Food Processing, Production and Technological Developments
Food Processing: From Raw Ingredient to Finished Product
Most food we eat has been processed in some way before it reaches our kitchens. Processing transforms raw ingredients into safe, convenient and long-lasting food products. Understanding the difference between primary and secondary processing — and how each stage affects the nutritional and sensory properties of food — is essential knowledge for this qualification.
Primary Processing
Primary processing is the first stage — converting raw plant or animal material into a basic ingredient. It includes:
- Growing and harvesting: wheat is planted, grows and is harvested by combine harvester. The grain is then cleaned and dried to a safe moisture level.
- Milling of wheat to flour: harvested wheat grains are milled (ground) between rollers to produce flour. Wholemeal flour retains all parts of the grain — bran, germ and endosperm. White flour removes the bran and germ, giving a lighter flour with a longer shelf life but reduced fibre, vitamins and minerals.
- Heat treatment of milk: raw milk from cows undergoes heat treatment to destroy harmful bacteria. Pasteurisation heats milk to 72°C for 15 seconds. UHT (ultra-heat treatment) heats milk to at least 135°C for one to two seconds, giving a shelf life of several months without refrigeration. Sterilised milk is heated to above 100°C in sealed bottles. Micro-filtered milk uses physical filtration rather than heat to remove bacteria.
- Fishing and rearing: catching fish from the sea or harvesting from aquaculture farms; slaughtering and dressing meat to produce cuts ready for secondary processing.
Primary processing converts a raw material into a basic ingredient. Examples: milling wheat into flour; pasteurising raw milk; harvesting fish; cleaning and drying grain after harvest.
Secondary Processing
Secondary processing takes a primary processed ingredient and turns it into a recognisable food product. Examples include:
- Flour into bread and pasta: flour is mixed with water (and yeast for bread) to form a dough. In breadmaking, yeast ferments sugars to produce carbon dioxide, which causes the dough to rise. Baking in the oven then sets the gluten network and browns the crust through dextrinisation. In pasta-making, semolina flour is extruded into shapes and dried.
- Milk into cheese and yoghurt: pasteurised milk is acidified with bacterial cultures. For yoghurt, Lactobacillus bacteria ferment lactose into lactic acid, thickening the milk and giving a tangy flavour. For cheese, rennet is added to coagulate the milk proteins, forming curds which are pressed, salted and matured. Blue cheese involves the growth of specific moulds to produce characteristic flavour and appearance.
- Fruit into jams: fruit is cooked with sugar. High temperatures destroy enzymes and most bacteria, preserving the jam. The pectin naturally present in some fruits gels with sugar to create the characteristic set. Strawberry jam made from British summer strawberries is a classic example of secondary processing transforming a seasonal fruit into a product that lasts all year.
A common exam error is to describe the whole production chain under “primary processing”. Primary processing turns a raw biological material into a basic ingredient: wheat → flour; raw milk → pasteurised milk. Secondary processing takes that ingredient and makes a food product: flour → bread; pasteurised milk → yoghurt. The test: can you eat the primary processed ingredient straight away? Flour and pasteurised milk are usable ingredients but are not finished food products. If the answer is “yes, this is a ready-to-eat or ready-to-cook product”, you are in secondary processing territory.
How Processing Affects Nutritional and Sensory Properties
Processing inevitably changes food. Some changes improve safety; others reduce nutritional value. Loss of vitamins through heating: water-soluble vitamins (B group vitamins and vitamin C) are vulnerable to heat and leach into cooking water. Blanching, pasteurisation and UHT processing all destroy some B vitamins. UHT milk loses more B vitamins and has a slightly cooked flavour compared with pasteurised milk because of the higher processing temperature. Milling white flour removes the bran and germ, stripping much of the thiamin (B1), niacin (B3), iron and fibre from the grain. Drying concentrates flavour and extends shelf life but similarly destroys heat-sensitive vitamins. Dried fruit has more sugar per gram and less vitamin C than fresh.
Water-soluble vitamins — including B group vitamins and vitamin C — are destroyed by heat. UHT milk is heated to a higher temperature than pasteurised milk, so it loses more B vitamins and has a slightly cooked taste. Milling white flour also strips out thiamin, niacin, iron and fibre.
Technological Developments: Fortification
Fortification is a technological response to nutrient loss. In the UK, it is a legal requirement to add thiamin (B1), niacin (B3), calcium and iron back into white flour to replace what is removed during milling. Breakfast cereals are often additionally fortified with folic acid and iron — partly because folic acid is important in reducing the risk of neural tube defects in early pregnancy, and many women consume cereal daily. Margarine and low-fat spreads are usually fortified with vitamins A and D on a voluntary basis, because these fat-soluble vitamins are naturally present in butter but lost when dairy fat is replaced with vegetable oil.
Fortification adds nutrients that were lost in processing or are lacking in the population’s diet — it is essentially restoration or supplementation. Modification (as in modified foods) changes the food’s functional properties or composition to deliver a specific health benefit, often through the addition of bioactive compounds not naturally present in significant amounts. Cholesterol-lowering spreads are modified: plant sterols (phytosterols) or stanols are added at concentrations far higher than naturally occur in food because at those levels they block cholesterol absorption in the gut. In your exam, use the correct term for the correct type of technological development: fortification = adding lost or missing vitamins/minerals; modification = adding bioactive ingredients to change a physiological function.
Technological Developments: Cholesterol-Lowering Spreads and Modified Foods
Cholesterol-lowering spreads are a well-established example of modified foods. They contain plant sterols or stanols, which are structurally similar to cholesterol. When consumed regularly, they compete with dietary cholesterol for absorption in the small intestine, reducing the amount of LDL (“bad”) cholesterol that enters the bloodstream. Clinical evidence supports a reduction of LDL cholesterol by approximately 10–15% when these spreads are consumed daily as directed. However, there are limitations: they are more expensive than standard spreads, the cholesterol-lowering effect requires daily consistent use, and they are not suitable for pregnant women or children without medical guidance.
Other examples of modified foods include probiotic yoghurts (containing live bacterial cultures claimed to support gut health), omega-3 enriched eggs (from hens fed flaxseed or fish oil) and high-fibre breads with added inulin. The positive and negative aspects of food additives — including colourings, emulsifiers, stabilisers, flavourings and preservatives — are also part of this topic. Preservatives such as sulphur dioxide (in dried fruit) and sodium nitrate (in processed meat) extend shelf life significantly but some consumers prefer to avoid them.