Feed Moisture Content Research Articles

Effects of Thermomechanical Extrusion and Particle Size Reduction on Bioconversion Rate of Corn Fiber for Ethanol Production

ABSTRACTThe objective of this research was to evaluate the effect of thermomechanical extrusion and particle size (PS) reduction on the bioconversion rate of corn fiber for ethanol production. Extrusion was conducted at a screw speed of 300 rpm, feed rate of 120 g/min, feed moisture content of 30%, melt temperature of 140°C, and die diameter of 3 mm. Raw and extruded corn fiber were separated into three different PSs (1 > PS ≥ 0.5, 0.5 > PS ≥ 0.3, and 0.3 > PS ≥ 0.15 mm) with a wire sieve. Extrusion pretreatment and PS reduction resulted in a significant (P < 0.05) difference in physical properties and color values of extruded corn fiber as a result of accelerated degradation of corn fiber structure. Significant increase in water solubility index of extruded corn fiber at 0.3 > PS ≥ 0.15 mm was an indication of high degradation of starch during extrusion for higher release of polysaccharides. Moreover, extruded corn fiber at PS reduction 0.3 > PS ≥ 0.15 mm also significantly increased (P < 0.05) ethanol yield (69.11 g/L) and conversion (68.18%) by increasing protein digestibility and free amino nitrogen, which are essential for higher fermentation efficiency.

The Effect of Extrusion Conditions on Water-extractable Arabinoxylans from Corn Fiber.

The effect of feed moisture contents (30%, 40%, and 50%) and screw speed (200 rpm, 250 rpm, and 300 rpm) on the corn fiber gum (CFG) yield and soluble arabinoxylans (SAX) content of destarched corn fiber was investigated. The CFG yields and SAX contents of extruded, destarched corn fiber were higher than that of destarched corn fiber. In extruded, destarched corn fiber, increased screw speed and decreased feed moisture contents resulted in a higher SAX contents. The maximum yields of CFG obtained from extruded, destarched corn fiber were 79.1±19.0 g/kg (30% feed moisture content) and 82.3±11.30 g/kg (300 rpm screw speed). The highest SAX content was also observed at a screw speed of 300 rpm. The results of the present study show that water extraction and extrusion combined have the potential to increase CFG and SAX yields from corn fiber.

Modeling of a Small-scale Biomass Updraft Gasifier

Biomass can be efficiently transformed into valuable gas products via gasification. Gasification converts biomass through partial oxidation into a gaseous mixture, small quantities of char and condensable compounds. In this work, an updraft gasifier is regarded because the updraft gasifier is suitable for wet fuels such as agricultural residues. Moreover, it is the most simple and can be used as a basis for the design and operation of small-scale gasifier. However, due to the high tar content of the gas produced, updraft gasifiers may not effectively be used without comprehensive gas cleaning. To improve an insight on the gasification process, app opriate mathematical models are required. Further, models are useful for gasifier design and operation such as prediction of operation behavior during normal operation, startup, and shutdown. This article presents a one-dimensional mathematical model for the simulation of a small-scale fixed-bed updraft gasifier of rice straw. The model is based on a set of differential eq ations describing the entire gasification process. The governing equations include conservation of mass and energy, complemented by boundary conditions, constitutive relationships. The main features of the model include homogeneous and heterogeneous combustion and gasification reactions, pyrolysis kinetics and drying, heat and mass transfer in the solid and gas phases as well as between phases. The simulation results were compared with experimental data, and showed good agreement. The model constructed was then used to predict the effects of varying moisture content and air feed temperature. Fuel with higher moisture content of fuel feed lowered the performance of the gasification process. But, higher temperature of air feed resulted in higher performance with lower tar content and more environmentally preferable.

