are, unlike most vegetables.
Fruits that tend to discolour can be frozen in the presence of ascorbic acid to prevent the slow
browning that may otherwise occur during freezing.
Fruits, unlike vegetables, are usually eaten raw. However, sometimes they are cooked to soften them
and initiate some desirable taste producing reactions.
Unlike vegetables, which are normally cooked in just water, most fruits are cooked in a syrup (a
mixture of sugar and water). If fruits were to be cooked in pure water, the sugar in the fruits would
move from the fruit into the cooking water by diffusion (since they are in a lower concentration in the
cooking water) and this would cause the fruits to lose their desired sweetness. Furthermore, some
water molecules from the cooking water pass into the fruit cells, which are less dilute, by osmosis. This
further dilutes the taste in the fruit, and additionally the influx of water may cause the fruits to explode.
So fruits are cooked in syrups to help retain their shape and sweet taste.
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The cooking paradox : However, if they are cooked in a syrup that is too concentrated in sugar, water
will actually leave the fruit cells by osmosis to dilute the cooking water and the fruit will shrivel up.
Ideally fruits should be cooked in a sugar solution where the sugar concentration of the syrup is
approximately the same as the sugar concentration in the fruit, so neither water nor sugar will move in
either direction, and the shape and the taste of the fruit can be preserved in the fruit. However, the
heating process will still allow the desired texture changes and flavour producing reactions. To prevent
any undesired shrivelling, when preparing candied chestnuts, the chestnuts are cooked in successive
syrups of increasing sugar concentration, to control the amount of water than leaves the chestnut
while maintaining its uptake of sugar from the syrup.
How to work out the ideal sugar concentration? H. This observed that when the sugar concentration of