Effects of moisture, temperature and level of pea grits on extrusion behaviour and product characteristics of rice

Study of extrusion behaviour and porridge making characteristics of wheat and guava blends

Extrusion cooking studies were carried out with a view to develop an instant porridge from wheat grits and guava pulp at different levels from 10 to 50 %. The mixtures were dried to bring down the moisture content to 12, 15 or 18 % and processed using twin screw extruder. The properties of extrudates (expansion ratio and density) and porridge (water absorption index, water solubility index and sensory quality) were studied. Increase in feed moisture content and guava pulp level resulted in the decrease in expansion ratio and increase in density of the extrudates. Water absorption index (WAI) increased and water solubility index (WSI) decreased with increase in feed moisture content. With increase in level of pulp, WAI decreased and WSI increased. Highly acceptable porridge was obtained at 15 % feed moisture content and 20 and 30 % guava pulp. To the samples with selected feed moisture and pulp levels, sugar was added at 20, 25 and 30 % levels to prepare the final product. Sugar level of 30 % was found out to be most acceptable. Fruit porridge stored in LDPE and aluminum laminate pouches at ambient temperature remained acceptable upto 6 months.

Development of flaxseed fortified rice - corn flour blend based extruded product by response surface methodology

Flaxseed imparted the evidence of health benefits in human being. Response surface methodology (RSM) was employed to develop flaxseed fortified rice - corn flour blend based extruded product using twin screw extruder. The effect of roasted flaxseed flour (RFF) fortification (15-25 %), moisture content of feed (12-16 %, wb), extruder barrel temperature (120-140 °C) and screw speed (300-330 RPM) on expansion ratio (ER), breaking strength (BS), bulk density (BD) and overall acceptability (OAA) score of extrudates were investigated using central composite rotatable design (CCRD). Increased RFF level decreased the ER and OAA score significantly while increased BS and BD of extrudates (p < 0.01). Moisture content of extruder feed was positively related to ER (p < 0.01) and OAA (p < 0.05) and negatively related to BD (p < 0.01). Extruder barrel temperature was found to be negatively related to ER and OAA (p < 0.05) and positively related to BD (p < 0.1). Quadratic effect of screw speed was significantly positively related to ER (p < 0.01), BS (p < 0.05) and negatively related to BD (p < 0.01). 15 % RFF fortification with rice flour, 16 % moisture content (wb) of extruder feed, 120 °C extruder barrel temperature and 330 RPM of screw speed gave an optimized product of high desirability with corresponding responses as 3.08 ER, 0.53 kgf BS, 0.106 g.cm(-3) BD and 7.86 OAA.

The effect of moisture content on physicochemical properties of extruded waxy and non-waxy rice flour

The properties of waxy rice flour (WRF) and non-waxy rice flour (RF) were modified using an extrusion process with different feeding material moisture contents. WRF was more affected by the thermomechanical stress from extrusion; consequently, it had a lower glass transition temperature but higher water solubility index (WSI) indicating higher molecular degradation than extruded RF. The lower moisture content of the feeding flour caused more severe flour damage (coarser surface of the extruded flour) and lowered relative crystallinity compared to higher moisture content processing. Moreover, low moisture content processing led to complete gelatinization, whereas, partial gelatinization occurred in the higher moisture content extrusion. Consequently, the extruded flours had a lower peak viscosity and gelatinization enthalpy but a higher water absorption index and WSI than native flour. In conclusion, the rice flour type and the moisture content of the extrusion feeding flour affected the physicochemical properties of the extruded flour.

Optimization of meat level and processing conditions for development of chicken meat noodles using response surface methodology

Response surface methodology (RSM) is a mathematical and statistical technique for testing multiple process variables and their interactive, linear and quadratic effects, and useful in solving multivariable equations obtained from experiments simultaneously. In present study optimum meat level and processing conditions for development of shelf stable chicken meat noodles was determined using central composite design of response surface methodology (RSM). Effects of meat level (110-130 g); processing conditions such as steaming time (12-18 min) and drying time (7-9 h) on the water activity, yield, water absorption index, water solubility index, hardness, overall acceptability and total colour change of chicken noodles were investigated. The aim of present study was to optimize meat level and processing conditions for development of chicken noodles. The coefficients of determination, R(2) of all the response variables were higher than 0.8. Based on the response surface and superimposed plots, the optimum conditions such as 60 % meat level, 12 min steaming time and 9 h drying time for development of chicken noodles with desired sensory quality was obtained.

Hydration kinetics of direct expanded tef flour breakfast cereals in water and milk

Hydration kinetics of tef flour breakfast cereals extruded at barrel temperatures of 110, 130, and 150°C was investigated by hydrating them in water and whole milk at 25°C (±1°C). The normalized Weibull model described the rehydration characteristics of the extrudates in water and milk adequately (R (2) = 0.98-0.99). Water absorption rate was significantly (P < 0.05) influenced by barrel temperature where extrudates processed at 150°C barrel temperature exhibited high water absorption rate followed by those extruded at 130 and 100°C, respectively. Hydration rate and equilibrium moisture content were higher for samples hydrated in water than those in milk. In view of the values of the shape parameter β, the hydration process is predominantly controlled by diffusion (β = 0.40-0.51) for samples extruded at 110°C whereas external resistance to mass transfer dominated (β = 0.60-0.73) those extruded using 150 and 130°C. Extrudates processed at 130 and 150°C exhibited better hydration characteristics. Thus, these temperature ranges could be used to produce extruded products from tef.

