Effect of Nanoemulsion Containing Enterocin GR17 and Cinnamaldehyde on Microbiological, Physicochemical and Sensory Properties and Shelf Life of Liquid-Smoked Salmon Fillets  
[PERSON]  
1 School of Food and Health, Beijing Technology and Business University, Beijing 100048, China 12 Beijing Engineering and Technology Research Center of Food Additives, Beijing Technology and Business University, Beijing 100  
Bacteriocins are proteins or peptides that exhibit antibacterial activity against various spoilage and pathogenic bacteria [5]. Bacteriocins from lactic acid bacteria (LAB) are non-toxic, highly potent, and safe, and so have been widely used as preservatives for food products [6]. However, bacteriocins have a relatively narrow spectrum, exerting strong inhibitory effects against Gram-positive (G\({}^{+}\)) bacteria and weak and even non-inhibitory effects against Gram-negative (G\({}^{-}\)) bacteria [7]. Essential oils (EOs) are complex mixtures of volatile organic compounds produced by plants, and they frequently exhibit antimicrobial activity against G\({}^{+}\) and G\({}^{-}\) bacteria as well as antioxidant properties. A high level of EOs in food showed unacceptable organoleptic properties, and low levels of EOs could not exert antibacterial effects in food products [7; 8]. The combination of bacteriocin and EOs demonstrates a synergistic effect and broadens the antibacterial spectrum of bacteriocins, decreasing the usage of both components, thereby effectively maintaining or improving the sensory attributes, inhibiting microbial growth, and delaying chemical changes to food during storage [5; 6; 7; 8]. In addition, the cost of additives would be further reduced using a combination of bacteriocins and EOs, facilitating their commercial production [9]. [PERSON] et al. [10] found that the combination of entercin with EOs induced a synergistic effect against _L. monocytogenes_ and _E. coli_. A mixed natural preservative presented better antimicrobial effects in milk with a combination of 16.25 \(\upmu\)g/mL of cinnamaldehyde and 31.25 \(\upmu\)g/mL of nisin, reducing the usage by about 75% compared with the individual MIC for cinnamaldehyde and nisin, respectively [11]. However, there are several challenges regarding the use of bacteriocins and EOs in actual food products. The unwanted interactions between food matrixes and bacteriocins, degradation caused by enzymes in the food system, and varied pH all decreased the antibacterial activity of bacteriocins [11; 12]. Bacteriocins with a high content of hydrophobic amino acids are easily bound to charged or hydrophobic macromolecules in food products [13]. The fat content of smoked salmon is about 8-14%, decreasing the antimicrobial activity of bacteriocins. As for EOs, intrinsic obstacles, such as their low water solubility, high volatility, low stability, and negative organoleptic effects, affect their antibacterial and antioxidant activities in food systems [14]. Instead of applying bacteriocins and bulk EOs to foods directly, one promising strategy is to encapsulate bacteriocins and EOs into a nanoemulsion, which can be used as a colloidal delivery system to protect the effects of bioactive compounds [15]. Moreover, the sustained release of a nanoemulsion enables a longer action time for the active substances, maintaining their antimicrobial activity for longer periods [16]. A nanoemulsion incorporating star anise essential oil and nisin is not only beneficial for the shelf-life extension of chicken fillets but also has no adverse effects on the flavor of chicken [17]. Additionally, star anise essential oil, polylysine, and nisin-loaded nanoemulsions revealed efficient activities when applied to ready-to-eat (RTE) pork meat products as antimicrobial agents [18]. However, the application of bacteriocin-EO-loaded nanoemulsion delivery systems to RTE seafood products to inhibit the spoilage process requires further study.