Food Processing

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

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

The food industry b 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. b But remember  The primary aim of a food company is to make money and stay in business

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

Food processing operations b Ambient temperature processes b Mechanical processes b High temperature processes b Low temperature processes b Fermentation processes b Post processing

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

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

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

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

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

Baking and Roasting b 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. b Surface undergoes chemical changes developing colour and flavour b The heat has nutritional effects  Food easier to eat and digest  loss of vitamins

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

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

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

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

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