Natural antioxidant assessment: Stabilizing effect on marine lipids

Transcription

1 Natural antioxidant assessment: Stabilizing effect on marine lipids Introduction Polyunsaturated fatty acids (PUFA) are readily oxidised by molecular oxygen. This beta-oxidation means a corrosion of the unsaturated compounds, which results in rancidity of the fats and consequently to a decrease in product quality after processing of these fats. Fishmeal and fishoil contain relatively high concentrations of PUFAs and are therefore especially prone to oxidation. To prevent the oxidation of fishmeal and oil, the industry currently uses synthetic antioxidants like ethoxyquin (E 324) and BHA (butylated hydroxy anisol, E 320) and BHT (butylated hydroxy toluene, E 321). Antioxidants prevent the oxidation of the fatty acids by preferential reaction with oxygen. However, there have been concerns about the possible negative health effects of ethoxyquin and other synthetic antioxidants (National Toxicology Program, 1990; Addis PB, Hassel CA. Safety issues with antioxidants in foods. ACS symposium series, 484. Washington, DC:American Chemical Society, 1992; ). Ethoxyquin is therefore not allowed for use in foods (only in animal feed) in the European community, Japan and Canada. There are a number of regulations for the use of ethoxyquin: - In the European Community, the use of ethoxyquin is approved for all animal feeds (except for dog feed), up to a maximum concentration (by itself or together with BHA (E 320) and/or BHT (E 321)) of 150mg/kg (= 150ppm). It is proven, that ethoxyquin passes from animal feed into the animal products. In the maximum residue regulation of the European Community (Rückstands-Höchstmengenverordnung, RHmV 1 Abs. 4 Nr. 1), a maximum residue of 0.01mg/ kg food has been defined. - The maximum quantity of ethoxyquin permitted to be used in dehydrated forage crops and treated poultry feed is 150 ppm [Office of the Federal Register, 1990]. - The FDA has established a tolerance of 0.5 ppm for residues of ethoxyquin in or on the uncooked meat and meat by-product (including milk and eggs) and 5.0 ppm for cooked meat and meat by-products of animals fed forage crops or feed supplements treated with ethoxyquin. For uncooked liver and fat of poultry fed treated feed, a tolerance of 3.0 ppm has been established. Tolerance residues of 3.0 ppm have been set for apples and pears [Office of the Federal Register, 1989, 1990]. - The World Health Organization has established an acceptable daily intake of 0.06 mg/kg of ethoxyquin for humans [FAO/WHO, 1977].

2 However, there are natural antioxidants (e.g. tocopherols, rosemary) that can potentially be used to stabilize fishmeal and oil. In this study, the effectivity of different antioxidant candidate products should be compared. 2 Material and methods Natural antioxidants, i.e. a blend of components that are extracted from natural sources, have been tested for antioxidative capacity on fish oil and on the residual lipids of dried fish press- cake, respectively. The results have been compared to that of synthetic antioxidants that most commonly are used to stabilize fish oil (i.e. BHT) and fish meal (i.e. ethoxyquin). Methods: Test method on fish oil. Salmon oil that contained the recommended amount of antioxidant, was transferred to a glass flask and incubated at 40 C. Air was led through the oil sample. Aliquots were taken for oxidation analyses at start of the incubation and after 2; 5; 20; 24; and 28 hours. The aliquots were immediately analysed for peroxide value (primary oxidation products; AOCS-Method Cd-8b-90) and anisidin value (secondary oxidation products; AOCS-Method Cd-18-90). Test method on press-cake. Press-cake was made from mackerel. Samples of 1kg press-cake were transferred to plastic bags and frozen. The respective antioxidants were mixed into 1 kg batches of the press-cake. The press-cake contained 60% water. The recommended amount of antioxidant (i.e. ppm calculated on dry-matter content) was dissolved in 10 ml ethanol and blended in the wet press-cake that successively was dried in a fluid-bed dryer (hot air at about 105 C was led through the material). Immediately, the dried material was transferred to a flask. The sealed flask contained an oxygen detector that detects atmospheric O 2 -gass in the in the flask ( OxyCons analysis). The oxygencontent was recorded during the time of incubation (each 15 min. for 20 hours at 40 C). Two parallels were run for each antioxidant type that was Test samples of antioxidants: Type Recommended concentration (ppm) Natural antioxidants ADM Decanox Mixed Tocopherols MTS ADM Decanox Mixed Tocopherols MTS KEMIN Paradigmox Green (based on tocopherols and gallates) 2000 Substance D (based on rosemary extract ad gallic acid) 2000 KEMIN Paradigmox Blue (based on different gallates) 500 Substance F (based on propylgallate) 750 Substance G (based on tocopherols) 600 ALLTECH Nature Ban Powder (based on tocopherols and rosemary) 1000 ALLTECH Nature Ban Liquid (based on tocopherols and rosemary) 1000 Synthetic antioxidants Butylated hydroxytoluene (BHT; in fish oil) 200 Ethoxyquin (EMQ; in fish meal) 100

