Study Of Mold Separated From The Main Producing Areas In Our Country Of Dry Cassava Piece And Mildew Controlling

In this thesis, cassava piece as raw material, the molds were isolated from cassava piece which was gathered from main producing areas (Guang Xi, Guang Dong, Hainan, Yun Nan and Fu Jian) and the dominant molds were identified. The effect of storage temperature and moisture content on moulding of casaava piece was studied,useing temperature of cassava piece, mildew rate and carrier volume as indicators. Mould-proof of cassava piece was studied,using natamycin, potassium sorbate, sodium sulfite, sodium diacetate and sodium benzoate. Their minimal inhibitory concentration(MIC) were measured.At the same time, antimould effects of cassava piece were evaluated by mildew rate, situation of mildew growth and antimould effects of mildew preventive. The results showed that:The dominant molds of Guang Xi were Aspergullus niger, Mucor racemosus, Aspergillus flavus, Aspergillus parasiticus and Penicillium. The dominant molds of Guang Dong were Aspergillus flavus, Penicillium, Aspergillus parasiticus, Aspergullus niger and Mucor racemosus. The dominant molds of Hai Nan were Aspergillus parasiticus, Aspergillus flavus,Penicillium and Rhizopus nigricans. The dominant molds of Yun Nan were Penicillium, Aspergillus paras iticus, Aspergullus niger and Aspergillus flavus. The dominant molds of Fu Jian were Rhizopus nigricans, Penicillium, Aspergillus flavus, Aspergillus parasiticus and Aspergullus niger.When moisture content of cassava piece was15%and storage temperature was10℃、20℃、30℃and40℃, cassava piece was not appeared moldy phenomenon and germ-carrying was about4×104cfu/g.When moisture content of cassava piece was17%and storage temperature was10℃and20℃, cassava piece was not appeared moldy phenomenon and germ-carrying was about4×104cfu/g.However, when storage temperature was30℃and40℃,cassava piece appeared moldy phenomenon during storage.When cassava piece had just appeared moldy phenomenon,germ-carrying was about8×10cfu/g.So cassava piece lost its storage security.When moisture content of cassava piece was20%,25%and30%and storage temperature was10℃～40℃,all of cassava piece appeared moldy phenomenon during storage. Germ-carry ing was about8×104cfu/g,when cassava piece had just appeared moldy phenomenon.At this moment, cassava piece lost its storage security. Therefore, when Germ-carrying of cassava piece was over8.0×10cfu/g, it would lose its storage security.Sensitivities of six dominant molds which were treatment with natamycin, potassium sorbate, sodium sulfite, sodium diacetate and sodium benzoate were measured. When their concentration respectively were10mg/L,250mg/L,200mg/L,70mg/L and450mg/L, the growth of the six dominant molds were inhibited. When natamycin solution, potassium sorbate solution, sodium diacetate solution and sodium benzoate solution concentration respectively were1.2g/L,8g/L,4g/L and20g/L, cassava piece was not appeared moldy phenomenon, the growth of molds was inhibited and antimould effects was good,under storage conditions that was storage temperature was30℃and moisture content of cassava piece was20%.However, when sodium sulfite solution was from10to50g/L, cassava piece appeared varying degrees moldy phenomenon, molds could grow and antimould effects were unsatisfactory, under the same storage conditions.