Fungal Polysaccharide Adulteration Detection Method

Fungus polysaccharides, isolated from the fruits, mycelium and fermentation broth,can control the cleavage and differentiation, adjust the growth and caducity of cells. The products of fungus polysaccharides have become a hot area because of their various functions and no poisonous effect. This paper first studied the characters of fungus polysaccharides, then added other polysaccharides as the adulterants, studied the characters of the mixture samples, finally provided information for building up an examination system of fungus polysaccharides.1. Extraction and purification of fungus polysaccharidesThis paper used the powders of Agaricus blazei Murill, Lentinus edodes and Ganoderma lucidum as the material ,used water and caustic lye of soda to extract, then freeze-dried the solution after wiping off the impurity, finally got the fungus polysaccharides. The results showed that the quantity of fungus polysaccharides we got using caustic lye of soda to extract was more than that of using water, the fungus polysaccharides isolated from Agaricus blazei Murill and Lentinus edodes were ivory or yellowish,but Ganoderma lucidum polysaccharides were sandy beige. The purity of fungus polysaccharide was high, so they were used as the standard substance of the adulteration testing experiment,at the same time chosen soluble starch, CMC, guar gum and maltodextrin as the adulterants of the experiment.2. The physicochemical properties of the fungus polysaccharides and the adulterants(1)IR:The fungus polysaccharides and the adulterants were both of polysaccharides, so the structure of them had commonness and differentia, this mainly embodied at the absorption peaks of the functional groups and the displacements of the absorption peaks on the FT-IR spectrum.(2)ESEM:The superficial shapes of fungus polysaccharides were velvet grain as bean, but the shapes of adulterants. were various.(3)XRD:The crystallinity of fungus polysaccharide was zero, but the adulterations except maltodextrin were crystalline state polymers. The crystallinity of soluble starch, CMC and Guar gum were respectively 20.50%, 18.39% and 2.26%.(4)[α]_λ~t:The fungus polysaccharides and the adulterations were both of dextrogyrate, different monosaccharide constitution of fungus polysaccharides have differen [α]_λ~t. The [α]_λ~t ofβ-configuration polysaccharides were lower than that ofα- configuration polysaccharides, this result was consistent with the information we got from FT-IR spectrum.3. The study of detection methods of adulteration testing(1)IR:The main differences of the FT-IR spectra of the fungus polysaccharides and the mixture samples were the characteristic absorption peaks of O-H, C-H and pyranose ring. Along with the increase of fungus polysaccharides, the wave numbers'changes presented certain trend.(2)ESEM:The fungus polysaccharides and the adulterants can be distinguished from the pictures of ESEM according to the differences of their superficial shapes. But we could not easily distinguish the polysaccharides which have the same shapes with the fungus polysaccharides, such as starch and maltodextrin , and need to use other methods to confirm.(3)XRD:The analysis of XRD got two characteristic parameters -the crystallinity and the position of the XRD highest diffraction peaks. As the crystallinity of fungus polysaccharide was zero, the method of XRD was available at the quality testing of fungus polysaccharides.(4) [α]_λ~t: It existed comparatively nicer linear relationship between the [α]_λ~t and the content of fungus polysaccharides.The methods we studied in this paper-IR, ESEM, XRD and [α]_λ~t had certain feasibility in the adulteration testing of fungus polysaccharides. We can choose different methods according to different circumstances in the adulteration testing.