Food processing

  • How do we make food last longer?
  • Is it possible to stop food from going off?
  • What can you do to prevent bacteria and germs getting into food?

Introducing this topic

This topic forms part of Food Science which is an exciting branch of Science that incorporates Chemistry, Biology and Physics with real-world applications.

Remind students that this term's work has focused on how food is made through photosynthesis and the important role that plants play in this process. We then moved on to investigate nutrition and the importance of a balanced diet before looking at the diseases and health problems associated with a poor diet. In this chapter we'll look at food processing and how humans have devised ways to keep food healthier for longer.

This is an excellent website for lesson plans and support materials:

Why do we need food processing?

People have been processing food for thousands of years. Before the invention of fridges and freezers, people had to collect food in summer and store it because in winter food is often scarce. They found out that they could preserve food like meat and fish by salting and spicing, and then drying it - this is called curing the meat. In South Africa biltong and bokkoms are examples of cured meat and fish.

Bokkoms (cured fish)
Pieces of meat are hung up to dry and turn into biltong.

Atime-travelling role play

This is a chance for learners to be creative and use their imaginations. Encourage them to do so. If time does not permit, the learners do not have to actually make the objects to take with them. But allow them time to discuss the possible objects they could make in their groups. They can then draw some designs and report back to the class as a group.

Work in groups of 4 - 5

You are time-travellers and you are joining the Thunderbolt Kids for your first jump through the wormhole! You may not take anything non-organic with you so no metal tins or plastic containers, and certainly no computers, cell phones or laptops!

Come on! Follow the Thunderbolt Kids and jump through the wormhole to go back in time!

Imagine being transported 250 years back into history and arriving with only the clothes you are wearing and whatever you have learnt in your head in EXACTLY the same place you are right now. It is late summer and you need to spend a year wherever you are and survive until the wormhole opens again at that exact spot and allows you to return to 'the future'.

Your mission: gather as much information on the local inhabitants and the food they eat, their ways of living and how they survive the elements and natural dangers in their environment. When you return you will need to explain how they preserved and processed different foods to last them through winter and how they packaged and protected this food from scavenging animals and pesky insects.

Brainstorm this problem with your group. List as many different questions or problems that you can think of that will affect you:

  • immediately,
  • in about a month's time,
  • in 6 month's time, and
  • right at the end of your stay - a week or so before you return to the present time.

Think especially of food and shelter, and specifically how you will collect, preserve and process any food that you collect. Remember you are not allowed to take anything that is not organic so no pocket knives, nylon rope or even lighters can go with you!

Design the following items that you can make and use when you land.

  1. Something that you can collect and carry water in, and store it for 'the future'.
  2. Something that you can collect and carry food in, and specifically something that you need to store it in to keep it away from scavenging animals and insects.
  3. Something that you can use to cut with - you will need to make a shelter to sleep in and keep safe from wild animals; and also cut material for your food and water containers.
  4. Something that you can use to hunt animals or catch fish if you are going to eat meat while you are there.
  5. A device that you can use to preserve meat or fish, or perhaps fruit and vegetables for the winter months.

Give each person in your group one of these items to make and bring to class. Make sure you do not use any modern tools or any metal, glass or plastic as it is highly unlikely that you would have any such items to use 250 years ago.


  1. List the possible dangers that you will face in your new 'home'.

  2. Can you predict how the locals will look and how they will treat you?

  3. Describe your first night there.

  4. Explain how you will decide what you can and cannot eat on your first day.

  5. Complete this sentence: If I want to preserve some of the fish I catch, I will...

  6. The local indigenous people use different methods to preserve their fresh fruit and vegetables. Find out about these methods and use one method to preserve some fruit of your own. At the end of this chapter, bring your preserved fruit to show the class. You have two weeks.

