Pea protein isolate-based active films for salmon preservation: The role of different essential oils in film properties, antioxidant, and antibacterial activities

To improve the packaging properties of pea protein isolate (PPI) films, 2 wt% of essential oil (EO) from garlic, ginger, or cinnamon was individually incorporated into the films. The film properties were evaluated after the addition of EOs. The resulting PPI active films were applied to salmon to explore their efficacy in a real food system. The results indicated that the moisture content (MC), total soluble matter (TSM), water vapor permeability (WVP), water contact angle (WCA), tensile strength (TS), and elongation at break (EAB) of PPI film decreased after adding EOs, with the extent of the decrease varying based on the type of oil. SEM images revealed that the distribution of EOs within the film matrix differed: garlic EO was mainly distributed within the internal structure, while ginger and cinnamon EOs were primarily on the surface. FTIR analysis confirmed the interactions between PPI and EOs. When applied to salmon, garlic EO and ginger EO promoted lipid oxidation, whereas cinnamon EO significantly delayed it. Although PPI-based active films containing garlic or cinnamon EOs showed remarkable antibacterial activity in vitro, they did not inhibit bacterial growth in salmon. Additionally, EOs in active films may notably alter the color and sensory properties of salmon, potentially influencing consumer acceptance. Our findings demonstrated that the EO type is a key factor in influencing the properties of edible films. More importantly, the effectiveness of active films is closely related to the specific food system in which they are applied.