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Food Processing

A.6.1 Define aeration, coagulation of protein and gelatinizing (gelling).

The incorporation of gas into a food product. It may be air, which is often beaten in, or carbon dioxide, which can be introduced under pressure (for example, to aerated water) or by the action of yeast (for example, in bread).
Coagulation of protein
The exposure of a protein to heat or acid, which results in irreversible changes that reduce solubility and change optical characteristics.
Gelatinizing (gelling)
The formation of a gel by using gelatin or by the heat-treatment of starch and water to break open the starch granules, for example, custard.

A.6.2 Explain how the processes of aeration, protein coagulation and gelatinization have been used to affect the physical and/or chemical properties of bread.

Bread is a staple food in many cultures and is a good example in which to consider aeration, protein coagulation and gelatinization. Flour is mixed with water, causing the formation of an extended gluten network, which contributes to the elastic nature of a bread dough. Yeast produces carbon dioxide, which aerates the dough and alters the density of the bread dough and the final bread. The final stable structure of the dough is achieved by baking the bread, which coagulates the protein and gelatinizes the starch.
  • Bread science with some pics

A.6.3 Explain the control systems used in the manufacturing process of bread.

Large-scale food processing requires a consistent final product that meets the product design specification. Production processes can be classified into three stages: input, process and output.

  • Input: the entry of raw materials for processing. Monitoring the quality of raw materials ensures a consistent starting point for food processing.
  • Process: the procedures that convert the raw materials to the final product, for example, kneading, mixing, cutting.
  • Output: the final product. The quality of the final product is determined by all stages of processing and each stage needs careful quality control.

A.6.4 Outline the influence of scale of production on the organoleptic properties of bread.

Craft-produced breads are generally more expensive because they are labour-intensive. These are made from raw materials (flour, water, yeast, salt) rather than from bread mixes. They are mixed by hand or with minimal use of machines and tend not to contain additives. The crust is usually chewier and the texture less uniform than for mass-produced breads. Designer breads may incorporate other ingredients, for example, bananas, olives, sun-dried tomatoes, walnuts.

A.6.5 Explain how food processing enhances the value of food commodities.

The value of farm products is increased by cleaning and cooling, processing, packaging and distribution. Compare the cost of potatoes per kilogram with potato crisps. A farmer sells potatoes to a food manufacturer and the food manufacturer makes the profit. Most of the “food dollar” comes from secondary processing of food products.

A.6.6 Explain how on-farm processing can enhance farm sustainability.

Processing raw products on the farm results in the production of higher-value consumer-ready products and gives farmers the opportunity to retain income and enhance the sustainability of the rural economy. Farmers can then capture a larger share of the “food dollar”. Small-scale food processing is more appropriate: it tends to be embedded in the local community, creates local jobs, distributes products locally and recirculates income in the local economy. However, technology transfer issues and other start-up costs cannot be ignored.


Bulleted list and italicised paragraphs are excerpted from Design Technology: guide. Cardiff Wales, UK: International Baccalaureate Organization, 2007.

Images are clickable links to its location.

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Page last modified on April 18, 2011, at 01:15 AM