Optimization of Physical Parameters for Cereals-Pulses Combination Based Extrudates Using Sequential Response Surface Methodology

Plant proteins in the form of flour, grits etc. are not in the palatable form as such due to lack of meat like texture, flavour and appearance. Thus the present need exists to prepare a palatable inexpensive vegetable based high protein foods. The extrusion cooking process converts the protein in its amorphous defatted flour form to fibrous structures. An extruded snack from Bengal gram brokens-sorghum blends was prepared by using Wenger X-5 extruder. The properties of the extrudates were studied at three different moisture levels (15, 20 and 25% w.b.) and three levels of barrel temperature (80, 90 and 100°C) with 5 levels of blending ratio of Bengal gram brokens-sorghum blends (10, 15, 20, 25 and 30%). All the physical parameters were optimized to have the best quality extrudates by RSM. The best quality extruded snack was obtained at 80°C barrel temperature, 15% moisture content of feed and 10% blending ratio followed by 15% moisture content of feed and 10% blending ratio at 100°C barrel temperature. Texture analysis of the optimized extrudate was also done for crispiness test and hardness test to have an idea of the resistance that the snack may offer on first bite to the consumer. The maximum value of crispness and minimum hardness was obtained at 15% moisture content, 100°C temperature. DOI: http://dx.doi.org/10.3126/jfstn.v7i0.10607 J. Food Sci. Technol. Nepal, Vol. 7 (61-63), 2012

Hull-less barley flour supplemented corn extrudates produced by conventional extrusion and CO2 injection process

Abstract The effects of feed moisture content (20, 25%), exit–die temperature (80, 130 °C), and extrusion-cooking method (with/without CO 2 injection) on β-glucan (BG) levels and physicochemical properties of hull-less barley flour (HBF) supplemented (15, 30, 45%) corn extrudates were investigated. The highest HBF supplementation level (45%) resulted in higher BG levels (2.87–3.28%) in all extrusion conditions. In general, increasing feed moisture content from 20 to 25% and exit–die temperature from 80 to 130 °C resulted in small increases in enzyme resistant starch type-3 (RS 3 ) levels. However, the investigated extrusion conditions did not form substantial amount of RS 3 and the highest RS 3 content was 540 mg/100 g. Lower feed moisture content and higher exit–die temperature resulted in higher water solubility (WS) and lower water-binding capacity (WBC) values. Cold-paste viscosity (CV) was observed in all extrudates. High WS and WBC values of extrudates and the existence of CV values in RVA curves indicated complete starch gelatinization. Industrial relevance CO 2 injection has been proved as a reliable alternative method to the conventional extrusion process used in the breakfast cereals and snack food industry. The overall quality of the product processed by CO 2 injection was comparable to that of the current process. The extrudates produced by CO 2 injection method had more uniform expansion and smoother surface. CO 2 injection did not have a reducing effect on β-glucan levels; however, it is expected to result in a better retention of heat labile micronutrients and hence more healthy food products.

English

Sweet potato flour and tomato pomace blend were used for the development of extruded products. The response surface methodology was adopted in the experimental design to investigate the effect of feed proportion (5-25% tomato waste powder), moisture content (13-17%), screw speed (275-325 rpm) and barrel temperature (120-140°C) on the quality of the extruded products. Regression equation describing the effect of each variable on the system parameters and product responses were obtained. In all the experiments, the responses were almost equally affected by changes in tomato pomace level, feed moisture, extrusion temperature and screw speed. Increase in barrel temperature results in maximum expansion, minimum hardness and maximum water absorption index (WAI). Higher tomato pomace proportion in feed composition showed minimum expansion, maximum bulk density, minimum WAI and maximum water solubility index (WSI). The compromised optimum condition obtained by numerical optimization were: barrel temperature, 137.01°C, screw speed 343.48 rpm, feed moisture 13.86% and tomato pomace 21.31%. The findings of this study demonstrate the feasibility in development of value added extruded products from tomato pomace and sweet potato flour. Key words: Twin screw extrusion, sweetpotato flour, tomato pomace, response surface methodology.

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 (150-250rpm) 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 150rpm screw speed. Use of pregelatinized rice flour increased expansion while it reduced hardness of extrudates.

Fish Oil‐Fortified Extruded Snacks: Evaluation of Physical Properties and Oxidative Stability by Response Surface Methodology