Introducing this lesson:

Start this lesson by brainstorming different types of processed foods and facilitating discussion to try and agree on a class definition for 'processed food'. It should be clear after this discussion that:

  • Almost all the food we eat is processed in one way or another.
  • Food and beverage companies change raw animal and plant products into food that we can eat or drink through various processes. This is called food processing.
  • Food processing can include: cooking, baking, roasting, grilling, smoking, drying, spray drying, juice concentrating, freezing, milling (wheat), and sometimes slaughtering animals for their meat is also considered a form of food processing.
  • We process food to make it more edible (preparing / cooking), last longer (preserving) and to increase the nutritional value (fermenting).

Make a class list of possible reasons WHY food is processed and possible examples of people who would benefit from this processing - write this on newsprint or poster paper to refer and add to as you go.

Food Processing - Then and Now

Hundreds of years ago explorers like Columbus, Da Gama and Diaz, had to pack supplies for their crews to last a very long time should they not find food and water on their expeditions. They too had to take as much preserved food and drink as they could.

Many of the foods we eat today cannot be eaten in their raw form - we need to process the food to make it edible.

Sometimes food is also processed to add to its nutritional value, for example when we ferment dairy products to make yogurt, cheese and buttermilk.

There are many reasons to process food. Can you think of any? Write them down below.

When you get home today ask your parents, family members and maybe your friends' parents if they think processed food is good or bad and why they say so. Write the results of what you learnt from this quick survey below.

Benefits of food processing

Food processing adds many benefits to our modern lives:

  • Transportation of fresh food is quite difficult. If producers can process the fresh fruit and vegetables in some way, the food is easier to transport. Delicate products like grapes, strawberries and peaches can be transported much more easily when they are preserved than if they were fresh. The processing also helps the fruit and vegetables to last longer.
This truck collects the pear and apple boxes and transports them.
  • Today people can eat fresh fruit and vegetables all year round and do not depend on seasonal availability because of modern methods to process and transport these products. Therefore, food processing and transportation makes the modern 'balanced' and varied diet possible.
  • Many times food and beverage producers add extra vitamins and nutrients to their food to make it healthier for their clients.
  • Buying and preparing processed food is also more convenient and less time-consuming.
  • Foods are processed to preserve them, for example when fruits are preserved to make jam, or pickled (eg. pickled onions).
This ginger has been preserved so that it lasts longer.
  • Food processing is lastly very important to people with allergies and diabetes because they are able to eat a greater variety of healthy food. An allergy for cow or goat milk is a very common allergy among small children. They are able to drink 'milk' only because modern food processing has found a way to make milk from rice, oats or soya.
Rice or soya milk are processed foods and an alternative to cow's milk for people with allergies.

Describing processed foods


  1. Look at the following photographs of various foods.
  2. Each one has either been processed in some way, or needs to be processed before we can eat it.
  3. Briefly describe why and how each food has or will be processed.


Reason for being processed

Raw meat


Pickled gherkins

Glacé cherries

Fried eggs



Frozen meals

Possible drawbacks of processed food

We have seen that processed foods have many advantages in our modern lives, but processed foods also have drawbacks (disadvantages), especially if they have been over-processed.

Write down some possible reasons why people think processed food is not good for you.

Class discussion


  1. We are going to have a class discussion about some of the possible drawbacks of processed foods and why some people do not like the idea.
  2. This is an opportunity for you to practise taking down notes from what was said in class.
  3. Your teacher will lead the discussion and also write some things on the board.
  4. You must take notes in the space below.

Class discussion: Discuss the results of their homework surveys with the class and make a mindmap on the board showing the possible reasons why people do or don't think processed food is good for you.

The following information must be used to facilitate the class discussion. Make sure to write the main points on the board so that learners can copy the main headings down. Also encourage learners to take down some additional notes. This is an important skill for their school career.

There are different ways to process food, but in almost all of these ways some of the nutrients, vitamins and minerals are destroyed. Any process that uses heat generally also destroys Vitamin C, for example. However, people tend to think that here is very little nutrients left in processed food when this is actually not the case. Research has shown that only between 5)% - 20% of nutrients are lost when food is processed - in a factory or a home. The amount of nutrient loss depends on the method used to process the food.

