1 .3 WHY IS IT NECESSARY TO PRESERVE FOODS?

 1 .4 WHY ARE ADDITIVES INCLUDED IN

PROCESSED FOOD?

Food Processing

What is food processing?

‘Food processing means using techniques that changes the original form of the food – for example cooking, refining and adding flavours or colours…’ (HEIA 2008)

Why process food?

To extend the life of food Processing can slow down or stop the growth of bacteria,

moulds, yeast and the chemical reactions of enzymes that can cause deterioration.

To make the food safe Foods contain potentially harmful microorganisms, which

can cause food poisoning if left to grow. Processing such as pasteurisation, heat and chilling can

reduce microorganism growth. For example, milk is pasteurised .

To increase the range of food available Allow production of a variety of food For example, grinding peanuts into peanut butter and

canning provides vegetables all year round.

Why process food?

To save time preparing food at home For example, a tomato based sauce saves the time

needed to prepare vegetables and herbs to make the sauce.

To reduce shopping frequency Stored for a longer period of time; thus, reducing

the need to shop weekly.

To reduce the cost of food Occasionally cheaper than fresh food

What is food preservation?

‘Food preservation means preparing food in a way that increases resistance to spoilage from decomposition or fermentation.’ (HEIA 2008)

Food preservation ensures a continuous and plentiful supply of food.

The aim is to: ‘destroy organisms by heat or to maintain conditions

that will render them inactive – cold, dryness or the use of chemicals that are unfavourable to the growth of the organisms.’ (Magee 2010)

‘Prevent any fresh organisms reaching the food by sealing it immediately after treatment.’ (Magee 2010)

Food Preservation Techniques

Removal of MoistureBacteria need water to live and most

enzyme reactions occur in water.Moisture is removed from food by:

Evaporation Dehydration Adding Salt Adding Sugar Freezing (water is trapped within food

cells) Freeze drying (Product is frozen and then

water is removed)

Food Preservation Techniques

Heat TreatmentFood can be preserved by heating to high

temperatures for set times.This kills some or all of the micro-organisms

and deactivates enzymesMethods include:

Boiling (100oC) Canning (121oC) Pasteurising (72oC for 15-20seconds) Ultra High Temperature (132oC for 1-3seconds) Blanching

Heating food with steam or water to inactivate enzymes that may affect colour, flavour, texture or nutritional value.

Food Preservation Techniques

Temperature ReductionFood can be preserved by storing

it below 4oCMethods include:

Chilling involves storing food between 0-4oC which slows down growth of micro-organisms.

If the temperature is allowed to increase above 4oC microorganisms will multiply

Freezing involves storing food below -18oC which stops growth of micro-organisms and extends storage time.

Food Preservation Techniques

Reduced oxygenMany bacteria are oxygen

dependent and so packaging methods that exclude air will extend storage time.

Methods include: Controlled atmosphere packaging

e.g. salad greens MAP (modified atmosphere

packaging) including barrier, vacuum and gas packaging

Antioxidants E.g. additives used to prevent oxidation

Food Preservation Techniques

Acid and alcoholDifferent bacteria prefer different

acidity levels.Altering the environment to make it

more acidic or alkaline will kill most micro-organisms

Methods include: Fermentation e.g. yoghurt Pickling in vinegar e.g. pickled onions Natural fruit juices are more acidic Acidulates can be added

Food Preservation Techniques

Food Irradiation‘During this procedure the food is exposed to doses of

ionising energy, or radiation. At low doses, irradiation extends a product’s shelf life. At higher doses, this process kills insects, moulds, bacteria and other potentially harmful micro-organisms.’ (Betterhealth 2012)

The food does not become radioactive because it does not contact the energy source and the dose is low.

This process delays ripening and kills bacteria, parasites and insects

Any irradiated food must go through a strict safety assessment by FSANZ and must be labelled to show this.

Preservatives

‘Preservatives are natural or man-made chemicals that are added to foods to stop them from spoiling. We actually 'preserve' fresh foods ourselves every day, by storing foods in the fridge or freezer. Natural preservatives that can be added to foods include salt and sugar.’

Food preservatives work by preventing spoilage of foods by moulds, yeast and bacteria. Preservatives have an acidic nature that makes the organisms unable to grow in the food.

Sulfur dioxide (220) in dried apricots and sodium nitrate (250) in salami

Food Additives

‘A food additive is a substance intentionally added to food to achieve one or more technological functions. Colours are added to improve or restore colour. For example, carotene is added to margarine to make it look more like butter.’

Food additives can: Improve flavours Change textures Increase nutritional value Sweeten thicken Increase shelf life Improve appearance of food

Reasons For Using Food AdditivesAdditive Function

Colours Added to improve or restore colour. For example, Carotene.

Artificial Sweetening Substances

Used to replace sugar in ‘diet’ foods increase overall sweetness. For example, Equal.

Food Acids Help maintain a constant acid level in food. For example, citric acid.

Antioxidants Slow down oxidation reactions that cause rancidity, colour changes and spoilage.

Vegetable gums and thickeners

Improve and stabilise texture.

Emulsifiers To prevent fats from clogging together.

Anti-Caking Agents

Prevent products such as salt, icing sugar and milk from sticking together and becoming lumpy.

Mineral Salts Enhance texture in products that may lose fat and fluids during processing.

Flavour Enhancers Bring out the flavour of food. For example, MSG HEIA 2008, P165

Food Additives

FSANZ ensures safe food by developing effective food standards for Australia and New Zealand.

Regulations state ‘all additives used in food must be listed on the ingredients list on the food label. Food additives must be listed under their functional name followed by the additive’s specific name or code number in brackets.’ (HEIA 2008)

Homework – Due Thursday W6

1. Describe the term ‘Additive’.

2. Refer to the following ingredients listed on a packet of savoury source:

i. Identify three food additive groups represented in the ingredients listed above.

ii. For each food additive group identified suggest one reason for its use in the sauce.

Ingredients

Coconut Milk, Lemon Grass, Chilli, Garlic, Red Capsicum, Spices, Herbs, Vinegar, Vegetable Gum (415), Saccharine (954), Vitamin - Ascorbic Acid (300), Flavour Enhancer (621), Water Added.

Homework – Due Thursday W6

3. State why the following two food additive groups are commonly added to some foods. For each group, give one example of the food in which it is used.

i. Antioxidants ii. Emulsifiers

4. State two legal requirements for identifying food additives on food labels.