Why does fruit….?

by on October 2, 2004

This has been worrying me for a while: why does fruit get juicer as it ripens? If it’s off the tree, then it’s not got any source of water, so why doesn’t it just dry up? Why does it appear to have less water in when it’s not ripe?

Hmmm. Ahmmmmm.

Comments

The juiciness thing…
is all about starch turning into sugar – as you’d know if you had kept up your subscription to the Perishables Handling Newsletter (Issue No. 80, November, 1994)

Optimum Procedures for Ripening Apples (Beth Mitcham)
Apples are climacteric fruit which continue to ripen after removal from the tree. For long-term storage, it is best to harvest apples before the climacteric increase in respiration and ethylene production rates. During maturation of the apple fruit there is a conversion of starch to sugars resulting in an increase in total soluble solids. Titratable acidity and firmness decrease during the same time period. The timing of apple harvest will determine its storage life and susceptibility to storage disorders such as scald and bitter pit. Early harvested fruit will contain significant levels of starch which has not yet been converted to sugars. These early fruit will also be firmer and have higher acidity levels than later harvested fruit.
Residual starch in the early-harvested apples will be converted into sugars during storage of the fruit, however if apples are to be marketed immediately after harvest they will have poor eating quality. Late harvested apples will contain little starch but will be softer and have lower acidity levels. Late harvested fruit are also more susceptible to physiological disorders and disease problems in storage. These later harvested fruit will have less storage potential and be better suited for immediate marketing and consumption.
However, the demand for freshly harvested apples at the beginning of the harvest season is often much greater than later into the season encouraging the immediate marketing of early season fruit. To improve the eating quality and consumer satisfaction of this fruit, further ripening can be promoted to convert the starch into sugar.

Bada bing!
Well, thanks for the information!

One of the interesting things about this question is that it’s hard to find the answer from a search engine. It’s in a class of question unlike, say, “What is the capital of Spain?” that is too complex to derive the answer by a brute force index search.

Thinking about this makes me more interested in things like the semantic web. Well, until I read that Clay Shirky essay. Maybe data visualisation techniques might play a role one day.

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