3 tested. The oxygen consumption during the period of incubation is a measure for the anti-oxidative potential of that particular antioxidant to stabilise the test material (Pettersen, J., & Bjørnsen, B.H: How to predict oxidative stability of residual fat in fish meal. Proceedings 18 th Scandinavian Symposium on Lipids (Reykjavik, Iceland, June 1995) ). 3 Results and discussion. The test results of the antioxidant capacity on stabilizing salmon oil are shown in Table 1. Only minor variations of the ansidin value (AV) were found during the period of incubation; Incubation Incubation Antoxidant (conc.) time (hours) POV AV Antoxidant (conc.) time (hours) POV AV MTS 90 (400ppm) 0,0 8,4 1,3 Subst. F (750ppm) 0,0 11,0 1,3 2,0 9,3 1,5 2,0 12,0 2,2 5,5 11,0 1,4 5,0 14,0 1,7 20,0 20,9 2,4 22,0 19,0 3,1 24,0 23,3 3,1 25,0 18,0 3,1 28,0 25,7 3,5 28,0 18,0 3,0 MTS 70 (400ppm) 0,0 8,4 1,3 Subst. G (600ppm) 0,0 11,0 1,3 2,0 10,0 1,4 2,0 13,0 1,9 5,5 12,0 1,4 5,0 15,0 1,9 20,0 23,8 2,6 22,0 25,0 3,2 24,0 27,3 3,5 25,0 26,0 3,5 28,0 26,0 3,8 28,0 29,0 3,7 Parad. Green (2000ppm) 0,0 8,4 1,3 Nat. B. Powder (1000ppm) 0,0 11,0 1,3 2,0 11,0 1,2 2,0 13,0 1,9 5,5 9,8 1,1 5,0 16,0 1,8 20,0 14,1 1,5 22,0 20,0 3,5 24,0 14,4 1,7 25,0 25,0 3,7 28,0 16,3 1,8 28,0 24,0 4,0 Subst. D (2000ppm) 0,0 8,4 1,3 BHT (200ppm) 0,0 11,0 1,3 2,0 9,9 1,7 2,0 12,0 1,6 5,5 9,5 1,2 5,0 14,0 1,7 20,0 13,1 1,4 22,0 18,0 2,4 24,0 13,3 2,0 25,0 20,0 2,7 28,0 11,6 2,0 28,0 20,0 2,9 Parad. Blue (500ppm) 0,0 8,4 1,3 Nat. B. Liquid. I (1000ppm) 0,0 11,0 1,3 2,0 8,4 1,6 2,0 13,0 1,4 5,5 9,2 1,3 5,0 14,0 1,7 20,0 12,2 1,5 22,0 20,0 2,7 24,0 12,9 1,8 25,0 22,0 2,8 28,0 12,9 1,9 28,0 25,0 3,0 Table1. Peroxide value (POV) and anisidin value (AV) of incubated salmon oil added different types of antioxidants. The incubation conditions were 40 C with air led through the oil samples. The concentrations of the antioxidants are written in the brackets. both within and between the antioxidant samples. However, the peroxide values (POV) increased significantly during the incubation period and the increments were differently affected by the respective antioxidants.

4 4 The increment of POV and AV, relative to that of the start-values (d(pov) and d(at)), are plotted in the diagrams of Figure 1A and 1B. The diagrams indicate a linear development of POV and AV during the period of incubation and show that the respective antioxidants had different effect on the peroxide values. Thus, the oil samples that contained Substance D and Paradigmox Blue gave lowest oxidation rates, although Substance F, Paradigmox Green and BHT also showed low POV. Figure 1A. The increment of peroxide value (d(pov)) and anisidin value (d(av)) in salmon oil added different antioxidants during incubation at 40 C in 28 hours with air led through the oil sample. Decanox MTS ppm Decanox MTS ppm Paradigmox Green 2000 ppm Substance D 2000 ppm Paradigmox Blue 500 ppm

5 Figure 1B. The increment of peroxide value (d(pov)) and anisidin value (d(av)) in salmon oil added different antioxidants during incubation at 40 C in 28 hours with air led through the oil sample. 5 Substance F 750 ppm Substance G 600 ppm Nature Ban Powder 1000 ppm Nature Ban Liquid 1000 ppm The results of the press-cake tests are shown in Figure 2A and 2B. Except the substance G-test, the results are the average-values of two parallel runs of the respective antioxidants. A failure was observed in the detection system of one of the substance G-parallels and consequently the results from this run were discarded. The parallels recorded for the other antioxidants were almost identical with regard to oxygen consumption during the period of incubation.

