Fortification of orange juice with antioxidant from orange by-products and evaluation of stability during in vitro digestion

Orange juice production provides large amounts of underutilised by-products that suppose an environmental problem for the food industry, despite their high content in bioactive compounds. The aims of this work have been the fortification of commercial orange juice with bioactive compounds from orange pulp in order to improve its antioxidant activity. Thus, different aqueous orange pulp extracts were encapsulated and incorporated into commercial orange juice at different proportions. The stability of the antioxidant ingredient was followed over 8 weeks. The total phenolic content and the antioxidant capacity of these formulations were measured with different antioxidant procedures. Additionally, the effect of an in-vitro digestion in the antioxidant activity of the fortified juices was studied. The total phenolic content of the developed ingredient decreased in 34 % during the two first weeks of storage, but after that it remain constant. The results revealed that the commercial orange juice fortified with the encapsulated extract from orange pulp showed an increase of total phenolic content of 10-22 %, while the antioxidant activity of the juice improved in all the antioxidant assays. The addition of the antioxidant extract showed a reduction in the decrease of the antioxidant activity of the juices after de in-vitro digestion.