You might have heard that there are dangerous additives in processed food that make it very bad for you. In the past many food manufacturers have in fact added many extra products to food:

  • Preservatives: preservatives, such as sulfur dioxide, are added to food to make it last longer. These are not always very healthy.
  • Colourings: Many food and beverage manufacturers used to add all sorts of artificial colourings to food to make it look more attractive to their consumers - a bit like adding paint to your food! Nowadays, with many consumers complaining, they no longer do this but only add natural colourants that can be made from berries or plants for example.
  • Artificial sweeteners, salt and flavourings: Manufacturers also used to add artificial sweeteners and flavourings, such as MSG (monosodium glutamate), that are cheaper and allow them to make a larger profit. Artificial flavourings are not very healthy and can cause organ and brain damage. Many people are also allergic to these products. Therefore, many companies have stopped adding artificial sweeteners, salt and flavourings and have instead chosen to add natural products instead.
  • Governments around the world have drawn up very strict laws that control the additives that get added to food and beverages, and food manufacturers have to be incredibly careful what they add nowadays. Only additives that have been proven to be safe for humans to eat or drink may be added to food.

How are foods processed?

Introducing this topic:

The CAPS require that learners research different ways of processing food (raw material) and then choose one way and process food (raw material) using this method. We have set this out as a project that teachers can use to assess. The unit briefly introduces some of the ways of processing food and very briefly touches on each of these. Learners are then required to research their preferred method and present their research using various methods, like posters / slideshows in PowerPoint / etc - about this method of food processing. They also need to process food (raw material) using this method and demonstrate the steps they followed to their class.

There are different levels of food processing. The key question is to ask: has any process occurred from when this plant or animal was in its natural habitat to where it is now? If you can say yes then you know that it has been processed in some way or another.

Levels of food processing

Minimally processed foods:

  • Fruit and vegetables, nuts, meat and milk undergo very little processing from when the plant or animal product was in its natural habitat to the point where it lands on your table.
  • They need to be harvested, washed and sometimes peeled, chopped, juiced or cut to remove inedible parts, before they are sold. These have a very short shelf-life.
Milk and juice are minimally processed.
Vegetables are washed, cut and cooked. This is minimal processing.

Processed food ingredients:

  • Products with a longer shelf-life, like flours, oils, fats, sugars, syrups margarine, sweeteners and starches, fall into this category.
  • The original product has been changed and the ingredient does not look like the original kernel or grain, or oil seed or beans.
  • These processing techniques often break down any nutrient values and the manufacturers often add in extra nutrients, vitamins and minerals to their foods.

Highly processed foods:

  • Highly processed foods include snack foods and desserts, biscuits, cereal bars, chips, cakes and pastries as well as soft drinks and breads, pastas, breakfast cereals and infant formula.
  • Animal products that are highly processed include processed meats (smoked, canned, salted or cured, nuggets, fish fingers, viennas, many sausages and boerewors, and burgers).
Polony is a highly processed food.

The table below shows how a raw product is processed to make a raw ingredient which looks very different to the original raw product. Then the processed raw ingredients are used to make highly processed foods, such as bread.

The raw product: Wheat

The processed ingredient: Flour

The highly processed food: Bread

Learning how to summarise

Sometimes we are presented with a lot of information and we need to condense it to make it easier to remember. This is called summarising and it is a very useful skill.


  1. Use the space below to draw a table to summarise the information above about the levels of food processing.
  2. Include a short description of the level of food processing and examples.
  3. Think about how many columns and rows you will need.
  4. Give your table a heading.

This question is aimed to help learners to summarise information into a table format. If they are finding this difficult, start them off with drawing the outline of the table on the board and filling in some of the information. One possible solution for a table is given below.


Minimally processed foods

Processed food ingredients

Highly processed foods


Products that undergo very little processing

Products that have been drastically changed and the ingredient does not look like the original

Products consisting of a combination of processed ingredients.


Fruit and vegetables, milk, nuts, meat

Flour, sugar, oil, syrup.

