Sulfonated cellulose nanocrystalline- and pea protein isolate-mixture stabilizes the citral nanoemulsion to maintain its functional activity for effectively preserving fruits.

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The instability of citral greatly limits its application in food field. This study aimed to develop a safe and green emulsifier-stabilized nanoemulsion (NE) to encapsulate citral for exerting its activities. A series of NEs were prepared using varying proportions (1:2 and 1:3) of sulfonated cellulose nanocrystalline- (CNC-C) and pea protein isolate- (PPI) mixture as emulsifier to encapsulate citral with different content (1%, 2%, and 3%), and their stability, antioxidant and antibacterial activities were evaluated to identify the optimal system. When CNC-C and PPI proportion was 1:3 and citral content was 2% (CC1-P3-C2), the obtained CC1-P3-C2 incorporated into pectin achieved the excellent preservation effect on kiwifruits and blueberries. It was attributed to the stability and functional activities of CC1-P3-C2. On the one hand, after storage (25 d) or at pH11 or 100mM NaCl, its size and polydispersity index were still within acceptance level (<300nm and 0.3). On the other hand, it showed good antioxidant and antibacterial activities against Escherichia coli, Staphylococcus aureus, Botrytis cinerea, and Botryosphaeria dothidea, which was due to its high encapsulation efficiency (96.78%). Therefore, CC1-P3-C2 showed a great application potential in fruit preservation, which also provided a feasible strategy to design stable citral NEs.