Respiration fruits

Fruits and vegetables which give off heat of respiration need to have perforated cases so that air may pass through the product. 

All fruits respire oxygen and, in doing so, start to decay. If the oxygen concentration can be reduced, the rate of respiration will be slowed and the storage life maybe extended. The maintenance of a low partial pressure of oxygen requires a gas-tight structure to prevent diffusion. Such controlled atmosphere stores are carefully constructed and sealed to achieve this, and are generally termed gas stores. 

The fruits are loaded and the store sealed. Within a few days they consume a proportion of the available oxygen and respire carbon dioxide. Considerable research over the past 60 years, mainlyin the UK [47], has determined the correct balance of gases to prolong the storage life of the different varieties of apples and pears, both home grown and imported. 

Queensland mango, Mangifera indica, fruit irradiated postharvest, single dose, 250 or 750 Gy At 250 Gy, skin and pulp color inhibited 50% due to irradiation-induced suppression of chlorophyll breakdown and reduction in carotenoid production. At 750 Gy, fruit respiration increased for 3-5 days, but no effect on fruit firmness 5... 

Carbohydrates are found in foods such as bread, pasta, potatoes, and fruits. They are the primary source of energy for the body. In a process called cellular respiration, carbohydrates combine with inhaled oxygen and are oxidized to produce carhon dioxide and water, plus energy. As shown in Figure 2.18, carhon dioxide and water vapour from cellular respiration are expelled in your hreath. 

Neotropical bats Desmodus rotundus, Artibeus literatus, and Phyllostomus discolor) are very sensitive to butanoic acid their detection threshold lies between 1.5 x 10 ° and 1.5 x 10 mol/1 (Schmidt, 1975). The short-tailed fruit bat Carollia perspicillata) has detection thresholds for 18 odorants ranging from 3.6 x 10 to 2.7 X 10 ° molecules/cm air. The animals were most sensitive to fruit-typical compounds such as ethyl butyrate (5.4 x 10 °molecules/cm ), w-pentyl acetate (2.8 X 10 °molecules/cm ), andlinalool(1.8 x 10 molecules/cm ), suggesting nutritional specialization of chemoreception (Laska, 1990). The bats increased their respiration rate from a basal rate of 2-4 Hz to as much as 12 Hz when confronted with an odor of high concentration. 

The chemical changes that take place in detached fruit are directly, or indirectly, related to the oxidative and fermentative activities collectively referred to as biological oxidations. Once the fruit is harvested, respiration, the process concerned with the oxidation of predominantly organic substances by the cell, assumes the dominant role, and the fruit no longer depends on absorption of water and minerals by the root, on conduction by vascular tissues, and on the photosynthetic activity of the leaves. After harvest, the fruit lives an independent life by utilizing substrates accumulated during maturation.385... 

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.]...

Laties and associates589-592 provided evidence for an alternative, cyanide-resistant path of respiration in avocado mitochondria. Uncouplers were considered to stimulate glycolysis to the point where the glycolytic flux exceeds the oxidative capacity of the cytochrome pathway, with the result that the alternative pathway is engaged. However, these authors concluded that the alternative pathway is not required in order to sustain the elevated rate of respiration that characterizes the climacteric. Clarification of the role, if any, of this alternative pathway in fruit ripening awaits further study. 

The effect of radiation on the biochemical processes of fresh fruits and vegetables is of considerable interest from the standpoint of its influence on shelf life. A number of studies on the effect of radiation on respiration have indicated a general stimulation of both oxygen uptake and carbon dioxide evolution during the irradiation period, subsiding to near-normal rates shortly following the cessation of treatment (21, 23, 24, 38). 

The tolerance limitation of fruit for irradiation establishes the maximum acceptable dose. If this dose controls decay organisms, the use of irradiation for a particular fruit may appear promising. Response to irradiation may be influenced by fruit maturity, variety, pre- and postharvest temperatures, handling, and extent of fungus growth. Climacteric fruits irradiated prior to the normal rapid increase in respiration usually show an immediate increase in respiration and the production of ethylene. These fruits are frequently retarded in ripening. 

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