COMBINED EFFECT OF GAMMA IRRADIATION AND FROZEN STORAGE ON THE MICROBIAL, BIO- CHEMICAL QUALITY AND SHELF LIFE OF SHRIMP

NICSTAR 2015

a, a b c c Manjanaik Bojayanaik *, Kavya Naroth , Veena Shetty , Somashekarappa Hiriyur, Rajashekar Patil a Department of Fish Processing Technology, Karnataka Veterinary, Animal and Fisheries Sciences

University, College of Fisheries, Mangalore – 575002, India.b Department of Microbiology, K S Hegde Medical Academy, Deralakatte, Mangalore- 575018, India.

c Centre for Application of Radioisotopes and Radiation Technology (CARRT), Mangalore University, Mangalore-574199, India

E- mail : manjanaikb@rediffmail.com

Gamma Rays Cobalt - 60, Cs-137X-Rays - 5 MeV, E beam - 10MeV

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Fig. 1. Total plate count of shrimp samples irradiated at 1, 3, 5kGy and stored at 4°C

Fig. 2. Total plate count of shrimp samples irradiated at 1, 3, 5kGy and stored at -18°C

Fig. 3. TVB-N of shrimp samples irradiated at 1, 3, 5kGy and stored at 4°C

Fig. 4. TVB-N of shrimp samples irradiated at 1, 3, 5kGy and stored at -18°C

Fig.5. TMA-N of shrimp samples Irradiatedat 1, 3, 5kGy and stored at 4°C

Fig.6. TMA-N of shrimp samples irradiated at1, 3, 5kGy and stored at -18°C

Fig. 7. pH of shrimp samples irradiatedat 1, 3, 5kGy and stored at 4°C

Fig. 8. pH of shrimp samples irradiated at 1, 3, 5kGy and stored at -18°C

Fig. 9. TBARS of shrimp samples irradiated at 1, 3, 5kGy and stored at 4°C

Fig. 10. TBARS of shrimp samples irradiatedat 1, 3, 5kGy and stored at -18°C

Among all the seafood consumed, shrimp being rich in proteins, free amino acids, minerals and other soluble non- nitrogenous substances demonstrates an exceptional nutritional value in the diet of human beings.

The shrimp used in the study had 74.90% moisture; 22.43% protein; 1.609% crude lipids and 1.06% ash.

The combination of low dose gamma irradiation and refrigerated or frozen storage resulted in a signicant reduction of microbial load.

The employed radiation dose (1,3,5 kGy) in combination with frozen storage extended the shelf-life of shrimp to 90 days.

The levels of pH, TBA, TVB-N and TMA-N in irradiated and non-irradiated shrimp samples were also examined. Irradiated samples of shrimp had signicantly lower concentrations of TVB-N and TMA-N during their refrigerated storage (p < 0.05) as compared with the controls, which may be attributed to the reduction of microbial population.

The irradiation at high dose (>5 kGy) might enhance lipid oxidation, although the growth of microorganisms and protein oxidation was inhibited.

The results obtained from this study showed that the combination of irradiation and frozen storage resulted in a signicant reduction of bacterial growth at irradiation dose of 3 and 5kGy.

The levels of TVB-N, TMA-N of irradiated samples were signicantly lower than the non-irradiated controls, which may be attributed to the reduction of microbial population.

Combination of low dose gamma irradiation and frozen storage resulted in signicant reduction of bacterial growth and stabilized the chemical characteristics of shrimp samples.

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The nancial support for the research work funded by BRNS, Mumbai, Dept. of Atomic Energy, Government of India is gratefully acknowledged .

Radiation processing is an effective method to reduce the post harvest losses and improve food safety in seafood .

Food preservation technique, prevent food losses and extends the shelf life of foods

Food safety from food born diseases (pathogens), parasites and viruses

Promote export of seafood by elimination of zero tolerance pathogenic bacteria (Staph, Salmonella, E. coli, Listeria, O157: H7, ) and parasites. V.parahaemolyticus

Overcome quarantine barriers

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APHA.,1998 Recommended Methods For The Microbial Examination of Foods, Broadway, American Public Health Association, 19 :181-188 AOAC., 2005. Ofcial Methods of Analysis AOAC International.Edt. Horwiz, W. Edn. 18 , Association of Ofcial Analytical Chemist International, Gaithersburg, Maryland,

USA. Asli Hocaoglu, Ahmet Sukru Demirci, Tuncay Gumus, Mehmet Demicri, 2012. Effects of gamma irradiation on chemical, microbial quality and shelf life of shrimp. Radiation

Physics and Chemistry. 81: 1923-1929. ICMSF, 1986. International commission on microbiological specications for foods, sampling plans for sh and shellsh. In: Microorganisms in Foods. Sampling for

Microbiological Analysis: Principles and Scientic Applications, second ed. 2. University of Toronto Press, Toronto, pp. 181–196.

Application of ionizing radiation in food is considered as one of the most efcient technological processes for the reduction of microorganisms in food. It can be used to improve the safety and quality of the aquatic food

products, and to extend their shelf life to reduce post harvest losses. The aim of this study was to evaluate the combined effects of gamma irradiation and frozen storage for improvement of microbial and bio- chemical quality

of fresh shrimp. Fresh farm raised shrimp (Penaeus monodon) were procured and packed aseptically in a polyethylene bags, and exposed to 0.0 (un-irradiated), 1.0, 3.0, 5.0 kGy of gamma irradiation and held for refrigeration o o(4 C) and frozen storage (-18 C) temperatures. The control and irradiated shrimp samples were underwent periodically for microbial analysis (total mesophilic counts, total coliforms, faecal coliforms, Salmonella, E. coli,

Staphylococcus aureus) and chemical characteristics (TMA-N, TVB-N, pH, TBARS) on different time intervals. Microbial analysis indicated that irradiation and frozen storage had a signicant effect (p< 0.05) on the reduction

of microbial loads. The chemical parameters (trimethylamine, total volatile base nitrogen values) for irradiated shrimp samples were signicantly lower than the non- irradiated samples at both storage temperatures and the

rate of decrease was more pronounced in samples irradiated at the higher dose (p<0.05). The results revealed that the combination of irradiation and frozen storage resulted in overall reductions on microbial load and

stabilized the biochemical characteristics of shrimp.Key words : gamma irradiation, frozen storage, TBARS, TMA-N.

ABSTRACT

INTRODUCTION

EXPERIMENTAL

SOURCE OF IONIZING RADIATION

EFFECT OF IRRADIATION

RESULTS AND DISCUSSION

CONCLUSION

ACKNOWLEDGEMENT

LITERATURE CITED