How Does Freezing Affect Fruit?

03 Mar.,2021

Freezing tends to involve minimal processing, with only brief heat treatment before freezing to stop enzymes breaking down the fruit that would otherwise lead to spoilage and flavour changes.

 

Freezing tends to involve minimal processing, with only brief heat treatment before freezing to stop enzymes breaking down the fruit that would otherwise lead to spoilage and flavour changes.

Freezing generally is a good way to preserve nutrients compared to other methods like canning and refrigeration. This is mainly linked to the relatively short period of heat treatment used to blanch food before freezing compared to longer heat treatments for canning.

Thawing should not lead to significant nutrient loss. However, the effect of ice crystals damaging cells during freezing soft fruit can lead to the fruit turning to a mush and then water soluble vitamins and minerals leaking out.

How does drying affect fruit?

Drying (losing water) concentrates the fruit's sugar dramatically. For example, apricot sugar levels rise from 9.5% when fresh to 54.2% when dried.

This is why some have described dried fruits as like sugar bombs. Although the World Health Organisation does not classify dried fruit as something we should limit in the diet.

Dried fruit, like these dried apricots, contain higher sugar levels than their fresh equivalent. from female activewear.

Dried fruit can also be six times higher in energy than their fresh equivalents, due to a concentration effect through the removal of water. So, if you are trying to watch your weight, it would be sensible to watch your serve sizes of dried fruits.

 

But it's not all bad news for dried fruit. Drying increases levels of some vitamins and minerals, again through the effect of concentrating the nutrients when water is lost. This means a 30g serve of dried apricots can contain over 5% the daily recommended intake of iron; you would need to eat 175g of fresh apricots to get the same amount.

 Freeze Dried Strawberries

How about freeze-drying?

Freeze-drying involves first freezing a fruit and then placing it in a vacuum under very low pressures. Low pressure causes ice crystals to rapidly sublime, turning them straight from solid ice into water vapour. This process removes water much more efficiently than traditional drying.

 

Effectively, the fruit's water content is reduced but the fruit's structure is maintained. This makes this method of preserving food particularly suited to soft fruit, like raspberries and strawberries, which are low in sugar.


Freeze-drying is said to be one of the fastest growing trend in food, with sales of freeze-dried fruit forecast to reach US$66.5 billion by 2021.

While the public perceives freeze-dried fruit as a healthier alternative to candied fruit and possibly dried fruit, freeze-dried fruit has a much higher sugar content than its fresh equivalent.

 

And as freeze-drying is a more efficient way to remove water than traditional drying, it can mean per 100g, freeze dried fruit can contain more sugar than dried fruit.

 

So, fresh strawberries contain 4.9% sugar. But freeze dried strawberries contain 71% sugar, a 14-fold increase. That's a sugar content similar to some lollies.

Like freezing, freeze-drying helps to preserve nutrients. However, we will still see losses in these, especially vitamin C.

But as freeze-dried fruits contain less water than fresh fruits, you could end up eating more pieces of them than fresh, which means more nutrients (but also more energy and sugar).