Non-climacteric fruits

The synthesis of endo-PG occurs in the ripening stage after an increase of ethylene production [21] and its appearance has been correlated with an increase in soluble pectin and softening [22]. Exo-PG is suggested to participate in the initiation of climacteric ethylene production [23]. Strawberry fruit has been accepted to be a non-climacteric fruit and ethylene... 

Application of ethylene-,4C to plants resulted in only a 2.4% conversion into soluble carbohydrates, 11% into ether-soluble materials, 6.9% into phytol, 31.7% into cellulose and lignin, and 9.6% into soluble protein and non-protein material, mainly phosphates. 9 Treatment of detached fruit (such as apples, bananas, peaches, figs, and pears) with synthetic auxins, especially (2,4,5-trichlorophenoxy) acetic acid, speeded up ripening, as indicated by color, taste, softness, and starch breakdown. 7 Other fruits have been similarly ripened, 8 and the treatments are effective both on climacteric and non-climacteric fruit. 

During ripening of non-climacteric fruits like citrus, the process of colour change is named degreening and the natural loss of chlorophylls, accumulated into the chromoplasts of the epidermis (flavedo) and vesicles, and the concomitant manifestation and new biosynthesis of carotenoids, generally occurs very slowly (Eaks 1977). 

Post-harvest application of AA to non-climacteric fruits has been reported to cause induction of CO2 production (a climacteric-like respiration) in orange (Fidler 1968 Pesis and Avissar 1989), fig (Hirai et al. 1968), strawberry and blueberry (Janes et al. 1978) and grape (Pesis and Marinansky 1992). In fig and orange, AA application leads to reduced acidity (Hirai et al. 1968 Pesis and Avissar 1989). 

Fruits ripen in two major ways climacteric and non-climacteric. The former type involves both autocatalytic evolution of ethylene and a rise in respiration whereas the latter shows no increase in ethylene formation and downward drifts in respiration [14]. In both types, fruit ripening is characterized by many biochemical and physiological changes such as chlorophyll d radation, pigment accumulation, textural modification and the production of volatile aromatic compounds. 

Ethylene gas is widely used commercially for ripening a variety of climacteric fruits and decoloring non-climacteric citrus fruits. However, the use of ethylene-releasing compounds to effect this response is confined to relatively few crops (Table 2), and normally when they are used as a preharvest application. This is probably due to the ease with which ethylene gas can be applied to harvested fruit, and the dangers of applying aqueous solutions to these disease-susceptible organs. 

Acetaldehyde (AA), a natural aroma component in almost every fruit, accumulates during ripening (Fidler 1968). Acetaldehyde in both climacteric (Dilley 1970) and non-climacteric (Yamashita et al. 1978) fruits is formed from pyruvate by the enzyme, pyruvate decarboxylase (PDC). The two immediate products formed from AA are (1) ethanol, by the enzyme, alcohol dehydrogenase (ADH), and (2) acetyl CoA by the enzyme, aldehyde dehydrogenase (Cossins 1978). 

Application of AA vapour has been shown to lead to major changes in fruitripening processes in non-climacteric and climacteric fruit (Fidler 1968). Yamashita et al. (1975,1976) showed that intact strawberries were able to synthesize carboxylic esters on addition of alcohols and acids or aldehydes and acids. In... 

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