Synergistic antibacterial properties of citral and α-terpineol against Alicyclobacillus acidoterrestris and the application of their nanoemulsions in apple juices

To control juice spoilage caused by Alicyclobacillus acidoterrestris ( A. acidoterrestris ), this study investigated the synergistic antibacterial properties of citral and α-terpineol (S CT ) and its application in apple juice. S CT at 1× MIC completely inhibited both vegetative cells and spores of within 24 h. It disrupted cell membrane integrity, inducing lipid peroxidation, shrinkage, permeabilization, and depolarization. These changes triggered intracellular redox imbalance, leading to excessive accumulation of reactive oxygen species (ROS) and hydrogen peroxide (H₂O₂), characterized by severe membrane lipid peroxidation, an increased NAD + /NADH ratio, and reductions of 84.180% and 70.780% in adenosine triphosphate (ATP) content and catalase activity, respectively, ultimately resulting in A. acidoterrestris cell death. In addition, an S CT nanoemulsion (S CT NE) delivery system was developed. Compared with conventional heat treatment, the addition of 1% S CT NE effectively inhibited the growth of A. acidoterrestris in artificially contaminated fresh apple juice. Under storage at 4 °C and 25 °C, 1% S CT NE enhanced the volatile flavor profile without significantly altering sensory acceptability or physicochemical properties. Therefore, 1% S CT NE may serve as a potential complementary strategy for maintaining apple juice quality. Summary diagram. • Citral and α-terpineol exhibited synergistic antibacterial enhancement. • S CT disrupted the membrane integrity and altered intracellular redox homeostasis. • The addition of exogenous antioxidants repaired the cellular damage caused by ROS. • The1% S CT nanoemulsion prolonged the shelf-life of apple juice. • This study lays foundation for S CT 's application as a natural juice preservative.