Abstract
A combination of soaking and extrusion processes of whole rice grain was studied. The effects of temperature (35–55 °C) and time (24–48 h) of soaking treatment on phytic acid (PA), protein and ashes losses using a factorial design were evaluated. Taking into account ash, protein and PA losses, whole rice was soaked 24 h at 45 °C and extruded using a Brabender single screw extruder. Effects of extrusion temperature (160–190 °C) and moisture content (14–19 g/100 g) on product characteristics were evaluated using surface response methodology. Values corresponding to the different responses were: Expansion (1.64–3.28), Specific Volume (5.68–11.06 cm3/g), Water absorption (3.41–4.43 mL/g) and Solubility (45.44–66.20 g/100 g). The content of PA was reduced from 740.09 to 163.47 mg/100 g (77%) after both processes, resulting in a higher mineral bio-accessibility, and a 7.3% decrease of protein digestibility. Total soluble phenolics and trolox equivalent antioxidant capacity (TEAC) were affected according to the treatment. Both treatments were important to obtain a nutritionally improved whole grain product.
Declaration of interest
The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.
This work was partially financed by UNL-CAI+D 2009 and ANPCYT (PICT 1105). Supporting Information Available: this information is available free of charge via the internet at http://pubs.acs.org