Quality Changes And Mechanisms Of Functional Lipids In Antarctic Krill During Storage

Antarctic krill(Euphausia superba),the largest marine invertebrate biomass in the southern ocean,is riched in protein,the human body necessary amino acid and calcium,potassium,magnesium,strontium and other mineral elements,also containing phosphorylated peptide,EPA/DHA phospholipids,astaxanthin esters and other functional food ingredients.So it has higher nutritional value.As a new resource of marine high quality protein and active lipid,Antarctic krill has become the most important development object in the world.The development and utilization of functional lipids is an important component of Antarctic krill processing industry,and is also a key driving force for the development and utilization of Antarctic krill resources.However,it is easy to change the quality of Antarctic krill lipids in the process of storage and processing of Antarctic krill from raw materials to products.There are few reports about its change rule and internal mechanism Therefore,it is of great significance to clarify the mechanism of lipid quality change and to form the basic quality and storage technology of Antarctic krill.Object of this paper: Study on the quality change of functional lipids in Antarctic krill under different storage conditions;The mechanism of the formation of harmful factors during the storage of Antarctic krill;The formation of the basic means of storage,the establishment of effective storage methods.Results:1.This paper makes a comprehensive evaluation and comparative analysis of four kinds of thawing methods: natural thawing,low temperature thawing,static water thawing and microwave thawing from the aspect of the development and utilization of lipids.The results showed that the thawing time taken by natural thawing,low-temperature thawing,still water thawing,microwave thawing was 210,450,90 and 5 min respectively.And the lipid qualities of the krill exhibited differences after being treated by different thawing methods,while the contents of free fatty acids and astaxanthin in the krill showed significant differences.The contents of free fatty acids were between 20.8%~23.0% and astaxanthin were 391.7~429.9 ?g/g.So,the contents of free fatty acids and astaxanthin would be the fast evaluation indexes for evaluating the lipid quality changes of the krill during the thawing process.The results of radar chart analysis showed that the evaluation results of thawing methods were ranked as still water thawing>low-temperature thawing>microwave thawing>natural thawing.2.Antarctic krill were stored under three conditions of frozen storage(-18?),cold storage(4?)and autolysis(20?),and the change trend of the quality evaluation index was basically the same.But the variation range was quite different.Antarctic krill extraction rate,phospholipid,cholesterol and triglyceride content and astaxanthin content have the downward trend with the extension of storage time.And free fatty acid content,peroxide value and anisidine value increased gradually.And endogenous lipase activity increased firstly and then decreased.3.The Antarctic krill oil quality deterioration in high temperature,and the effect of different antioxidants on lipid quality is different.The antioxidant effect of TBHQ is better than that of vitamin E and ascorbic acid palmitate.The less hydrophilic pyrrole content change trend is not obvious,while the hydrophobic pyrrole decreased firstly and then increased.Three different forms of products in bulk,common capsule and micro capsule of Antarctic krill oil during storage,microcapsules had the slow strain rate of degradation.Conclusion:1.Due to the difference of thawing temperature and thawing mechanism,different thawing methods had different thawing time.Antarctic krill quality changed in the process of thawing,including lipid hydrolysis and oxidation.And the lipid qualities of the krill exhibited differences after being treated by different thawing methods,while the contents of free fatty acids and astaxanthin in the krill showed significant differences(p<0.05).That free fatty acids and astaxanthin can be used as the thawing process of Antarctic krill lipid quality deterioration indicators.The radar chart analysis results,combined with the factor of product quality,thawing time and energy comsumption,still water thawing should be firstly chosen when extracting the krill oil using the frozen krill material.That can greatly reduce the hydrolysis and oxidation of lipids,ensure that the Antarctic krill oil terminal product quality.2.The storage temperature had a great influence on the lipid quality of Antarctic krill.Under the action of endogenous lipase,the lipids will be hydrolyzed and oxidized,resulting in lower quality.So in practical production,we should try to avoid prolonged storage under high temperature.3.The addition of antioxidants can effectively delay the oxidation of oil,and the antioxidant effect of TBHQ is better than that of vitamin E and ascorbic acid palmitate.TBHQ is a commonly used antioxidant in industry,but the synthetic antioxidants have been found in recent years to have side effects that can lead to deformity and even cancer.Therefore,considering the scope of application of oil,natural selection oxidation antioxidant vitamin E added to the oil in order to reduce lipid.The pyrrole can resist oil oxidation rate.The decrease of the storage period may be used as an antioxidant to slow down the oxidation of lipids.The increase of the content of pyrrole in the later period of storage is due to the increase of lipid oxidation,which leads to the increase of the production of pyrrole.The oxidative degradation of oil bulk becomes the highest level of that wall material capsule shell and micro capsule has a protective effect on the oxidative degradation of oil oil,slowed down the quality of lipids,which better protective effect of micro capsule capsule is.Therefore,microencapsulation is the Antarctic krill oil storage process suitable for the best products form.