**10. Chemical approaches**

102 Salmonella – A Dangerous Foodborne Pathogen

depends on the dose of irradiation, storage temperature, packaging conditions and fish species (Özden et al., 2007). For example a study, showed complete elimination of *Salmonella* on frozen shrimp when irradiated at 4.0 kGy. Similarly it is also reported that doses of 4.0–5.0 kGy were required to reduce the numbers of *S. typhimurium* on shrimp by 6.0 log cycles. According to Oraei et al., (2011), low-dose gamma irradiation (especially 3 kGy) can be applied for microbial control and the safety of rainbow trout and shelf life extension in frozen state. Gamma irradiation at 3 kGy was more effective than irradiation at 1 and 5 kGy in eliminating microorganisms of rainbow trout fillets. The irridation doses are also reported in the range 1.5–2.0 kGy effectively control all pathogenic bacteria tested in shellfish except *Salmonella* spp., particularly, *S. enteritidis*, which requires 3.0 kGy (IAEA,2001). Similarly to achieve safety levels against *Salmonella* spp., particularly *S. enteritidis*, in raw oysters, a dose of 3.0 kGy is recommended by Gelli (2001). As a results although irradiation appears to be effective in eliminating pathogens in fishery product, there is an unsubstantiated view amongst the public that food irradiation is unsafe and undesirable. There is also evidence some that irradiation may reduce the nutritional value of some foods by the destruction of aromatic amino acids and producing rancidity and

Modifed atmosphere packaging (MAP) has been widely used for extending the shelf life of a wide variety of food, including fish and fish products since 1980. Packages are injected with carbon dioxide, nitrogen, and very small (0.4 percent) amounts of carbon monoxide. The effciency of MAP in eliminating pathogens from fish depends on the gas mixture in MAP and, most importantly, the storage temperature (Redman, 2007; Hudecová et al., 2010). There is limited information on the effect of MAP with elevated O2 level on *Salmonella* in the literature. A study by Hudecová et al., (2010), for example, showed a signifcant decrease in the microbial growth rate on fresh chilled common carp (Cyprinus carpio) during storage at +4 ± 0.5 °C in two different MAP (70% N2/30% CO2 and 80% O2/20% CO2) for 10 days when compared to air packaging and no *Salmonella* was reported in these conditions. Ingham et al., (1990) reported that modified atmosphere storage using 50% CO2/10% O2 dose effectively reduce the growth rate of *S. typhimurium*, but it cannot, in the absence of

**9. High-pressure processing (HPP) and superheated steam drying (SSD)** 

High-pressure processing is an emerging non-thermal process that can be used to destroy pathogenic microorganisms in seafood without greatly affecting the quality of the product. In addition to improving the safety of shrimp, HPP has also been demonstrated to extend shrimp shelf-life. Shrimp are generally spoiled by Gram-negative bacteria, which tend to be relatively pressure sensitive due to their cell wall structure and HPP may therefore prove to be a valuable processing technology for shrimp. Although research has demonstrated the benefit of using HPP on shrimp and shrimp products, limited studies have been carried out specifically to eliminate or reduce *Salmonella* in fishery product using this technology. Superheated steam drying (SSD) is a promising drying technology to a variety of industries. Superheated steam is steam heated to a temperature higher than the boiling point

off-odours (Norhana et al., 2010).

**8. Modified atmosphere packaging (MAP)** 

proper refrigeration, be relied upon to prevent salmonellosis.

corresponding to its pressure (Norhana et al., 2010).
