All grains in their natural state, growing in the field, are wholegrains. The wholegrain kernel comprises three distinct parts – the bran, germ and endosperm. In order to make grains suitable for human consumption, they must (to some degree) be processed. This may be as simple as de-hulling or could involve processes such as grinding, milling, or flaking.

Processing grains does not necessarily produce ‘refined grains’ or exclude them from the Australian definition of a ‘wholegrain’. Wholegrains are defined in the Australia New Zealand Food Standards Code as “the intact grain or the dehulled, ground, milled, cracked or flaked grain where the constituents – endosperm, germ and bran – are present in such proportions that represent the typical ratio of those fractions occurring in the whole cereal, and includes wholemeal.”

Wholemeal is produced by milling wholegrains to a finer texture. Wholemeal is defined in the Food Standards Code as “containing all the milled constituents of the grain in such proportions that it represents the typical ratio of those fractions occurring in the whole cereal”. Wholemeal flour and rye flour are examples of wholemeal products.

Examples of foods made with wholegrain or wholemeal ingredients include wholemeal and mixed-grain breads, rolls, wraps, flat breads and English muffins, wholegrain breakfast cereals, wheat or oat flake breakfast biscuits, wholegrain crispbreads, rolled oats, wholemeal pasta, brown rice, popcorn, bulgar (cracked wheat) and rice cakes.

Wholegrain nutritional and functional components:

Wholegrains are low in fat and are important sources of protein, dietary fibre (lignans, beta-glucan and soluble pentosans), vitamins (especially B-group vitamins and antioxidant Vitamin E), minerals (iron, zinc, magnesium and selenium) and many bioactive phytochemicals, including:

• Phytosterols – which have cholesterol-lowering properties.
• Sphingolipids – are associated with tumour control and maintenance of normal epithelia.
• Polyphenols and phenolics – such as hydroxycinnamic, ferulic, vanillic and p-coumaric acids, which have antioxidant properties.
• Carotenoids – such as alpha- and beta-carotene, lutein and zeaxanthin), which have antioxidant functions.
• Phytates – which may have a role in lowering glycaemic responses and reducing oxidation of cholesterol.

Antioxidants in wholegrains:

The antioxidant content of wholegrains is of worthy note, with research showing the in vitro antioxidant activity of wholegrain foods is on par with, or higher than that of vegetables and fruits. A 2007 study by the Agricultural Research Service of the United States Department of Agriculture ranked foods for their antioxidant capacity. Cereal based foods including ready-to-eat cereals, oats, wholegrain breads and legumes were found to be amongst the highest antioxidant containing foods by ORAC (oxygen radical absorbance capacity) score.

Table 1: ORAC Antioxidant Capacity of Selected Fruits, Vegetables, Grains and Legumes (μmolTE/100g)

Grains                                             Total ORAC Fruit and Vegetables          Total ORAC

Rice bran                                       24287                     Blueberries                           6552

Cornflakes                                    2359                        Blackberries                        5347

Granola                                          2294                       Strawberries                       3577

Oat bran                                         2183                       Apples                                   2828

Rolled oats                                    2169                        Avocados                              1933

Pumpernickel                              1963                        Oranges                                 1819

Popcorn                                         1743                        Spinach                                  1515

Mixed grain bread                      1421                          Broccoli                                 1362

Shredded wheat cereal              1303                         Green tea, brewed          1253

Legumes                                                                        Mangoes                               1002

Pinto beans                                  904                         Carrots                                    666

Chickpeas                                     847                         Green peas                            600

Lima beans                                  243

Antioxidant vitamins such as vitamin E and its isomers (tocopherols and tocotrienols) and minerals such as selenium contribute to the antioxidant activity, as do phytochemicals like phytates, phenolics, and lignans or alkylresorcinols.

Grain-specific antioxidants exist, such as oryzonol in rice, avenanthramides in oats and ferulic acid in corn and wheat. Some of these phenolics have anti-atherogenic activity. Certain other phenolics, phenolic lipids, flavonoids, tocopherols and dietary fibers (e.g. beta-glucan) found in grains are anti-mutagenic and anti-inflammatory.

Choline, betaine and alkylresorcinols (which is particularly abundant in rye) are other important compounds found in wholegrains which play a role in the prevention of cell mutations and tumor formation.

Research has shown (and continues to bring to light) the many nutritional and functional components of wholegrain cereals that work alone and/or in synergy to promote human health and offer significant protection against many of the lifestyle diseases that plague our world today. More detailed information on the health attributes of wholegrains can be found in the section – ‘Grains and Health’.

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