Snacks, biscuits, desserts, meat products such as fish fingers, boerewors, etc.

Food processing methods

As you could see in the above breakdown, the degree in which food is processed determines many of the food preserving processes involved.

Food processing methods have changed in many ways, but the basic principles are still applied. Food is still dried or heated to preserve it, just like people did 300 years ago, but there are many modern methods that are also used today.

  • sun drying
  • fermenting dairy into cheese, buttermilk (Amasi) or yogurt, or barley or grapes
  • pickling vegetables (onions or gherkins, for example)
  • salting and spicing meat to preserve it (then drying it)
  • adding sugar to berries and/or fruit to make preserves
  • pasteurisation: using just the right amount of heat to warm up milk or juice for example, to extend the shelf life
  • cooking: roasting, smoking, baking, frying
  • toasting
  • freezing or refrigerating
  • freeze drying
  • spray drying
  • making juice concentrates

When you go home from school today, make a list of the food products that you have at your house (whether they are in the cupboard, the fridge or the freezer). Next to each item, write down the type of processing it might have gone through, using the list above as a guideline.

No matter what food processing method is used, there are 5 extremely important performance parameters that all food processing must adhere to:

  1. hygiene
  2. energy efficient
  3. minimal wastage
  4. labour efficient
  5. minimal factory shutdowns

Discuss why you think each of these 5 points are important in food processing. You might need to do some extra reading and have a class discussion.

Below are guidelines to facilitate the discussion and answers.

  1. Hygiene - it is very easy for germs and bacteria to start growing in food. Therefore, manufacturers have to take every possible precaution to ensure that every utensil, mixer, piece of equipment and specifically the workers' hands and clothing is sterile and remains that way.
  2. Energy efficient - the extremely high cost of energy sources such as electricity, oil or diesel, makes it vital that food production uses the smallest amount of energy to 'get the job done safely'. The more money that needs to be spent on energy the smaller the profit for the company will be.
  3. minimal wastage - manufacturers make every effort to cut down as much as possible on any and all waste. The more waste there is the less profit they make and the more they have to spend on removing and 'getting rid' of the waste.
  4. Labour (measured as the number of working hours per ton of finished product) - manufacturers try to cut down on the amount of people that handle any given food product because that increases the cost to the company. Labour in certain countries costs more than in others which also pushes up the price of the goods.
  5. Minimal factory shutdowns - each time the factory or operation gets shut down to clean it the factory is not making money. Manufacturers therefore try to keep every small part of their production line as clean and 'maintenance' free as possible. They even try to invent machines that are self-cleaning!

Comparing traditional and commercial food processing methods

We have learnt a lot about food processing methods in our modern lives. However, the indigenous people of southern Africa have been preserving and processing food for many generations, and still use some of their traditional methods today.


  1. Read the following description of how beer is made in the Zulu culture.
  2. Then answer the questions that follow.

Zulu beer making

Beer (utshwala) forms an integral part in the Zulu culture, especially at social gatherings and traditional ceremonies. Zulu beer is traditionally made by the women. To brew the beer, the women soak coarse sorghum and maize in water for one day, typically in a big drum-like imbiza pot. The following day, the broth is boiled over a fire and more dry sorghum is added to the mixture. After this, the mixture is mashed together and then allowed to cool for the rest of the day. The next day (day 3 of the brewing process), the mixture is filtered through a sieve to remove the big fibres. The sieve is made from palm fronds and the brew is poured from the big imbiza vessel into the serving vessel, iphangela, made from clay. The beer is now ready to be served. The iphangela is carried from brewery in the kraal (a semi-thatched hut which allows the smoke from the fire to escape and ensures a good supply of oxygen to ferment the mixture) to the drinking assembly. A woman scoops the beer into a drinking vessel, ukhamba (a small, round clay pot decorated with traditional patterns) using a dried gourd and presents it on her knees to the men. She will first taste the beer to show the head of the household that she has brewed the beer properly, and then hand him the ukhamba, before passing it around to the rest. The beer contains 3% alcohol and it is nutritious as it is made from plant products without modern additives or colourants.

