Nutrition
TYPES
Wheat is usually ground to flour which is used to produce a wide range of products. The type of flour produced differs according to the rate of extraction. Cous cous is also made from wheat.
Maize may be processed to make many different ingredients and food products. It may be milled in a similar process to wheat. Its germ is rich in oil, which is refined to produce corn oil.
Brown rice has its outer husk removed, and white rice is milled and polished further to remove the bran and germ. There are many different types of rice, categorised by size, shape and the region where they are grown. Rice can be ground to make flour.
Rye contains little gluten, so produces breads with low volume and a dense texture.
CHARACTERISTICS
Protein : The amount of proteins in each cereal differs, and this affects the final product. Bread, with its characteristic open texture and appearance, relies on high protein flour, eg wheat flour. In products such as cakes, biscuits and pastry, low protein cereals are used to produce crumbly and light textures.
Gelatinisation (thickening) : When flour (wheat, corn, rye or rice) is added to a liquid, the starch granules begin to swell on heating. This causes the granules to rupture and starch is released into the liquid. The starch granules absorb liquid, causing the sauce to thicken. Rice flour can be used in acidic sauces as it is resistant to the effects of low pH. Pearl barley may also be used to thicken a soup or casserole. However, small lumps of barley will remain.
Rice : Rice grain is eaten whole and is used less frequently for manufacturing other products than wheat and maize. It is sometimes used to ‘bulk’ a food product, eg vegetarian burger, or used as a side or main dish, eg risotto, pilaf.
Products : Cereals are used in a variety of breakfast cereals; they are processed by different methods to produce a range of products. Some nutrients are lost during this processing but are added at a later stage known as ‘fortification.
STORAGE
Cereals should be kept in a cool dry place. They are prone to infestation by insects if kept for long periods of time.
Fish
Now, countries have jurisdiction over their local waters. The uses of new technologies and improvements in modern trawlers have maintained the supply. Selected fish are also bred on ‘farms’ where large quantities are produced to meet the market demand, eg trout and salmon, shrimps.
COMPOSITION
The structure of muscle in fish is made up from segments of short fibres which give fish its characteristic flaky texture. These segments are separated by sheets of fine connective tissue. This substance is very fragile and is easily converted to gelatine. The combination of short muscle fibres and gelatine gives fish its tenderness, and is the reason why overcooking will result in fish falling apart.
STORAGE
Fresh fish should be cooked, chilled or frozen as soon as possible. Fish Products should be stored as directed on the packaging.
CHARACTERISTICS
- Fat Content : Oily fish have more than 5% fat in their flesh, eg sardine and salmon. White fish have less than 5% fat in their flesh, eg cod and halibut.
- Tenderness : As fish muscle is composed of short segments of fibres, it does not need to be tenderised. The segments are easily broken and care needs to be taken in preparation and cooking.
- Cooking : Fish may be cooked very easily and quickly. Cooking is used to improve colour and flavour and destroy harmful bacteria. Some fish is eaten raw, eg sushi, or immersed in vinegar, which has a similar effect to cooking, eg roll-mops.
- Preservation : Fish start to deteriorate as soon as they are caught. Most fish are put on ice or frozen to halt this process. This increases their shelf-life.
Salting - this is a traditional method of preserving fish, still commonly used today.
Marinading - Adding salt or an acid (vinegar) can help the flavour of the fish and increase its shelf-life.
Drying - sun drying is traditional in many warm areas of the world.
Smoking - this gives a characteristic odour and flavour to the fish, as well as acting as a form of preservation.
Canning - the size and shape of the fish is of particular importance here. It must be gutted, cleaned and trimmed before canning in brine (salty water), tomato sauce or oil.
Freezing - usually demersal fish, eg cod, is gutted, cleaned and filleted.
- Processing : Fish can be reformed into blocks and frozen. These blocks are usually made of fillets. Minced fish comes from trimming of fillets and recovery from the skeleton. The mince can be formed into blocks or used to fill spaces in the fillet blocks.
- Products : Much of the fish that is bought by consumers have been processed, eg frozen fillets, or manufactured into coated fish products, eg fish fingers, where blocks of fish have been cut into shapes and covered with batter or breadcrumbs.
TYPES
Fresh water salmon, trout
Sea water pelagic. These swim near to the surface of the sea, eg herring, mackerel, sprat and sardine.
Demersal these swim close to the sea bed, eg cod, haddock, plaice and sole.
Shellfish molluscs, eg cockles, winkles and mussels. Crustaceans, eg lobster, scampi, prawn and crab.
There is also a growing market for squid and octopus.
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