EFFECT of EXTRUSION ON TRYPSIN INHIBITOR CONTENTS of SOY-SWEET POTATO MIXTURES

Mixtures of soy and sweet potato ( Ipomoea batatas ) (L.) Lam), flours containing 18%, 25% and 30% moisture, respectively, were extruded in a single screw extruder. Results showed that inactivation of trypsin inhibitor was enhanced by both reductions in feed moisture and soy flour contents of sample mixtures. Hence subsequent extrusion was carried at 18% feed moisture with variable feed ratio, screw rotation speed and die diameter, using a central composite rotatable, near orthogonal experimental design. Results further showed that the effect of increasing the ratio of soy in the mixture was linearly significant (p > 0.05). Optimum Trypsin Inhibitor (TI) inactivation value of 3.40 mg/g was predicted at a feed composition of 80% sweet potato, 9 mm die diameter and 154 rpm, respectively.     

PRODUCTION AND PROXIMATE COMPOSITION OF A HYDROPONIC SWEET POTATO FLOUR DURING EXTENDED STORAGE

In developing countries, where limited transport infrastructure exists, processing the sweet potato (Ipomoea batatas (L.) Lam) into flour provides an alternative to the difficulties associated with storage and transport of the raw roots. The objectives of this study were: (1) to process hydroponic sweet potato roots into flour; and (2) to evaluate the nutritive composition and the color of the processed hydroponic sweet potato flour during storage. The TU–82–155 hydroponic sweet potatoes were processed into flour and stored for five months at room and refrigerated temperatures. The sweet potato flour contained 3.0%, 4.5%, 1.0%, 1.0%, 90.6% moisture, ash, fat, protein, and carbohydrate, respectively, with no significant changes during storage. The *L values for the sweet potato flour increased as storage time increased, but the *a and *b values decreased. Hydroponic sweet potato roots could be processed into flour and stored at 4C or 21C to 25C for five months without deterioration in quality.     

Effects of extrusion conditions on secondary extrusion variables and physical properties of fish, rice-based snacks

A formulation containing rice flour, fish powder, menhaden oil and vitamin E was extruded at a feed rate of 10 kg/h using a co-rotating twin-screw extruder. Primary extrusion (independent) variables were temperature (125-145 °C), screw speed (150-300 rpm) and feed moisture (19-23 g/100 g db). Response surface methodology (RSM) was used to study the effects of extrusion conditions on secondary extrusion variables (product temperature, pressure at the die, motor torque, specific mechanical energy input and mean residence time) and physical properties of the extrudates. Second-order polynomial models were computed and used to generate contour plots. Increasing feed moisture and screw speed decreased pressure at the die. Increased screw speed increased product temperature at the die but increased feed moisture lowered it. Increased barrel temperature, feed moisture and screw speed decreased motor torque. Increased screw speed increased specific mechanical energy, while increased feed moisture reduced it. Longer mean residence times were observed at lower screw speeds. Product density increased as feed moisture increased, but decreased with screw speed. Increased feed moisture decreased radial expansion.     

Extrusion behaviour of grits from flint and sweet corn

Studies were conducted to investigate the effect of feed moisture, extrusion temperature and screw speed on the extrusion behaviour and product characteristics of flint and sweet corn grits. The extruder die pressure and extrudate properties, such as expansion and water solubility index (WSI), were analyzed. Second order polynomials were computed to describe the extruder response and product properties of grits from both corn types as a function of feed moisture, extrusion temperature and screw speed. Among feed moisture, extrusion temperature and screw speed, feed moisture showed the most pronounced effect on die pressure, expansion and WSI. Die pressure of the extruder was significantly greater for sweet corn than flint corn grits. The grits from both the corn types differ significantly with respect to extrusion behaviour and product characteristics under similar extrusion conditions. The particle size distribution revealed that flint corn grits had more fine and opaque particles and resulted in extrudates with lower WSI and expansion than those from sweet corn grits which had fewer fine particles.     