This watertight, hand woven basket, called Ukhamba, is used to store any leftover beer.


  1. What are the ingredients used to make utshwala?

    Sorghum, dried sorghum, maize and water

  2. What are the Zulu names for the three different clay pots (vessels) used in the beer making process?

    Imbiza (brewing vessel), iphangela (serving vessel), ukhamba (drinking vessel)

  3. What are these vessels made from?


  4. Why does the brewery hut only have a semi-thatched roof and not a fully, enclosed roof?

    This is because the women have to make a fire inside to boil the mixture. So they need an opening to allow the smoke to escape, and they need a supply of oxygen for the fire to burn and the fermentation process.

  5. Use the space below to draw a flow diagram to illustrate the Zulu beer-making process. Remember to include arrows to show the direction.

  6. For the following task, you need to do some research outside of class, using books and the internet. Find out how beer is made in a modern brewery, such as the South African Brewery in Newlands, Cape Town. In the space below, write a paragraph where you compare this modern beer-making process to the indigenous method of the Zulu people.

Food Processing Project

Now that you have a better idea of the different ways that raw food can be processed, choose one particular method that you found really interesting to further research and then process the food at the end.

After researching the method, learners are encouraged to actually carry out the food processing, either at home or in class. On a specified day when learners present their projects, they can bring the actual food product to class for others to taste.


  1. You need to read as much as possible about your chosen method of food processing.
  2. You will need to interview at least one person who uses this method of food processing. Before your interview you will need write down at least 10 different questions to ask this person during the interview. You need to include these questions and the person's answers in your project's presentation.
  3. After your research and interview you need to include a few paragraphs headed: "What I learnt about food processing ... " This must be a summary of the information you learnt.
  4. Present your findings in a visible form that you like - perhaps a poster, PowerPoint slide show or in a flip-file as a brochure. Be creative and present your information in a lively and interesting way!
  5. Use the knowledge and understanding that you gained and process the food using this method.
  6. You will need to make your presentation to the class. You must include all the steps you followed to process your chosen food. Bring some of your processed food to class so that you can all enjoy what everyone has made.
  7. When you choose a processing method make sure you have food that you will be able to process using this method! If you cannot find fresh (raw) peaches to poach because it is winter then consider choosing another processing method!

Teacher note: Below is a guideline rubric to assess each learner's project.






Research skills

Rigorous pursuit of knowledge and understanding; information paraphrased very clearly.

Good coverage of information and new knowledge / understanding; some evidence of paraphrasing

Adequate and fairly precise knowledge gathered. Mostly copied information.

Information gathered by copying and pasting information in random without much planning.

Not much information gathered. Some information is space-filling and serves little purpose.

Interview skills

Questions and answers displays very clear understanding of processes involved and information needed.

Questions are clear and to the point though not always focused. Some answers are well structured.

At least 1/2 of questions are well structured / formulated but not always relevant and focused.

Some questions were formulated well but these are not in any particular order and do not flow one from the other.

Questions don't always pertain to the topic. Some questions are difficult to understand. Did not formulate 10 questions.

Ability to synthesise information in a summary

Summary creates a very good overview of main ideas. Clear and precise synthesis of information from research and interview.

Summary is fairly concise and contains many main ideas but often supporting ideas have been included as well making it too long.

Summary is in places a copy of the previous texts. Some main and many supportive ideas included. Incomplete.

Summary is very short and contains only a few strands of information. Imprecise and lacking.

If summary is included it is no more than one or at the most two short sentences. Incomplete and containing many misunderstandings

Referencing and bibliography

All references are noted and bibliography is complete and well presented.

Some sources acknowledged and referenced. Fairly good bibliography.

One or two sources acknowledged. Bibliography contains titles yet incomplete.

No sources referenced in text, but one or two sources were included in bibliography.

No bibliography or referencing of sources.

General impression of presentation

Well presented, neat and creative presentation. Good use of language and resources. Interactive and lively.

