Eight for apples, 46 for muffins and other chemistry stories


Eight for apples, 46 for muffins

Plants protect plants and triple yields in East Africa

Spinning the world clean

Thursday, 8 July 2010 at Chemistry for a Sustainable World, an international conference organised by RACI, the Royal Australian Chemical Institute. Speakers in Melbourne and available for interview. More info on all stories online.

Eight for apples, 46 for muffins

What does food do – time to move beyond the glycaemic index

It’s time to get smarter about food labelling according to Dr John Monro, speaking at RACI’s international chemistry conference in Melbourne this week.

“We need to know not just what is in the food, but what the food is going to do in our bodies,” he says. John is a researcher with the New Zealand Institute for Plant and Food Research.

“And we need easy to follow guides that make sense when we’re pushing our trolleys around the supermarket.”

He is proposing a new food value that acts like a nutrient value – the glycaemic glucose equivalent. In effect it tells you how much glucose consumed would have the same impact on blood sugar as an amount of food , such as a serving. Blood sugar is one of the keys to metabolism and control of diabetes.

He says the glycaemic index – which compares only the carbohydrates in foods – used well is a good tool. But it doesn’t go far enough and it’s poorly understood by consumers. For one thing, people eat foods, not just the carbohydrates in them, and also, the glycaemic index is accurate only when you compare equal amounts of carbohydrates in food, which is difficult to do in the supermarket where almost all foods differ in carbohydrate content. Another important difference is that the glycaemic index does not change with increasing food intake, whereas the glycaemic glucose equivalent depends on how much food is consumed.

His index is much simpler. A typical apple would score a 8 because it has the same impact on blood sugar as eight grams of glucose and two apples would score 16. A typical muffin would score 46 because it has the same effect as 46 grams of glucose.

The “glycaemic impact” which is the glucose equivalents score for a quantity of food, has the support of the American Association of Cereal Chemists and meets the expectations of the US FDA who are looking for whole food measurements that apply to amounts of food that people usually consume.

The work has just been published in the Journal of Nutrition: Monro JA, Mishra S  Glycaemic impact as a property of foods is accurately measured by an available carbohydrate method that mimics the glycaemic response. Journal of Nutrition 140, 1328-1334, (2010) (Issue 7, July)

Plants protect plants and triple yields in East Africa – Thursday

More than 30,000 East African farmers are using plants to protect their corn (maize) crops from insect and weed attack. The crop protection strategy was developed by Kenyan and UK scientists.

Termed “Push-Pull’, it relies on strategically deploying attractive and repellent plants in alternating rows to control the growth of African witchweed and stemborer insects. These are the biggest threat to cereal crops in Sub-Saharan Africa. Stem borers often destroy 80% of a crop.

Zeyaur Khan and his team at the International Centre of Insect Physiology and Ecology in Kenya, working with John Pickett at the Rothamsted Research in the United Kingdom, have come up with a way to use plants which release either repellents, used to “push” pests away or attractants used to “pull” pests into traps. These plants can also cause the witchweed to undergo suicidal germination so it cannot reproduce.

A border of attractive trap plant, such as Napier grass are planted around the crop. This grass releases attractants which lure and entrap stemborers and attracts predatory insects to attack them. Planted close to the cereal crops are repellent plants such as Desmodium which not only repels insects, it also causes suicidal germination in weeds, and it acts as a live mulch.

To date it has been adopted by over 30,000 smallholder farmers in East Africa, Their maize yields have increased from about one ton per hectare to three tons per hectare (1 t/ha to 3.5 t/ha).

It may be the economically feasible answer to pest control that African farmers are desperate for.

Spinning the world clean

Prof Colin Raston and his colleagues in the Centre for Strategic Nano-Fabrication at the University of Western Australia are setting about cleaning up the world—and chemical industry in particular—through developing a suite of technologies to enable continuous, rather than batch, processing.

“We’re working at getting rid of the round-bottom glass in the laboratory, and the array of tanks and pipes in chemical plants.”

The advantages of continuous processing, says Raston, are that it can be controlled precisely and is easy to scale up from the work bench to production. The initial impetus came from manufacturing nano-particles to within a narrow size distribution. The technology to do this involved the need to build in high levels of control. “Every molecule has to be treated in the same way.”

One of the techniques which the University of Western Australia researchers have been developing is spinning disc processing, where chemicals are injected through feed jets at the centre of the disc and react in the thin film which forms as they are flung across the disc under the influence of centrifugal force. Another technique involves using a rotating tube as a reaction surface.

The efficiency of these processes leads to a smaller energy expenditure and less waste. It fits generally in with the principles of environmentally sustainable, “green” chemistry, Raston says.

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  • Is GM working for cotton growers
  • And more stories at www.scienceinpublic.com.au/blog/raci

For interviews: Niall Byrne, 0417 131 977, niall@scienceinpublic.com.au
AJ Epstein, +61 (433) 339-141, aj@scienceinpublic.com.au
Further information online at www.scienceinpublic.com.au/blog/raci