engleski

Effect of maize hybrid antioxidant potential on egg yolk oxidative stability – correlation analysis

Lipid oxidation during food production and processing is of main concern today. Due to the egg shell stability, severe oxidation in egg yolk will not occur before processing. These conditions are usually tested in induced oxidation methods. Major preventive factors of lipid oxidation are natural or synthetics antioxidants. Yellow maize grain, paramount cereal in poultry nutrition, is the cereal offering significant concentrations of natural antioxidants: carotenoids, vitamin E, and phenols. The objective of the study was to explore the relationship between distinctive amounts of antioxidants found in maize hybrids and oxidative stability of eggs during induced oxidation. In total 90 hybrid Tetra-SL lying hens were fed diets based on five different maize hybrids (Bc 572, Mejaš, Kekec, Pajdaš and Riđan) while control diet contained hybrid of unknown origin. The hens were grouped, three in one cage, in a random block design with five repetitions per hybrid. Levels of carotenoids and tocols in hexane extracts were determined using HPLC while bound, free and total phenols and flavonoids were determined spectrophotometrically using the Folin- Ciocalteu reagent (galic acid equivalents) and Al-complexation reaction (catechin equivalents), respectively. The Fe- induced lipid oxidation measured as TBARS was used to determine oxidative stability of egg yolks. Egg yolk stability was significantly affected by maize hybrid (P<0.001), which differed in contents of all evaluated natural antioxidants (P<0.001). Their contents varied as follows, all on DM basis: lutein (6.21-12.27 μg/g), zeaxanthin (9.63-16.66 μg/g), β- kryptoxanthin (1.22-2.79 μg/g), β-carotene (1.87-2.90 μg/g), total tocols (69.10-89.76 μg/g), bound phenols (3575-4824 μg/g), free phenols (959-1289 μg/g), total phenols (4620- 5784 μg/g), bound flavonoids (639.4-835.4 μg/g), free flavonoids (142.2-280.0 μg/g) and total flavonoids (821.8- 978.2 μg/g). The correlation analysis showed negative correlation between concentration of TBARS substances and contents of lutein (P<0.05), total tocols (P<0.05), free phenols (P<0.01), bound phenols (P<0.001), total phenols (P<0.001), free flavonoids (P<0.001) and total flavonoids (P<0.001). Results clearly show that antioxidant properties of maize hybrids define egg yolk oxidative stability. In order to minimise expenses and effects of possible lipid oxidation during processing of shelled eggs animal nutritionists should choose maize hybrids not based only on their energy value and should account them for their antioxidant potential.

Antioxidants ; Egg yolk ; Maize hybrids ; Oxidative stability

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