“Eat more fruit and vegetables” is one of the most common recommendations we hear when we’re encouraged to eat healthily. Fruits and vegetables come in many different forms these days however, from fresh, frozen, dried and even freeze dried. So when trying to eat healthier, which type is best?
The idea that fruit is good for you is largely based on the fact that many fruits have a low energy (calorie) content and are packed with nutrients. Nutrients include vitamins, minerals, fibre and bioactive nutrients (often pigment compounds known as polyphenols and carotenoids). So how do different processes change the composition?
Effects of freezing fruit
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.
Effects of drying on fruit
Drying (losing water) concentrates the fruit’s sugar dramatically. For example, apricot sugar levels rise from 9.5 per cent when fresh to 54.2 per cent 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 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 30 g serve of dried apricots can contain over 5 per cent the daily recommended intake of iron; you would need to eat 175 g of fresh apricots to get the same amount.
Effects of freeze drying on fruit
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.
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 100 g, freeze-dried fruit can contain more sugar than dried fruit.
So, fresh strawberries contain 4.9 per cent sugar. But freeze-dried strawberries contain 71 per cent sugar, a 14-fold increase. That’s a sugar content similar to some lollies.
The verdict
The bottom line is to try and eat more fruit, in the least processed form possible, ideally fresh. If you choose dried or freeze-dried fruit for convenience, these contain more concentrated sugar than the original fresh product.
Source: sbs.com.au
