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In broad terms wheat can be classified according to its hardness.

The hardest wheat grain is Durum and this flour is mainly used to make pasta and noodles. Hard wheat flours are best for making bread. Semi-hard wheat flours are used for general purpose flour. Soft wheat flours are used for making products like cakes and biscuits. There are also small amounts of specialty wheats, such as the purple grain coloured wheat, produced for use in certain types of breads. It is used for providing colour and texture in a number of wholemeal and specialty bread types.

Wheat may also be classified in several other ways, which may differ from country to country:
• cultivar
• protein content
• hardness
• according to where it’s grown
• grain colour (red or white)
• when it was sown (spring or winter)

A variety of cereal chemistry tests such as the Falling Number test, which measures the amount of alpha-amylase enzyme present in wheat, and the Ash test, which measures the mineral content of flour, are also used to classify wheat. Often a classification system uses a combination of these factors.

Spring or winter wheat
Winter wheat is sown in autumn and continues to grow through the winter, while spring wheat is sown in spring. The difference is more significant in countries like Canada, where the ground is covered with snow for months on end. In New Zealand, it means that winter (autumn sown) wheat ripens faster than spring wheat because it has more time to establish a sound root system.

Red or white wheat
Most New Zealand grown wheat is red, that is, the seed coats are reddish brown. White wheat has a yellowish white colour.
Red wheat is more commonly grown in New Zealand because it is more resistant to premature sprouting. Sprouting (or sprout damage) occurs when conditions are damp during, or just prior to, harvesting. When the mature seed gets wet or sufficiently damp, the seed becomes metabolically active and begins to germinate.

Wheat is used in many human foodstuffs and for animal feed. The most important use of wheat in New Zealand is for bread baking, which accounts for around 60% of total wheat production. Other major foodstuffs made using wheat include biscuits and pasta.
The wheat used for pasta is called Durum wheat. Durum wheat is different from the type of wheat used to make bread and is much harder, with different cooking properties than bread wheat flour, making it satisfactory for pasta manufacture.
The requirements for bread baking wheats are quite different. The grains are semi-hard or hard, which produce flours that flow easily through a conventional milling system. Bread flours must absorb a relatively large amount of water, and good bread baking doughs must also have the capacity to stretch into a large volume. Bread baking doughs are expanded by gas from the fermenting yeast and then must retain that volume when cooked.

Biscuit wheats differ from bread wheats in the hardness of their grains and in the type of doughs which are made from their flour. Biscuit wheats are soft, which means special mills are required to extract their flours.

Soft wheats in a conventional hard wheat or bread wheat mill would clog up the sieves used to separate the white inner part of the grain called the endosperm from the rest of the grain. The softness of biscuit flours means they only absorb small amounts of water when mixed into a dough. Doughs made with biscuit flours spread out sideways when baking, and so produce high quality biscuits.

There are also some small amounts of specialty wheats, such as the purple grain coloured wheat, produced for use in certain types of breads. Purple wheat, which was first commercially produced in New Zealand, is a small but significant part of the New Zealand bread wheat industry. It is used for providing colour and texture in a number of wholemeal and specialty bread types.

A flour specification is a list of quality standards that a flour must meet. For instance, moisture content is to be between 14-15% and protein content between 10-11.5% and so on.

Flour specifications are usually written by Bakers to list out the requirements for the quality of flour they want to buy. Millers then produce flour that meets the required flour specifications. When a bakery receives a delivery of flour, a flour report that includes the flour specifications is usually obtained. Bakers can then test the flour to ensure that it matches the specifications and meets their requirements by doing a bake test.

The flour specifications that a bakery prefers may not work as well for another bakery, even if both make the same type of product. This is because different combinations of processing equipment, ovens and recipes make each bakery unique.

There are many different types of flour made for different purposes. The quality and best use of the flour depends on the wheat and the blending processes used to make it. The intended use of various types of flour is usually stated on the packaging in which you buy the flour.

White baker’s flour (bread)
This is a general purpose baker’s flour, milled from bread wheat to give medium dough strength. White flour contains only the inner portion of the wheat grain called the endosperm.
Use: bread, buns, bread rolls, pastry products.

Wholemeal flour
Wholemeal flour contains all parts of the wheat grain including the outer layers of bran and germ. When using wholemeal flour more water may need to be added to the recipe as the bran absorbs
more water than the white part of the grain.
Use: bread, buns, rolls, shortbread, cakes, biscuits.

Flour for pastry
For puff pastry, flour should have a high protein content. This is important because it is the absorption of water by gluten that gives the “puff”. It is also very important that the flour be very white and free of any bran particles if the pastry is to be stored or sold before being baked.
Use: Particularly suitable for making pastry and pasta. You can use the same type of flour that you would use for making bread.

Flour for biscuits and cakes
The ideal flour for making most cakes and biscuits has a lower protein content than bread making
flour, and is milled from soft wheat varieties. For commercial biscuits, it is very important to achieve consistent size and thickness for packaging. Flour quality is largely responsible for these attributes. Strong flour is undesirable in biscuits; a flour with less strength will spread more in the oven, and will make more tender, shorter biscuits.
Use: soft biscuits, and baked products requiring a very weak, soft flour.

Self-raising/Self-rising flours
These are made by combining biscuit flours with chemical aerating agents similar to baking powder. The aerating agents cause batters to rise when heated. The flour and raising agents are sifted together many times to ensure even distribution and consistent product quality. Note: plain flour should be used on the bench to pat out scones to avoid a bitter after-taste.
Use: scones and pikelets.

