Protein Isolate from Orange (Citrus sinensis L.) Seeds: Effect of High-Intensity Ultrasound on Its Physicochemical and Functional Properties

The seeds from fruit processing are by-products that contain proteins which can be recovered for use as food ingredient. The seeds from fruit processing are protein-containing by-products that can be recovered for use as a food ingredient. Although orange seeds are an interesting source due to high protein content, they have not been used to elaborate protein products for food use. In the present study, a protein isolate from orange seeds (OSPI) was obtained by alkaline extraction and isoelectric precipitation methods. Then, OSPI was treated in an ultrasonic bath (42 kHz, 130 W) for 15 or 30 min and the effect on its physicochemical and functional properties was evaluated. The protein content of OSPI was 86.40–90.06%. Ultrasound treatment had a beneficial effect on protein solubility (in the pH range 6–12), as well as on emulsifying and gelling properties. In addition, ultrasound treatment increased the size of protein aggregates and modified the fractional composition of proteins, increasing albumins and globulins, and reducing prolamines and glutelins. OSPI treated with ultrasound could be used as ingredients in the food industry or in the development of new food products.