NUTRITION – CSIRO RESEARCH

CSIRO research leading

to healthier foods

In the not too distant future, a bowl of cereal, muesli bar, sandwich or steaming bowl of pasta will not only satiate the appetite but have highly targeted nutritional roles.

CSIRO’s Food Futures National Research Flagship is developing new grain varieties and tailoring fibre content to optimise health benefits to consumers. Cereal grains are major sources of dietary fibre, an important contributor to human health. Dietary fibre fractions, such as non-starch polysaccharides (NSP), have the potential to lower cholesterol and the glycaemic response of foods as well as to promote regularity and improve bowel health. New grain varieties with improved health benefits also have the potential to be easier to process, thus saving on energy.

Benefits of fibre and NSP

FIBRE is important because of its contribution to human health, including promotion of regularity, improved bowel health and, in the long term, protection against diverticular disease. Total dietary fibre consumption has been associated with lower risk of colorectal cancer. Fibre components can also lower plasma cholesterol and lower the glycaemic response of foods. Dietary fibre is that fraction of the edible part of plants or their extracts that is resistant to digestion and absorption in the small intestine, usually with complete or partial fermentation in the large intestine. The main contributors in typical diets are NSP (e.g. pectin in jam), resistant starch (e.g. high amylose maize) and oligosaccharides (e.g. inulin derivatives found in artichokes). Dietary fibre also includes lignins such as those found in wheat bran. The benefits of increased consumption of cereal NSP include enhanced laxation and the associated lowered risk of diverticular disease, and a possible reduction in the risk of coronary heart disease, diabetes, certain cancers, especially of the large bowel, and obesity. Human trials have shown that the soluble NSP found in particular grains, such as oats and barley, lower plasma cholesterol. Most of these issues will be of interest and concern to many older orienteers. Nearly all starch is consumed as cooked foods and is broken down into glucose in the small intestine, where it is absorbed into the body. However, resistant starch – the fraction that escapes digestion in the small intestine and passes into the colon, where it is broken down by resident bacteria – has important health attributes. Amylose, one component of starch, has been targeted because of its established health benefits. It is more resistant to digestion so it releases glucose more slowly, leading to a low glycaemic response. Research suggests that it can promote bowel health, reduce colorectal cancer risk and improve the control of blood glucose. Controlling blood glucose is important in managing Type 2 diabetes and may also help lower the risk of obesity.

Reducing food waste

CSIRO is also working on ways to reuse the fruit and vegetable materials which are currently wasted during food processing. The beneficial fibres and bioactive components from these waste streams can be added back into processed food products to replace currently added gums and stabilisers. Food processors waste between 20% and 40% of the vegetable material they process. Such items as stalks, skins, cores, outer leaves, etc, are all sent to waste. It is known that one food manufacturer discards 8,500 tonnes of apple, pear, peach and tomato components each year. Many processed foods have textures which are controlled by added gums and stabilisers such as guar or xanthan. By working out how these additives create texture and mouth feel, CSIRO researchers hope to develop ways to replace them with natural additives developed from the current fruit and vegetable waste stream. Components such as broccoli stems, apple cores and peels, oranges and lemons waste, and grape seeds and skins from wine making, are being targeted for reuse. Researchers are finding ways of reducing the unhealthy components of processed foods and of adding back many phytonutrients and antioxidants which consumers are missing in their regular diets. As well, natural colours and flavours may be extracted from these fruit and vegetable wastes. Researchers have already developed a colour palette made from 100% natural colourings.

The gluten problem

Gluten is a protein found in wheat, rye, barley and oats. Eating gluten triggers an auto immune reaction in people affected by coeliac disease, resulting in intestinal inflammation and damage. One in 100 Australians have coeliac disease (although four out of five are as yet undiagnosed) and the only management option is life-long avoidance of products containing gluten.

