Lesson 4: Chapter 5: Make the most of food
Chefs have a wide array of skills to apply to make the most of food.
There are many ways to prolong shelf life and enjoy foods outside
of the season including:
• Preserving
• Canning
• Drying
• Fermenting
• Freezing
Preparation and cooking
With a bit of creativity, there are always opportunities to utilise food in new ways. Consider the potential uses for commonly discarded trimmings such as vegetable peelings and onion skins.
Make the most of local and seasonal foods by preserving!
Preservation of food has been taking place since ancient times when, in order to survive,
humans needed to harness what nature gave them. Preserving food is an art in itself and as with many other food waste related issues, it takes a bit of work and effort to keep on top of it.
The process of preserving food either kills or slows down the activity of micro-organisms which cause food spoilage. Preserving methods such as curing, canning and freezing inhibits this growth. Preserving food is environmentally friendly – by using seasonally grown and locally sourced fresh produce, food miles are reduced, plus re-use of preserving jars also reduces food packaging.
Facts about fermentation
- Many everyday foods and drinks are fermented, including chocolate, coffee, cheeses, breads, cured meats, soy sauce, and vinegars.
- Fermentation is a bio-chemical process where foods are exposed to bacteria and
yeasts. These cause chemical changes in the food, giving it a different taste and a
longer shelf-life. Luckily, you don’t need to understand the science in order to make it work. - Historically, fermentation was fundamental to extend the life of perishable foods,
before refrigeration became available. Fermentation is a great way to preserve foods when we encounter gluts in the garden, or when your favourite vegetable is in season and the shops are full of it.
What’s happening when food goes off?
See more: Natural decay
Chemical changes
e.g. meat changing from red to brown & potatoes going green
Moisture loss
e.g. wilting leaves and bendy carrots
Enzymes
e.g. peeled fruit browning when exposed to air
See more: Micro-organism growth
Yeasts
Yeasts grow in sugary foods and cause fermentation e.g.
lid popping when orange juice is opened.
Moulds (Fungi)
e.g. mould on bread
Bacteria
e.g. this affects lots of foods including cooked rice, coleslaw, dairy
See more: The Food Storage Factors
There are a few main factors which contribute to natural decay and micro-organism growth in food. Keep these in mind when deciding how best to store your stock/ingredients.
Moisture
Many foods, especially vegetables first spoil due to moisture loss. Lettuce and other greens wilt as water leaves their cells. To keep these foods fresh, prevent them from drying out. For example, storing lettuce heads, spring onions or celery with the bottoms (the stems/roots) in a little bit of water does the trick. If your vegetables have already wilted or gone a bit soft, putting them in ice-cold water for 10-20 minutes can reintroduce moisture and freshen them up.
Air
Exposure to the oxygen in air causes a chemical reaction (oxidisation) in many types of food. Limiting exposure to air, can slow this down. Air also contains moisture. When exposed to air, some dry foods can absorb water (e.g. biscuits going soft), while other foods can become dried out (e.g. bread going stale). Many packaged foods are sealed in modified atmosphere packaging. This keeps oxygen out which helps them last longer e.g. packets of crisps and crackers. Keeping these foods well sealed once opened will help them last longer.
Temperature
The temperature that foods are stored at has a big effect on how quickly they will spoil, particularly in terms of micro-organisms. Most micro-organisms responsible for food spoilage like to be warm and cosy at 37ºC, or body temperature to be exact. Keeping foods cold slows down their growth. That’s why storing food in the fridge at 1-4ºC makes such a difference to the shelf life of foods.
Putting foods in the freezer at -18ºC stops micro-organisms from growing all together. It’s important to remember that freezing acts as a pause, not a reset. Once food is defrosted, it will not have any extra shelf-life than it did before it was frozen. This is one of the reasons labelling food for the freezer is such a good idea.
Micro-organisms
While the micro-organisms that cause food spoilage are all around us, keeping fridges and presses clean can prevent their growth. In addition, storing foods in sealed containers can prevent these micro-organisms from finding your food so easily.
For more information on food safety, visit
safefood.net.
Light
Some vegetables, e.g. potatoes and onions, can continue to grow post-harvest. Keeping these vegetables out of the light will prevent chemical changes from occurring as they try to sprout.
Best before and Use By…
There are only two types of date you need to know about when it comes to food storage.
Use by and Best before.
Best before is a guideline and refers to food quality…
“Food might not be the same quality after this date but is still edible”
Use by is a deadline and refers to food safety…
“Food is not safe to eat after this date”
Think about what actions you can take personally and professionally to prevent and reduce food waste from now on. Watch the video below to prompt some ideas.