BACKGROUND Shrimp is nowadays recognized as a rich source of proteins and omega‐3 fatty acids. Edible nano‐emulsion coatings containing eugenol, as an antioxidant agent, and Aloe vera, as a functional compound, were prepared for the storage of pink shrimp over 7 days at 277 K. Samples of the nano‐emulsion were prepared under ultrasonication using 0, 10 and 20 g L−1 of Aloe vera as well as 0, 15 and 30 mL L−1 of eugenol along with Tween 80. RESULTS Results indicated that the low pH of Aloe vera reduced that of the nano‐emulsions while the particle size and turbidity increased with increasing Aloe vera concentration. Moreover, both colour and antioxidant activity of the nano‐emulsions were significantly affected by eugenol and Aloe vera concentrations (p < 0.05). Increasing eugenol concentration led to increased nano‐emulsion pickup but to reduced lightness. Higher concentrations of Aloe vera significantly (p < 0.05) decreased drip loss, cooking loss, pH rise and oxidation rates but enhanced hardness in the shrimp samples. CONCLUSIONS The best results were recorded for the nano‐emulsion coating containing 30 mL L−1 of eugenol and 20 g L−1 of Aloe vera. The nano‐emulsion was successfully able to upgrade shrimp quality over 7 days of cold storage. © 2019 Society of Chemical Industry

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Lipid oxidation is a common phenomenon in emulsions that can be controlled by different techniques. Since proteins are beneficial emulsifiers but with low antioxidant ability, they are used in combination with an antioxidant compound such as polyphenols. Strong interaction between the protein and the polyphenol makes this combination more effective. In this study, soluble fraction of faba protein concentrate (FPC) was conjugated with tannic acid via the free radical grafting, and the structural and functional characteristics of the conjugates were determined in comparison with the mixture of the protein and tannic acid, and the pure protein. After dialysis, the amount of protein and polyphenol from the conjugated materials was significantly reduced, indicating that the unreacted peptides and polyphenol left the solutions. The reduction of the free amino and thiol groups in the protein specified the establishment of a strong interaction between the protein and tannic acid remaining in the solution. Moreover, the conjugate showed high ABTS, hydroxyl radical scavenging activity and ferric reducing power than the protein alone. As the purpose of making the conjugate was to be used as a multilayer film around the oil droplets, the film formation ability of the conjugates was investigated using Langmuir-Blodgett technique. Depending on the size of the trough and the nature of the compounds being used, the concentration and surface pressure required to form a strong film will vary. All samples showed an extended gas state of the film that changed abruptly and directly into a solid state below a critical surface area. Such LB film of the protein-tannic acid conjugate will be used to test its free radical scavenging ability so that its ability to prevent lipid oxidation in emulsions can be predicted.