Fruit, irradiated

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... 

Queensland mango, Mangifera indica, fruit irradiated postharvest, single dose, 250 or 750 Gy... 

Figure 7. Schematic diagram of fruit irradiation apparatus...

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. 

Shown in Table 1 is the change in major carotenoid components of tomato (1st harvest) as a function of irradiation dose irradiation level of 0.5 and 2 kGy resulted in a rapid accumulation of carotenoids mainly lycopene. In fruits treated with 0.5 kGy the whole carotenoid profile was improved. Whereas conversion of lycopene to p-carotene and lutein via cyclization and hydroxylation reaction respectively was partially distributed in fruit irradiated with a dose of 2 kGy. 

The several polymeric metal carbonyls studied have led to some surprisingly high yields [e.g., Fe3(CO),2 and Ruj(CO)j2 in Table IV] but to no substantiated mechanisms. The 17% yield of Fe3(CO),2 in neutron-irradiated Fe(CO)j was interpreted as a reaction of Fe(CO)4 with the Fe(CO)5, but no further evidence is available. The study of Mn2(CO),o has been fruitful (44, 46). The insensitivity of the parent yield MnMn(CO),o to heat indicates that the molecule is formed by a reaction quite early in the sequence, perhaps epithermal. The discovery (46) of a species which reacts rapidly with I2 and exchanges with IMn(CO)5 led to the conclusion that the Mn(CO)5 radical is produced prominently (4.5%) by nuclear reactions in the solid decacarbonyl. The availability of this labeled Mn(CO)5 has made possible several interesting observations about the exchange properties of this radical in the solid (45) and in solution (42). 

Perhaps the most fruitful of these studies was the radiolysis of HCo(C0)4 in a Kr matrix (61,62). Free radicals detected in the irradiated material corresponded to processes of H-Co fission, electron capture, H-atom additions and clustering. Initial examination at 77 K or lower temperatures revealed the presence of two radicals, Co(C0)4 and HCo(C0)4 , having similar geometries (IV and V) and electronic structures. Both have practically all of the unpaired spin-density confined to nuclei located on the three-fold axis, in Co 3dz2, C 2s or H Is orbitals. Under certain conditions, a radical product of hydrogen-atom addition, H2Co(C0)3, was observed this species is believed to have a distorted trigonal bipyramidal structure in which the H-atoms occupy apical positions. 

The use of ionizing irradiation on fruits and vegetables has not been intensively studied, but a few experiments have suggested that irradiation has potential for such an application (Allende et al., 2006 Zhang et al., 2006). Results from Buchanan et al. (1998) indicated that low-dose irradiation could easily eliminate E. coli 0157 H7 from fresh apple juice, but they also showed that acid-adapted strains needed higher doses of irradiation in order to obtain a 5 D inactivation in juice (73-value decimal reduction time, i.e. the amount of time it takes at a certain temperature to kill 90% of the organisms being studied (Wikipedia, 2006)). In experiments where sprouts were irradiated... 

Korkmaz, M. and Polat, M. (2005) Irradiation of fresh fruit and vegetables , in Jongen, W., Improving the Safety of Fresh Fruit and Vegetables, Woodhead Publishing, Cambridge 387-428. 

Lower doses (at or below 200 Gy) of irradiation coupled with 35 days of storage at 10°C were not harmful in the retention of lycopene and other health-promoting compounds in early-season grapefruit, but higher doses (400 and 700 Gy) and 35 days of storage had detrimental effects. However, no significant effect of radiation and storage was observed in late-season fruit (Patil and others 2004). 

A similar effect was observed in other fruits and vegetables, where UV-C treated strawberries showed a higher increment of phenols and PAL activity 12 hours after treatment than unirradiated (control)(Pan and others 2004), which could be the reason for the increment in total phenol constituents (Lancaster and others 2000). UV-C and UV-B caused a two- and threefold increase in content of resveratrol (a grape phenol constituent). Thus, mature Napoleon grapes that had been irradiated with UV-C light can provide up to 3 mg of resveratrol per serving (Cantos and others 2001). Therefore, UV-C treatments clearly cause a benefit effect, increasing total phenol content, which can be mainly attributed to the increment of PAL activity. 

As discussed previously, UV-C irradiation increased the phenol and flavonoid content such compounds present high radical-quenching activity by themselves (Robles-Sanchez and others 2007). Few studies have been reported specifically about the effect of UV-C irradiation on antioxidant capacity of treated fruit. However, Fan and others... 

Cantos E, Espin JC and Tomas-Barberan FA. 2001. Postharvest induction modeling method using UV irradiation pulses for obtaining resveratrol-enriched table grapes A new functional fruit J Agric Food Chem 49(10) 5052-5058. 

Fan X, Niemira BA and Prakash A. 2008. Irradiation of fresh fruits and vegetables. Food Technol-Chicago 62(3) 36. 

Pan J, Vicente AR, Martinez GA, Chaves AR and Civello PM. 2004. Combined use of UV-C irradiation and heat treatment to improve postharvest life of strawberry fruit. J Sci Food Agric 84(14) 1831—1838. 

Rivera-Pastrana DM, Bejar AAG, Martinez-Tellez MA, Rivera-Dominguez M and Gonzalez-Aguilar GA. 2007. Postharvest biochemical effects of UV-C irradiation on fruit and vegetables. Revista Fitotecnia... 

Ismail FA and Afifi SA. 1976. Control of postharvest decay in fruits and vegetables by irradiation. Nahrung 20(6) 585-592. 

The objective of irradiation of food with y-rays is elimination of parasitizing insects, fungi, and bacteria to prevent premature spoiling of the food and the outbreak of diseases. In addition, retardation of aging and ripening of fruits and vegetables can be achieved. In the Federal Republic of Germany, irradiation of food with the exception of spices is not permissible. 

Possible industrial applications include screening of substances with antiradical activity, quality testing of raw materials, pharmaceuticals, cosmetic products, fruit juices, wines, beers, edible oils, detection of food irradiation, and many more. 

Boag, T.S., G.I. Johnson, M. Izard, C. Murray, and K.C. Fitzsimmons. 1990. Physiological responses of mangoes cv. Kensington Pride to gamma irradiation treatment as affected by fruit maturity and ripeness. Ann. Appl. Biol. 116 177-187. 

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