Human norovirus (HuNV) infects humans through the consumption of contaminated food, contact with the excrement or vomit of an infected person, and via airborne droplets. Being highly infectious and highly viable in the environment, inactivation of norovirus requires an extremely effective inactivating agent. In this study, we characterized the norovirus-inactivating effects of thermally denatured lysozyme. We observed that lysozymes heat-treated for 40 min at 100°C caused a 4.5 log reduction in the infectivity of norovirus. Transmission electron microscope analysis showed that viral particles exposed to heat-denatured lysozymes were expanded compared to those before exposure. Moreover, we confirmed breaking of the capsid proteins of murine norovirus and HuNV by real-time PCR combined with propidium monoazide.
The emulsification properties of various phospholipids in egg yolk lecithin were evaluated using emulsion droplet size and surface potential (zeta potential). Five different phospholipids (phosphatidylcholine, lysophosphatidylcholine, phosphatidylethanolamine, phosphatidic acid and sphingomyelin) were assessed in this study. Also, cholesterol was employed as a co-emulsifier of phosphatidylcholine. Based on the results of mean diameter of oil droplets in emulsion, lysophosphatidylcholine and phosphatidylcholine showed excellent properties as emulsifiers. The results of zeta potential measurement identified phosphatidylcholine and phosphatidylethanolamine as excellent emulsifiers for the preparation of stable emulsions compared to the other phospholipids. Further, the addition of cholesterol to phosphatidylcholine resulted in increased stability of the emulsion.