Investigation of the effect of essential oil along with nanocoatings containing gums in the development of fish fillet storage time

Impact of alginate coating combined with free and nanoencapsulated Carum copticum essential oil on rainbow trout burgers

Carum copticum essential oil (CEO) is known as a valuable active food and pharmaceutical ingredient with antimicrobial and antioxidant activities. Solid lipid nanoparticles incorporated with CEO can overcome their limitations, namely low physicochemical stability and water solubility. In the current study, the antimicrobial and antioxidant activity of free and nanoencapsulated CEO were measured. The results revealed that although the nanoparticles of CEO had higher DPPH radical scavenging activity compared to free CEO, the antimicrobial activity of free CEO toward Escherichia coli and Listeria monocytogenes was higher than nanoparticles. Fish burger samples coated with free and nanoencapsulated CEO and stored for 12 days at 4°C. Alginate coating without CEO was considered as a control sample. The mean zeta potential, particle size, and polydispersity index (PDI) of nanoparticles were 19.18 ± 0.9 mV, 286.5 ± 18.2 nm, and 0.32 ± 0.01, respectively. The results revealed that lipid oxidation, microbial growth, and production of total volatile basic nitrogen in fish burger samples coated with alginate enriched with nanoencapsulated CEO were lower than free CEO. The main volatile compounds of CEO were para-cymene, γ-terpinene, and thymol, which were responsible for the antioxidant and antimicrobial activity of CEO. The data obtained by the current study suggest the application of alginate coating with CEO in form of nanoparticle to enhance fish burgers' shelf life stored at 4°C.

Influence of Essential Oils on the Microbiological Quality of Fish Meat during Storage

Simple Summary

Fish meat is highly perishable due to its composition and the naturally present microbiota. The food industry aims to provide healthy, safe, and high-quality products to the market. Several strategies, including the use of natural preservatives, may be used to enhance food shelf life, and they can also be combined with others, such as vacuum packaging. This being the case, essential oils are natural plant components that, due to their composition, possess high antimicrobial and antioxidant effects, and are therefore good candidates to be tested as fish preservatives together with vacuum packaging. In the present study, essential oils from Citrus lemon and Cinnamomum camphora were added to rainbow trout meat for evaluating the microbiological quality (counts of bacteria and identification of present microbiota) of the fish when vacuum packed and stored for 7 days at 4 °C. Our results show that lemon (0.5% and 1%) as well as C. camphora essential oils (0.5% and 1%) had a positive effect on the microbiological quality of fish meat, keeping a high microbial quality of the fish fillets during 7 days of cold storage. The use of these essential oils in combination with vacuum packaging is beneficial in extending the shelf life of rainbow trout meat. All isolated species under the tested conditions are identified in the present study; such information will be useful for the future development of preservation methodologies that target isolated microorganisms, which will enable the food industry to enhance the shelf life and safety of fish.

Abstract

The aim of the present study was to evaluate the microbiological quality of rainbow trout meat treated with essential oils (EOs from Citrus limon and Cinnamomum camphora) at concentrations of 0.5% and 1.0% in combination with vacuum packaging during storage. The composition of the EOs were analyzed by gas chromatography coupled with mass spectrometry, and total viable counts (TVCs), coliform bacteria (CB), and lactic acid bacteria (LAB) were determined on the zeroth, first, third, fifth, and seventh days of storage at 4 °C. Individual species of isolated microorganisms were identified using a MALDI-TOF MS Biotyper. The results show that the major components of the EOs were linalool (98.1%) in C. camphora and α-limonene in C. limon. The highest number of TVCs and CB were 4.49 log CFU/g and 2.65 log CFU/g in aerobically packed samples at the seventh day. The lowest TVCs were those of samples treated with 1% C. camphora EO. For CB the most effective treatment was 1% lemon EO. LAB were only detected in a few samples, and were never present in aerobically packed samples; the highest number of LAB was 1.39 log CFU/g in samples treated with 1% lemon EO at day seven. The most commonly isolated coliform bacteria were Hafnia alvei, Serratia fonticola, Serratia proteamaculans, Pantoea agglomerans, and Yersinia ruckeri. Lactobacillus sakei, Staphylococcus hominis, and Carnobacterium maltaromaticum were the most frequently isolated bacteria from lactic acid bacteria. In conclusion, C. camphora EO at a concentration of 1% showed the highest antimicrobial activity.