Grains Research and Development

Date: 01.06.2004

Backing up Australia's clean, green image

Australian farmers work hard to maintain their clean, green image and peanut growers are no exception. "We present consumers with paddock to palate accountability, where we are able to trace the product back through the production line to the farm," says Burnett grower Wayne Weller.

One of the quality issues facing dryland farmers is aflatoxin contamination. Aflatoxins are removed during processing, so are not a food safety issue in Australia. However, this is an expensive process and the industry focus is now on minimising contamination in the field.

"Over the past five years, GRDC-funded projects have been successful in reducing on-farm aflatoxin contamination. These projects focus on integrating varietal and in-season harvesting management practices into computer-based decision support tools," says QDPI&F researcher, Dr Graeme Wright.

Mr Weller believes the greatest innovation for growers like himself is the advancement in harvesting procedures. "To avoid aflatoxin contamination, peanuts must be dried to below 15 percent moisture as quickly as possible after harvesting," he says.

The fungus Aspergillus flavus produces aflatoxins in peanut kernels under certain conditions of high temperatures and lowered moisture availability. This can occur both pre- and post-harvest when moisture content in kernels is around 15 to 30 percent. "Some product might come out of the field at 25 percent moisture content - but you have to dry the peanuts at no faster than, and the equivalent of, half a percent per hour, otherwise the quality is affected," Mr Weller says.

Cadmium (heavy metal) contamination is another quality issue facing the peanut industry, especially as it expands into sugar regions.

"Cane growers diversifying into peanuts need to avoid any potential problems associated with organo-chlorine residues and cadmium uptake," says QDPI&F principal extension officer for pulses, Mr Greg Mills.

"These new industry entrants have been very active in participating in soil testing programs and agronomic avoidance strategies to eliminate problems.

"Peanuts are very efficient at taking up cadmium - so they have to be grown on soils relatively free of cadmium problems or engage in practices that minimise the incidence of cadmium in kernels, such as repeat foliar zinc applications," he says.

The Australian peanut industry has been proactive in minimising aflatoxin and cadmium contamination. Australia may be a small player in the international marketplace, but it has a big reputation for producing high-quality peanuts.

GRDC Research Code: DAQ 543, program 2