Antibacterial mechanisms of diacetyl on Listeria monocytogenes and its application in Inner Mongolian cheese preservation via gelatin-based edible films

Cheese spoilage caused by Listeria monocytogenes (L. monocytogenes) contamination results in food waste, economic losses, and even threatens human health. Diacetyl, a natural microbial metabolite derived from lactic acid bacteria with efficient antimicrobial activity, is commonly found in fermented dairy products, but its inhibitory effect on L. monocytogenes was few reported. This study aimed to explore the antibacterial effects and mechanisms of diacetyl on L. monocytogenes, and its application in Inner Mongolian cheese preservation was conducted by fabricating it into gelatin-based edible films. Diacetyl showed excellent antioxidant and antibacterial activities. The minimal inhibitory concentration (MIC) of diacetyl was 1 mg/mL. Upon exposure to 2MIC diacetyl, the bacterial membrane integrity was significantly impaired, leading to intracellular materials leakage, and the cytoplasmic reactive oxygen species (ROS) level was markedly elevated. To overcome the disadvantages of diacetyl such as unstable and volatile, gelatin-based edible films incorporated with diacetyl were fabricated, and the characterization tests showed the composite edible films exhibited good mechanical, barrier, and antibacterial and antioxidant properties. In the challenge test, the composite edible films could extend the shelf life of cheese samples by maintaining the stability of moisture and pH, stabilizing the color and texture changes, and slowing down the bacterial growth and lipid oxidation. These findings offer new insights into the antibacterial effects of diacetyl on L. monocytogenes, and the fabricated edible films were anticipated to serve as a promising packaging material for preserving Inner Mongolian cheese.