AbstractResponse surface methodology was employed to study the physical characteristics and oxidative stability of fish oil‐fortified extruded snack. Process temperature (80–140C), feed moisture (12–20%), screw speed (300–400 rpm) and fish oil content (0.5–2.5%) were selected as the independent variables at five levels. A central composite design was developed to study the linear, quadratic and interactive effect of the selected independent variables on responses studied viz. expansion ratio, porosity, hardness, crispness and thiobarbituric acid reactive substance values. The physical properties of extruded samples such as expansion ratio, porosity and crispness were mostly influenced by feed moisture followed by fish oil content. Fish oil showed significant interactive effect with temperature on expansion ratio and porosity. The product with fish oil content up to 0.8% was found significantly oxidatively stable and fish oil can therefore be added to improve the nutritive and functional value of extruded snacks.Practical ApplicationsThe more frequently consumed products like rice‐based extruded snack can be fortified with fish oil, a source of cardioprotective omega‐3 fatty acids without causing undesirable changes in the physical properties. Any change in the feed formulation can influence the physical properties of the extrudate and it is essential to optimize the processing conditions for achieving the acceptable product characteristics. The present study gives an account on the effect of fish oil fortification on the physical properties of an extruded snack. The results of the study will be useful for the food processors to decide on the optimum parameters for developing fish oil‐fortified extruded snack with acceptable product quality characteristics.

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 6months.

Effects of formulation, extrusion cooking conditions, and CO2 injection on the formation of acrylamide in corn extrudates

Acrylamide is a possible carcinogen and known to form in heat-treated carbohydrate-rich foods. This study was designed to investigate the effects of different ingredients (reducing sugars, chemical leavening agents, citric acid), processing conditions (feed moisture content: 22, 24 or 26%, exit die temperature: 110, 150 °C), and extrusion cooking methods (with or without CO2 injection) on acrylamide formation. The type of reducing sugar did not have a considerable effect on acrylamide formation, while increased exit die temperature had a promoting effect. Addition of chemical leavening agents (sodium bicarbonate and ammonium bicarbonate) into formulations increased acrylamide formation levels. The addition of citric acid prevented acrylamide formation, but its effect on textural properties was detrimental. Acrylamide levels of extrudates decreased gradually with increasing feed moisture in all formulations. Acrylamide content of extrudates produced with 22% feed moisture decreased by 61% in the CO2 injection method compared to conventional extrusion. Furthermore, an 82% decrease in acrylamide content was observed with the combined effect of CO2 injection and increasing feed moisture content from 22 to 24% and decreased below the limit of quantification with a further increase in feed moisture. A substantial decrease in final acrylamide level is probably due to restriction of two major steps of acrylamide formation: dehydration and decarboxylation.

Physico‐functional and antioxidant properties of purple‐flesh sweet potato flours as affected by extrusion and drum‐drying treatments

SummaryEffects of extrusion and drum‐drying treatments on physico‐functional and antioxidant properties of flours prepared from purple‐flesh sweet potato were evaluated. Extrusion variables were feed moisture contents (MC; 10%, 13%, 16%) and screw speeds (SS; 250, 325, 400 r.p.m.), whereas drum‐drying was done at 120, 130 or 140 °C. Effects of MC were generally greater than SS on flour properties. Extruded flours showed higher water absorption and water solubility indices compared with control nonextruded flours. Regardless of SS, total phenolic content and antioxidant activities (DPPH and ABTS) of flours processed at 10% MC were significantly higher than those at 13% and 16%. Both extruded and drum‐dried flours exhibited no peak viscosity, indicating complete gelatinisation of starch. Maximum phenolic content and antioxidant activities of drum‐dried flours were obtained at 140 °C. Although drum‐dried flours had higher antioxidant capacity than extruded flours, both flours could potentially be used as food ingredients.

Effect of Different Extrusion Treatments and Particle Size Distribution on the Physicochemical Properties of Rice Flour

Rice flour is an interesting alternative for developing gluten free products, but its features do not always meet the process requirements. The objective of this study was to modify the functional properties of rice flour by combining extrusion and size fractionation. Different extrusion conditions (barrel temperature, feed moisture content and feed rate) were applied to vary the severity of the treatment on the flour constituents. Extrusion and mechanical fractionation of the rice flours modified their behavior affecting hydration, thermal and pasting features, besides their susceptibility to enzymatic hydrolysis. Specifically, onset and peak temperature increased and gelatinization enthalpy decreased when increasing barrel temperature of the extrusion. Fine flours with stronger extrusion (high temperature barrel) showed the highest susceptibility to enzymatic hydrolysis. Overall, the combination of both physical treatments maybe an attractive alternative for obtaining clean label rice flours with modified features.

