Evaluation of the effectiveness of a new active packaging film containing natural antioxidants (from barley husks) that retard lipid damage in frozen Atlantic salmon (Salmo salar L.) D.A. Pereira de Abreu a , P. Paseiro Losada a , J. Maroto b , J.M. Cruz c, * a Department of Analytical Chemistry, Nutrition and Bromatology, Faculty of Pharmacy, University of Santiago de Compostela, 15782-Santiago de Compostela, Spain b Centro Tecnológico del Mar (CETMAR). C/Eduardo Cabello s/n. E-36208 Bouzas-Vigo, Spain c Department of Chemical Engineering, E.T.S.E.I., University of Vigo, 36200-Vigo (Pontevedra), Spain article info Article history: Received 12 February 2010 Accepted 8 March 2010 Keywords: Salmon Oxidation Natural antioxidant Active packaging Food safety Lipid oxidation abstract Salmon is a perishable fish that contains high level of PUFAs (polyunsaturated fatty acids), which have many positive effects on human health, but which are extremely susceptible to oxidation. The develop- ment of new food packaging films by incorporation of antioxidants is expected to improve the shelf life of food and thus increase consumer safety and health. Determination of peroxide value (PV), conjugated dienes (CD), conjugated triene hydroperoxides (TH), free fatty acids (FFA), totox value (TV), thiobarbituric acid index (TBARS) and p-anisidine value (AV) by established methods proved suitable for studying lipid hydrolysis and primary and secondary lipid oxidation in samples of salmon during frozen storage. The results obtained confirm the efficacy of natural antioxidants derived from barley husks (NABH) in slowing down lipid hydrolysis and increasing the oxidative stability of salmon flesh. This study demonstrates the potential usefulness of natural antioxidants extracted from barley husks in the development of active packaging films for food preservation. Ó 2010 Elsevier Ltd. All rights reserved. 1. Introduction Fish flesh contains long chain polyunsaturated fatty acids with a variety of health benefits (Abeywardena & Head, 2001; Baybutt, Rosales, Brady, & Molteni, 2002; Chagan, Ioselovich, Asherova, & Cheng, 2002; Fantoni, Cuccio, & Barrera-Arellano, 1996; Herrera, 2002; Rafflenbeul, 2001; Uauy & Valenzuela, 2000). However, poly- unsaturated fatty acids are highly susceptible to undergoing oxida- tion reactions and their composition varies largely between species (Aidos et al., 2002; Gamazo-Vázquez, García-Falcón, & Simal-Gánd- ara, 2003; Jensen, Birk, Jokumsen, Skibsted, & Bertelsen, 1998; Ka- mal-Eldin & Yanishlieva, 2002; Kulas, Olsen, & Ackman, 2002; Yanishlieva & Marinova, 2001). Oxidation of fats is one of the most important mechanisms leading to food spoilage, second only to alterations produced by microorganisms. The oxidation of lipids in food leads to a reduction in shelf life due to changes in taste and/or odour, deterioration of the texture and functionality of the muscle, and a reduction in nutritional quality. In live organisms, the oxidative damage suffered by macromol- ecules is controlled by two types of antioxidant systems. One is represented by the enzymes that eliminate reactive oxygen species such as superoxide, hydrogen peroxide and lipid hydroperoxide, and includes superoxide dismutase (SOD), catalase (CAT) and per- oxidases. The other group of antioxidant compounds are generally of low molecular weight and may be soluble in polar or apolar sol- vents, and react with free radicals to form less reactive compounds. Examples of these are ascorbate, polyphenols and glutathione, which are soluble in polar solvents, while tocopherol and ubiquinol (reduced coenzyme Q) are soluble in apolar solvents. When organ- isms die, the flesh deteriorates rapidly due to the action of different mechanisms, such as microbiological growth, endogenous enzyme activity and lipid oxidation. Oxidation is a chain reaction, i.e., once started, it further accel- erates the oxidation of sensitive substances. This is a complex pro- cess that occurs in stages: initial, auto-oxidation and final phase. During each stage, products are formed at fluctuating rates. Hydro- peroxides (primary oxidation products) are formed when molecu- lar oxygen and unsaturated fatty acids are combined in the presence of a catalyst, such as iron, copper, enzymes, heat, light, etc., during the initial stage. Peroxide compounds are reactive and can combine with fats to form additional reactive products during the auto-oxidation stage. Secondary oxidation products, al- kanes, alkenes, aldehydes and ketones, are formed during the final stage. These compounds are volatile, and are responsible for rancid odour characteristic of decomposed fish. Aldehydes can form cross-links with different compounds such as proteins, thereby hardening muscle tissue. Aldehydes, particularly those with two 0963-9969/$ - see front matter Ó 2010 Elsevier Ltd. All rights reserved. doi:10.1016/j.foodres.2010.03.019 * Corresponding author. E-mail address: jmcruz@uvigo.es (J.M. Cruz). Food Research International 43 (2010) 1277–1282 Contents lists available at ScienceDirect Food Research International journal homepage: www.elsevier.com/locate/foodres