Water Absorption Index Values Research Articles

Relative effect of particle size on the physical properties of corn meal extrudates: Effect of particle size on the extrusion of corn meal

Corn meal of various particle sizes ranging from 180 to 710 lm were processed in a twin-screw extruder to produce directly expanded extrudates. The extrusion process effects on the specific mechanical energy (SME), expansion indexes (radial, longitudinal and volumetric), pasting viscosity, water absorption index (WAI) texture properties, and microstructure were determined. Increasing the particle size decreased the SME input. Extrudates produced with corn meal of higher particle sizes expanded more than extrudates produced with smaller particle sizes. For all treatments there was no peak viscosity at 95 C. But expanded corn meal extrudate from the 180 lm fraction showed a discontinuous gel matrix phase. Increasing corn meal particle size decreased WAI values. The mechanical resistance of the extrudates from the smallest particle size was significantly higher (p < 0.05) than that of the largest particle size. The microstructure of raw corn meal revealed large fractured particles with small rounded particles adhering to the surface.

The effects of water and sucrose contents on the physicochemical properties of non-directly expanded rice flour extrudates

Rice flour was processed by extrusion cooking in the presence of variable contents of water and sucrose. The process was carried out in a twin-screw extruder under the conditions given by a centre rotational experimental design of second order. The effects of the independent variables, water content (27.9 to 42.1%), and sucrose content (0.1 to 19.9%) on the physicochemical properties of the extrudates were investigated. The water absorption index (WAI), water solubility index (WSI), volumetric expansion index (VEI), and bulk density (BD) were determined as dependent variables. BD was determined for samples before and after frying. An increase in water contents resulted in higher WAI and VEI, and lower WSI and BD for extrudates before and after frying. Higher sucrose levels led to increased values of WAI and VEI and to reduced values of WSI and BD. Both independent variables had significant influence on the physicochemical properties of rice flour extrudates. However, the sucrose content was the most significant. The interaction between these two independent variables and their quadratic effect were also important for the responses studied.

Rheological and Thermal Properties of Extruded Mixtures of Rice Starch and Isolated Soy Protein

AbstractMany foods gain new mechanical, thermal and textural properties after being processed due to interactions between carbohydrates and proteins. This effect is characteristic for each foodstuff. The properties of extruded isolated soy protein (ISP) and rice starch were studied considering the following extrusion variables: starch proportion with respect to ISP (0–100%), pH (3–9), moisture content (20–30%) and temperature (140–180ºC). The following characteristics were measured: Water absorption index (WAI), water solubility index (WSI), glass transition temperature (Tg), melting temperature (Tm), viscosity at 90ºC and at 50ºC, storage (G′), loss modulus (G′′) and tan δ. The results indicate that the extruded starch exhibits higher WAI and WSI values than untreated starch. For extruded ISP these values are much lower than for untreated ISP. Extrudates with higher starch proportion had higher Tg and Tm values; pH has a significant effect (p&lt;0.05), at pH 3 higher Tg values were observed, and at pH 9 higher values of Tm. The highest viscosities at 90ºC and 50ºC were observed for extrudates with a higher starch proportion and pH 9. Extruded mixtures showed a more elastic than viscous behavior and an extruded 1:1 blend of starch‐ISP exhibited the behavior of a viscous liquid.

Effect of superfine grinding on properties of ginger powder

The superfine grinding could produce a narrow and uniform particle size distribution in dry ginger. The physical–chemical properties of five types of ginger powders with particles size of 300, 149, 74, 37 and 8.34 μm were investigated. The size was smaller for ginger powders, greater for the surface area (from 0.331 to 1.320 m 2/g) and bulk density (from 0.3069 to 0.3426 g/ml) and smaller for the angle of repose (from 51.50° to 46.33°) and slide (from 45.80° to 39.50°). The values of water absorption index (WAI), water solubility index (WSI) and protein content significantly increased with decreasing the size of ginger particles ( p < 0.05). Interestingly, the values of WAI, WSI and protein content of ginger powder with a particle size of 8.34 μm during soaking reached 0.52 g/g, 33.70% and 84.93% for 60 min, respectively. SEM observations revealed the shape and surface morphology of five types of ginger powders.

