Effects of Processing Conditions on Single Screw Extrusion of Feed Ingredients Containing DDGS

Distillers dried grains with solubles (DDGS), a feed coproduct from the fuel ethanol industry, has been shown to be a viable potential alternative protein source for aquaculture feeds. To investigate this, three isocaloric (3.5kcal/g) ingredient blends containing 20, 30, and 40% DDGS, with a net protein adjusted to 28% (wet basis, wb), were prepared for use as Nile tilapia feed. Extrusion processing was then conducted using three DDGS contents (20, 30, and 40%, wb), three moisture contents (15, 20, and 25%, wb), three barrel temperature gradients (90–100–100°C, 90–130–130°C, and 90–160–160°C), and five screw speeds (80, 100, 120, 140, and 160rpm) using a single screw laboratory extruder. Several processing parameters, including mass flow rate, net torque required, specific mechanical energy consumption, apparent viscosity, and temperature and pressure of the dough inside the barrel and die, were measured to quantify the extrusion behavior of the DDGS-based blends. For all blends, as the temperature profile increased, mass flow rate exhibited a slight decrease, die pressure decreased, and apparent viscosity exhibited a slight decrease as well. Likewise, the net torque requirement, specific mechanical energy consumption, and apparent viscosity decreased as screw speed increased, but mass flow rate increased. Additionally, as moisture content increased, die pressure decreased. At higher temperatures in the barrel and die, the viscosity of the dough was lower, leading to lower torque and specific mechanical energy requirements. Increasing the DDGS content, on the other hand, resulted in a higher mass flow rate and decreased pressure inside the die. As demonstrated in this study, the selection of suitable temperature and moisture content levels are critical for processing DDGS-based ingredient blends.     

Effect of Starch Sources and Protein Content on Extruded Aquaculture Feed Containing DDGS

A 3 × 3 × 3 completely randomized design was used to investigate extrusion cooking behavior and product characteristics of distillers dried grains with solubles (DDGS), protein levels, and various starch sources in a laboratory scale single screw extruder. Cassava, corn, and potato starches with varying levels of DDGS (20%, 30%, and 40% wet basis (wb)) were extruded with three different proportions of protein levels (28%, 30%, and 32% wb). The extrusion cooking was performed at a constant feed moisture content of 20% wb, barrel temperature of 120 °C, and a preset screw speed of 130 rpm (13.6 rad/s). Extrudate properties such as expansion ratio, unit density, sinking velocity, color, water absorption and solubility indices, and pellet durability index were determined to judge the suitability for various fish species. For all three starch bases, increasing the DDGS levels resulted in a significant increase in sinking velocity, redness (a*), and blueness (b*) and showed a decrease in whiteness (L*). With the increase in DDGS and protein levels, a noticeable increase was observed for unit density and pellet durability indices for cassava and potato starch extrudates. The DDGS-based extrudates produced from cassava starch with lower proportions of DDGS (20%) and protein (28%) levels exhibited better expansion and floatability. Also, the extrudates produced from corn starch with higher levels of DDGS (40%) and protein (32%) levels were more durable and possessed sinking characteristics. Overall, cassava and corn starch with lower and higher levels of DDGS could be more appropriate for the production of floating and sinking aquaculture feeds, respectively.     

Effect of protein,moisture content and barrel temperature on the physicochemical characteristics of pea flour extrudates

The effects of protein content (6%, 12% or 18%, db), moisture content (15%, 18% or 21%, wb), temperature (set temperature of the final barrel section—100, 120 or 140 °C) and a leavening agent (0.5% sodium bicarbonate) on the direct expansion characteristics of pea flour were determined with a twin-screw, co-rotating extruder. The various levels of protein were obtained by blending air-classified pea starch (6% protein, 85% starch) and pea flour (24% protein, 56% starch). Extrusion of pea flour containing 6% protein and 15% moisture at a set temperature of 120 °C resulted in expansion indices (EIs) of 3.3 and 3.6, respectively, in the absence or presence of the leavening agent. EI decreased, and extrudate bulk, particle densities and hardness increased with increase in protein or moisture content. Lysine losses were proportionally lower at higher protein and moisture contents.     

