Physicochemical, microstructural and functional characterization of dietary fibers extracted from lemon, orange and grapefruit seeds press meals
- Bioactive carbohydrates and dietary fibre, 11, p.9-17, 2017 .
The aim of this study was to characterize dietary fibers extracted from defatted press meals of lemon, orange and grapefruit seeds. After an ultrasound-assisted aqueous extraction, the fibers were investigated for proximate composition, soluble/insoluble fiber contents, color, viscosity, degradation temperature and enthalpy, near infrared (NIR)spectra, X-ray diffraction patterns, scanning electron microscopy (SEM)images, and functional (water and oil holding capacity, swelling capacity)properties. The fibers contain 2.0-3.45 mg/g phytate, 1.36-2.26 percent ash, 4.95-7.95 percent soluble fiber, 75.95-82.24 percent insoluble fiber. NIR spectra showed the presence of cellulose and lignin as main components with corresponding bands. Major peak at 22-23 Å X-ray diffraction also indicated presence of cellulose crystals. Crystallinity values of 33-80 percent were measured. SEM images showed the microfibrillar structures present in the samples. Water and oil holding capacities (4.79-7.76 g/g and 3.44-4.19 g/g), and swelling capacities (22.44-24.55 mL/g)proved that the fibers are functional, and especially good for oil containing foods. The utilization of these new fiber sources would be important in terms of by-product valorisation. The data presented in this study may provoke further studies and/or applications of these new dietary fibers.