SHELF LIFE OF EGGS FROM HENS FED DIETS RICH IN POLYUNSATURATED FATTY ACIDS AND ANTIOXIDANTS UNDER THE EFFECT OF DIFFERENT STORAGE TIME AND TEMPERATURES

We investigated the effectiveness of diets enriched with natural sources of polyunsaturated fatty acids and antioxidants on shelf life, internal and external quality parameters of eggs in different storage time and temperature. The diets given were as follow: basal diet (C), a diet containing mixture of rapeseed and grapeseed meal (T1) and a diet containing mixture of flaxseed and sea buckthorn meal (T2). A total of 108 eggs were selected (36 eggs/group) and were separated into 6 batches with 6 eggs in each. The experimental design was consisted of 3 storage periods (0, 14 and 28 days) and 2 storage temperatures (5 degrees C, 21 degrees C). Each egg was weighed and broken, and the physiochemical properties of eggs such as albumen, yolk and eggshell weight, eggshell thickness and breaking strength and the most important freshness parameters Haugh Unit (HU), albumen and yolk pH were determined using an Egg Analyzer TM, manufactured by Orka Technology Ltd. The egg, albumen, shell weight and HU significantly decreased with increasing storage time and temperature, especially for eggs stored at 21 degrees C for 28 days from C group. The albumen and yolk pH significantly (P<0.05) increased with increasing storage time and temperature in all samples, but those from group C were significantly (P<0.05) higher compared with eggs from T1 and T2 groups. The interaction effects between the storage time and temperature were significant for all determined parameters, which can conclude that storage time and temperature are the major factors affecting egg quality, but temperature is a more sensitive determinant of egg quality deterioration compared with the storage period. Eggs from groups fed diets rich in polyunsaturated fatty acids and antioxidants significantly (P<0.05) delayed egg deterioration in both storage temperatures.