruit and vegetables that deliver value to customers," she said.