Physical Properties of Extruded Products from Three Mexican Common Beans (Phaseolus vulgaris L.) Cultivars

The physical properties of extruded products from three Mexican common bean cultivars were investigated. Common bean cultivars Flor de Mayo, Pinto Villa and Bayo Victoria from the same harvesting season (2006) were used in this work. Beans were milled and the flour was hydrated to 24, 26 and 28 g of water/100 g of dry weight. Two temperatures, 130 degrees C and 165 degrees C at the end of the extruder barrel without die, were experimented. Common bean flour extrudates were evaluated for water absorption index (WAI), water absorption capacity (WAC), oil absorption capacity (OAC), and emulsifying capacity (EC). Flor de Mayo extrudates showed the highest WAC and WAI values. Thus starch from Flor de Mayo beans showed minor restricted water availability. In all cases, the OAC of extruded products was lower than the crude bean flour. The EC for Bayo Victoria flour increased as a consequence of the extrusion process. The EC for Flor de Mayo was higher at lower temperature and lower moisture content than Pinto Villa and Bayo Victoria beans. EC behavior of Pinto Villa was similar to Bayo cultivar. These results indicate that it is possible to produce new extruded products with good physical properties from these common bean cultivars.

Extrusion of banana starch: characterization of the extrudates

AbstractExtrusion of banana starch was carried out for obtaining extrudates with functional and digestibility characteristics. Experimental design with temperature, screw speed and moisture content as independent variables produced 20 experiments that were studied using response surface methodology to discover the effect of these variables on resistant starch content, water absorption index and water solubility index. The amylose content was 37.4% with high resistant starch (RS) content in the ungelatinized sample, which decreased when banana starch was gelatinized (1.9%). Extrudate samples had a higher RS content than the gelatinized native starch, showing that the extrusion process increased RS content of native starch due to starch depolymerization and during cooling of extrudates those linear chains form an arrangement that cannot be hydrolyzed by α‐amylase. The response surface regression model fitted to experimental results of resistant starch showed good determination coefficient (84%). During model validation for RS, the model explains the experimental results up to 90%. Response surface showed that water absorption index values were high when the temperature, moisture content and screw speed were also high; water solubility values were not affected by screw speed, and both temperature and moisture content had a quadratic effect. Cylindrical structures were observed in powders where RS was present and as RS level increased the cylinders became coarser. Copyright © 2006 Society of Chemical Industry

The influence of time and storage temperature on resistant starch formation from autoclaved debranched banana starch

Debranching and autoclaving processes of banana starch were carried out for obtaining a resistant starch-rich powder with functional characteristics. Debranching was carried out using pullulanase for 24 h and the autoclaving was done at 121 °C for 30 min, the samples were then cooled down and stored between 24 and 48 h, and temperatures between 4 and 60 °C. The resistant starch level increased due to the debranching and autoclaving processes. The water absorption index values decreased when the storage time increased, pattern that agrees with the higher RS content. The water solubility index (WSI) was affected by the storage temperature but not by the storage time. The autoclaved sample was hydrolyzed to a lesser extent than native starch. The RS-rich powder presented also crystallinity because the process of autoclaving and storage induced starch retrogradation. The procedure proposed might be used for production of a RS-rich powder from banana starch with high RS level and functional properties.

Resistant starch production from mango starch using a single‐screw extruder

AbstractResistant starches were prepared from mango starch by extrusion. An experimental design with independent variables temperature, screw speed and moisture content produced 20 samples that were studied to determine the effect of these variables on resistant starch (RS) content, water absorption index (WAI) and water solubility index (WSI). RS content was affected by moisture content and temperature. Screw speed and temperature also influenced RS content, the highest level (97 g kg−1) being obtained at low screw speed and high temperature, this pattern can be associated with a longer residence time, which gives rise to more opportunity for amylose chain association. The regression model fitted to the RS experimental results showed a good correlation coefficient (0.80). When moisture content and temperature decreased, WAI increased (105–142 g kg−1), but low WAI values (70–77 g kg−1) were obtained at moisture contents between 200 and 300 g kg−1 and high temperatures (140–150 °C). When moisture content and temperature increased, WSI increased (222–332 g kg−1), but at high temperature value (120 °C) assayed and the lowest moisture content (150 g kg−1), WSI also increased. In the range of moisture contents tested and at low temperatures, only partial gelatinisation occurred and low solubility was obtained. Copyright © 2005 Society of Chemical Industry