Model for Gelatinization of Wheat Starch in a Twin-Screw Extruder

Wheat starch was processed in a co-rotating twin-screw extruder, at moisture contents 25% and 30%, screw speeds 200 and 300 rpm, feed rate 30 kg/hr, and barrel temperature settings 100, 120, 140, and 160°C. Degree of starch gelatinization at each point along the extruder channel was determined by sampling and analyzing material inside the extruder. Kinetics of the gelatinization during extrusion was investigated. A first-order rate equation was developed to predict degree of starch gelatinization during extrusion. The rate constant was a function of both temperature and shear stress.     

Kinetics of Starch Gelatinization During Extrusion Cooking

Ordinary corn (30% amylose) and waxy corn (1% amylose) were extruded at 17.8, 20, 30, 40 and 42.2% product moisture contents (d.b.) and extruder barrel temperatures of 116°, 120°, 140°, 160° and 164°C. Screw speeds of 93.5, 100, 130, 160 and 166.5 rpm were used to generate different residence times. The extruded products were evaluated for extent of starch gelatinization. Results indicate that the degree of gelatinization decreased with increasing moisture content but increased with increasing temperature. Starch gelatinization exhibited pseudo-zero-order reaction kinetics with higher rate constants for waxy corn than for high amylose corn. The rate constants decreased with decreasing temperature.     

Optimum Extrusion-Cooking Conditions for Maximum Expansion of Corn Starch

Normal corn starch was extrusion-cooked in a C. W. Brabender Laboratory model single-screw extruder at various extruder barrel temperatures, screw speeds, feed rates, and moisture contents. The expansion ratios and shear strengths of the products were highly dependent on extrusion-cooking conditions. The maximum expansion ratio of 16.1 was obtained when 14% moisture content (d.b.) starch was fed at a rate of 60g min^-1 with a screw speed of 150 rpm, a barrel temperature of 140°C and a die-nozzle L/D ratio of 3.1. The shear strengths of the extruded starch products were inversely proportional to the expansion ratios.     

Gelling properties of extruded yam (Dioscorea alata) starch

Yam (Dioscorea alata) starch was pregelatinized in a single screw extruder. Response Surface Methodology was used to study the effect of extrusion variables: feed moisture (18, 21, 24%), extruder temperature (120, 150, 180°C) and die diameter (3, 4, 5 mm) on cold viscosity, gel-forming capacity and retrogradation of extruded starches. Cold viscosity was higher from starch samples processed at higher moisture and die diameter, at lower temperatures. Slurries of the extruded starch (8%, w/v, d.b.) formed opaque and firm gels. Higher values for gel strength were found in samples extruded at highest and lowest moistures at intermediate temperature and increasing die diameter. Gels of extruded starch had lower retrogradation values than non-extruded gelatinized starch after one and two weeks storage at refrigeration temperature. Prediction equations for the studied functional properties can be used in selecting processing conditions for specific food applications.     

Physicochemical Properties of Casein‐Starch Interaction Obtained by Extrusion Process

Extruded samples of starch‐casein blends were processed by using a single‐screw extruder. The independent variables in the process were temperature (126–194°C), moisture content (18–29%) and starch‐casein blend (5–95%). These independent variables affected significantly the physicochemical and textural properties of the biopolymers. The highest values for expansion (EXP) and water absorption index (WAI) were found when a higher starch proportion was present in the blends, at 126°C barrel temperature and moisture content higher than 25%. By increasing the barrel temperature, from 126°C to 194°C, the water solubility index (WSI) and color parameter were increased. Initial viscosity (IV) and viscosity at 90°C (V90) were mainly affected by the barrel temperature at 194°C. However, the viscosity at 50°C (V50) was affected neither by the different extrusion variables nor by the biopolymer proportion in the blends. Compression force (CF) was strongly dependent on moisture content and casein proportion in the blend. The higher CF values were found at starch concentrations around 50% and 25% moisture content, for higher or lower values than these the obtained extruded products were softer and consequently had lower CF values.     

