| A great number of wasted materials--viscera, head and skin are produced duringprocessing of squid, which account for about20%of the total weight of squid. In2009, squid fishing production of China was more than350thousand tons and it isincreasing year by year. Therefore, converting these wasted materials to highly valueeconomic products is highly desired. In this paper, viscera of squid which are bigproportion in those wasted materials were researched. Extraction and refinement offish oil, deodorization of enzymatic hydrolysates were studied.Firstly, the basic nutrient constituents of fresh squid viscera were determined bygeneral methods. The results showed content of protein of the pancreas was about21.75%,and that of crude fat was22.00%, moisture was55.83%. Besides that, the squid viscerawere rich in7essential amino acids which were49.55%of total amino acids.Secondly, three different methods were studied in extracting fish oil from squidviscera which are regarded as the industry processing wastes. In diluted alkalihydrolytic method, the conditions of fish oil extraction, including pH, hydrolysis time,temperature, liquid-solid ratio, and NaCl quantity, were optimized. Results showedthat, under the condition of pH9.0,90minutes’ hydrolysis, temperature80℃,liquid-solid ratio1:1.5, and quantity of NaCl4%, the extraction rate was69.3%.According to SC/T3502-2000, the fish oil extracted by diluted alkali hydrolyticmethod accorded with the secondary standard of the refined fish oil. The content ofPUFA was50.81%by GC. The PUFA were mainly consisted of EPA and DHA, whosecontents were13.33%and29.91%, respectively. In the method of animal proteolyticenzymes hydrolysis, conditions of fish oil extraction were analyzed, including pH,liquid-solid ratio, the amount of enzyme, hydrolysis time and temperature. Theoptimal process parameters were hydrolysis time4h, pH7.0and the dose of enzyme(E/S)500u/g, liquid-solid ratio1:0.5, and reaction temperature50℃. Under theseconditions, the extraction of fish oil was76.1%, acid value of this fish oil was high--67.15mg/g. The total content of PUFA was38.34%in the fish oil, the contentsof EPA and DHA were11.49%and22.14%, respectively. In the method of alkaliprotease hydrolysis, conditions of fish oil extraction were analyzed, including pH,liquid-solid ratio, the amount of enzyme, hydrolysis time and temperature. Theoptimal process parameters were obtained by RSM: hydrolysis time4h, pH8, anddose of enzyme (E/S)900u/g, solid to liquid ratio1:0, temperature50℃. Underthese conditions, the extraction rate of fish oil was65.68%. The acid value of fish oilwas14.8mg/g; the other physical and chemical properties of this fish oil wereaccorded with the second grade of crude fish oil for SC/T3502-2000. The content ofPUFA was50.97%by GC. The PUFA were mainly consisted of EPA and DHA, whosecontents were15.19%and28.71%respectively.Thirdly, fish oil extracted by three different methods was refined. To the fact thatfish oil extracted by the method of animal proteolytic enzymes hydrolysis from squidviscera was of high acid value, which restricted its application. Firstly, sodiumbisulfate was used to catalyze the reaction of ethyl esterification, then deacidification,decolorization, deodorization were done to refine it. Fish oil extracted by the othertwo methods was of low acid value, conventional process was used to refine it. All therefined fish oil was low-acid-valued、yellowish and clarified, with very light fishlikesmell, physical and chemical indexes accorded with the first grade of refined fish oildemand for SC/T3502-2000standard.Fourthly, deodorization of enzymatic hydrolysates was done. Sensory evaluationand recovery rate of protein were taken on as indexes, the optimal process parametersof deodorization to squid viscera enzymatic hydrolysates were gotten by doing singlefactor experiment, which were yeast powder amount2.5%, yeast powder fermentationtime30minutes, β-CD amount2.5%, β-CD reaction temperature65℃, β-CDreaction time30minutes. Under these conditions, recovery rate of protein was89.45%, score of sensory evaluation was4.In this study, fish oil of high quality and enzymatic hydrolysates that are rich inpeptide and amino acids are obtained. Crude fat and protein in squid viscus are madefull use of and there is no new waste generated in this process. A new field is initiated for squid industry even the entire aquatic products processing industry of China. |
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