Effect of extrusion process parameters and pregelatinized rice flour on physicochemical properties of ready-to-eat expanded snacks

Present study was conducted to investigate effects of pregelatinized rice flour and extrusion process parameters such as feed moisture (16-19 %), die temperature (115-145 °C) and screw speed (150-250 rpm) on physicochemical properties of ready-to-eat expanded snacks by using co-rotating twin-screw extruder. Higher die temperature increased extrudate density and WSI but reduced die pressure, torque and expansion. Increased feed moisture content resulted in extrudates with increased density, WAI and hardness but reduced die pressure, expansion and WSI. Screw speed was found to have no significant effect on expansion and hardness of extrudates, while increase in screw speed resulted in increased WAI of extrudates and reduced torque of extrudates. Effect of pregelatinized rice flour on extrudate expansion and hardness was analysed at 16 % feed moisture, 135 °C die temperature and 150 rpm screw speed. Use of pregelatinized rice flour increased expansion while it reduced hardness of extrudates.

Effect of feed composition, moisture content and extrusion temperature on extrudate characteristics of yam-corn-rice based snack food

Blends of yam, rice and corn flour were processed in a twin-screw extruder. Effects of yam flour (10-40 %), feed moisture content (12-24 %) and extruder barrel temperature (100-140 °C) on the characteristics of the dried extrudates was investigated using a statistical technique response surface methodology (RSM). Radial expansion ratio differed significantly (p ≤ 0.05) with change in all the independent variables. Highest expansion (3.97) was found at lowest moisture content (12 %) and highest barrel temperature (140 °C). Increased yam flour level decreased the expansion ratio significantly. Water absorption index (WAI) increased significantly with increase of all variables. However, water solubility index (WSI) did not change with change in yam flour percent. Hardness of extrudates that varied from 3.86 to 6.94 N was positively correlated with yam flour level and feed moisture content, however it decreased significantly (p ≤ 0.001) with increase of barrel temperature. Yam percent of 15.75 with feed moisture and barrel temperature at 12.00 % and 140 °C respectively gave an optimized product of high desirability (> 0.90) with optimum responses of 3.29 expansion ratio, 5.64 g/g dry solid water absorption index, 30.39 % water solubility index and 3.86 N hardness. The predicted values registered non-significant (p < 0.10) differences from the experimental results. Further study would include the sensory properties enhancement of extruded snacks and little emphasis on the chemistry of interaction between different components.

Extruder Responses, Textural Properties and Color of Meat Analogs Made by High Moisture Soybean Residue and Soy Protein Isolate

The effect of mixture material with different levels which consisted in soybean residue, soy protein isolate and wheat gluten(0/65/35%-60/5/35%) during high-moisture extrusion, using a laboratory size co-rotating, twin screw food extruder under 50%-60% feed moisture content and 130-150 °C cooking temperature on selected extruder responses, color and textural properties of extruded products was studied. The results show that soybean residue content and feed moisture is negative correlation (r=-0.666 and -0.601) with the hardness of fibrous meat analogs. But cooking temperature has not significant correlation (P>0.05) with the changes of extruder response, color or textural properties of meat analogs.

Extrusion Conditions and Amylose Content Affect Physicochemical Properties of Extrudates Obtained from Brown Rice Grains

The utilization of whole grains in food formulations is nowadays recommended. Extrusion cooking allows obtaining precooked cereal products and a wide range of ready-to-eat foods. Two rice varieties having different amylose content (Fortuna 16% and Paso 144, 27%) were extruded using a Brabender single screw extruder. Factorial experimental design was used to study the effects of extrusion temperature (160, 175, and 190°C) and grits moisture content (14%, 16.5%, and 19%) on extrudate properties. Specific mechanical energy consumption (SMEC), radial expansion (E), specific volume (SV), water absorption (WA), and solubility (S) were determined on each extrudate sample. In general, Fortuna variety showed higher values of SMEC and S (703–409 versus 637–407 J/g; 33.0–21.0 versus 20.1–11.0%, resp.) than those of Paso 144; on the contrary SV (8.64–3.47 versus 8.27–4.53 mL/g) and WA tended to be lower (7.7–5.1 versus 8.4–6.6 mL/g). Both varieties showed similar values of expansion rate (3.60–2.18). Physical characteristics depended on extrusion conditions and rice variety used. The degree of cooking reached by Paso rice samples was lower than that obtained for Fortuna. It is suggested that the presence of germ and bran interfered with the cooking process, decreasing friction level and broadening residence time distribution.

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.