The Effects of Extrusion Conditions on the Physical Properties of Wheat Flour Extrudates

The effects of extrusion conditions (feed moisture content and rate, process temperature, screw speed and geometry, and die diameter) on expansion ratio, bulk density, and breaking strength of wheat flour extrudates were investigated. Extrudate samples were prepared by using a Brabender single-screw extruder. Higher feed moisture content and process temperature were required for proper expansion. At 3.18mm die opening, the relationship between expansion and bulk density was positive. Feed rate was the most effective factor for increasing bulk density. Breaking strength was significantly decreased with increasing process temperature. Under extrusion conditions of 22% feed moisture, 110g/min feed rate, 160°C process temperature, and 130rpm screw speed with 5:1 CR, wheat flour was puffed with low bulk density and breaking strength.     

Properties of extruded blends of wheat dried distiller grain flour with other flours

Zero, 10, 20 and 40% dried distiller grain (DDG) from wheat was blended with corn, potato, rice, and wheat flours at total moisture levels of 15 and 22% and extruded in a Brabender laboratory single screw extruder at three sets of barrel temperatures of 80, 130, 160°C; 100, 160, 210°C and 120, 190, 250°C at a constant screw speed (100 r.p.m.), screw configuration (3:1 compression ratio) and die size (3.175 mm). Resulting torque, yield, radial expansion (RA), longitudinal expansion index (LEI), density, water absorption index and colour were measured.
All the blends were successfully extruded over a wide temperature range. As the amount of DDG increased, in general torque, yield and RE decreased, and colour darkened while density and LEI increased. Wheat flour was the base material found to vary most from the above trends.     

SINGLE-SCREW EXTRUSION OF PORK AND SOY FLOUR BLEND

This study examined the rheological properties of defatted soy flour and lean pork blend of various moisture contents extruded in a single-screw extruder and the sensory texture property of extruded meat analogs as the first step to develop commercial low-cost meat analogs that not only resemble real meats but have excellent sensory textures. Additional work was also conducted to examine the effect of moisture content of soy flour under the extrusion condition (high temperature and pressure) on the fiber structure and overall texturization of the extrudate as a result of changes in chemical bonds between soy proteins. The mixture of soy meal with ground lean pork showed significant decrease in viscosity as compared with either soy meal or ground meat alone. The best sensory texture was obtained for the pork-soy flour blend with 41. 3% moisture content at screw speed of 180 rpm under the feeding-metering-die temperature setting of 140–170–80C.     

Effect of formulation and processing parameters on acrylamide formation: A case study on extrusion of blends of potato flour and semolina

Acrylamide formation in extruded snacks prepared using blends of potato flour:semolina in ratios ranging from 30:70 to 70:30 showed maximum acrylamide formation in the 70:30 blend. The extrusion was carried out at a screw speed of 120 rpm, temperature of 170 °C and moisture content of 18%. Further, the influence of extrusion processing parameters on the acrylamide formation in extruded snacks prepared from a 70:30 blend of potato flour:semolina was investigated using response surface methodology (RSM). The feed moisture was varied from 12.6% to 19.4%, die temperature from 163 to 197 °C and screw speed from 106 to 173 rpm. The extrudates so obtained showed acrylamide content ranging from 704 to 1560 μg/kg. The effect of different additives such as citric acid, calcium salts, amino acids, vitamins and their combinations on the mitigation of acrylamide formation showed calcium chloride at 50 μmol/g flour blend to reduce acrylamide formation by 65% without altering the sensory properties of the extrudates.     

棉籽饼粕双螺杆挤压脱毒中的参数研究

考察了棉籽饼粕双螺杆挤压脱毒中不同加工参数对脱毒效果的影响。结果表明：增大螺杆转速、减低喂料速度，脱毒效果变好。但考虑到产量要求，喂料速度不宜过低，故实际中应做到均衡。含水率的影响较为复杂，因原料、操作条件不同而异，一定范围内含水率提高可配以较高螺杆转速、温度及较小口模直径，不同捏合盘长度和位置其效果也不一样，因而一定操作条件下各加工参数间应适宜匹配。此外，实验结果还表明棉籽饼粕双螺杆挤压脱毒是成功的，效果显著。     

