Preparation And Antimicrobial Preservation Of Gum Acacia ?-polylysine Nanoparticles Application Research On

?-polylysine is a safe and healthy natural nutritional biological preservative,its antibacterial spectrum is wide,high heat resistance,has a good effect on the delay of quality deterioration of aquatic products,but ?-polylysine alone,will act with food ingredients,reduce its antimicrobial effect.Using carrier embedding strategy can eliminate the above ?-polylysine application defects to a certain extent,Gum arabic has the advantages of low viscosity,film formation and so on.It is an ideal material to prepare the delivery carrier of biological active ingredients.In order to improve the antibacterial activity and comprehensive application performance of ?-polylysine,the antibacterial activity and preservation effect of gum acacia?-polylysine nanoparticles were systematically evaluated.The main research contents and results of this paper are as follows:(1)The preparative conditions,physicochemical properties,acting forces,antibacterial activity and anti-hygroscopicity of ?-polylysine loaded gum Arabic nanoparticles were studied.?-polylysine was coated in gum Arabic nanoparticles(PGH)by a two-step method of ion crosslinking and thermal induction.The optimal preparation conditions were determined as follows:?-polylysine:gum acacia material ratio of 1:4,heat treatment temperature of 90?,heat treatment time of 3 h,pH 5.The encapsulation efficiency of optimized PGH particles is 93.29%,the average particle size is 200.6 nm,and the PDI is 0.155.Fourier transform infrared spectroscopy(FTIR),X-ray diffraction(XRD)and differential scanning calorimetry(DSC)analysis showed that ?-polylysine was successfully encapsulated.Transmission electron microscope images showed that PGH particles were nanoparticles with core-shell structure,and the distribution of PGH particles was more uniform and the binding was more compact than that of ion crosslinked nanoparticles(PG0).C ompared with the free ?-polylysine,PG0 and PGH nanoparticles,the MICs and MBC of Salmonella,Listeria,Shivella and Pseudomonas were decreased by 2-4 times,which could significantly inhibit the growth of the bacteria.The hygroscopicity decreased from 97%to 18%after the incorporation of ?-polylysine into gum acacia.This technology can improve the antibacterial effect of ?-polylysine in food and the limitation of its application.PGH granules can be directly used as food additives.(2)On the basis of PGH nanoparticles,the surface modification of whey protein was carried out to prepare ternary nanoparticles(PGH-WPE)by cross-linking with TG enzyme.The encapsulation efficiency of PGH-WPE nanoparticles reached 97.14%and the average particle size was 265.3±9.32 nm when the enzyme reaction time was 10 min and the enzyme reaction temperature was 5?.Compared with PGH nanoparticles,the particle size became larger.According to the analysis of CD spectrum,different TG enzyme action time showed different effects on the protein structure,which improved the surface hydrophobicity,emulsification,solubility and other physical and chemical properties.The results of Fourier transform infrared spectroscopy(FTIR)and differential scanning calorimetry(DSC)showed that the whey protein was successfully modified onto the surface of PGH nanoparticles.The water content of PGH-WPE nanoparticles at 48 h is only 5.55%,which is 7.38%less than that of PGH nanoparticles.The emulsification and hygroscopicity resistance of PGH-WPE nanoparticles were superior to those of PGH nanoparticles.The antimicrobial activity of PGH-WPE nanoparticles was similar to that of PGH nanoparticles,and the MIC of PGH-WPE nanoparticles was 2?4 times higher than that of free ?-polyly sine.MBC only doubled the increase in Listeria.(3)The stability and sustained-release ability of PGH nanoparticles and PGH-WPE nanoparticles before and after coated with whey protein were studied,and the application effect of PGH-WPE nanoparticles on fish preservation was evaluated systematically.The results showed that compared with PGH nanoparticles,PGH-WPE nanoparticles had good stability and sustained-release ability in the pH range of 3?11.The maximum particle size change of PGH-WPE nanoparticles is 100 nm lower than that of PGH,and the maximum particle size of PDI is 0.2 lower than that of PGH.The release rate of PGH-WPE nanoparticles was 13.7%lower than that of PGH nanoparticles at 196 h.The effects of ?-polylysine and different nanoparticles on pH,color difference,texture,juice loss rate,lipid oxidation,protein oxidation and total number of colonies of grass carp were compared under 4? and 25? storage condition.The results showed that PGH-WPE nanoparticles could better protect the fish color,inhibit the growth of the total number of bacteria on the fish surface,delay lipid oxidation and protein oxidation,and prolong the shelf life of fresh grass carp.