Respiration climacteric rise

Fig. 13.—Pattern of Post-harvest Respiration at 20 in Mangoes (After Krishnamurthy and Subramanyam384). [(a) Preclimacteric period, (b) climacteric rise, (c) climacteric peak, (d) over-ripeness (senescence). Solid line (1) shows the pattern obtained in a single fruit, and dotted line (2) shows the pattern obtained by averaging results from randomly selected fruits.]...

Figure 1. Effect of ethylene on respiration of climacteric and nonclimacteric fruit. Ethylene causes greatest response in climacteric fruit when applied to mature fruit prior to the climacteric rise. In nonclimacteric fruit high concentrations of ethylene stimulate respiration for short time periods. This stimulation is observed at any time upon application of ethylene (3).

Studies on banana tissue slices have shown that valine and leucine concentrations increase about threefold following the climacteric rise in respiration [10]. Radioactive labeling studies have shown that valine and leucine are transformed into branched chain flavor compounds that are essential to banana flavor (2-methyl propyl esters and 3-methyl butyl esters, respectively). As can be seen in Figure 4.6, the initial step is deamination of the amino acid followed by decarboxylation. Various reductions and esterifications then lead to a number of volatiles that are significant to fruit flavor (acids, alcohols, and esters). Recent work has shown that amino acids play a role in apple flavor as well. For example, isoleucine is the precursor of 2-methyl butyl and 2-methyl butenyl esters in apples [24,25]. An unusual flavor compound, 2-isobutylthiazole, has been found to be important to the flavor of tomato. It is hypothesized that this compound is formed from the reaction of 3-methyl-l-butanal (from leucine) with cysteamine. 

The respiration rate is affected by the development stage of the fruit. A rise in respiration rate occurs with growth. This is followed by a slow decrease in respiration rate until the fruit is fully ripe. In a number of fruits ripening is associated with a renewed rise in respiration rate, which is often denoted as a climacteric rise. Maximal CO2 production occurs in the climacteric stage. De-... 

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. 

The climacteric respiration rise is so specific that fruits can be divided into ... 

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