High Hydrostatic Pressure and Mild Heat Treatments for the Modification of Orange Peel Dietary Fiber: Effects on Hygroscopic Properties and Functionality

Fruit by-products, such as orange peels, are non-conventional sources of dietary fiber (DF) suitable for developing food ingredients with novel applications. Orange peels were processed at 600 MPa (come up time-CUT, 2, 5, 10, or 20 min) and two temperatures (55 or 70 A degrees C) with the aim to study changes in total (TDF), soluble (SDF), and insoluble (IDF) dietary fiber contents, water-/oil-holding capacity (WHC/OHC), solubility, swelling capacity (SC), pH, tap density, and hygroscopic properties. Increments of 1.9 times on the SDF content were observed after HHP treatment at 55 and 70 A degrees C, compared to the untreated sample content (7.17% dw). Constant values of TDF (51.2-54.6% dw) suggested the significant conversion of assayable IDF to SDF. An increase on SC (6.5%) and OHC (20.1%) values were observed in samples treated with CUT at 70 and 55 A degrees C, respectively. Compared to control samples, HHP (55 A degrees C/5 min) exerted changes on moisture isotherms expressed as relative water sorption content. HHP improved the adsorption and desorption water retention of samples in the 0.1-0.93 a (w) range studied. Results indicate that HHP combined with heat treatment has potential to modify the functionality of orange peels with short processing times.