Effect of Gamma Radiation on the Quality and Shelf Life of Refrigerated Rainbow Trout (Oncorhynchus mykiss) Fillets

Abstract

The effect of gamma radiation (0, 1, 3, and 5 kGy) on the shelf life of farmed rainbow trout (Oncorhynchus mykiss) fillets that were treated with sodium acetate and vacuum packaged and subsequently stored under refrigeration was studied by measuring microbiological, chemical, and organoleptic changes. Radiation affected populations of bacteria, namely, H2S-producing bacteria and Enterobacteriaceae (P < 0.05). Initial total viable counts of the control samples were ca. 4.41 log CFU/g, whereas the respective counts in samples irradiated at 1, 3, and 5 kGy were 3.08, 1.46, and < or = 1 log CFU/g at day 1 of refrigerated storage. The maximum count of Enterobacteriaceae reached 2.29 and 1.45 log CFU/g at the end of storage for 1 and 3 kGy, respectively, but at a 5-kGy dose no growth of Enterobacteriaceae was observed. Of the biochemical indicators, thiobarbituric acid values for irradiated trout were higher than for nonirradiated fish (P < 0.05). Sensory evaluation (taste) showed a reasonable and good correlation with bacterial populations with storage time. The results revealed that radiation at a high dose (5 kGy) might induce lipid and protein oxidation, although the growth of microorganisms was inhibited. Therefore, radiation at a low dose (3 kGy) could be used to control the microbial and safety biochemical indices of O. mykiss for up to 4 weeks at refrigerator temperature without adverse effects on quality and acceptability.

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“…TVC count at the end of storage for irradiated at 3 kGy, Tio2 nanocomposite+3kGy, at 5 kGy and Tio2 nanocomposite became 4.12, 2.27, 1.91 and 6.41 logs CFU/g respectively. Similar result reported by Oraei, Motalebi, Hoseini and Javan (2010); Mohamed et al (2009) and Moini et al (2009). They concluded that irradiation can reduce survival of TVC in fish fillet.…”

“…However, Tio2 nanocomposites caused decrease in pH value during refrigerator storage (P<0.05). A similar trend in irradiation effect on fish, was observed for farmed sea bass, turbot on ice and rainbow trout in refrigerator storage (Papadopoulos, Chouliara, Badeka, Savvaidid & Kontominas, 2004;Moini et al, 2009). …”

“…The difference between treatment was significant (P<0.05). TVB-N values for 3kGy, 5kGy and 3kGy+ Tio2 nanocomposite, Banu, Hossain, & Hossain, 1997;Moini et al, 2009;Ahmed et al, 2009). There was no research report about TVB-N value in packaged food by Tio2 nanocomposite.…”

Microbiological evolution of gilthead sea bream (Sparus aurata) in Canary Islands during ice storage

“…Other authors have reported similar values in different species (initial and final counts), such as sea bass with counts of 2 and 4.2 log CFU/g (Papadopoulos et al 2003), sea bream with 3.9 and 5.6 log CFU/g (Özden et al 2007) and sardines with 3.5 and 5.08 log CFU/g (Erkan and Özden 2008). The contribution of Enterobacteriaceae to the microflora of fish and its potential spoilage must be taken into consideration especially in the case of polluted water or delay in chilling after catch (Chouliara et al 2004), as well as in the filleting process (Moini et al 2009). Although this group of bacteria can grow at low temperatures, their abundance decreases during ice storage, possibly because their growth rate is lower than in others Gramnegative psychrotrophic spoilers (Bahmani et al 2011).…”

Microbial Growth Models in Gilthead Sea Bream (Sparus aurata) Stored in Ice

“…The contribution of Enterobacteriaceae to the microflora of fish and its spoilage potential must be taken into consideration especially in the case of polluted water or delay in chilling after catch (Chouliara et al, 2004), as well as in the filleting process (Moini et al, 2009). Although this group can grow at low temperatures, their abundance decreases during iced storage, possibly because their growth rate is lower than that of other Gram-negative psychrotrophic spoilers, making them poor competitors (Bahmani et al, 2011).…”