Simulation study of the effect of feed moisture on autothermal reforming in short contact time catalytic micro channels

In this work, a set of cylindrical rhodium coated micro channels with diameter range of 0.2–0.8 mm and a length of 1 cm is considered to simulate the behavior of the autothermal reforming reactions of methane to synthesis gas. A one-dimensional heterogeneous model is used to describe the flow field. Gas phase reactions are modeled by GRI 3.0 mechanism, and a 38-step detailed surface mechanism over a rhodium catalyst is considered for catalytic reactions. The effect of feed moisture content on product selectivity and yield, minimum required preheat temperature, length of the reforming and oxidation zones, and reactor thermal efficiency is studied at two different operating pressures of 1 and 20 atm, methane to oxygen feed ratios of 1.2–2.5, and pore diameters of 0.2–0.8 mm. Moreover, the simulation results are compared with the experimental data of Michael et al. [13].

Effect of Extrusion Cooking Variables on the Torque and Specific Mechanical Energy of a Single Screw Extruder

Aims : The operation of a single screw extruder under the influence of locally available raw materials (African yam bean (AYB) and cassava products were determined using the measures of torque and specific mechanical energy of the extruder. The specific mechanical energy (SME) is a good quantitative description in extrusion processes, since it allows the direct comparison of different combinations such as screw speed, feed rate and torque, while torque is directly correlated with power usage. Study Design : A three- factor five level response surface methodology central composite design (CCD) was adopted to study the effect of feed moisture content (MC), feed composition (FC) and the screw speed (SS) on the energy efficiency of a single screw extruder using torque and specific mechanical energy (SME). Place and Duration of Study : The raw materials for the work were obtained from Abia State Nigeria. The extrusion work was done at the Federal polytechnic Mubi Adamawa State Nigeria, while the statistical analysis was done at Michael Okpara University of Agriculture, Umudike Abia State Nigeria. Methodology : African yam bean (AYB), cassava tubers and Ighu (pre-gelatinized

Effect of Thermo-extrusion Process Parameters on Selected Quality Attributes of Meat Analogue from Mucuna Bean Seed Flour

ABSTRACT Flour from mucuna beans ( Mucuna pruriens ) were used in producing texturized meat analogue using a single screw extruder with the intention to monitor modifications on some functional properties of the extrudate. Response surface methodology based on Box Behnken design at three levels of barrel temperature (110, 120, 130°C), screw speed (100, 120, 140 rpm) and feed moisture content (44, 47, 50%) were used in 17 runs. Regression models describing the effect of process variables on the product quality attributes were obtained. Result obtained showed that the moisture contents of the meat analogue samples decreased from 13.23 to 6.53%. Increasing feed moisture content resulted in extruded meat analogue with a higher density (0.988), water absorption index (WAI) (2.30), oil absorption index (OAI) (2.350), swelling power (3.47) and lower lateral expansion (0.84). Lateral expansion, OAI and swelling power increased as barrel temperature increased with peak values of 1.39, 2.39 and 3.47 respectively, while bulk density and WAI decreased. The product functional responses with coefficients of determination (R 2 ) ranging between 0.658 and 0.894 were most affected by changes in barrel temperature and feed moisture and to lesser extent by screw speed. Optimization results based on desirability concept indicated that a barrel temperature of 120.15°C, feed moisture of 47% and screw speed of 119.19 rpm would produce meat analogue of preferable functional properties.

Effect of Extrusion Process Parameters on Physical, Functional and Textural Properties of Broken Rice-Foxtail Millet-Maize based Extrudates

The effect of extrusion on the physical, functional and textural properties of broken rice extrudates blended with foxtail millet and maize flours of various formulations (10:80:10, 20:60:20, 30:40:30, 10:60:30 and 30:60:10) on density, true density, porosity, expansion ratio, water absorption index (WAI), water solubility index (WSI), solubility index, swelling power, colour values, hardness and fracturability by varying the parameters of feed moisture content, screw speed and barrel temperature were investigated. The density of blends ranged from 0.09 to 0.57 g/cm3 , expansion ratio (1.47-2.58), true density (40.08-559.48 kg/m3 ), porosity (22.83-38.18 per cent), WAI (3.52-7.81 g/g), WSI (0.0-6.6 per cent), swelling power (5.03-8.18 g/g) and hardness (1.91-10.44 N). It was observed that the increase in feed moisture content resulted in extrudates with a lower expansion ratio and WAI, higher density, WSI and hardness. Among the various combinations investigated the blend with broken rice (30), foxtail millet (60) and maize (10) yielded good sensory results. The results obtained from the experiments were significantly different at (P≤0.01) all combinations.