Effect of the addition of whole‐grain wheat flour and of extrusion process parameters on dietary fibre content,starch transformation and mechanical properties of a ready‐to‐eat breakfast cereal

This study evaluates the effect of the incorporation of whole‐grain wheat flour (WGWF) and of extrusion process parameters on the nutritional and technological quality of breakfast cereals. The corn flour‐based breakfast cereals were elaborated in a twin‐screw extruder following a rotatable central composite design with varied WGWF (0–100%), feed moisture (14–24%) and zones 3 and 4 barrel temperature (76–143 °C). Dietary fibre and resistant starch were significantly increased with WGWF addition. Total and digestible starch showed a decrease when WGWF increased. The RVA parameters were significantly affected by all the extrusion conditions and WGWF content. The cell structure of the extrudates was dependent of WGWF and moisture.     

Effect of extrusion conditions on the physicochemical properties of a snack made from purple rice (Hom Nil) and soybean flour blend

Soy flour was added at levels of 5%, 10%, and 15% of Hom Nil rice flour for extrusion at 190 °C barrel temperature and 350 rpm screw speed. The extruded snack qualities decreased inversely with soy flour. However, product qualities were considered to be optimised when soy flour at 5% was added. The effect of feed moisture content (15, 17, 19 g (100 g)^?1 wb), barrel temperature (150, 170, 190 °C) and screw speed (350, 400, 450 rpm) on physicochemical properties of the snack were then investigated. The physicochemical properties of the product including expansion ratio, density, water absorption index (WAI), water solubility index (WSI) and hardness were evaluated. All properties were related, as linear equations, in terms of feed moisture content, barrel temperature, screw speed with relative correlation (R²) at 0.83–0.94. The snack properties along with consumer acceptance were all highest when the extruded condition were 15 g (100 g)^?1 wb feed moisture content, 170 °C of barrel temperature and 450 rpm of screw speed.     

Tapioca-Fish and Tapioca-Peanut Snacks by Twin-Screw Extrusion and Deep-Fat Frying

Two half-products were prepared from tapioca starch/catfish fillet-belly flap mince (60:40) and tapioca starch/partially defatted peanut flour (PDPF) (60:40) by twin-screw extrusion. The process variables were temperature in the last two zones of the extruder (90,95,100°C) and screw speeds (100, 250, 400 rpm). Moisture content (40%, wet basis) and feed rate (27 g/min) were held constant. Simultaneously increasing temperature and screw speed resulted in increased expansion, and decreased bulk density and shear strength. Degree of starch gelatinization in half-products ranged from 87 to 95%. Optimum conditions predicted by response surface methodology were: for fish half-products 94–100°C and 220–400 rpm and for peanut half-products, 95–100°C and 230–400 rpm.     

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

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 (R²) 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.     

Extrusion Studies of Aquaculture Feed using Distillers Dried Grains with Solubles and Whey

Three isocaloric (3.5 kcal/g) ingredient blends containing 20, 30, and 40% distiller-dried grains with solubles (DDGS) along with 5% whey were prepared with a net protein content adjusted to 28% (wet basis [wb]). Other ingredients in the blends included soy flour, corn flour, fish meal, vitamin, and mineral mix. These blends were extruded in a single-screw extruder at 15, 20, and 25% (wb) moisture content and at 130 and 160 rpm screw speeds. Compared to previous research, the durability and unit density of the extrudates in this study were found to increase substantially by the addition of whey to the blends. Increasing the DDGS content from 20 to 40% resulted in a 5.8 and 16.8% increase in extrudate moisture content and redness, respectively, but produced a decrease of 11.2% in brightness and 3.6% in yellowness of the extrudates. Increasing the moisture content of the ingredient blends from 15 to 25% resulted in an increase of 16.1, 8.7, and 9.3% in moisture content, durability, and redness, respectively, but a decrease of 9.8 and 5.6%, respectively, in brightness and yellowness of the extrudates. Neither DDGS level nor screw speed significantly affected extrudate durability or unit density. In fact, changing the screw speed had no significant effect on many of the properties of the extrudates studied, except for moisture content, redness, and yellowness. As demonstrated in this study, ingredient moisture content and screw speed are critical considerations when producing extrudates with feed blends containing DDGS; further work is needed to optimize processing conditions and to produce floating feeds.     

