Study On Synthesis And Antimicrobial Activity Of Starch Methyl Fumarate

As one of the most abundant renewable nature resource in the world, starch has good characteristics such as biocompatibility, biodegradability and being modified by physics, chemistry and enzyme method. So study, production and application about starches have been paid more attention by people recently. But starch is an excellent nutrient source which is conductive to bacteria breeding. It is apt to be infected by microorganisms such as bacteria to lead to its properties being deteriorated. And this limits its application in many areas. To solve this problem,α,β-unsaturated carbonyl group, which has high antimicrobial activity, is introduced to starch molecules by the chemical modification method in this paper., Starch with this group is able to have antibacterial property, as result of the comprehensive property of starch manufacture being improved, the use time lengthen, and application areas broaden.The following synthesis route is adopted:maleic anhydride is esterified and isomerized by maleic anhydride to form monomethyl fumarate(MMF), then MMF is acylchlorided to form monomethyl fumarate chloride(MMFC), and last, starch methyl fumarate(SMF) is prepared by MMFC and starch. The optimum reaction conditions of MMFC is the molar ratio of monomethyl fumarate to SOCl2 1:2.5, reaction temperature 100℃, reaction time 50 minutes., the yield of MMFC reaches 91.99%. By single factor and orthogonal experiment, the optimized condition of SMF is the molar ratio of MMFC to starch 2:1, TAMB 5%, K2CO3 10%(total mass fraction of dry starch), reaction temperature 45℃and reaction time 5 h., the DE of SMF is 0.460. The synthesis product is characterized by infra-red spectrometry.The antimicrobial activity of SMF study result indicates that the antimicrobial activity of SMF is directly relevant with its DE, the lower DE or higher DE both can influence the antimicrobial activity of SMF. SMF with 0.442-0.463 DE has higher antimicrobial activity. The minimum inhibition concentration of SMF to the streptococcus lactis is 0.4 g/L, its antimicrobial activity is under sorbicacid and dimethyl fumarate. The physicochemical property research of SMF shows that comparing with corn starch, the transparency, pasting temperature, cold and hot viscosity stability of SMF are improved, and with the DE increases, the transparency, pasting temperature, cold and hot viscosity stability are enhanced; but its viscosity, freeze-thaw stability, solubility and swelling power are reduced comparing with corn starch.