Effect of Specific Mechanical Energy on <i>In-Vitro</i> Digestion and Physical Properties of Extruded Rice-Based Snacks

The effect of specific mechanical energy (SME) on in-vitro digestion and physical properties of extruded rice-based snacks was investigated in this study. Whole grains of medium grain brown rice (BR), medium grain sushi rice (SR) and long grain jasmine rice (JR) were extruded to prepare the rice-based snacks using a single screw extruder without additional thermal energy input. SME during extrusion was varied by changing feed moisture content. The feed moisture content (wet basis) was 9.99% - 12.55% for BR, 11.37% - 13.92% for SR and 12.42% - 14.39% for JR, respectively. Six extruded samples of each type of rice with different SME were collected and analyzed. With the decreasing SME, all three types of rice-based snacks showed significant decreases (p < 0.05) on rapidly digestible starch (RDS) and significant increases (p < 0.05) on slowly digestible starch (SDS). Physical properties, including expansion ratio (ER), bulk density (BD) and fracture energy (FE) were found to be highly correlated to SME. The results indicated that SME has significant effects on in-vitro digestibility and potentially glycemic index of extruded rice snacks. SME also can be an indicative parameter for the physical properties of rice-based extruded snacks.

Effect of extrusion temperature, moisture content and screw speed on the functional properties of aquaculture balanced feed

The aim of this study is to analyze the effect of feed moisture content, temperature, and screw velocity on the functional properties of extruded feeds for aquaculture with a bean flour and soy protein base. Fishmeal was substituted at different concentrations of bean flour or soy protein. Later, the diets were extruded and the expansion index, apparent density, and the extrusion sinking velocity were analyzed and an optimization of the process was carried out. The extrusion moisture content has an effect (p < 0.05) on the extrusion expansion index. The extrusion conditions were optimized with 93, 186 and 279 g/kg of bean flour or soy protein. The diets with soy protein require a higher amount of moisture, higher temperature, and a higher screw velocity than diets with bean flour, to obtain diets that are within range of the physical characteristics similar to commercial diets.

Effect of Extrusion Parameters on the Physical and Functional Properties of Cocoyam (Colocasia esculenta) Flour

Cocoyam (Colocasia esculenta) flour was cooked and extruded in a single screw extruder (DD85G, 201132, IBG Monforts Gmbhi & Co, D-4050 Monchengladbach, Germany). A second order central composite response surface design was adopted in designing the experiment which generated 20 runs on selected process parameters including feed moisture (22,24,26%), screw speed (60,70,80rpm) and barrel temperature (200,220,240 0 C) on the functional and physical properties (density, expansion, water absorption index (WAI), water solubility index (WSI) and textural characteristics) of the extrudates. At high feed moisture content there was increase in extrudates density, decrease in expansion, increase in WAI, decrease in WSI and increase in hardness while high barrel temperature lead to decrease in extrudates density, WAI and hardness but increased the expansion ratio and WSI of the extrudates. Keywords: Cocoyam, single screw extrusion, physical and functional properties

Co‐extrusion of pearl millet‐whey protein concentrate for expanded snacks

SummaryA study was conducted to develop pearl millet‐based extruded snacks with whey protein concentrate (WPC) to enhance its acceptability and nutritional value. Pearl millet grits (841 μ) was extruded with different levels (0%, 2.5%, 5.0% and 7.5%) of WPC at constant feed rate (10.5 kg h−1) and moisture content (14%). Addition of whey protein at 7.5% level significantly (P ≤ 0.05) increased Tg from 75.1 ± 0.26 °C to 120.5 ± 1.28 °C and Tm from 89.1 ± 1.51 °C to 158.7 ± 1.37 °C, which resulted in less expanded and harder extrudates. The expansion index of extrudates was negatively correlated (P ≤ 0.05) with protein (r = −0.940), bulk density (r = −0.949), hardness (r = −0.971) and breaking strength (r = −0.921), while positively correlated (P ≤ 0.05) with overall acceptability (OAA; r = 0.988). Keeping in view the nutritional, textural and consumer's acceptability, incorporation of 5% WPC in pearl millet grits (841 μ) was recommended for preparation of acceptable expanded snacks.