In this study, soy isolate protein / chitooligosaccharide (SPI/COS) glycosylated conjugates was prepared and employed as an emulsifier to stabilize carvacrol-loaded nanoemulsions (CNE-SPI/COS). The antibacterial properties and mechanism of CNE-SPI/COS against S. putrefaciens was investigated. The results of microbial growth curves and confocal laser scanning microscopy (CLSM) results showed that CNE-SPI/COS effectively inhibited the growth of S. putrefaciens and the killing effect of CNE-SPI/COS on S. putrefaciens was concentration-dependent. Field emission scanning electron microscopy (FESEM) images showed that CNE-SPI/COS caused folds, shrinkage, rupture and even lysis of S. putrefaciens. The results showed that CNE-SPI/COS inhibited the growth and reproduction of S. putrefaciens mainly through three targets: (i) the reduction of alkaline phosphatase (AKP) activity and protein leakage indicated that CNE-SPI/COS disrupted the integrity of cell wall and cell membrane
(ii) the reduction of intracellular protein and ATP content indicated that CNE-SPI/COS interfered the synthesis of intracellular nutrient and synthesis of energy-supplying substances
(iii) changes in the activities of succinate dehydrogenase, pyruvate kinase, and glucose 6-phosphate dehydrogenase indicated that CNE-SPI/COS impeded the normal cellular metabolic pathways such as the tricarboxylic acid cycle, the glycolytic pathway, and the pentose phosphate pathway, and the decrease in superoxide dismutase activity indicated that CNE-SPI/COS disrupted the defense system against oxidative stress. In conclusion, the encapsulation of carvacrol into the nanoemulsion system can provide theoretical support and methodological guidance for the application of nanoemulsions in microbial decontamination of aquatic products.