Preparation Of Microcapsule With Antibacterial Peptide From Brevibacillus Laterosporus And The Application In Bread

The B.laterosporus S62-9 antimicrobial peptides named as Brevilaterin found in our laboratory exhibit broad antibacterial activity against various pathogens.They can be used in foods for preservation.In order to improve the stability of Brevilaterin in food processing,Brevilaterin were microencapsulated in this study.The properties and applications of antibacterial peptide microcapsule were studied.The main conclusions are listed as follows:Usingβ-cyclodextrin as wall material for embedding antimicrobial peptides,the relative optimum embedding conditions were that the concentration ofβ-cyclodextrin was 0.05 g/m L,the concentration of Brevilaterin solution was 5000 AU/m L,the antimicrobial peptides was embedded in 40°C,3000 r/min for 1 h,and the encapsulation efficiency was 45.7%.Using pectin as wall material for embedding antimicrobial peptides,the relative optimum embedding conditions were that the concentration of pectin was0.8 mg/m L,the concentration of Brevilaterin was 0.4 mg/m L,and the p H of solution was5.5,the antimicrobial peptides was homogenized at 3000 r/min,50°C for 30 min.The encapsulation efficiency could reach as high as 98%,and the embedding effect is better.The antibacterial peptide microcapsule were prepared using pectin as wall material,then the structure and properties of the microcapsule were analyzed.The results of scanning electron microscopy photographs showed that the antimicrobial peptide microcapsule were spherical,and the surface of the microcapsule had wrinkles and depressions.The average particle size of the microcapsule detected by the laser particle size analyzer was 1.8μm.The structure of the microcapsule analyzed by FT-IR showed that no characteristic peak of the antimicrobial peptide was found in the infrared spectrum.It was proved that the antimicrobial peptide was embedded in the pectin.Moreover,the thermogravimetric analysis of the microcapsule showed that the antimicrobial peptide was embedded in the pectin.The Brevilaterin microcapsule exhibited significant antibacterial activity by agar diffusion method.After the incubation time was extended to 48 h,the inhibition zone continued to increase 10.5 mm,and the incubation time was extended to 60 h,the inhibition zone continued to increase 2.6 mm,demonstrating the sustained release of microcapsule.Studies have shown that Brevilaterin microcapsule have good storage stability.Brevilaterin microcapsule were prepared using pectin as wall material.2000 AU/g,3000 AU/g and 3500 AU/g microcapsule were added into flour to make breads for preservation and preservative test.When the amount of microcapsule added was2000 AU/g,the number of mold and bacterial colonies on the third day of the blank control group was 10~6CFU/g,while the number of mold and bacterial colonies in the microcapsule-added bread was 10~3CFU/g and 10~4CFU/g respectively,both of them have decreased.When the amount of microcapsule added was 3000 AU/g and 3500 AU/g,the number of mold colonies on the third day of the bread in the blank control group was 10~5CFU/g.At this time,the number of mold colonies in the 3000 AU/g microcapsule-added bread was 10~3CFU/g,the number of mold colonies in the 3500 AU/g microcapsule-added bread was less than 10~2CFU/g;the number of bacterial colonies on the third day of the bread in the blank control group was 10~7CFU/g,and the number of bacterial colonies in the 3000 AU/g microcapsule-added bread was lower than 10~2CFU/g,and no bacteria were detected in the 3500 AU/g microcapsule-added bread.The results showed that the antimicrobial peptides can be slowly released in bread,which can inhibit the growth of bacteria and fungi in the bread within a certain period of time,and effectively extend the shelf life of the bread.Brevilaterin microcapsule prepared with pectin as wall material can be applied to bread systems for preservation.