Preparation, physicochemical, and antibacterial properties of bovine serum albumin microspheres loaded with sodium nitrite

In this study, NaNO2-embedded bovine serum albumin microspheres (BSAMs) were prepared by oil-in-water emulsification method, which was covalently cross-linked with transglutaminase (TGase). Moreover, the physicochemical properties and antibacterial effect of BSAMs on Escherichia coli, Staphylococcus aureus, Pseudomonas, and beef and pork jerky were also analyzed. The particle size of BSAMs was about 0.5-2.5 mu m observed by scanning electron microscopy. Almost all NaNO2 was encapsulated inside BSAMs, and there was no NaNO2 attaching on the surface of BSAMs. The encapsulation rate of NaNO2 first increased from 0 to 20 U/g TGase and then decreased from 20 to 40 U/g TGase; likewise, the release of NO first increased with the increase of TGase (0-20 U/g) and it decreased when the TGase concentration was 30 and 40 U/g. Based the results of minimal inhibitory concentration and minimal bactericidal concentration, E. coli and Pseudomonas were more sensitive to BSAMs than S. aureus. In addition, the slow release of NO from BSAMs could significantly inhibit the growth of bacteria on the surface of beef and pork jerky in a weak acidic environment compared with NaNO2 used directly, so as to achieve long-term antibacterial effect and prolong the shelf life of meat products.