The Effect of Suni-Bug (Eurygaster spp.) Damaged Wheat on the Physical Properties of Extrusion Cooked Product

The effects of supplementation of high protease activity wheat (Triticum aestivum) flour due to bug (Eurygaster spp.) damage on characteristics of wheat flour extrudates were investigated. Different proportions of high protease activity flour (HPAF) were blended with wheat flour (0, 10, 20, 30 and 40%) and extruded with a twin-screw Brabender laboratory extruder (Model CTSE-V) at two different barrel temperatures (140°C and 160°C). The obtained extrudates were tested for extrusion quality parameters. Significant differences were observed between two barrel temperatures (140°C and 160°C) in terms of water absorption index (WAI), specific mechanical energy (SME), bulk density (BD) and color (redness) values of the extrudates (p<0.05). Statistical analysis showed that addition of HPAF had significant effect on SME, WAI and WSI (water solubility index) values of extruded samples at 140°C. At higher process temperatures (160°C), SME, color, WAI and WSI values of the extrudates were significantly affected by the addition levels of HPAF. At both process temperatures, a significant decrease and a significant increase were observed in BD and ER (expansion ratio) values of the extrudates, respectively. These results suggested HPAF had positive effects on some quality parameters (BD, ER, WAI and WSI) of the extrudates in the proportions examined.

Effect of processing conditions on some functional characteristics of extrusion‐cooked cassava starch/wheat gluten blends

AbstractExtrusion‐cooked blends of cassava starch (CS) and wheat gluten (WG) were studied. The data were analysed using response surface methodology. The results showed the formation of new structures characterised by lower radial expansion (RE) and specific volume (SV) when gluten was added to CS. WG content was the most important variable affecting RE, water absorption index (WAI), water solubility index (WSI), SV and difference in colour (ΔE) of the extruded products, but feed moisture content and barrel temperature also influenced RE. WAI was affected by a significant interaction between WG content and barrel temperature. The extruded products had lower WAI values and higher WSI values than WG‐free products. Heat, high shear rate and high pressure during extrusion cooking caused mechanical destruction or denaturation of the WG and gelatinisation and dextrinisation of the starch components. The extruded blends could have diverse applications.© 2002 Society of Chemical Industry

FUNCTIONAL PROPERTIES OF SPRAY DRIED TARHANA

ABSTRACT Tarhana, a traditional Turkish fermented yogurl-wheat mixture used in soups, was subjected to dilute acid hydrolysis in 0.5 M HCL (40% dry matter) at 55°C for 4 hours followed by simmering for 10 minutes. The resulting slurry was dried using a laboratory scale spray dryer. Water absorption index (WAI), water solubility index (WSI) and viscosity of spray dried tarhana powder were investigated. The WAI and WSI values for spray dried tarhana powder were found as 1.2 g gel/g dry tarhana powder and 70%, respectively, whereas these values for control sample were 4.0g gel/ g dry tarhana powder and 20% The viscosity of spray dried tarhana soup was found as 100 cp whereas the value for the control sample was 800 cp. When the soups were subject to sensory analysis, panelists found significant differences between the control and spray dried tarhana soups in terms of taste, mouth feel and overall acceptability in favor of the control sample.

Effects of Roasting and Malting on Physicochemical Properties of Select Cereals and Legumes

ABSTRACTPearl millet, teff, cowpea, and peanut used in the formulation of experimental weaning foods were evaluated for changes in physicochemical properties resulting from roasting and malting. The particle size index (PSI) value for cowpea was significantly higher, indicating a finer flour than that obtained from pearl millet. Pearl millet and teff flours did not have significantly different PSI values, water absorption index values, or gruel viscosities. Viscosities for control and roasted cowpea gruels (15%, w/v) were significantly higher than those obtained from peanut gruels. Malting had the greatest impact on physicochemical properties for all grains, whereas roasting produced no significant differences from control flours. Malting yielded apparent increases in grain protein content, and malted seeds yielded finer flours with reduced water absorption and pasting qualities.