| In 2020,the national output was close to 200,000 tons,of which Shandong and Liaoning were the main production origins.Sea cucumber is favored by consumers because of its high nutritional and medicinal value.However,due to the unique autolysis characteristics of sea cucumber,there are problems such as nutrient loss and quality decline in processing and storage.It is urgent to establish green and efficient key technologies for sea cucumber nutrition maintenance and quality control.Therefore,taking sea cucumber as the research object,based on the analysis and comparison of the nutritional quality differences of sea cucumber from different producing origins,this paper studies the effects of different heat treatment methods on the nutritional quality of sea cucumber during processing,and discusses the change law of main nutritional components of instant sea cucumber during storage.Finally,in vitro simulated biomimetic digestive system and proteomics technology were used to study the protein change law of instant sea cucumber during continuous gastrointestinal digestion.The specific research results are as follows:1.Taking Bangchui Island,Haiyang Island and Wafangdian sea cucumber as the research objects,the basic components,functional components,mineral elements,amino acids composition and fatty acids composition were measured respectively for quality analysis.The results show that: the contents of protein(54.05%)and ash(32.80%)of sea cucumber in Haiyang Island were significantly higher than Bangchui Island and Wafangdian sea cucumber,while the fat content of Bangchui Island sea cucumber(7.03%)and the total sugar content of Wafangdian sea cucumber(10.89%)were higher.The analysis of functional components showed that the contents of saponin,taurine and chondroitin sulfate of sea cucumber in Bangchui Island were rich,the content of vitamin E in Haiyang Island was the highest,while the content of vitamin A was low,and the content of vitamin A in Wafangdian was the highest.There were significant differences in the content of mineral elements in sea cucumber from different producing origins.The contents of Na,Mg,Ca,Zn and Se in Haiyang Island sea cucumber were the highest.The contents of K,P and Cu of sea cucumber in Bangchui Island were the highest.The contents of four major metal elements(Na,Mg,Ca and K)in Wafangdian sea cucumber were the lowest,but the contents of Fe,Mn and V were the highest.The analysis of amino acids composition shows that the total amount of amino acids of sea cucumber from different producing origins is 37.5399g/100g-42.5143 g/100 g,and the total amount of essential amino acids is 11.8772g/100g-14.0275 g/100 g,the content of pharmacodynamic amino acids in sea cucumber is rich,the content of sweet amino acids is higher,and the content of fresh amino acids is slightly lower than bitter amino acids.The fatty acid composition of sea cucumber from different producing origins was significantly different.A total of24 kinds of fatty acids were detected,including 9 kinds of saturated fatty acids,6kinds of monounsaturated fatty acids and 9 kinds of polyunsaturated fatty acids.Sea cucumber is rich in EHA and DPA.The saturated fatty acids(32.84%),monounsaturated fatty acids(33.31%)and polyunsaturated fatty acids(33.84%)of sea cucumber in Wafangdian are evenly distributed.The monounsaturated fatty acids(17.37%)of sea cucumber in Haiyang Island is relatively low,and the unsaturated fatty acids of sea cucumber in Bangchui Island is significantly higher than other places,reaching 74.08%.2.Select Bangchui Island,Wafangdian,Suizhong,Qingdao and Yantai sea cucumber were treated with different thermal processes(blanching,atmospheric pressure boil cooking and high pressure steam cooking)to explore the changes of basic components,functional components,amino acids,fatty acids and monosaccharide compositions.The results show that: different nutrients have different degrees of heating effect,which show significant differences.The relative content of total sugar in atmospheric-pressure and high-pressure sea cucumber decreased in varying degrees compared with that in blanching sea cucumber,and the relative content of ash was significantly lower than that in blanching sea cucumber.The relative content of ash in atmospheric-pressure sea cucumber was slightly lower than that in high-pressure sea cucumber due to osmotic pressure.The relative protein content of atmospheric-pressure sea cucumber is the highest,while that of blanching sea cucumber is the lowest.Different heat processing methods had no significant effect on the relative fat content of sea cucumber.Saponin and taurine in sea cucumber are very sensitive to heat treatment,but the relative contents of vitamin A and vitamin E have no significant change.The relative contents of chondroitin sulfate and collagen in sea cucumber increased significantly after thermal processing.It is worth noting that chondroitin sulfate in Shandong sea cucumber is more sensitive to high temperature and high pressure.Protein evaluation analysis found that different thermal processing methods had a significant impact on the composition and structure of amino acids,and the relative content of each amino acids increased in varying degrees after thermal processing.After