4. Food Process Engineering

4.1 Food processing methods

Nature of food science and technology:

Food processing is the transformation of raw ingredients, by physical or chemical means into food, or of food into other forms. Food processing can be primary or secondary to extend the shelf life and/or add value to a product. (1.10, 1.12, 2.2)

Understandings:

Application and guidance:

Primary, secondary and tertiary processing e.g. cleaning and grading of the wheat, wheat milled into flour, flour made into bread.
Physical processing methods e.g. milling.
Chemical processing methods e.g. nitrates and nitrites in food preservation.
The use of salt, sugar, vinegar and smoking in the preservation of foods.
The positive and negative effects of micro-organisms and enzymes in the production of alcohol, cheeses, yoghurts, bread making and mycoproteins.
How food processing enhances the value of food commodities.
How foods are processed ethically e.g. fair-trade, organic and free range.
Sustainability and food security.

Nature of food science and technology:

The deterioration of food products can be slowed by processing foods at different temperatures to reduce the rate of microbial growth, thereby extending shelf life. (1.1, 1.9)

Understandings:

Application and guidance:

Methods of heat processing: pasteurisation, sterilization, canning and aseptic canning.
Methods of chilling and freezing (horizontal plate freezing, blast freezing, fluidised bed freezing. Cryogenic freezing).
The advantages and disadvantages to the manufacturer and consumer of different heat and cold processing methods.
How organoleptic properties are changed during heat and cold processing.

Nature of food science and technology:

The deterioration of food products can be slowed by processing foods by the removal or reduction in the water content and through irradiation to change the chemical structure, thereby extending shelf life. (1.1, 1.9)

Understandings:

Application and guidance:

How water activity impacts on dehydration of different foods.
Methods of dehydration (tunnel drying, roller drying, sun drying, warm air drying, spray drying, freeze drying).
The process of food irradiation, as an application of ionizing radiation to food.
The use of irradiated foods to reduce microbial spoilage, insect damage and inhibition of sprouting and ripening of fruits and vegetables.
Consumer reaction to the wholesomeness of irradiated foods.
How organoleptic properties are changed through dehydration and irradiation processing.

Nature of food science and technology:

When food is processed manufacturers may attempt: to minimise colour damage, restore colour or introduce new colour. This involves an understanding of both synthetic dyes and naturally occurring colours pigments (1.13, 2.1)

Understandings:

Application and guidance:

How naturally occurring pigments give colour to food e.g. anthocyanins, carotenoids and chlorophyll.
How synthetic food dyes give colour to food e.g. tartrazine, quinoline and erythrosine.
Reasons for the use of natural food colours and synthetic food dyes to restore or introduce new colour to food products.
The effect of heat, acids, alkalis and other preservation techniques on anthocyanins, carotenoids, chlorophyll.
Consumer attitudes to the use of natural and synthetic food colours.
Why many countries have strict legislation to control the use of colours in food.

Nature of food science and technology:

Food processing can impact on flavour. An understanding of natural, nature identical and synthetic flavours is needed to maintain flavour uniformity and restore flavour lost through processing. (1.5, 2.1)

Understandings:

Application and guidance:

The five main tastes: umami, salt, sweet, sour and bitter; other flavours are odours.
The sources and use of natural flavours e.g. spices, herbs, essential oils.
The sources and use of nature identical e.g. nature identical vanillin.
The sources and use of synthetic flavours e.g. strawberry flavour may contain 10 to 12 synthetic organic chemicals.
How preservation techniques impact on flavour.
The advantages and disadvantages of natural, nature identical and synthetic flavours.
The use of flavour enhancers such as MSG and ribonucleotides.
How the use of gas chromatography and spectrometry has contributed to the study of flavour and aroma.

Nature of food science and technology:

During food processing texture can be modified by the use of thickeners, stabilisers and emulsifiers, and also by mechanical action and heating. (2.3, 2.5)

Understandings:

Application and guidance:

Colloidal systems in food and how to distinguish between suspensions, emulsions and foams.
The use of maize and wheat as a traditional thickener, and pectin as a gelling agent in jam.
The types of starch modification (e.g. cross linking, acid modified, stabilisation, pre-gelatinised) and their impact on food processing.
The reasons for modifying starch, including thickening, stabilising, and improving mouthfeel.
The reasons for using gums include thickening and stabilising. Types of gums (e.g. Xanthan gum, alginates) and their impact on food processing.
The role of emulsifiers to form stable emulsions including lecithin and glyceryl monostearate (GMS); the role stabilisers absorbing large amounts of water.
How traditional preservation techniques have an impact on the texture of food.
How mechanical action is used to create foams and heat is used to create solid foams.

Last updated 2 years ago