Tracing phenolic compounds through manufacturing of edible films from orange and grapefruit peels

 

J.G. Hernández-Carrillo, A. Valdez-Fragoso, J. Welti-Chanes, H. Mújica-Paz

 

 

Edible films naturally rich in phenolic compounds were prepared from orange and grapefruit peels. Free and total polyphenols were determined by Folin-Ciocalteau method and flavonoids were identified and quantified by HPLC in the manufacturing processes of films. Films from grapefruit and orange peel had 24.95 and 28.18 mg GAE/g (Gallic Acid Equivalents/g), respectively, retaining more than 50% of total phenolics from the raw material. Hesperidin (33.39 mg/g) was the main flavonoid in orange peel based films and naringin (31.42 mg/g) in grapefruit peel films. Recoveries of the identified flavonoids in films were in the range of 31-60%. Residues, mainly those from orange peel process, retained important fraction of phenolics. Edible films with high levels of polyphenols were manufactured from orange and grapefruit peel without the addition of external phenolics extracts.