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Climacteric fruits undergo a number of changes during fruit ripening. The major changes include fruit softening, sweetening, decreased bitterness, and colour change. These changes begin in an inner part of the fruit, the locule, which is the gel-like tissue surrounding the seeds.
Fruit ripening The first GM food available in stores was a genetically modified tomato (also known as Flavr Savr ) that had a longer shelf life and was ideal for shipping. Its delayed ripening was achieved by preventing polygalacturonase from destroying pectin, which makes tomatoes firm.
In fruit, polygalacturonase plays an important role in cell wall metabolism during ripening. In plant bacterial pathogens such as Erwinia carotovora or Ralstonia solanacearum (Pseudomonas solanacearum) and fungal pathogens such as Aspergillus niger, polygalacturonase is involved in maceration and soft-rotting of plant tissue.
As ripening continues, the fruit becomes attractive to animals due to changes in aroma from acidic to sweet with fruitiness. As ripening occurs, herbaceous aromas (e.g. methoxypyrazines) are degraded. It is unknown whether the degradation of herbaceous aromas allows fruit aromas to be detected, or if fruity aromas develop later in berry ripening.
Generally, fleshy fruits can be divided into two groups based on the presence or absence of a respiratory increase at the onset of ripening. This respiratory increase—which is preceded, or accompanied, by a rise in ethylene—is called a climacteric, and there are marked differences in the development of climacteric and non-climacteric fruits. [1]
Ethylene chemical structure. Ethylene signaling pathway is a signal transduction in plant cells to regulate important growth and developmental processes. [1] [2] Acting as a plant hormone, the gas ethylene is responsible for promoting the germination of seeds, ripening of fruits, the opening of flowers, the abscission (or shedding) of leaves and stress responses. [3]
Commercial fruit-ripening rooms use "catalytic generators" to make ethylene gas from a liquid supply of ethanol. Typically, a gassing level of 500 to 2,000 ppm is used, for 24 to 48 hours. Care must be taken to control carbon dioxide levels in ripening rooms when gassing, as high temperature ripening (20 °C; 68 °F) [ 6 ] has been seen to ...
In the practice, this means that farmers can alter this balance to make all fruits mature a little later, at a same time, or 'glue' the fruit in the trees until the harvest day (because ABA participates in the maturation of the fruits, and many crops mature and drop a few fruits a day for several weeks, that is undesirable for markets).