Is oxidation bad for fruit and vegetables?
What is oxidation and how does it happen?
Oxidation is the name for the ripening and rotting process in fruit and vegetables. Molecules called enzymes, are found in all fresh fruit and vegetables. These are special proteins trapped within the tissues that help to speed up the ripening of fruit. When fruit is damaged, cut, squashed or sliced; oxygen transmits through the cell walls and membranes causing a natural chemical process within the fruit, this is known as Oxidation.
Phenolase, an enzyme present in the fruit, turns phenols into melanin and consequently the fruit or vegetable turns brown, yes we have hit the rotting part.
Does oxidation effect nutrient content?
Yes, oxidation increases the chance of the produce becoming rancid. Fruit and vegetables lose colour, texture and flavour. It also damages the nutrient content of them as the vitamins oxidise when exposed to air.
The longer fruit and vegetables are exposed to the air, the less vitamins they will have.
Below you can see the effects of oxidation on an apple and a potato which has just been cut, after 1 hour, after 12 hours and finally after 24 hours. You can see how the apple and potato loses its colour, texture and moisture.
Oxidation of a potato
Oxidation of an apple
How can we prevent oxidation?
- To help prevent fruit from turning brown, citric acid can be used. Toss cut fruit in the juice from any citric fruits such as lemons, oranges or grapefruit. As they have high acidity, they will slow the activity of the enzymes.
- Soak chopped fruit and vegetables in plain water. The water acts as a barrier and limits the oxygen on cell surfaces helping to prevent Oxidation.
- When chopping salads or herbs tear them rather than cutting them with a knife as the iron metal can increase the rate of oxidation.
- Another way to stop fruits from browning is to cook them with water and sugar.
- To prevent oxidation in smoothies and to keep the nutrients in them longer use a vacuum blender like the VAC 2 from Froothie. By blending in a Vacuum environment, the nutrients in the ingredients are fully preserved and freshness is retained until you open the lid and the smoothie doesn’t separate either.
How to store fruits and vegetables
- Store fruits and vegetables in a cool place. High temperatures also cause them to lose the nutrients quickly.
- Consume fresh fruit and veg within a few days of purchase to get the most nutritional value, or freeze it for later use.
- It’s better to eat fruit and vegetables immediately after they’re cut and avoid storing them for long periods once cut.
- Making smoothies and juice is a great way to add vitamins and minerals into your diet. It’s also a good way to include vegetables such as kale and spinach which are very high in antioxidants. Use a vacuum blender to keep the nutrients locked in.
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