Heavy Metals Analtzing On Edible Mushroom And Auricvlaria Polytricha Processed Food Developmenting

Edible mushroom not only contain proteins, amino acids, vitamins, minerals and other fungal polysaccharides, but also contain low fat, none of starch. Additionally, they have medicinal ingredients such as antibiotics, interferon inducers and nucleotides, so edible mushroom are safe as diet and drugs. Although mushroom industry in china is developing upward, so many primary products show the low level of processing. Deep processings of edible mushroom lack independent R&D and innovation. In addition, the phenomenon of heavy metals pollution in edible mushroom is arising widely, which impedes the development of edible mushroom industrial seriously in China. To enhance the quality and safety research on edible mushroom and promote the healthy development of edible mushroom processing industry, this paper did quality and safety research on raw materials of edible mushroom which collected in Nanjing market. And we developed edible mushroom food. The main findings were as follows:1. This paper analyzied heavy metal limits at home and abroad on edible fungi. According to Hygienic standard for edible fungi (GB7096-2003), form59edible fungi samples, the content of Hg in two fresh samples and one dried samples and the content of Pb in two dried samples were out of the limits. According to single pollution index evaluation method, assessment of heavy metals showed that different mushroom species had different contents of heavy metals and one dried sample of dictyophora indusiata, one dried sample of Lentinus edodes, one fresh sample of Lentinus edodes were light polluted, while one fresh sample of Agaricus bisporus even reached severe pollution. The others were not polluted. For the rationality of the limits of heavy metals in edible mushroom standards, the situation shows significant flaws in standards for edible mushroom that partial fresh edible mushrooms of the fit heavy metal content were exceeded in some heavy metal(Pb、As、Hg) content when transformed them to dry samples with12%water. Further research and revision were needed for dry and fresh edible mushroom limited standards,especially dry edible mushroom of heavy metals.2. Materials exploited for processed Auricularia polytricha product of low nitrite content. Some factors affected the nitrite content of processed food of Auricularia polytricha. Primary factor was sugar concentration, the secondary one was salt concentration and the last was fermentation time. Comprehensive consideration of sensory quality, the optimum fermentation conditions of processed food were that salt concentration of8%,10days fermentation time, sugar concentration of0.5%. Texture protection was introduced into the process for soluting the phenomenons of soften, hair sticky and so on in the traditional products. The optimum parameters were calcium lactate concentration of0.05%. Therefore, the best prescription of processed food of Auricularia polytricha identified as:the ratio of materials and water was1:2, salt concentration was8%, sugar concentration was5%, wine concentration and dry chili, ginger content were both2%, pepper content was0.05%, anise content was0.02%, calcium lactate was0.05%, fermentation time was10days.3. HPLC method for simultaneous determination of nitrate and nitrite in processed food of Auricularia polytricha was established. Analysis requirement were as follows:The column of the SUPELCOSILTM LC-SAX1(2.5cmx4.6mm,5um) was used for separation;0.02mol/L KH2PO4-H3PO4and acetonitrile of5%(V/V) were used as mobile phase;flow rate was1.0mL/min, wavelength was215nm; injection volume was20μL; the column temperature was25℃. This condition could separate nitrite and nitrate completely. Comparing with national standards, this method had high precision and repeatability. Detection limit of nitrite and nitrate was0.005,0.01mg/L. Recovery rate of nitrite and nitrate was87.45%～103.48%, according with testing requirements. This method was advised as national standard of nitrite and nitrate detecting in food.4. Physicochemical and hygienic indexes of processed food of Auricularia polytricha were in accordance with the limits of national or industry standards. The outcome showed that the content of nitrite was below the limits of standard (20mg/Kg) significantly, but it was suitable for eating after10days of fermentation. To ensure the safety of nitrite content in products, reasonable cropping of fresh vegetables and timely processing were necessary. In addition, acidic environment during the fermentation process was forming as soon as possible.