Enzymatic Conversion of Starch in Twin-Screw HTST-Extruder

Wheat starch was liquefied to DE 25–30 employing heat stable α-amylase and twin-screw Werner & Pfleiderer Continua 58 HTST-extruder. Most significant reduction in batch saccharification time was obtained when starch was liquefied as a slurry containing 60% water at 120°C mass temperature, feed rate 1 500 g min⁻¹, screw rotation rate 250 min⁻¹, and 0.9% (w/w, d.s.) Novo Termamyl 120 L α-amylase was added immediately after initiation of gelatinization in the extruder. Saccharification was carried out at 60°C employing 0.36% (w/w, d.s.) Novo glucoamylase 150 L to reach a DE 96 in 22 h. Best total conversion was, however, obtained when also saccharification was initiated in the extruder by adding glucoamylase just before the die element, after lowering mass temperature to 60°C, and by allowing the saccharification to continue at 60°C after extrusion processing to reach a DE 94 in 5 h and DE 97 in 21 h.     

Functional and Biochemical Alterations of Fish Meal,Soybean Meal,and Distillers Dried Grains with Solubles as Affected by a Single-Screw Extruder

The goal of this study was to investigate the effect of extrusion-forced structural changes on the extent of functional and biochemical changes of three selected protein sources that are predominantly used in aquafeed, i.e., fish meal (FM), soybean meal (SBM), and distillers dried grains with solubles (DDGS). The samples were individually extruded in a single-screw extruder using a factorial design with replicated central composite points at a temperature of 80, 110, and 140 °C; screw speed of 80, 150, and 220 rpm; and moisture content of 150, 225, and 300 (g/kg). Extrusion temperature and feed moisture significantly affected the nitrogen solubility in water (NSI), sodium dodecyl sulfate, and 2-mercaptoethanol solvents. Screw speed had only a minor effect on this value (P?<?0.05). Solubility results indicated that the contribution of hydrophobic and ionic interactions were more significant than that of the disulfide bonds, particularly for FM and SBM extrudates. For all extrudates, the highest peak viscosity was observed at the highest temperature and lowest screw speed. Extrusion processing led to considerable increase in T _g of 79 % and 67 % for the DDGS and SBM samples, and a reduction of 19 % for the FM sample, respectively. Extrusion processing increased relative protein digestibility (RPD) of the SBM extrudates the most, followed by those of DDGS and FM. Overall, the severity of the extrusion conditions adversely affected available lysine content (AL) and L* color score, but relatively increased RPD of the extrudates. SBM extrudates had the lowest reduction in AL. Despite the decrease in AL, the results for both plant-based protein extrudates were comparable in quality to those of FM. The outputs of this study provide viable information for feed formulator and feed technologist in feed and food industries.     

Volume Expansion during Hot Air Puffing of a Fat-free Starch-Based Snack

Puffed volume and puffing uniformity of a fat-free snack were investigated. Strips of drum-dried sweet potato-tapioca pastes were puffed 15 set at 200°C in a fluidized bed. Puffed product specific volume (SV) was related to starch gelatinization, soluble solids content, initial moisture and method of half-product preparation. SV was maximum (490% increase) and most uniform (3.94% coef. of variation) when 70% moisture paste was drum-dried at 100°C and 1 rpm to produce the half-product. Starch was 93% gelatinized in this process. Soluble solids reduced nuffine by reducine starch gelatinization. Half-product produced by sheeting dough coitaining- pregelatinized starch had puffed volumes which significantly correlated with starch gelatinization.     

Effect of extrusion conditions and storage temperature on texture,colour and acidity of butter

The effect of extruder shear rate (500, 750, 1125, 1500 and 1750/s), feed temperature (5, 7, 10, 13 and 15 °C) and storage temperature (5, 7, 10, 13 and 15 °C) on the acid value, colour (L*, a* and b*values) and texture (hardness and adhesiveness) of organic butter was examined. The optimised conditions in terms of extruder shear rate, feed temperature and storage temperature were 1345/s, 13 °C and 7 °C, respectively. At the optimised conditions; the predicted responses were determined as hardness 42.5 g/cm, work softening 67.2%, adhesiveness 42.5 gf/cm, acid value 3.4 mg KOH/kg and L* value 99.57.     

