Development Of A Caked Snack Food Based On The Egg Of Large Yellow Croaker And Study Of Its Fat Stability

Large yellow croaker (Pseudosciaena crocea) is a kind of pseudosciaena, which belongs to Queenfishes. It is one of the four major traditional seafood in our country and chiefly produced in Ningde Fujian, where its annual output has been close to 67 thousand tons. The egg of large yellow croaker was usually discarded as waste during the processing of the dried salted yellow croakers and not fully used. In this study, to improve the added value and comprehensive utilization of large yellow croaker, the egg of large yellow croaker was used to develop a snack food–caked fish egg. The effect of the temperature, packaging, light and anti-oxidants on fat stability of the caked fish eggs during storage was also investigated. The shelf life prediction model was established to provide adequate theoretical basis for predicting and extending the shelf life of the caked fish egg. The major achievements and results were concluded as follows:1. The basic chemical composition of the egg of large yellow croaker were as follows: protein 23.00%, fat 19.60%, and ash 4.14%. The ratio of monounsaturated fatty acids and polyunsaturated fatty acid to total fatty acid in egg of large yellow croaker was up to 47.40%.2. The optimum de-fishy condition of the egg of large yellow croaker was researched in this paper. It was showed that the smell of the egg of large yellow croaker could be removed effectively by the de-fishy liquid which was composited of white vinegar 0.75g/L and ginger juice 0.75g/L. The optimal condition of de-fishy was concluded as follows: the temperature of the de-fishy liquid 30℃, the time of the de-fishy 180min, the ratio of the egg of large yellow croaker to the solution 1∶5.3. The method of fuzzy mathematics comprehensive evaluation was applied to in this study, and the model of fuzzy comprehensive evaluation was established. The results showed that the best formula of the caked fish egg was that maltodextrin 5.0%, Carrageenan 2.0%, salt 1.0%, and sugar 6.0%.4. The effect of the storage temperature on the caked fish egg was researched. It was showed that the TBARS value, POV and AV of the caked fish egg were on the upward trend basically under different temperatures during storage, and the temperature effect on the various indicators of fat oxidation was significant(P<0.01), the higher the temperature was, the faster the oxidative rancidity of fat. Therefore, the caked fish egg were required stored at low temperatures as far as possible.5. The relation between the determination indicators of fats oxidation and the sensory evaluation was researched. It was showed that, the quality of the caked fish egg was declined and the brightness of the caked fish egg was decreased during storge, while redness and yellowness were increased. It was showed that the relation between the TBARS value, POV and AV of the indicators of fat oxidation and sensory evaluation was significant correlation(︱P︱>0.9)according to the Pearson correlation coefficient which was obtained by the sensory evaluation of the caked fish egg (sensory score, L, a, b) and determination of indicators and fat oxidation (TBARS, POV, AV) measured during storage. It was indicated that the three indicators could be used as quality indicator of the caked fish egg.6. The effect of different packaging on the caked fish egg was researched. It was showed that the value of all determination indicators (TBARS, POV, AV) of the caked fish egg with vacuum packaging stored at 25℃were less than that with normal packaging. It was revealed by significant analysis that the effect of different packaging on the POV of the caked fish egg was extremely significant, TBARS value and AV were also significant. It was showed that the rate of fat oxidation of the caked fish egg by vacuum packaging was inhibited to some extent.7. The effect of the light on the caked fish egg was researched. It was showed that the value of determination indicators of the caked fish egg with dark packaging stored at 25℃was less than packaging with light. It was revealed by significant analysis that that the effect of light on the POV of the caked fish egg was extremely significant, TBARS value and AV were significant. It was showed that the rate of fat oxidation of the caked fish egg was accelerated by the light to some extent.8. According to the index of POV, the antioxidant effect of several antioxidants and synerg on the caked fish egg were studied by Schaal experiment. It was showed that the order of single antioxidant activity was TP>VE>VC, the antioxidant combined with TP 0.01% and VE 0.01% had good antioxidant activity for the caked fish egg, and was better than single TP, citric acid has synergistic effect on it. TP 0.01%, VE 0.01% together with citric acid 0.01%was identified as the best antioxidant of the caked fish egg.9. The changes of the AV of the caked fish egg with the storage time under different storage temperature was studied, the dynamic model between the AV and storage temperature, storage time were established respectively, which was to predicted the quality changes and shelf life of the caked fish during storage. It was indicated that the change of the AV had a highly fitting accuracy to first order chemical reaction and Arrhenius equation, and the Ea, k_a0 of the AV change reaction were calculated when the caked fish egg were packaged in different packaging, that was 41.67 kJ/mol, 5.290×10⁵ when the caked fish egg with normal packaging, and 47.74 kJ/mol, 5.515×10⁶ when the caked fish egg with vacuum packaging. The reference to predict the quality changes and shelf life of the caked fish egg with different packaging during storage was provided by the dynamic model, and the shelf life of the caked fish egg with two kinds of packaging among three kinds of temperatures were predicted based on the dynamic model, the results as follows: 297 days(20℃), 223 days (25℃)and 167 days(30℃) when the caked fish egg with normal package; 344 days(20℃), 248 days (25℃)and 180 days(30℃) when the caked fish egg with vacuum packaging.