Elsevier

Food Chemistry

Volume 120, Issue 1, 1 May 2010, Pages 193-198
Food Chemistry

Effect of chitosan coatings enriched with cinnamon oil on the quality of refrigerated rainbow trout

https://doi.org/10.1016/j.foodchem.2009.10.006Get rights and content

Abstract

The effects of a chitosan (Ch) coating enriched with cinnamon oil (Ch + C) on quality of rainbow trout (Oncorhynchus mykiss) during refrigerated storage (4 ± 1 °C) were examined over a period of 16 days. A solution of Ch (2%, w/v) and Ch + C (2%, w/v Ch + 1.5%, v/v C) was used for the coating. The control and the coated fish samples were analysed periodically for microbiological (total viable count, psychrotrophic count), chemical (TVB-N, PV, TBA), and sensory (raw and cooked fish) characteristics. The results indicated that the effect of the Ch + C coating on the fish samples was to enable the good quality characteristics to be retained longer and to extend the shelf life during the refrigerated storage.

Introduction

Edible coatings from polysaccharides, proteins, and lipids can extend the shelf life of foods by functioning as solute, gas, and vapour barriers. Chitosan (poly-β-(1–4)-d-glucosamine) is a versatile biopolymer, having a broad range of applications in the food industry (Kanatt, Chander, & Sharma, 2008). It has been reported to have a number of functional properties that make chitosan useful in nutrition (Shahidi, Arachchi, & Jeon, 1999); these include its antimicrobial activity and its ability to form protective films or coatings (Jeon, Kamil, & Shahidi, 2002), its binding action (Shahidi et al., 1999) and antioxidant activity (L´opez-Caballero, G´omez-Guill´en, P´erez-Mateos, & Montero, 2005). Fresh fish is highly perishable due to its biological composition. Spoilage of fish muscle results from changes brought about by biological reactions such as oxidation of lipids, reactions due to activities of the fish’s own enzymes, and the metabolic activities of microorganisms. These activities lead to a short shelf life in fish and other seafood products (Arashisara, Hisara, Kayab, & Yanik, 2004).

Numerous studies have indicated that lipid oxidation in fish and fish products may be curtailed through the use of chitosan (Jeon et al., 2002, L´opez-Caballero et al., 2005, Sathivel et al., 2007, Tsai et al., 2002). However, chitosan does not have significant antioxidant activity (Kanatt et al., 2008).

Spices and herbs have been used in many cuisines to impart flavour, aroma and pungency to food (Kanatt et al., 2008). Several studies have shown that the antimicrobial and antioxidative effect of chitosan was greatly enhanced by the addition of chitosan to essential oils (Georgantelis et al., 2007, Kanatt et al., 2008). Cinnamomum zeylanicum (L.), commonly known as cinnamon is rich in cinnamaldehyde as well as β-caryophyllene, linalool and other terpenes. Cinnamaldehyde is the major constituent of cinnamon leaf oil and provides the distinctive odour and flavour associated with cinnamon. It is used worldwide as a food additive and flavouring agent, and the Food and Drug Administration lists it as “Generally Recognized as Safe-GRAS” (Tzortzakis, 2009). Earlier studies have shown that cinnamon has a good antioxidant and antimicrobial potential (Du and Li, 2008, Ouattara et al., 1997, Shan et al., 2007, Tzortzakis, 2009).

Incorporation of essential oils into chitosan films or coatings may not only enhance the film’s antimicrobial and antioxidant properties but also reduce water vapour permeability and slow lipid oxidation of the product on which the film is applied (Yanishlieva, Marinova, Gordon, & Raneva, 1999).

Development of natural preservative coatings or films with high antioxidant, antibacterial activities that prolong the shelf life of fish and fish products is desirable. The objective of this study was to determine the potential of chitosan and chitosan enriched with cinnamon oil as an antioxidant and antibacterial coating in preservation of rainbow trout fresh fillets.

Section snippets

Fish sample preparation

Fresh water rainbow trouts with an average weight of 550–600 g were purchased at a public market alive and were transferred to the Meat Processing Laboratory in Food Science Department at Tehran University, decapitated and filleted by hand. The fish were harvested during the period of January–March 2009. Two fillets were obtained from each fish after removing the head and bone.

Preparation of coating solutions and treatment of fish fillet

Food grade essential oils (EO) of cinnamon were purchased from Zardband Essential Oil Co., Tehran, Iran. Medium

Proximate composition

The mean (±SD) compositional contents of moisture, protein, lipid, and ash (g/100 g fish muscle) in the rainbow trout fillet analyzed were 69.70 ± 2.13, 23.21 ± 0.36, 2.2 ± 0.37, and 4.12 ± 0.3, respectively. The proximate composition of the rainbow trout fillet reported in different studies (Chen et al., 2008, Gonza´lez-Fandos et al., 2005) showed some differences especially for the lipid content. Such variations in the chemical composition of fish is strongly related to the nutrition, catching season

Conclusions

Successful inhibition of lipid oxidation and microbial growth in refrigerated rainbow trout fillet was possible with Ch + C (chitosan and cinnamon oil) coating, as together they kept the sensory characteristics within acceptable limits throughout storage. Ch + C treatment could maintain trout fillet shelf life till the end of the storage period (day 16) without any significant loss of texture, odour, colour or overall acceptability and without significant microbial growth, while control samples had

Acknowledgements

The authors wish to thank Ellen Vuosalo Tavakoli for the English editing.

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