Gluten free beer

Sorghum, millet or corn based gluten free beers are commercially available. However these products lack the authentic taste of barleybased beer. By Australian law, a gluten free product must contain no detectable gluten. This is 5 parts per million or below, with current testing methods. CSIRO scientists are now working to produce barley varieties with gluten levels below the acceptable limit for coeliacs. Barley is genetically simpler than wheat, so achieving a gluten free barley variety is faster. This is an important proof-of-principle step on the way towards producing a range of gluten free cereals. In barley, the class of gluten-like proteins is called hordeins, and these are toxic to coeliacs. Scientists are working to remove these hordeins from barley. They started by combining two non-genetically modified barley mutations bred in 1975 by the Carlsberg Laboratories in Denmark. These mutations make the plants very low in hordein, providing a perfect starting point for the project. These lines have been crossed to reduce the hordein in the grain by over 90 per cent. Work is proceeding to further reduce the hordein level in barley. The initial taste tests on beers made from barley with 90 per cent reduction in hordeins are promising. The gluten free characteristics will be bred into current malting varieties, suited for growth in Australia, which will reduce the price of the final product to consumers. If all tests and research are successful, barley gluten free beer may be available on the Australian market by 2014. www.csiro.au/ff

Lupin-enriched bakery items may slash blood pressure, boost heart health

SCIENTISTS at the University of Western Australia in Perth have found that bread enriched with lupin kernel flour, at the expense of wheat flour, may reduce blood pressure and boost heart health. Overweight and obese men and women who consumed the lupin-enriched bread experienced decreases in their systolic and diastolic blood pressures of 3.0 and 0.6 mm Hg respectively, according to findings published in the American Journal of Clinical Nutrition. “These results suggest that a diet moderately higher in dietary protein and fibre can significantly reduce blood pressure,” wrote the researchers, led by Jonathan Hodgson from the University of Western Australia. “They also confirm the potential of lupin kernel flour as a novel food ingredient to bring about these outcomes. This approach may be a relatively simple and acceptable dietary measure for helping to reduce cardiovascular risk in overweight and obese persons.” Lupin flour has been earmarked as the next major competitor to soybean as a high protein source. Lupin (Lupinus angustifolius L.), is the major grain legume grown in Australia and production exceeds 800,000 tons per year. Used mainly for stock feed, since 2001 lupin bran and flour have been used in Australia in food formulations as a substitute for more expensive traditional cereal grains. The average protein content of lupin is just over 30 per cent, compared with 44 to 48 per cent in soybeans. In Europe, the flour is already being used in bakery and pasta products because it can replace eggs and butter to enhance colour, and additional potential uses of lupins are in crunchy cereals and snacks, baby formula, soups and salads. In addition to the protein, lupin flour is also said to contain non-starch polysaccharides which act like both soluble (oat fibre) and insoluble (wheat bran) fibre.

Study details

Dr. Hodgson and his co-workers recruited 88 overweight and obese men and women with an average age of 57.9 and an average BMI of 30.6 kg/m2, and randomly assigned them to receive either a white bread group or a lupin kernel flour enriched bread group for 16 weeks. Both interventions contributed between 15 and 20 per cent of the participants’ usual daily energy intake. At the end of the study, results for the 74 people who completed the study showed that systolic and diastolic blood pressures decreased by 3.0 and 0.6 mm Hg, respectively, in the lupin-flour group. The pulse pressure of participants in the lupin-flour group also decreased by 3.5 mm Hg, but the researchers noted no change in heart rate. The researchers could not pinpoint the mechanism causing these changes since “a range of mechanisms may be involved”, they said. One such possibility is the high content of arginine, which is a known precursor for the vasodilator nitric oxide. “The decrease in blood pressure could result from an improvement in vascular tone mediated by nitric oxide, a potent endothelium-derived relaxing factor,” wrote the authors. “However, it is difficult to speculate on the mechanisms behind the observed differences in blood pressure, given that multiple factors in the diet - protein, carbohydrate, and fibre - were changed,” they added.

Role for lupin in weight management

Previously, Dr Hodgson has reported that lupin flour may increase satiety and play a role in weight loss. A study from 2006 reported that eating a breakfast containing lupin bread resulted in significantly higher self-reported satiety than a group eating white bread, and a lower energy intake (488 kJ less) at lunch by the lupin bread group than those eating the white bread breakfast. Eating the lupin-enriched bread at lunch also reduced betweenmeal energy intake (1028 kJ less) than the white bread lunch (American Journal of Clinical Nutrition, Vol. 84, pp. 975-980).

Source: American Journal of Clinical Nutrition 2009, Volume 89, Pages 766‑772 “Effects of lupin kernel flour-enriched bread on blood pressure: a controlled intervention study” Authors: Y.P. Lee, T.A. Mori, I.B. Puddey, S. Sipsas, T.R. Ackland, L.J. Beilin, J.M. Hodgson