Study On Extraction,physicochemical Properties,gelation Properties And Application In Jelly Of Polysaccharides From Mesona Chinensis

Mesona chinesis also known as fairy grass,salary grass,grass kueh,is an annual herb of the genus Mesona in the family Labiatae,with a long history of edible and medicinal use,rich in flavonoids,terpenoids,phenols,organic acids and other active ingredients.Among them,polysaccharide is one of the main components,with antioxidant,hypoglycemic,antibacterial and other biological activities,as well as good heat resistance and coagulability,mixed with starch can be cooked to form a jelly-like semi-solid,known as cold powder or cold powder jelly.In this paper,the extraction process,physicochemical properties and gelation properties of polysaccharides from fresh herb were studied,and a green and healthy herb jelly product was developed on this basis.The main contents of this paper are as follows:1.The extraction process of polysaccharides from fresh Mesona chinesis.The optimum extraction process of polysaccharides was obtained by the response surface optimization method with the following single-factor experiments:material-liquid ratio of 1:6 g/m L,heat soak time of 11 min,Na HCO₃1.6%and extraction rate of 7.73±0.1%.2.Physicochemical characterizations of fresh Mesona chinesis polysaccharide.Polysaccharides under optimal extraction conditions were obtained by acid precipitation and alcohol precipitation to obtain two polysaccharides,MCP-A and MCP-B,respectively.The acid precipitated polysaccharide（MCP-A）contained 7.03%total sugars,1.8%protein and 25.63%glyoxylate;the alcohol precipitated polysaccharide（MCP-B）contained 21.89%total sugars,0.58%protein and 24.92%glyoxylate.the viscosity of MCP-A was 49.62 m L/g and that of MCP-B was 34.45 m L/g.the viscosity of MCP-A and the onset thermal decomposition temperatures of MCP-A and MCP-B were 176°C and 147°C respectively,with MCP-A being more heat resistant than MCP-B.The IR spectra and X-ray diffraction results showed that MCP-A is a pyranosyl ring skeleton withα-glycosidic andβ-glycosidic bonds,and MCP-B is a pyranosyl ring skeleton withβ-glycosidic bonds,both of which have the typical spectral characteristics of polysaccharides and are in non-crystalline form.Sweeping electron microscopy revealed that MCP-A was irregularly granular;MCP-B had a lamellar structure with more pores and a larger specific surface area than MCP-A.The in vitro antioxidant results showed that both polysaccharides had strong antioxidant capacity,with MCP-A having a stronger ability to scavenge DPPH and ABTS radicals than MCP-B.3.Gelation properties of fresh Mesona chinesis polysaccharide compounded with corn starch.The polysaccharides extracted under optimal conditions were dried and non-dried to obtain two polysaccharides,DMCP and WMCP,and different concentrations of polysaccharides（0.3%,0.6%,0.9%,1.2%,1.5%）were compounded with corn starch（4%）and their gelation properties were investigated.The results showed that WMCP was significantly more effective than DMCP in increasing the solubility and swelling power of corn starch granules,elasticity,hardness and cohesion of the complex gels,but DMCP was more effective than WMCP in reducing the pasting enthalpy of the gels and enhancing the starch crystalline structure.FT-IR and SEM results showed that both WMCP and DMC could increase the hydrogen bonding force in the gel system,promote the formation of short-range ordering,enhance the gel wall thickness,and make the lattice arrangement more orderly.Meanwhile,WMCP and DMCP can effectively inhibit the water precipitation rate of complex gels and long-term starch regrowth by hindering the reorganization of hydrogen bonds between starch molecules and changing the X-ray diffraction pattern of starch.The results of in vitro digestion experiments showed that WMCP and DMCP increased the content of slowly digested starch（SDS）and decreased the content of resistant starch（RS）in the gels,indicating that polysaccharides can reduce the digestibility of corn starch and promote the balance of postprandial glucose and insulin levels to different degrees.4.Research on the formulation of fresh Mesona chinesis jelly.Using the sensory score of the jelly as an index,the four factors of polysaccharide concentration,starch concentration,white granulated sugar concentration and condensed milk concentration were judged by fuzzy evaluation method and orthogonal experiment to have the following effects on the jelly:starch concentration>polysaccharide concentration>condensed milk concentration>white granulated sugar concentration.The best combination was 0.9%polysaccharide concentration,4%starch concentration,4%white sugar concentration and 6%condensed milk concentration,which gave the jelly an organoleptic score of 91points.