The application relates to the field of new packaging materials, and provides a
composite film for fresh-keeping of
green leaf vegetables and a preparation method thereof, main raw materials of the
composite film including a base material,
citric acid, glacial
acetic acid and
nicotinamide; the base material is a mixture of
chitosan and
polyvinyl alcohol; the preparation method is that
chitosan and
polyvinyl alcohol are dissolved and mixed, then a
nicotinamide solution is added, stirring and ultrasonic treatment are conducted to uniformly distribute the components, and finally a flow
casting process is adopted to form a film. The
composite film can effectively
delay oxidation and corruption of
green leaf vegetables, and significantly prolong the
shelf life of the
green leaf vegetables. The composite film has good mechanical properties and flexibility, and is suitable for various fresh-keeping applications. The preparation process is simple, easy for large-scale production, the material is environment-friendly and biodegradable, and the composite film has a wide application prospect.