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Grain processing and manufacture - Suggested answers
Activity 1
- Why are grains processed?
Grains are processed to:- make grains digestible
- inactivate natural toxins and prevent bacterial growth and food spoilage
- optimise the appearance, taste and texture of foods
- improve convenience to meet consumer demand for quick and easy meal solutions
- maximise their nutritional value, processing can make it easier for nutrients from grains to be digested or for nutrients to be added (fortification).
- What is the nutrient content of a) the bran, b) the endosperm, c) the aleurone and d) the germ?
The main nutrients in the following components of the grain are:- the bran: dietary fibre
- the endosperm: protein and carbohydrate
- the aleurone: vitamins and minerals
- the germ: fat and vitamin E.
- What is meant by extraction rate
? (Select Nutritional implications of flour milling button).
Extraction rate is the number of parts by weight of flour that is produced from 100 parts of wheat. The higher the extraction rate, the more bran is included in the wheat flour and hence the higher the amount of dietary fibre, vitamins and minerals in the flour. Extract from Grains Research and Development Centre, Nutrition recommendations, viewed 10.12.2002, <http://gograins.com.au/grainsnutrition/ns/7frame.html>
Activity 2
- Compare the vitamin retention rate for wholemeal flour (100% extraction rate) and white flour (78% extraction rate) for a) vitamin E, b) riboflavin, and c) folic acid.
- vitamin E: 100% compared to 75%
- riboflavin: 100% compared to 42%
- folic acid: 100% compared to 33%
- What is the impact of flour milling on the bioavailability of nutrients?
Although phytate and dietary fibre bind minerals, particularly calcium, iron, magnesium and zinc which reduces their absorption in the body, and white flour has a lower phytate content than wholemeal flour therefore the absorption of minerals would not be affected as much as for wholemeal flour. The wholemeal flour is higher in minerals so overall they provide more minerals to the body than white flour. Extract from Grains Research and Development Centre, Nutrition recommendations, viewed 10.12.2002, <http://gograins.com.au/grainsnutrition/ns/7frame.html>
Activity 3
Explain why Nature's Gold™ was developed and how the nutritional profile of the resulting bread, VitaGold®, was better than traditional wholemeal bread.
Nature's Gold™ was developed to increase the availability of nutrients from the aleurone cell layers. The fibrous layers of the aleurone and bran are not easily digested which is why the aleurone and bran layers are normally separated from the flour during milling.
The new milling system allows the nutrients in these layers to be available for the body to digest, this is why the nutrient profile of VitaGold® is better than wholemeal bread.
Extract from Grains Research and Development Centre, Nutrition recommendations, viewed 10.12.2002, <http://gograins.com.au/grainsnutrition/ns/17frame.html>
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