Document Type : Complete scientific research article
Authors
1
Department of Food Hygiene, Faculty of Veterinary Medicine, Shahid Chamran University of Ahvaz,, Ahvaz, Iran
2
Department of Food Hygiene, Faculty of Veterinary Medicine, Shahid Chamran University of Ahvaz, Ahvaz, Iran
3
Department of Food Hygiene, Faculty of Veterinary Medicine, Shahid Chamran University of Ahvaz, Box: 61355-145, Ahvaz, Iran
4
Department of Horticultural Science, Faculty of Agriculture, Shahid Chamran University of Ahvaz, Ahvaz, Iran
10.22069/fppj.2024.22153.1798
Abstract
Background and objectives: Fish, a significant component of human diet, is prone to early spoilage due to nutrient content. Supplying fresh fish, preventing spoilage and increasing shelf life have been considered in the food industry, and therefore, the use of edible films and coatings to increase the shelf life of fresh fish has been considered. Oliveria decumbens essential oil contains compounds such as thymol and carvacrol, which cause antimicrobial properties. To improve the antimicrobial and antioxidant properties and solve the problem of volatility and high consumption of essential oils, their nanoemulsions can be used. In this study, the effect of edible sodium caseinate coating containing emulsion and nanoemulsion of Oliveria decumbens essential oil on the growth of Pseudomonas aeruginosa and Listeria monocytogenes inoculated into rainbow salmon fillet during storage in the refrigerator was investigated.
Materials and methods: The essential oil of Oliveria decumbens (Od-EO) was extracted according to standard methods using a Clevenger apparatus, and a concentration of 2% nanoemulsion of the essential oil was prepared. The antibacterial effect of essential oil and nanoemulsion of essential oil were evaluated by the microdilution method and the antioxidant property of essential oil by the free radical reduction method. To evaluate the antibacterial effects, first, 100 µL of the prepared bacterial suspension with a concentration of 105 CFU/mL was inoculated to the surface of samples and then treated. To create a coating on the fish fillet, the pieces were immersed for 2 minutes in different treatments including sterile physiological serum (control), pure sodium caseinate coating solution, caseinate coating solution containing essential oil and caseinate coating solution containing essential oil nanoemulsion. The samples were dried for 2 minutes at room temperature and under sterile conditions to form the desired edible coating . The samples were stored for 15 days in a refrigerator and were examined every 3 days.
Results: Thymol (53.4%) was identified as the most important compound in the chemical composition of Oliveria decumbens essential oil. The MIC and MBC of of essential oil for Pseudomonas aeruginosa bacteria is 10 and 20 mg/ml, respectively, and against Listeria monocytogenes bacteria, 2.5 and 5 mg/ml, respectively. The MIC and MBC of essential oil nanoemulsion for Pseudomonas aeruginosa bacteria, it was 2.5 and 10 mg/ml, respectively, and for Listeria monocytogenes bacteria, it was 1.25 and 2.5 mg/ml, respectively. The antioxidant activity of Oliveria decumbens essential oil and nanoemulsion was 1456.95 and 757.29 µg/µl, respectively. Treatment with sodium caseinate containing essential oil or sodium caseinate containing nanoemulsion of Oliveria decumbens essential oil could significantly reduce the amount of Listeria monocytogenes and Pseudomonas aeruginosa inoculated in fish fillet during 15 days of storage in refrigerator temperature (P <0.05).
Conclusion: Results of this study have shown that coating of sodium caseinate containing nanoemulsion of Oliveria decumbens essential oil is effectively capable of inhibiting the growth of Listeria monocytogenes and Pseudomonas aeruginosa in rainbow trout fillets at cold temperatures. Furthermore, the nanoemultion can be used in food industries.
Keywords
Main Subjects
)