The Effects Of Deacid Agents On Deacidification And Quality Influence Of Dosidicus Gigas

Dosidicus gigas with larger body, rapid growth, abundant resources, has thecharacteristics of high protein, low fat and low cholesterol. It is a kind of nutritious anddelicious food and good seafood processing raw materials. But D. gigas has a sour taste,which seriously affects its taste and eating quality, hinders the diversification, and also isan important constraint in the deep processing and utilization of D. gigas. Currently, themarket is using some expensive deacid agents to deacidificate on D. gigas. Therefore,developing an effective, inexpensive deacid gent has important implications for improvingthe eating quality, reducing the cost of production, and promoting diversification ofproducts.The topic used D. gigas as the research object, and screened four single deacid agent（sodium hexametaphosphate, ethyl maltol, sodium citrate and sodium polyphosphate）, anddetermined the optimal condition and the best ratio of composite deacid agent whichcomposed by the four by orthogonal experiment and response surface methodology. Andthen the quality change of D. gigas during immersion process has been studied. Finally, itfurtherly studied changes of physical and chemical properties during frozen storage atdifferent temperatures, which can provide a theoretical basis to quality change of D. gigasduring storage. Test results are as follows:1. Single factor experimental results showed that Sensory scores, pH value, TVB-Nvalue, the electronic nose analysis results, texture profile analysis, myofibril protein andCa²⁺-ATPase activity of myofibril protein of D. gigas soaking in different concentrationsof deacid agent and different soaking time were different. Sodium hexametaphosphate,potassium sorbate, disodium hydrogen phosphate, ethyl maltol, sodium tripolyphosphate,sodium citrate and sodium polyphosphate these seven deacid agent had some effect ofdeacidification under2℃environment. And sodium hexametaphosphate, sodium citrate,ethyl maltol and sodium polyphosphate had a better effect of deacidification. The optimalconcentration of deacidification respectively was0.5g/L,0.08g/L,0.7g/L and0.7g/L,optimum soaking time respectively was8h,10h,8h and8h. Compared with the controlgroup, D. gigas soaking in the deacid agent could significantly improve the sensory quality, raise the pH and reduce the TVB-N value, making characteristic odor ingredients of squidblock changed, and sour taste weakened. Compared with other deacid agents, sodiumhexametaphosphate, sodium citrate, ethyl maltol and sodium polyphosphate had smallerimpact on the quality of D. gigas, the flexibility, myofibrillar protein and its Ca2+-ATPaseactivity is small, the hardness and cohesiveness is lower than other deacid agents treatmentgroups.2. By using the orthogonal method to investigate the pH value and sensory evaluationof D. gigas block which soaking in composite deacid agent8h with the temperature of2℃and the material ratio of1:3, it ultimately determined the best concentration ofcomposite deacid agent was sodium hexametaphosphate0.6g/L, ethyl maltol0.09g/L,sodium citrate0.6g/L, sodium polyphosphate0.8g/L. By using response surfacemethodology to optimize conditions of deacidification, we assured that the optimaldeacidification conditions are as follows: soaking time8.26h, temperature6℃, materialratio0.35.3. Quality changes of D. gigas during soaking in composite deacid agent8.25h with6℃temperature and the material ratio of1:3were studied. The results showed that: as theimmersion time increased, the composite deacid agent could effectively improve theorganoleptic quality, increase muscles’ pH, reduce TVB-N value to a relatively low level,and also can effectively remove volatile characteristic odor of D. gigas. With the increaseof immersion time, the hardness, springiness and cohesiveness of D.gigas were declined.The total protein, myofibril protein content and its Ca²⁺-ATPase activity decreased withthe increase of immersion time.4. Finally, quality changes of D. gigas storaged at temperature of-18℃and-22℃after treatment with composite deacid agent were studied. The results showed that: underdifferent storage temperatures, quality changes of D. gigas were different, but they had thesame change trend. Under different storage temperatures, with storage time increased, pHvalue showed an upward trend and then a dounward trend, and characteristic odor of D.gigas changed and finally made aromatic ingredients, organic sulfides, sulfides andnitrogen oxides become the main odor identification markers of D.gigas muscle. Moisture content, L*value decreases and TVB-N values increased, and the hardness, springinessand cohesiveness of D.gigas were declined. The total protein, myofibril protein contentand its Ca²⁺-ATPase activity also decreased. With increasing storage time, the quality of D.gigas would deteriorate. The lower the storage temperature was, the smaller the qualitychanged. Storage temperature-22℃could better maintain the quality of D. gigas thanthe temperature of-18℃.