| Blue whiting(Micromesistius poutassou) is a fish with high economic values.During its processing, it can produce a large number of wastes, in which a small part are sold as fodder in a low price, and most are abandoned, which result in a great waste of resources and environmental pollution. Actually, the processing wastes are rich in nutrients, containing fish oil, protein, a variety of physiological active substances and trace elements, etc. Therefore it has broad application prospects in food development health care and other fields. DHA and EPA in fish oil have aroused more and more attention in the field of food and drugs for they play a prominent role in human health.This paper, using processing wastes as experiment material, proposes gradient cooling urea complexation method to establish a method of extraction and separation of DHA and EPA. And subsequents enzymatic hydrolysates after extracting fish oil can be used for the development of the feed or condiment after debitterizing and deodorization. It would improve the utilization of seafood processing wastes, raise the product quality and added value, and reduce environmental pollution, which had important theoretical and practical significance.In this study, the basic nutrient composition of blue whiting heads were analyzed in the first plan. The results indicated contents of protein, crude fat moisture and ash of the blue whiting heads were about 13.72 %, 6.72 %, 75.34 %, and 4.25 %, respectively.Besides that, blue whiting heads contained 17 kinds of amino acids, including 7 kinds of essential amino acids which accounted for 40.07 % of total amino acids.The effects of different methods of extracting fish oil from blue whiting heads were studied. Compared with diluted alkali hydrolysis and enzyme hydrolysis methods, fish oil extraction rate and protein recovery rate of alkaline protease hydrolysis method were highest. The extraction rate of fish oil(72.10 %) was obtained under the conditions of a solid to liquid ratio 1: 1, p H 8.0, dose of enzyme 600 U/g, temperature 50 °C and hydrolysis time 4 h.Production of DHA and EPA concentrates of blue whiting oil from processing wastes by gradient cooling urea complexation was optimized. The optimal process parameters were studied by Design-Expert. A quadratic regression model of the total amount of DHA and EPA was built and the optimal conditions of urea-to-fatty acid ratio3.5, crystallization temperature-12 °C and crystallization time of 12 h were verified and determined. Then direct cooling was substituted for gradient cooling in the urea complexation, which raised the total amount of DHA and EPA methyl ester to 81.42 %.These results would provided vital parameters for large-scale fermentation of EPA and DHA.The method of yeast fermentation combined with activated carbon was selectedafter comparing the effects of three different debitterizing and deodorizing agents on enzymatic hydrolysates after extracting fish oil. Recovery rate of protein and sensory evaluation were taken on as indexes. The recovery rate of protein(84.45 %) was obtained under the conditions of yeast powder amount 1.0 %, fermentation temperature30 °C, fermentation time 1.0 h, active carbon amount 0.6 %, active carbon reaction temperature 40 °C, active carbon reaction time 40 min. And under this conditions,sensory index is good.In this research, alkaline protease hydrolysis method was used to extract fish oil.Gradient cooling urea complexation method was proposed for the first time to establish a method of extraction and separation of DHA and EPA. Debitterizing and deodorizing of enzymatic hydrolysates after extracting fish oil were studied. The results provided an important theoretical basis to produce high value-added products for the depth development of processing wastes from the blue whiting heads. |
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