atmospheric-pressure and high-pressure,the essential amino acids,pharmacodynamic amino acids and total amino acids of sea cucumber were significantly higher than blanching sea cucumber.After atmospheric-pressure and high-pressure,the relative content of sweet amino acids in sea cucumber increased significantly,while the relative content of fresh amino acids and bitter amino acids increased only slightly.A variety of fatty acids are more sensitive to heat treatment.The saturated fatty acids and monounsaturated fatty acids in atmospheric-pressure and high-pressure sea cucumber is generally significantly less than blanching sea cucumber,while the polyunsaturated fatty acids is the opposite.The proportion of EPA and DHA increased significantly after atmospheric-pressure and high-pressure.Different kinds of monosaccharides have different sensitivity to heat treatment.Mannose is sensitive to heat treatment.The relative contents of glucuronic acid,glucose,galactose and fucose in blanching sea cucumber are generally significantly lower than those in atmospheric-pressure and high-pressure sea cucumber.The relative content of ribose and xylose has no significant change due to their special connection mode.3.Instant sea cucumber is stored at 4℃ and sampled every 7 d.The biochemical changes of instant sea cucumber during storage are analyzed from the perspectives of basic components,functional components,texture,volatile substances,dissolved substances and volatile base nitrogen.The results show that: during the storage period of 0-7 d,the volume and quality of instant sea cucumber decreased significantly.After14 d,viscous substances appeared on the surface with peculiar smell,and wart feet began to disappear after 35 d.Due to the large amount of water precipitation,the content of ash and total sugar of water-soluble substances decreased significantly.The ash content tended to be stable after 21 d,and the final content was 4.37%,and the total sugar content tended to be stable after 35 d,and the final content was 5.40%.The protein content decreased first and then increased.At 42 d,the protein content reached84.07%.The fat and saponin increased first and then decreased.After 42 d of storage,the fat content was only 2.31% and the saponin content was 1.79%.The ratio of collagen content to protein content shows that collagen degradation is serious in the early stage and slow in the later stage.After 7 d of storage,the hardness,viscosity and chewability of instant sea cucumber began to decrease significantly,the cohesion showed an upward trend,but the elasticity and recovery had no significant changes.During storage,the contents of sulfide,organic sulfide,nitrogen oxides,methyl,alcohol,aldehyde and ketone volatile components are rich,showing a trend of increasing first and then decreasing.The methyl volatile components reach the peak at35 d,and the remaining volatile components reach the peak at 28 d.During storage,a large amount of protein was precipitated in sea cucumber.After 42 d the soluble protein reached 7.25 mg/mL,and the total sugar was degraded and precipitated in the form of polysaccharide.The content of total volatile basic nitrogen reached 175.51mg/100 g at 35 d and decreased slightly at 42 d.At 14 days,the content has exceeded20 mg/100 g,which has lost its edible value.The denaturation temperature of collagen in the body wall of instant sea cucumber increased first and then decreased with the increase of storage due to the increase of exposure stability of hydrophobic groups.The lowest denaturation temperature of collagen was 110.52℃ at 0 d and the highest denaturation temperature was 137.38℃ at 28 d.4.Based on proteomics technology,this part of study detected the changes of protein in instant sea cucumber during digestion(different digestion parts and different intestinal digestion time).The results showed that: although the water content of instant sea cucumber is high,there are still obvious emptying stagnation period(63.24 min)and half emptying time(80.70 min).The digestion is mainly concentrated between stomach and intestine for 120 min.1880 and 1729 proteins were quantified in different digestion parts and intestinal digestion time,respectively.Most of the proteins had a coverage of more than 30% and corresponded to more than two specific peptides.The molecular weights were mainly distributed between 20-30 kDa,10-20 kDa and 30-40 kDa.The number of differential proteins in oral digestive products was the least,while the number of differential proteins in gastric digestive products was the most.In the process of intestinal digestion,the number of up-regulated and down-regulated differential proteins increased first and then decreased.Differential proteins are mainly involved in cellular process,biological regulation and metabolic process.Most of them have binding and catalytic activities,and are mainly located in cells,intracellular and protein-containing complex.57 functional proteins were screened by orthogonal partial least squares discriminant analysis,which were mainly enriched in KEGG pathways such as metabolic,protein processing in endoplasmic reticulum,phagosome,ECM-receptor interaction,protein secretion and renin secretion. |
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