Valorization of orange by-products for packaging films production
Résumé
Oranges are one of the most extensively cultivated fruits in the world, with Spain being one of the largest producers worldwide. However, the culture generates a lot of by-products which have so far not many applications. This project aims at the valorization of orange peels for food packaging applications, using a green, low-impact process. The interest in pectin (one of the main components of orange peel) for food packaging is known, notably for edible food packaging. However, orange peel contains many more components such as phenolic compounds, terpenes, vitamin C and so forth with interesting properties such as antioxidant activity.
In this project, we are comparing two by-products of orange production: the orange peel flour (ground orange peel, washed) and orange peel pectin, extracted from the latter with a low-impact process (room temperature and a weak acid as a solvent, citric acid) intensified by the application of power-ultrasounds. Those products were used to form films or to coat packaging paper. The mechanical and rheological properties were optimized when necessary by adding a plasticizer (glycerol) or mixing with another polysaccharide (chitosan or alginate). Oxygen and water vapour barrier properties of all the formulations were measured and proved the interest of orange peel by-products for food packaging applications. Besides, antioxidant activity was also studied. All these results were compared with the corresponding values for commercially available pectin, which is obtained through a much longer and more complex process.