N.Z. wheats high yielders but have ‘mediocre’ quality

Press, 21 October 1983, Page 27

N.Z. wheats high yielders but have ‘mediocre’ quality

The present acceptance score of 12 in the M.D.D. (mechanical dough development) test for wheat is so low as to be pointless, according to Mr T. A. Mitchell, director of the Wheat Research Institute. In a normal season only about 5 per cent of lines scored less than 12 and these lines would have no eaffect on bread baking grists if they were accepted into the system, Mr Mitchell told the Cereal Science Conference in Christchurch. He said there was a strong case for raising the acceptance level by at least five points. Some of the improvement in wheat quality gained by breeding better cultivatars' had been negated because more wheat now reached acceptance level and less was rejected. Compared with the quality of the world’s wheat much of New Zealand’s wheat was in the mediocre bracket and all was below world standards, said Mr Mitchell. Oroua could perhaps be classed as a bread cultivar and was regarded by New Zealand bakers as being quite good. However all

New Zealand’s other cultivars were either marginal or sub-standard for bread making. New Zealand produced adequate supplies of wheat in the biscuit class but was short of bread class wheat, said Mr Mitchell. Because of this shortage, New Zealand either used inferior lines and suffered a loss of bread quality with its resultant loss to bakers, or when there was an overall shortfall in production, wheat was imported from Australia. Mr Mitchell said there were no technical or scientific obstacles to breeding and growing high quality bread wheats in New Zealand. The reason why New Zealand cultivars were so far below world standards lay with the policies which have guided the wheat industry since 1936. The goals imposed on the industry have been maximum production of homegrown wheat to the point of self sufficiency; total utilisation of all the wheat produced; and uniform pricing of wheat regardless of market requirements. “In short, quantity and yield have a high priority

but quality is not a market requirement,” said Mr Mitchell. Although the quality of New Zealand’s wheat was well below the world’s, New Zealand’s yields were higher. There was no proven physiological or genetic barrier to breeding cultivars which had both high yield and high quality, but the statistical odds against this combination being found were high, he said. The only real way to drastically improve the odds was to change the industry’s goals, and this was an adminstrative matter not a scientific one. “The cultivars are already in existence which could raise our national average quality to 24 or 25, but we might have to accept yields as low as 90 per cent of current cultivars.” The baking test, used for testing commercial lines of wheat, could identify strong and weak wheats in the national crop and could positively identify serious defects, said Mr Mitchell. It is the nearest approach we have to a universal quality test. Although test baking was

not used to the same extent overseas, all cereal chemists agreed that test baking was the ultimate test of bread making quality.

“It is however difficult to do en masse and requires care and skill to give reproducible results. For these reasons most countries use test baking as the final criterion in the selection and designation of cultivars for bread-making purposes. “We make no such designations in New Zealand so the test needs to be done on the actual commercial crops.” Mr Mitchell said perhaps the biggest problem with the test baking had been the need to do single tests on samples rather than duplicates. Single tests or analyses were bad practice and laboratories avoided this wherever possible. The institute had been unable to do tests in duplicate because growers and brokers had objected to the

extra time required. “We now see precision as more important than speed and hope to introduce duplicate testing as soon as we’ll have agreement to do so,” he said.

New Zealand had largely solved the problems raised by doing a large number of test bakes. Mass test baking required mass milling of small samples and this has been made possible by the availability of a junior mill. The institute solved the problem of mixing large numbers of small flour samples into doughs by designing a test bake mixer which can eject the whole dough after it has been mixed and can measure and add all the ingredients automatically. The institute had therefore been able to introduce a unique testing system which was tailored to the problems of New Zealand and the marketing system used here, said Mr Mitchell.