| Agar is a kind of polysaccharide extracted from Gracilaria,Gelidium and other red algae those were boiled by hot water.Biochemical agar is an important deep processing product.At present,the industrial production of biochemical agar has not been realized in China.In this paper,we take Chinese main food agar products as raw materials,use the indexes of several biochemical agar as reference,analyze the shortcomings of Gracilaria agar,and prepare biochemical agar by carboxymethyl modification.Finally,we design a process that can produce300 tons of biochemical agar every year.The main contributions of this paper are summarized as follows:?1?By comparing with the physicochemical indexes of Gracilaria agar and biochemical agar,we found the shortcomings of Gracilaria agar.Namely,Gracilaria agar has a poor transparency,a high melting temperature and dissolving point.?2?By single factor test,we optimize the preparation conditions of carboxymethyl agar:the concentration of NaOH is 8%,chloroacetic acid is 1.5 g,reaction temperature is 60oC and reaction time is 1.5 h.Alkali recovery after the reaction can save 70.5%of the anhydrous sodium sulfate,57%sodium hydroxide.?3?The products we got from pilot scale experiments have a good physicochemical properties.The melting temperature of 86.0oC,dissolving point of 94oC,gel strength of 1110g·cm-2,transparency of 84%,and whiteness of 66.1%.They have a good appearance,a stable quality and meet the requirements of microbial culture.Through the colony counting of E.coli and Bacillus subtilis,we know that there is no significant difference between carboxymethyl agar and commercial biochemical agar.?4?The design capacity of annual output of 300 tons,with two shifts working system,and production workshop for 13.The main equipment selection for GSH-6000 type stainless steel reactor,SS1500 type link-suspended basket centrifuge,BSFS-40 type wet material crusher,DW type conveyor dryer,etc.The amount of equipment investment in the production workshop is 1.1million yuan,and the amount of investment in the new plant is 0.54 million yuan.So,the overall investment of the workshop is 1.64 million yuan.The annual cost of the total cost of electricity and water is 0.26 million yuan,total cost of raw materials of 36.5 million yuan,total workshop staff salary of 0.66 million yuan,production costs of 37.7 million yuan,after-tax profits of 0.9million yuan.If the construction period is 0.5 year,the stable investment recovery period is 2.3years.This paper designed the technology for the production of biochemical agar that was based on carboxymethyl modification.The quality of the product was the same as that of the commercial biochemical agar.Finally,on the basis of laboratory testing and pilot,we design a preliminary process that can produce industrial biochemical agar.These results provide technical references for realizing the localization of biochemical agar. |
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