Ripening

Ripening is a process in fruits that causes them to become more edible. In general, a fruit becomes sweeter, less acidic when tasted, less green, and softer as it ripens. But the sweetness as well as acidity rises in the fruits. But still the fruits taste sweeter and better. The reason for this is the Brix-Acid Ratio.

The life stages of a plant are influenced by hormones. An important plant hormone involved with ripening is ethylene, a gas created by plants from the amino acid methionine. Ethylene increases the intracellular levels of certain enzymes in fruit and fresh-cut products, which include:

• Amylase, which hydrolyzes starch to produce simple sugars, and
• Pectinase, which hydrolyzes pectin, a substance that keeps fruit hard.

Other enzymes break down the green pigment chlorophyll, which is replaced by blue, yellow, or red pigments.

Hormone levels in fruit are often connected to pollination. If too few seeds in a multiseeded fruit are formed (by fertilization of the ovules), the flesh of the fruit may not develop in some areas, and as a consequence ripening will be retarded or prevented. Fruit growers increasingly monitor seed ratios in developing and/or mature fruit and adjust pollination management accordingly.

Many fruits are picked prior to full ripening because ripened fruits do not ship well. For example, bananas are picked when green and artificially ripened after shipment by being gassed with ethylene.

Some fruits, such as persimmons, are eaten only after bletting, the fermenting process of decay after severe ripening.

SmartFresh is a technology useful to maintain fresh-picked quality of whole fruits and vegetables. 1-Methylcyclopropene (1-MCP 0.14%) works with the ripening process to dramatically slow down ethylene production and prevent over-ripening and problems associated with aging.

Iodine (I) can be used to check if the fruit is ripening or rotting by showing whether starch in the fruit has turned into sugar. For example, in an apple that has rotted (not bruised, just rotted) a drop of iodine on a slightly rotten part (not skin) will turn a dark blue or black color if there is starch there. If it stays yellow, then most of the starch did turn into sugar.

References

• http://plantphys.info/plants_human/fruitgrowripe.html
• http://www.actahort.org/books/398/398_17.htm
• http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=549760

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Last updated on Monday March 03, 2008 at 05:50:37 PST (GMT -0800)
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