Even though all fruit can be frozen, upon thawing many fruits lose their flavor and their texture and become very mushy. Raspberries are a possible exception—they can often be found frozen in the grocery store. Normally, to freeze fruit, the fruit is first cut into small pieces and when thawed, these pieces can be used to make purees or smoothies.
The good news is that freezing tends to retain the nutritional value of the fruit. Several fruits, such as bananas, can be damaged by chilling and this limits this approach [ 2 ]. That is why we do not put bananas in the fridge! Another way to slow down ripening is by controlling the atmosphere around the fruit, primarily by increasing carbon dioxide levels and reducing oxygen levels.
Fruit need oxygen to ripen, so if there is less oxygen in the atmosphere, the fruit will ripen more slowly. One final way to slow down ripening is to block the action of ethylene. Ethylene is a hormone required to trigger fruit ripening, and it can be blocked by using synthetic compounds, such as 1-methyl-cyclo-propene 1-MCP.
However, in some fruits, ethylene levels shoot up when the fruit starts ripening. Based on their response to ethylene during maturation, fruits can be classified into two major groups. The first group is called the climacteric fruits, in which ripening are accompanied by a burst of ethylene. These fruits can also respond to external ethylene by increasing their ripening rate. These include fleshy fruits, such as tomato, avocado, apple, melon peach, kiwi, and banana.
The second group is called the non-climacteric fruits, in which ethylene production does not increase during ripening. However, these fruits can still ripen if they are exposed to an external ethylene source, such as a ripening climacteric fruit.
These include strawberry, grape, and citrus fruits [ 3 ]. We will focus on ripening of climacteric fruits that are influenced by ethylene. For climacteric fruit, exposure to an initial, small concentration of ethylene causes the fruit to produce greater quantities of ethylene until a peak concentration is achieved [ 4 ]. The methods we described above for slowing down ripening work in this way, because, in general, low temperatures reduce metabolism in fruit. Controlled atmospheres limit the amount of oxygen around the fruit, and oxygen is needed to make ethylene.
Ethylene action is inhibited by carbon dioxide and by 1-MCP. When the fruit are ripe they become brightly coloured. Apples, strawberries and peaches become red, bananas become yellow and, of course, oranges become orange. Next time you go the supermarket, look at the beautiful colours of the fruit in there and see how many different colours you can find.
At the same time as fruit change colour, they also become soft. This is because fruit are made from many tiny things called cells. In plants, each cell has a wall. I bet the thing you most like about fruit is that they are sweet and yummy to eat. When the fruits ripen, the plant cleverly removes all of the bad-tasting stuff from the fruit and replaces them with sugars.
That, of course, makes the fruit sweet and nice to eat. The last thing that changes when fruit ripen is that they make stuff that helps them smell really nice, which makes animals and people want to eat them. Why does spicy food make me hiccup? Biology History Medicine. The sex appeal of symmetry. Physics Space. Why is space cold? History Medicine. Why did plagues stop? Your name. Leave this field blank. Support Us! Make a donation to support the Naked Scientists.
Forum discussions What are some low-tech ways to address climate change? Covid19 amp Mental Health? Talk the Talk. At this point your produce pedant lets slip a weary sigh: Never mind where they fit in the menu, botanically, anything that contains a seed is a fruit, and yes, that includes tomatoes, as well as cucumbers, aubergines and courgettes. But of those only tomatoes are climacteric. Rather, it is a process that begins with hard, green and sour and ends in a puddle of fermented mush.
The ideal spot is somewhere in between, but exactly where depends upon your taste. All of this is not just botanical mumbo-jumbo. It has tremendous practical implications. You can buy peaches rock-hard and, provided they were harvested at a reasonable level of maturity, they will still become delicious and juicy.
Sugar only increases on the tree. But they may actually seem sweeter because they taste and smell so good. In fact, you are probably better off buying them firm. Fruit that is ripe and soft is extremely susceptible to damage, particularly given the kind of rough handling that is common in harvesting and shipping. Imagine what a tree-ripe peach shipped from Spain might look like by the time it arrives in Ireland.
So how do you work this magic? Patience is all that is required to ripen fruit at home. The only thing that peach really needs is a little bit of time. If you want to speed the process, put it in a paper bag. Ripening fruit gives off ethylene gas, which actually hurries along the process. The paper bag will collect the gas, without collecting the moisture that will lead to spoiling.
If you really want to speed it up, add an apple or a banana — these are super ethylene generators. A watched pot may never boil, but an unwatched peach will turn to rot before you know it.
There is one thing you never want to do with any climacteric fruit.
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