Science saves it!
1. Learn Science
Before we get our hands dirty, let's learn some science behind the food preservation techniques!
Click on techniques that interest you!
Putting it in an airtight container
Clumpy flour, soggy crackers, rancid food… What happened to them? Air and moisture are essential for certain germs to live and grow. Germs will work together to change the taste, colour, and smell of your food when you leave the package wide open. By preventing excess air and moisture from our food products, airtight containers can help slow down the growth of harmful germs that spoil your food.
Wrapping it with a beeswax wrap
Have you ever seen anyone using cling wrap before? It can keep your food fresh by forming a tight seal. It can prevent foods (e.g., your sandwich) from losing their moisture or absorbing too much moisture.
Beeswax wrap is just like cling wrap but more environmentally friendly. It is made from all organic ingredients and materials. It is 100% compostable and leaves no toxicity in the soil. However, beeswax can easily melt. It is more suitable for cold and room temperature foods (e.g., fruit, cheese).
Refrigeration and freezing are the most popular techniques of food preservation. Refrigeration will slow down the growth of germs that cause food spoilage 😢 Freezing will prevent germs from growing completely and therefore, preserve food longer than refrigeration.
Drying is the OLDEST method of food preservation. It can be traced back to the prehistoric period. Most germs need air and water to grow. Drying will remove most water in our food, which will slow down the growth of germs.
You don’t need a fancy dehydrator. There are various ways you can do it: sun drying, air drying, oven drying and microwave drying. Removing water from food will make food smaller and lighter, but nutrients will be more concentrated.
Do you like pickles in hamburgers? Their texture and flavour are very different from fresh cucumbers.
Pickling is very simple. We just need WATER, SALT, and VINEGAR. Then fruit or veggies are immersed in that liquid mixture. The acid from the vinegar slows down the decaying process by kill off most germs.
Do you like chocolate and yoghurt? Do you know how they are made?
Fermentation happens through the work of MICROBES such as yeasts, bacteria, and moulds. Unlike freezing and pickling where we try to kill off the germs, we grow beneficial bacteria in food and turn the product into something else (e.g., milk becomes yogurt).
Canning was invented by a French guy called Nicolas Francios Appert. Cans were used to supply fresh food to soldiers in wars. But how do cans preserve the food inside?
Raw products are put into cans and SEALED. They are then heated to a temperature that kills off germs so that germs cannot spoil the food inside. No germs can come in as cans are fully sealed. Once you open a can, remember to use other ways to preserve it as the food has been exposed to germs from the outside.
Making it into a jam
What jam goes with your morning toast? Strawberry jam is a favourite amongst Australian kids! All fresh ripened fruit can be made into jams, and jams can be stored for a long time. Why is that?
To make jams, we first need to boil the fruit. The high temperature will kill most germs. The fruit then keeps bubbling. It will reduce the available water in our fruit so that germs cannot grow. It is why jams are so sticky. We also need sugar and lemon juice. They can bind with water to form an environment that germs can hardly survive and move around. The boiling process and sugar-adding process work together to reduce available water to make the environment very unattractive to tiny germs.
Making it into a new food
Spotted squashy bananas can still taste good. Soft carrots do not have to be thrown away! They just need a make-over. Transform them into a new food! Give them a chance to live a new life.
2. Do Science
Now that you have learnt some Preservation Techniques, it’s time to have FUN.
Think about how we can use the techniques above to PRESERVE your chosen food.
Your task is:
Take photos of your attempt to preserve your food.
Write a short description of what you are doing and why this technique can extend the shelf life.