Ovos enriquecidos com ômega-3: influência do tempo e da temperatura de estocagem sobre o teor de carotenóides e ácidos graxos

Abstract

Currently there is a growing demand for foods that offer in their composition something extra to improve health such as enriched polyunsaturated fatty acids omega-3 eggs, whose production is performed with the supplementation of these acids in poultry diets. However the unsaturated fatty acids are easily oxidized and the number of unsaturations in the molecules is an important factor to increase the reaction rate. Quantitative information about the temperature and storage time impact on the changes are crucial to achieving quality of eggs from laying to consumption. The experiment was carried out to evaluate the time and storage temperature influence on fatty acids an carotenoids content of enriched omega-3 eggs. Evaluation of total carotenoids, fatty acid content and peroxide, as well as quality parameters, such as Haugh Unit, yolk index and pH were determined in brown enriched omega-3 eggs. A batch of 300 eggs were divided into 2 batches of 150 eggs, classified as A and B. The eggs of batch A were stored at room temperature (average of 26,48ºC and 56% moisture) while the batch B were kept under refrigeration (average of 8,25°C and 32% moisture). The samples were analyzed 4 days after laying (time 4) and every 7 days. At each time (4, 11, 18, 25, 32 and 39) and storage temperatures 12 eggs were analyzed individually to obtain the quality parameters. A pool was made with the raw egg yolks analised and with it the other tests were performed. For statistical analysis, a randomized design in factorial 2 x 6 (storage temperature x storage time) was adopted. The results were submitted to ANOVA and means compared by t test with 5% significance, using the software Sisvar 4.3. The main fatty acids in ω-3 enriched eggs were: C16:0, C18:0, C16:1, C18:1, C18:2, C20:4, C18:3 and C22:6. The quality parameters underwent significant change over the 39 days, being affected mainly at room temperature storage. The Haugh Unit was the one that suffered the greatest change, going from 76,97 to 12,01 in non refrigerated and 76,97 to 58,79 for eggs kept under refrigeration. The total carotenoid content was reduced by 19,79% in out of refrigeration stored eggs and 17,44% in under refrigeration stored eggs. Regarding the content of fatty acids, the storage time significantly influenced the behavior of polyunsaturated fatty acids ω- 3, but not uniformly. At the end of 39 days of study in both storage temperatures, the ω-3 fatty acids (C18:3 and C22:6) were still present in significant amounts in a total of 3,40% of the fatty acid composition of out of refrigeration stored eggs and 3,24% of under refrigeration eggs. Storage temperatures did not significantly affect the amount of polyunsaturated fatty acids ω-3. The peroxide value did not change during the time studied under different storage conditions. The yolks did not show signs of lipid oxidation in relation to storage time and temperature conditions.