Soaking and extrusion effects on physicochemical parameters, phytic acid, nutrient content and mineral bio-accessibility of whole rice grain

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 cm(3)/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.

Modification of nutritional properties of whole rice flours ( Oryza sativa L. ) by soaking, germination, and extrusion

“…It was observed that soaking decreased more than a half of total IPs mainly because of 65% of IP6 losses. In this case, losses were attributed to leaching of PA in acid soaking medium (45°C–−24 hr) and also by the activation of endogenous phytases, which degrade PA to low molecular IPs increasing IP4 and IP3 contents (Albarracín, González, & Drago, ). The combination of soaking and extrusion (ESR) produced a 20% decrease in IP6 compared to SR.…”

“…Soaking can be used as a process to decrease phytic acid (PA) content of the grains, since both phytase activation and PA lixiviation are promoted (Albarracín, González, & Drago, 2013;Egli, Davidsson, Juillerat, Barclay, & Hurrell, 2003). Also, before germination, grains are soaked to achieve the adequate moisture.…”

In vitro assays predicts mineral retention and apparent protein digestibility of different fish feed measured using a juvenileP. mesopotamicusmodel

“…This method is more reproducible than those mentioned above, since it uses commercial enzymes whose activity is standardized. In addition, protein digestibility of different extruded food such as extruded maize products added with a red seaweed Porphyra columbina (Cian, Caballero, Sabbag, González, & Drago, ), extruded whole grain red sorghum (Llopart et al., ) and extruded whole rice grain (Albarracín, González, & Drago, ), was estimated by Rudloff and Lönnerdal () method.…”

Physicochemical properties and structural characteristics of whole grain Oryza sativa L. with different treatments

“…An amount of 3 kg of rough rice was previously washed in a 0.2 % NaClO solution during 15 minutes and then soaked in a 5.5 g/L lactic acid solution at 45 ºC for 24 h (Albarracín et al, 2015). After that, the grains were washed with tap water, dried to almost 13 g/100 g moisture content using a tray dryer at 40 ºC, dehulled in a laboratory rice mill (Galicet, San Salvador, Entre Ríos, Argentina), and grinded to grits (1190 -420 µm particle size), as mentioned in 2.2.1.…”

“…Regarding that, Albarracín et al (2015) showed 50% and 77% reduction of phytates after soaking and soaking-extrusion, respectively. Also, a 50% reduction of phytates was observed after germination-extrusion process (unpublished results).…”