6 Figure 2A. 6 O2-consumption (%) Atmospheric O2 O2 consumption (%) (%) during of fish the presscake period of added incubation different of fish types presscake of antioxidants added different and incubated types of at antioxidants 40 C for 20 at hours 40 C in for 100,0 20 hours a sealed flask. 90,0 Parad. Blue Blue 80,0 Fort. Subst. RG16 D 70,0 Parad. Paradig. Green 60,0 MTS-70 50,0 MTS-90 40,0 30,0 20,0 10,0 0, Minutes Figure 2B. Atmospheric O2 consumption during (%) during the period the period of incubation of incubation of fish of fish presscake added added different different types types of of antioxidants at 40 C at 40 C for 20 for 20 hours hours. O2-consumption (%) 100,0 90,0 80,0 70,0 60,0 50,0 40,0 30,0 20,0 10,0 0, Minutes Nat. Nat. B. Liquid Preser Subst. Oil F Vitalox Subst. G Nat. B.Powder EMQ The atmospheric oxygen-content (O 2 ) during the period of incubation was significantly influenced by the type of antioxidant added in the press-cake. The results reveal that, in particular the antioxidant-blend MTS 90 inhibited oxygen consumption. The antioxidants MTS 70, Nature Ban Powder and Paradigmox Green also showed stabilizing effects on the press-cake lipids (Figure 2A, 2B). However, the sample that contained ethoxyquin (EMQ) showed the lowest oxidation rate (Figure 2B). The respective antioxidant-samples showed different capacity, or ability on stabilising fish oil and lipids of the dried press-cake; i.e. the antioxidants were graded differently

7 7 from the oil and press-cake tests. The results showed that substance D and Paradigmox Blue gave the best antioxidative effect on the oil sample, while MTS 90 and MTS 70 gave the lowest protection. Considering the antioxidative effect on the press-cake the conclusion is the almost opposite; MTS 90 and MTS 70 gave the best protection, and substance D and Paradigmox Blue showed significantly less antioxidative effect. This is consistent with the antioxidative effect of EMQ that is an excellent antioxidant in fish meal and feed mixtures, but has insignificant stabilising effect on fish oil. Conclusion. The results showed that some of the natural antioxidants that were tested were almost as good as the synthetic antioxidants that to day are used in fish oil (BHT) and fish meal products (EMQ). However, the results should be considered indicative as we do not know how the antioxidants affect lipidoxidation during the processing of fish meal and fish oil and feed production. Moreover, we have to study and document the nutritional value (e.g. health effects and feed conversion values) of feed lipids that are stabilized with the antioxidants of interest. Acknowledgements This project was financed by the Coop Naturaplan 1 fund. Also we thank the participating companies for providing us with product samples for testing. The antioxidant tests and report were conducted by: Jan Pettersen Fiskeriforskning Kjerreidviken 12, N-5141 Fyllingsdalen, Norway jan.pettersen@fiskeriforskning.no 1 Coop Naturaplan is the organic flagship label of coop supermarket stores in Switzerland. The Naturaplan label stands for organically produced food, as well as meat and eggs from humane animal husbandry with access to free range. The organically produced Naturaplan-products bear the Bio bud logo issued by BioSuisse, Switzerland s umbrella organisation of organic farmers. In the field of Certified Organic Aquaculture, BioSuisse is closely cooperating with Naturland association. The Coop Naturaplan Fund was launched in 2003 to mark the 10th anniversary of the Coop Naturaplan label. The Fund is an expression of Coop s commitment to people, animals and the environment, as outlined in its corporate profile. Coop wants to see its environmental and ethical credentials more firmly institutionalized in business and society and to build on its role as Switzerland s leading supplier of environmental and ethical products and services.

8 8 Company contact: ADM Specialty Ingredients (Europe) B.V Dr. Manfred Peisker Stationsstraat 76, 1541 LJ Koog aan de Zaan The Netherlands Tel Fax Kemin Agrifoods Europa NV Tom Verleyen Technical Service Manager Tel : Mobile : tom.verleyen@kemin.com Alltech (Deutschland) GmbH Dr. Susanne Roth Area Sales Manager Poppenbütteler Bogen Hamburg Germany Tel Fax Mobile sroth@alltech.com