Research On Thawing Process And Quality Change Of Antarctic Krill

In this research, Antarctic krill was studied from the effects of thawing methods on Antarctic krill processing quality, autolysis and melanosis of Antarctic krill after thawing process and mechanism has been studied.1、Effects of thawing process on the Antarctic krill processing qualityThree ways as natural air thawing, static water thawing and low temperature air thawing were designed in this study. The results showed that the thawing time taken by natural air way, static water way and low temperature air way were 220 min, 51 min and 826 min respectively. The sensory score of Antarctic krill with static water thawing was the highest, followed by natural air way and low temperature air way. NPN values of Antarctic krill thawed by three ways have significant difference(P<0.01), with highest value of low temperature air way, followed by natural air way and static water way in sequence. TVB-N value of low temperature air way was significantly higher than the other two ways(P<0.01). TVB-N values of the static water way and natural air way have no significant difference(P>0.05). TBARS values of Antarctic krill thawed by three ways have significant difference(P<0.01), with highest value of static water way, followed by natural air way and low temperature air way. The proportion of polyunsaturated fatty acids of total fat from Antarctic krill is more than 30%. Low temperature air thawing has a certain effect on protection of polyunsaturated fatty acids.2、Antarctic krill after thawing autolysis process and autoenzyme biochemical properties1)The changes in protein component of Antarctic Krill during 4℃ and 20℃ storage were analyzed. The results showed that NPN contents increased with the extension of time, and reached 8.40 mg/g and 12.67 mg/g after 8 hours respectively. Changes in TCA soluble protein and amino acid nitrogen were similar with NPN. However, the contents of amino acid nitrogen were significantly lower than TCA soluble protein. TVB-N value also increased, with 0.16 mg/g and 0.21 mg/g after 8 hours under 4℃and 20 ℃ respectively.2)The activity of Antarctic krill autolytic enzyme was highest at pH7; The optimum temperature temperature was about 50℃; Mg2+, Ca2+, K+ could activate the protease of Antarctic krill; PMSF and SBTI have obvious inhibitory effect on autolysis enzyme activity, The maximum inhibition rate was 78% and 71% respectively. The inhibitory effect of EDTA on autolytic enzyme was weak,the highest inhibition rate was only 11.2%.3、Antarctic krill after thawing blacken process and biochemical properties of POAntarctic krill turned blacken storage after 8 hours under 4℃and 20℃, after 24 h are more serious, after 48 h lose the value of goods basically. After extracted the crud PO, monium sulfate precipitation, Sephacryl S-100 chromatography, acquired purified components,specific activity was 38.21 U/mg,was increased by 21.47 times than crude enzyme liquid. pH6 was the optimum for PO, enzyme activity was inhibited significantly under pH4.0 and above pH9.0; 0.1%(w/v)4-HR\Sodium Pyrosulfite\Sodium Hydrogen Sulfite\L(+)-Cysteine\Ascorbic Acid could significantly inhibit the activity of PO. The inhibition rate of 4-HR on enzyme activity was the highest, which could reach 80.2%.After the treatment by compound preservative:phytic acid,EDTA,4-HR and Vc,had prevent and reduce melanosis effectively,the sensory quality of Antarctic krill was improved during storage.