Chlorinated flour/High – Ratio Flour
Cake flour may be treated with up to 1500 parts per million (ppm) of chlorine to make chlorinated or high-ratio flour. The amount of chlorine treatment or chlorination determines what products the flour will be suitable for. When chlorine gas is mixed with flour, it reacts with other flour components, such as proteins, fats, and starches. The main effect of chlorinating flour is to increase the ability of the starch to hold water, or liquids. This improves cake quality because it allows bakers to use high ratios of sugar, eggs and milk. The increased amounts of sugar and liquids, together with special emulsifiers, make very light, moist, fine textured cakes with a very soft crumb that also keep well. Chlorinating the flour also weakens, or denatures, the gluten, which helps to produce fine, soft cakes. A third effect is to oxidize or bleach water soluble pigments in the flour, making it whiter. As chlorination increases, the flour produced makes better cakes, but worse biscuits because of the increased water absorption.
Use: high ratio sponge cakes and baked products.

Pre-mixes are made of ingredients which are carefully measured out to a formula and well mixed. The main advantage of using pre-mixes is the savings on time and labour which would be required to otherwise measure out individual ingredients for every batch of a product. Premixes also have advantages in that they produce uniform products, reduce inventory and less space is required for storage of ingredients.

There are a range of pre-mixes available which include:

Pre-mixes for yeast-raised goods. These premixes usually require yeast and water to be added. Although pre-mixes are available with instant dried yeast already included. The yeast is combined with special low moisture flour, which keeps better, and for this reason is often used in pre-mixes.

Scone-type pre-mixes. These premixes have baking powder mixed in, and liquid or melted fat sprayed onto the flour as it enters a blender during manufacture. It is very important not to have any lumps of fat and for the pre-mix to be free running.

Cake pre-mixes. These are the most complex pre-mixes due to the high levels of fat present. They may contain baking powder and fat, egg solids, many flavours, and dried milk solids as well as flour.

Yeast is used for the leavening of bread. Yeast uses the sugars and oxygen in dough to produce more yeast cells and carbon dioxide gas. This is called multiplication. The carbon dioxide makes the dough rise which gives the bread a light and spongy texture. Yeast also works on the gluten network. The by-products of "fermentation", or rising, give bread its characteristic flavour and aroma. The yeast continues to grow and ferment until the dough reaches around 46°C at which temperature yeast dies.

Fermentation

Yeast uses sugars by breaking them down into carbon dioxide and water. The yeast needs lots of oxygen in order to complete this type of fermentation. In a bread dough, oxygen supply is limited and the yeast can only achieve partial fermentation and instead of carbon dioxide and water being given off, carbon dioxide and alcohol are produced. This is called alcoholic fermentation.

Production, Growth and Reproduction

To live and grow, yeast needs moisture, warmth, food and nutrients. Commercial yeast is manufactured on an aerated suspension of molasses. Molasses, a form of sugar, provides the food for the yeast so it can reproduce. The molasses is mixed with water and sterilised to kill off unwanted bacteria, clarified by removal of sludge and then held in vats. Once it has been through this process it is called wort.

Yeast has a phenomenal growth rate and can duplicate itself every 90 minutes by a process called budding. During budding, a mature yeast cell puts out one or more buds, each bud growing bigger and bigger until it finally leaves the mother cell to start a new life on its own as a separate cell.
When conditions are unfavourable for the yeast, for example when no food is or very dry conditions, it doesn't die but goes through a process called sporulation. The yeast spores can then withstand long periods of drought, cold and high temperatures until conditions are right for reproduction and it starts to bud all over again.

Most people should aim for at least six servings of breads & cereals per day, although this is dependent on your personal requirements. It is important to choose wholegrain varieties, such as brown rice and wholegrain (brown) breads. Achieving this is easy, try having a couple of wheat biscuits for breakfast (this is one serve), a wholegrain bread sandwich for lunch (another two serves), some wholegrain crackers topped with tomato for a mid afternoon snack (another serve) and a stir fry with brown rice for dinner (another serve) with a wholemeal pita bread on the side (another serve).

The breads and cereals group provides many important nutrients, including carbohydrates, protein, fibre, B vitamins and vitamin E as well as a range of minerals, including, magnesium, calcium, iron, zinc and selenium.

The primary role of carbohydrates is to supply the body’s cells with glucose, the basic unit of carbohydrates and an important energy source. Nearly all of the energy required by the brain to function each day is supplied by glucose from the diet. Carbohydrates also maintain blood glucose levels and have a role in gastrointestinal health. Many Nutritionists believe that at least half the energy in our diets should come from carbohydrate, mostly as complex carbohydrates. In addition the types of fibre bread and cereal products provide may help lower cholesterol levels and can help to prevent constipation

Protein is required in the body for building and repairing tissue, for making enzymes that assist with many of the chemical reactions in the body, and for the production of haemoglobin which carries oxygen in the blood.

B Vitamins present, such as Vitamin B1 (Thaimin) and Vitamin B3 (Niacin) help the body use energy efficiently, while Vitamin E is an antioxidant which protects the body’s cell against damage. Minerals, such as, Calcium is important for bone structure, muscle and nerve functioning; while Zinc is responsible for growth and tissue repair of the body.