The Research On Recycling Technology Of Protein In Cassava Gluten Wastewater

Guangxi is the largest province of cassava production in China. Cassava production is mainly used for processing starch. When wet production of cassava starch, wastewater emissions is huge, cassava starch to produce1ton of about12-16tons of cassava yellow slurry discharged wastewater. Cassava wastewater main ingredient is a protein, which has high concentrations of pollutants. Therefore, recycling yellow cassava pulp wastewater protein has great value for development. This experimental study analyzed the water quality characteristics of cassava yellow pulp wastewater, focused exploration on the basis of the protein recovery methods, and the recovery of cassava protein amino acid components were measured. The main conclusions are as follows:(1) Study on the factors of affecting cassava protein extraction. Selecting pH, liquid ratio, temperature and extraction time as testing factors, proteins were extracted under optimization conditions. The results showed that, pH8.0,3.5liquid ratios, extraction time15min and temperature35℃, the best cassava protein extraction rate was25.2%.(2) Cassava wastewater natural acidification and natural precipitation conditions were determined. At35℃, water acidification started after placing5-6h, pH5.2, and precipitated proteins; after20h, the yellow pulp effluent pH stabilized at about4.1, and protein precipitation rate was73.3%.(3) Recovery of cassava protein at isoelectric point. By measuring the isoelectric point of the protein cassava yellow pulp wastewater, changing pH, temperature, protein concentration and the settling time of the yellow cassava wastewater protein, precipitation process was optimized. Optimize operating processes:pH4.0, temperature35℃, the protein concentration of1400mg/L, the settling time3h, the protein precipitation rate of yellow cassava pulp wastewater is greater than98.3%.(4) The factors of recycling proteins from yellow cassava pulp wastewater by flocculation were studied. Selecting the PAC and polyacrylamide as flocculant, the research obtained the optimal operation of the process of two flocculants, respectively, by controlling yellow pulp wastewater temperature, pH, settling time and coagulant dosage. The results showed that the maximum precipitation was83.1%when the addition of9mg/100mL, pH7, temperature30℃, stirring time3min were achieved with PAC; optimum operating process of polyacrylamide method is addition of9mg/100mL, pH6.5, temperature35℃, stirring time2min, while protein precipitation rate is82.1%.(5) Cassava protein drying and browning conditions were studied. Research showed that the protein moisture content, drying temperature, pH and drying time affected the drying process of cassava protein. By controlling pH<4and protein moisture<40%,,this protein was not obvious changed to color browning after drying16h at55℃.And the water content of dried protein was13.1%.(6) Determination of protein nutritional value of cassava. The protein contains15kinds of amino acids, in which8kinds of essential amino acids and seven kinds of non-essential amino acids. Essential amino acids take up40.9%of the total value, indicating a high nutritional value.