Study On Antibacterial Modification Of Starch

Due to wide variety of sources,low price,biodegradability and renewability,starches are widely used in many fields.But the structure unit of starch is glucose which can encourage the growth of bacteria,so the performance and development of starches have been degraded.The research on the antibacterial starches not only can enhance the performance of starch,but also can widen the application range.Based on the index of embedding rate,embedding efficiency,embedding yield,inclusion compound of β-CD was prepared.The method of measuring surface oil and inclusion oil were mainly studied.Processing conditions of preparation inclusion compound were researched and the antibacterial properties of inclusion compound were tested.The results show that when testing surface oil,it is perferable to wash two times in ethyl alcohol,35 min for first time and 5min for second time;when testing inclusion oil,it is perferable to extract 3 times in ethyl alcohol,each time for 20 min,at 80℃.The optional inclusion parameters of preparing inclusion compound are as follows: inclusion time is 3h,inclusion temperature is 40℃,the concentration of β-CD is 3 %,the concentration of cinnamic aldehyde is 0.7% and the concentration of ethanol is 2.7%.That the β-CD included cinnamic aldehyde successfully was testified by FTIR for inclusion complexes.The antibacterial rate of β-CD-cinnamic aldehyde for SA and EC are both more than 70 %.and the antibacterial properties of β-CD-cinnamic aldehyde are good.The stability of inclusion compound is good when the temperature is 50℃ and the concentration of NaOH is 0.007g/10 mL.This article studied the concentration of crosslinking agent in the crosslinking reaction between the β-CD and the starch.Results showed that the content of β-CD is most in β-CD-starch,which is 99.10 mg/g,when the concentration of crosslinking agent is 32%.FTIR proved that the crosslinking reaction has happened.Based on the preparation of inclusion compound and β-CD-starch,the antibacterial starch was prepared by two process routes,“inclusion after crosslinking” and “crosslinking after inclusion”.Antibacterial properties,MIC,slow-releasing of cinnamic aldehyde and cinnamic aldehyde retention rate were tested.Results show that,the embedding rate,embedding efficiency and embedding yield of the antibacterial starch prepared by “inclusion after crosslinking” are better than the starch prepared by “crosslinking after inclusion”.And the antibacterial properties express the same trend.The antibacterial properties of starch against SA precede against EC,and all of which are over 70%.MIC of antibacterial starch prepared by “inclusion after crosslinking” was 0.045g/10 mL and 0.060g/10 mL,respectively.MIC of antibacterial starch prepared by “crosslinking after inclusion” was 0.058g/10 mL and 0.070g/10 mL,respectively.The slow-release time of cinnamic aldehyde was as long as 36 hand the antibacterial starch has good slow-release property.And due to the combination of chemical bonds,β-CD-cinnamic aldehyde has good retention rate.FTIR proofed that both crosslinking and inclusion were happened in the antibacterial starch.