16 March 2000 Seeing the Science among the Trees

A unique relationship between a university and a commercial industry is putting the development of New Zealand tree crops on a firm scientific basis.

"What's being done here at Lincoln University is science in the service of industry," says Dr David McNeil, a plant scientist with a specialisation in tree crops.

Before David arrived at Lincoln University in the mid-1980s there was little coordinated scientific research across the three main nut tree crops at the heart of the industry in the South Island – walnuts, chestnuts and hazelnuts.

A lot of research was being done by separate industry groups but Lincoln University now provides a level of leadership and scientific credibility not previously enjoyed by growers and processors.

The centre of the scientific research and the source of the raw material for analysis and investigation is a two-hectare nut tree trial block on Lincoln University land in the Horticultural Research Area. It was first planted out in 1985 and contains about 500 trees.

The trees are owned by the New Zealand Tree Crops Association, a voluntary national organisation which encourages investigations into tree cropping and promotes interest in useful trees such as those producing fruit, nuts, timber, fuel wood, stock fodder, bee forage and other useful products.

The association pays rent to Lincoln for the trial block and provides much of the operational funding. The University, in turn, provides the services of Dr McNeil to do the research.

Because the Tree Crops Association ‘owns’ the trials, they have an advisory group which manages the operation and provides information from the nut industry on areas of concern. Dr McNeil reports on his research to this group.

"It's a unique set up," he says.

"I attempt to design scientifically valid ways of addressing the problems presented. I do the trial analysis, the statistics, the writing up and present all this back to the advisory group and it then gets published in the Tree Crops Association's magazine. Later the research is also written up for the academic literature."

While Dr McNeil works on the tree side – the science of cultivation and production – Lincoln University colleague Dr Geoffrey Savage, a biochemist, works on the food chemistry side of the tree crops, checking out their dietary benefits and other nutritional aspects.

Chestnuts, walnuts, hazelnuts, macadamia and to a lesser extent almonds have all been studied and interesting facts have emerged. For example walnuts are low in saturated fatty acids (regarded as a dietary 'nasty') but have reasonably high levels of monounsaturated fatty acid (a dietary 'goodie'), oleic acid and linoleic acid (also 'goodies').

"Research has shown that eating walnuts and walnut oil can have a very positive effect on the lipid (fat) metabolism in humans," says Dr Savage, "and can lower LDL cholesterol levels."

Dr Savage has also confirmed a high level of monounsaturated fatty acids and a low level of saturated fatty acids in the oil of macadamia nuts.

"High levels of Vitamin E are also a feature of most nuts," says Dr Savage, "and as daily sources of this essential vitamin can often be limited in conventional diets, a regular intake of nuts in some form or another is an obvious solution to dietary deficiency."

Dr Savage says that although few reports on the protein content of hazelnuts can be found in the literature, the overall pattern of amino acids present confirms the nuts as a source of high quality protein. Like the other nuts they are also a rich source of essential fatty acids.

So with a tree cultivation expert and a nutritional biochemist working together with the Tree Crops Association the direction is well set for a productive future for the industry. Both will be speaking at the Tree Crops New Zealand Conference at Lincoln University over 22-25 April.

Ian Collins, Journalist, Lincoln University, Canterbury, New Zealand