Food Processing

1. Food Processing

2. The Food Industry • Three Main Sectors • Primary producers • Food Processing • Food Retailing • The food production complex is called the food chain.

3. Crops Land Material & Energy inputs Food processing and distribution Consumer System Food Animals Cash Cash Flow Cash Materials & Equipment Cash Cash Cash Ancillary Industries Banking System Cash The food chain

4. The food industry • Purpose of food processing is to produce foods that • Between them provide constituents of a balanced diet • Are free from contamination • Are appealing in colour, taste and texture. • But remember • The primary aim of a food company is to make money and stay in business

5. Food processing • Why process foods? • Safety • Nutritional reasons • Improve storage (shelf) life • Improve flavours, colour, texture etc.

6. Food processing operations • Ambient temperature processes • Mechanical processes • High temperature processes • Low temperature processes • Fermentation processes • Post processing

7. Ambient temperature processes • Include • Cleaning and sorting • Peeling, shredding, chopping and milling • Mixing, blending and forming • Are often preparation processes for subsequent operations.

8. Physical Separations • Include • Filtration, centrifuging, • Expression and extraction • Membrane separations • These often involve recovering a particular component from a raw material.

9. High temperature processes • Two major purposes • Safety; pasteurisation and sterilisation • Cooking; modifies flavour, texture, nutritional qualities. • A single process may serve both functions simultaneously.

10. High temperature processes include • Sterilisation and pasteurisation • Blanching • Baking & Roasting • Frying • Microwave and infra red heating

11. Blanching • Purpose: As a pre-treatment, esp. for • Dehydration • Sterilisation • Freezing • Heat is sufficient to inactivate enzymes but not to cook but • Under processing is as bad as over processing

12. Baking and Roasting • These are essentially the same process involving dry heating in hot air. • Baking usually refers to dough products • Roasting usually refers to meat, nuts & vegetables. • Surface undergoes chemical changes developing colour and flavour • The heat has nutritional effects • Food easier to eat and digest • loss of vitamins

13. Frying • Frying is cooking in hot oil • Its purpose is to improve eating quality of the food (flavour, texture) • Effects of frying are similar to those of baking • Because of direct contact between hot oil and food, frying is generally quicker than roasting or baking

14. Microwave and infra red heating • Microwave and infra red heating use electromagnetic radiation for heating. • Microwave heating involves short wavelength radiation. The frequency of the waves coincides with the natural vibration frequency of water molecules. • Infra red is radiation just beyond the visible light region of the spectrum • The energy is dependant on • Temperature • surface properties • shape of the bodies

15. Processing at low temperatures • Low temperature slows the rate of microbial growth, but does not kill microbes • Up to a point, the lower the temperature, the longer the shelf life • Below -10 oC, all microbial growth stops, but some residual enzyme activity may remain • The main function of chilling and freezing, therefore, is for storage and prolonged shelf life.

16. Fermentation • Fermented foods have been around for a long time • Fermentation serves a number of purposes, including; • Preservation • Improve nutritional quality • Improve digestibility • Health Benefits • Increase variety • There is a wide variety of fermented foods including • Dairy products • Fermented Meat and vegetables • Beverages • Bread, etc.

17. Post processing operations • These include packaging and storage. • Purposes include • Protection • Display • Increase storage life. • Increasingly modified atmospheres are being used to increase shelf life, often by reducing oxygen and increasing nitrogen content.