Effect Of Low-pressure Steaming On The Composition,Structure And Activities Of Polysaccharides In Apostichopus Japonicus

Sea cucumber is a valuable ingredient and one of the "eight treasures" of seafood.However,due to the presence of autolysis enzymes in its body wall,sea cucumbers will be autolyzed when left in seawater for a long time,so they need to be processed immediately to prolong their preservation time.At present,the main sea cucumber products in the market are mainly dried products,which have many inconveniences when cooking.The emergence of ready-to-eat sea cucumbers has enriched the variety of sea cucumber products and made the consumption of sea cucumbers faster.At present,there are few studies on the effect of processing process of ready-to-eat sea cucumbers on the nutrients of sea cucumbers.In this paper,the polysaccharide change pattern of low-pressure steamed ready-to-eat sea cucumber was used as an entry point to investigate the effect of this process on the polysaccharide composition,structure and activity of sea cucumber body wall by comparing it with freeze-cooked sea cucumber precooked for 5 min,and the main findings were as follows:The crude body wall polysaccharides(RSCP)of low-pressure steamed ready-toeat sea cucumbers and the crude body wall polysaccharides(FSCP)of pre-cooked 5-min freeze-cooked sea cucumbers were obtained by enzymatic digestion with papain and precipitation with quaternary ammonium cetyl pyridinium chloride(CPC),and the composition,monosaccharide composition and infrared spectra of the two crude polysaccharides were compared.The results showed that there were no significant differences between RSCP and FSCP in polysaccharide extraction rate,purity and sulfate content;the mass percentages of monosaccharide composition mannose:glucosamine:glucuronide:galacturonide:aminogalactose:glucose:galactose:fu cose of RSCP were 2.5:6.5:2.1:0.6:5.9:1.0:8.1:75.4;the The monosaccharide mannose:glucosamine:glucuronide:galacturonide:aminogalactose:glucose:galactose:fu cose composition mass percentage was 2.5:4.9:4.4:0.8:5.4:0.5:5.9:75.6,and the monosaccharide composition of the two crude polysaccharides were of the same type,both with the highest fucose content.The results of infrared spectrograms showed that both crude polysaccharides were polysaccharides containing fucose,sulfate and acetamido.Hydrogen peroxide was used to decolorize RSCP,and the purity and sulfate content of RSCP were improved after decolorization.The antioxidant activities of RSCP,FSCP and decolorized RSCP were analyzed,and the results showed that FSCP had the highest radical scavenging rate of DPPH with 92%,followed by RSCP(61%),and the decolorized RSCP had the lowest DPPH radical scavenging ability,indicating that low-pressure steaming and decolorization reduced the DPPH radical scavenging ability of ginseng polysaccharides.The decolorized RSCP and FSCP were separated and purified using anionexchange chromatography,and eight fractions of FSCP-X1,FSCP-X2,FSCP-X3,FSCP-X4,RSCP-J1,RSCP-J2,RSCP-J3 and RSCP-J4 were obtained.Infrared spectroscopy analysis of six fractions,FSCP-X1,FSCP-X2,RSCP-J1,RSCP-J2,RSCP-J3 and RSCP-J4,showed that all six fractions were polysaccharides containing sulfate and acetylamine.f SCP-X1 consisted of seven monosaccharides,mannose,glucosamine,glucuronide,aminogalactose,glucose,galactose and fucose FSCP-X2 consisted of 6 monosaccharides,mannose,aminoglucose,aminogalactose,glucose,galactose,and fucose,with the highest percentage of aminoglucose;RSCP-J1 consisted of 6 monosaccharides,mannose,aminoglucose,glucuronide,glucose,galactose,and fucose,and RSCP-J2 consisted of mannose,aminoglucose,glucuronide,aminogalactose,glucose,galactose,and fucose;RSCP-J1 and RSCP-J2 had the highest proportion of mannose;RSCP-J3 consisted of seven monosaccharides,mannose,aminoglucose,glucuronic acid,galacturonic acid,aminogalactose,galactose,and fucose,while RSCP-J4 consisted of four monosaccharides,mannose,aminoglucose,galactose,and fucose However,RSCP-J3 and RSCP-J4 had the highest percentage of fucose,but their monosaccharide composition was more different.The structures of RSCP-J3 and RSCP-J4 were further analyzed by 1D NMR,and it was tentatively determined that RSCP-J3 contained fucose methyl and glucosamine by 1D NMR hydrogen spectroscopy,which was consistent with the monosaccharide composition,while RSCP-J4 contained only fucose methyl.The four fractions of FSCP-X3,FSCP-X4,RSCP-J3 and RSCP-J4 eluted at high salinity were further purified by gel chromatography,and the results showed that the composition of the monosaccharide content and molecular weight of the four fractions differed.The molecular weight of FSCP-X3-1 in FSCP-X3 was 2,861 k Da,which was similar to that of RSCP-J4-1.The 12 fractions further purified from FSCP-X3,FSCPX4,RSCP-J3 and RSCP-J4 contained four monosaccharides,namely aminoglucose,aminogalactose,galactose and fucose,except for FSCP-X3-4,fucose was the monosaccharide with the highest content in the fractions,among which the fractional mass of fucose in FSCP-X4-3,FSCP-X4-4,RSCP-J4-1 and RSCP-J4-2 were all higher than 80%;FSCP-X3-4 contained the highest content of glucosamine at44.94%;none of the four fractions of FSCP-X4 contained glucuronic acid,FSCP-X4-3 and FSCP-X4-4 did not contain arabinose,and FSCP-X4-2 and FSCP-X4-4 did not contain mannose.