Study On The Method Of Modification And The Performance Of Gelatin Modified By Glutaraldehyde And Transglutaminase

In the process of the extraction,production,storage and application of gelatin and gelatin material,which was limited to be used in the industry due to the presence of the mechanical strength and vulnerable to be attack by bacterial.The gelatin material usually could be modified to improve its performance for overcoming the shortcomings.At present,the mechanism of gelatin modification need further study.This article obtained the best resistance to proteolytic modified gelatin.To modified the gelatin by the method of chemical(glutaraldehyde,hereinafter referred to as GTA)and enzyme(transglutaminase,hereinafter referred to as TG).To obtain a optimum modified condition by single factor and uniform design by he index of hydrolysis.The optimum modified conditions as follows: the concentration of GTA was 0.9%,pH = 6.0,57 ℃,16 min.The hydrolysis was 4.35% under the optimum modified conditions of modified gelatin hydrolysis time at 60 min,and the actual degree of hydrolysis was 4.68%.However,the relative error was 7.05%.Compared with the unmodified gelatin,the capacity of hydrolysis resistance increased by 18.75%.The optimum treatment conditions of TG-modified gelatin as follows: the concentration of TG was 0.20 g/L,pH = 6.0,44 ℃,35 min.The hydrolysis was 4.89% under the optimum modified conditions of modified gelatin hydrolysis time at 60 min,and the actual degree of hydrolysis was 4.89%,and the actual degree of hydrolysis was 5.08%.However,the relative error was 3.74%.Compared with the unmodified gelatin,the capacity of hydrolysis resistance increased by 14.44%.It suggested that the DPS data processing system for the analysis of test data and partial least squares regression quadratic model is more credible,and the optimal prediction model can be established.Study the modification time affect the mechanical properties of gelatin gel found:modified high gel hardness than the unmodified gelatin,modified gelatin gel which GTA hardness than the unmodified increased by 15%,with significant difference(p<0.05),and TG did not significantly improve its gel hardness.In the performance of swelling,modified gelatin than unmodified equilibrium swelling rate decreased.The swelling ratio of glutaraldehyde modified gelatin equilibrium decreased significantly(p<0.05),but not to a large extent reduce the TG equilibrium swelling ratio.In this study,scanning electron microscopy(SEM),Fourier transform infrared spectroscopy(FT-IR),differential scanning calorimetry(DSC),thermal gravimetricanalysis(TGA)and X-ray diffraction(XRD)were used to characterize the gelatin structure and thermal properties of the gel.SEM showed that the modified gelatin gel had more order structure than the TG-modified gelatin,the distribution of the gel network structure exhibits a certain order.FTIR showed that glutaraldehyde changed the secondary structure of the protein gelatin,cross-linked to form a new C-N bond and a transglutaminase-modified gelatin so that theβ-sheet of gelatin was converted to random coil and α-helix;TGA showed that glutaraldehyde-modified gelatin improves the thermal decomposition temperature of gelatin.However,the modified gelatin and transglutaminase thermal decomposition temperature has minor increase(p<0.05);DSC indicated that the thermal denaturation temperature of the modified gelatin were improved.The denaturation onset temperature and peak temperature of GTA modified by gelatin material TG modified gelatin ratio significantly improved(p<0.05),showing that the modified gelatin GTA thermal stability has been enhanced;XRD suggested that the peak position and the value of d-modified gelatin has been changed.Modified gelatin after GTA molecular peptide chain pitch is smaller,indicating a strong cross-linking between glutaraldehyde and gelatin.In the study of embedded dye gelatin gel swelling properties found,GTA modified gelatin than unmodified equilibrium swelling was reduced by 6.35%,while the TG-modified gelatin only decreased by 3.39%,thus significantly enhancing the stability of GTA modified gelatin gel;In the dye-diffusion study,the apparent diffusion rate constants Kα glutaraldehyde-modified gelatin and diffusion coefficient De are smaller than the transglutaminase enzyme,because the glutaraldehyde-modified gelatin gel structure was more closely,resulting in pigment molecules diffusion resistance increases.By studying the release medium temperature situation gelatin gel dye diffusion,indicating dye diffusion,and there were no significant temperature sensitivity;pH under different media,GTA-modified gelatin and TG-modified gelatin than the unmodified dye diffusion equilibrium point of release time nearly two hours,and in an acidic solution,gelatin gel ultimate dissolution basic,basic dye release rate of 100%.