Fairly well presented but could be neater. Presentation was good. Fair amount of effort applied.

Some effort applied but presentation could be far more creative and interesting. Could have used resources more effectively

Presentation was generally simplistic with little use of colour, layout or creativity. At times the reader feels confused and cannot follow.

Presentation was untidy and sloppy. Information was inaccurate. Poor use of language. Very little evidence of effort applied.

Effective use of information to process food

Used knowledge and understanding gained in research and interview very effectively to plan food processing.

Fairly good understanding of food processing procedure and application in own process.

Good correlation between some aspects learnt and practical application, though not all.

Applied at least 3 theoretical concepts learnt but could not sustain this without support.

Could not correlate knowledge from research with practical application.

Appropriate choice of food to process

Excellent choice guided by research, interview and food availability.

Considered majority of constraints and made a good choice.

Choice was made difficult as did not consider all constraints.

Chose a random food that posed tremendous problems as did not consider all constraints.

Did not prepare beforehand. Chose inappropriate food.

Outcome of the food processing

Food was very well processed and looked and tasted delicious.

Some items were processed correctly and looked and tasted fine.

One or two items were successfully processed. Others 'didn't work'

Although the idea was correct the result did not work and tasted / looked unappetising.

Lack of preparation thus food processing was unsuccessful.

Demonstration of food processing

Demonstration was lively and entertaining. Audience enjoyed it very much!

Demonstration was fairly well presented yet with a few hiccups.

Very nervous presenting yet tried hard. Audience was lost in places.

Demonstration was short / incomplete. Battled to explain the process.

Tried to present / demonstrate but lacked confidence or understanding of process.

Breakdown of steps to process food

Very precise and clear breakdown of steps.

Fairly precise yet not always clearly communicated breakdown of steps.

Steps were not well ordered but could break down process in main phases.

Could only identify some of the main phases but not in logical order.

Needed much prompting to identify one or two of the main phases in the process..



  • Food is processed to make it edible, by cooking or preparing it for example.
  • Food is processed to make it last longer - we say to preserve it.
  • Food is processed to improve its nutritional value by fermenting it for example.
  • During processing many foods may lose some of their nutrients.
  • Various methods are used to process food.

Write a definition for 'food processing' that will explain what it means.

Changing raw animal or plant material into products and food that we can eat and use.

There are three main reasons why we process food. Explain what is meant by the following words in relation to food processing.

  1. preserving

  2. cooking / frying

  3. fermenting

  1. making food last longer
  2. making food edible
  3. increasing the nutritional value of food

Many people believe that processing food is not good for their health. List three possible drawbacks of food processing.

  1. There are many additives added to food - preservatives, colourings, artificial sweeteners and salt, etc.
  2. Nutrients may be lost in the process.
  3. There is a risk of contamination from various sources.

Describe how you would preserve extra fish that you had caught while on an overnight camping trip.

clean and gut the fish; wash it in salt water and fillet the fish; sprinkle course salt and spices over it; hang it to air-dry in a well-ventilated space, away from scavengers and pesky insects.

A farmer wants to export table grapes to Australia from his farm near Worcester in the Western Cape. Suggest the best form of transport that you know of that he should use and explain why you gave him this advice.

He should pack these grapes in special boxes that will protect them and place these directly into cold rooms. A special cooling truck should fetch these boxes and take them to the airport from where they can fly to Australia in the freight planes.

Below is a table. Next to each item in column A write the degree to which the raw materials were processed.


Degree of processing

mealie bread

fresh mealie washed and half-way peeled packaged in a styrofoam container

sunflower oil

Explain why many people believe that highly processed food is bad for your health.

The food processes involved in making highly processed foods destroy many nutrients. Some methods of processing add a lot of extra sugar, fats or oils.

Compare the methods of any two food processing techniques.

Here the idea is that learners use their project's information to support their explanation of the food processing methods.

Write a short paragraph summarising what you have learnt about food processing and why you think it is important in your daily life.

Learner directed answer.