Puffing Characteristics of Parboiled Milled Rice in a Domestic Convective–Microwave Oven and Process Optimization

Microwavable products are gaining worldwide acceptance as convenience foods, where hygiene can be maintained when processed in small quantities at the domestic level. One such ready to eat products are puffed or popped starchy grains like corn, rice, sorghum, etc. Owing to its high starch content, rice has high expandability, and the puffed rice produce thence has better digestibility. Considering these aspects, an attempt was made to produce puffed rice in a domestic convective–microwave oven. Puffing characteristics were studied for Gurjari variety of rice at 14 % (wb) moisture content for different preheating temperatures of the glass base plate (180, 200, and 220 °C), microwave power level (300, 600, and 900 W), and residence time (10–100 s), from which the range of residence time was selected for the optimization study. It was found that the puffing of rice was better at higher power level and preheating temperature of the base plate, and puffing started only after certain residence time. Further study was carried out to optimize the process parameters by using response surface methodology, for a Box–Behnken design at three levels for four parameters, i.e., moisture content (12, 14, and 16 % wb), preheating temperature of the base plate (180, 200, and 220 °C), microwave power level (300, 600, and 900 W), and residence time (50, 60, and 70 s). The optimized conditions were found to be 14 % (wb), 220 °C, 900 W, and 60 s. The second-order polynomial model was validated by conducting three trials at the optimized point and found to be agreeing with the predicted values.     

Effects of Extrusion Process Variables on Quality Properties of Wheat-Ginseng Extrudates

The present study investigated the effects of extrusion process variables (feed moisture, screw speed, and barrel temperature) on the physical [expansion ratio, water absorption index (WAI), and water solubility index (WSI)], pasting, and thermal properties of wheat-ginseng extrudates (WGE). A wheat flour-ginseng powder (GP) blend (10% GP, w/w) was extruded in a twin-screw extruder (L/D ratio of 25:1) with full factorial combinations of feed moisture (25, 30, and 35%), screw speed (200 and 300 rpm), and zone 5 barrel temperature (110, 120, 130, and 140°C). The expansion ratios of WGE were significantly increased with decreasing feed moisture, decreasing screw speed, and increasing barrel temperature. Increasing feed moisture significantly increased WAI values of WGE and significantly decreased WSI values of WGE. However, an increase in either screw speed or barrel temperature caused a significant decrease in WAI values of WGE and a significant increase in WSI values of WGE. Rapid visco analyzer peak viscosity values of WGE were significantly affected by changes in extrusion process variables studied, indicating that the degree of starch degradation and/or gelatinization in WGE is a very important factor associated with their peak viscosity. WAI values of WGE were positively correlated (r = 0.88, p ≤ 0.001) with peak viscosity values of WGE samples, whereas WSI values of WGE samples were negatively correlated (r = 0.82, p ≤ 0.001). Increasing feed moisture resulted in an increase in values of transition peak temperature (T_p) of WGE, whereas increasing screw speed and barrel temperature each led to a decrease in T_p values of WGE, determined by differential scanning calorimetry.     

The effect of rice bran on physicochemical,textural and glycaemic properties of ready-to-eat extruded corn snacks

In this work, corn extruded snack products were enriched with rice bran (RB) at 10% and 15%. A co-rotating twin-screw extruder was used with a feed moisture content of 16 g 100 g⁻¹, a screw speed of 240 r.p.m. and four heating sections of the barrel (100, 140, 150 and 150 °C). The impact of RB inclusion on nutritional profile, starch digestion, physicochemical and textural properties of snack products was evaluated. RB-enriched extrudates showed a lower specific volume and hardness and higher crispness than control. RB at 15% gave a water-holding capacity lower than control. Rheology of extrudate dispersions indicated an increase in elastic interactions and solid-like behaviour with RB supplementation. Differences in rheological properties resulted in attenuation of predictive glycaemic response for RB-enriched snacks.