PHYSICOCHEMICAL PROPERTIES OF TEXTURIZED MEAT ANALOG MADE FROM PEANUT FLOUR AND SOY PROTEIN ISOLATE WITH A SINGLE‐SCREW EXTRUDER 1

The objective of this study was to establish conditions for the texturization of soy protein isolate and peanut flour mixture using a single‐screw extruder. The effects of feed moisture, screw‐speed, and barrel temperature on the characteristics of the texturized products were studied. Feed moisture was the most important factor affecting the texture. Feeding ingredients with 22% moisture had the highest water absorption and expansion indices, and Hunter L value (P < 0.05). When the screw speed was above 180 RPM, the meat analog had a 12% decrease in the expansion index and a 5% decrease in moisture content (P < 0.05). When the barrel temperature was increased to 165C, there was a 12% decrease in the water absorption index, and a 23% decrease in the expansion index of the meat analogs (P < 0.05). Overall, an acceptable meat analog could be successfully produced with 22% moisture in the raw ingredient, screw speed at 140 RPM, and barrel temperatures at 150, 155, and 160C for the three temperature zones respectively.     

Extrusion Cooking Process for Amaranth (Amaranthus caudatus L.)

ABSTRACT: Amaranth ( Amaranthus caudatus L.) extrusion was optimized by response surface methodology (RSM). Response (dependent) variables were: expansion ratio, shearing strength, and sensory texture acceptability. Independent variables were processing temperature and feed moisture. All other process variables (screw speed, screw compression ratio, feed speed, and die diameter) were kept constant (200 rpm, 70 g.min⁻¹, and 3 mm, respectively). The most expanded products also had the best texture and were obtained at 150 °C and 15% moisture. These conditions resulted in greater expansion, greater shearing force of extrudates, greater extrudate surface area per unit weight, and reduced shearing stress at maximum shearing force. This study showed that under conditions that induced the maximum expansion ratio, extrusion produced a highly acceptable snack product based on amaranth flour.     

PHYSICOCHEMICAL PROPERTIES OF GLUTEN-FREE PANCAKES FROM RICE AND SWEET POTATO FLOURS

Gluten‐free pancakes were prepared using rice flour and rice flour replaced with various amounts, at 10, 20 and 40%, of sweet potato flour. Textural properties of the cooked pancakes, such as hardness and chewiness generally increased with time after cooking, whereas they decreased with increased sweet potato flour replacement. On the other hand, cohesiveness decreased with time, but increased with increased sweet potato flour in the pancake. Nutritional properties of the rice–sweet potato pancakes, such as protein content, dietary fiber, total carbohydrate and calories were generally comparable with those of their wheat counterpart. The only significant difference was in the beta‐carotene content, which increased from 5.2 to 236.1 μg/g when sweet potato flour was incorporated, from 0 to 40%, into the rice pancake formulation.     

Effects of process variables and addition of polydextrose and whey protein isolate on the properties of barley extrudates

Extrusion cooking is commonly used in the production of snacks. In the present study, extrudates were prepared using barley flour alone and with the addition of either polydextrose (PD) or whey protein isolate (WPI) and both PD and WPI. Independent process variables were water content of the mass (17%, 20% and 23%), screw speed (200, 350 and 500 rpm) and temperature of section 6 and die (110, 130 and 150 °C). Expansion, hardness, water content, porosity and chemical composition of the extrudates were analysed. Highly porous and expanded snack products with high dietary fibre and protein contents were obtained from barley flour and WPI when water content of mass was 17%, screw speed 500 rpm and temperature of section 6 and die 130 °C. Barley flour alone or with PD resulted in hard and non‐expanded extrudates. Expansion of extrudates was statistically significantly increased with decreasing water content of the mass and increasing screw speed in all trials.     

Physico‐chemical and antioxidant properties of extrudates developed from honey and barley

Barley flour and honey, being concentrated source of nutrients, were used to develop extruded product using twin‐screw extruder. Response surface methodology was applied to study the effects of honey (5–25%), moisture content (17–21%) temperature (120–160 °C) and screw speed (180–220 rpm) on product responses. The variation in moisture content and die temperature affected the physicochemical properties of extrudate but screw speed had significant effect only on hardness. It was established that with increase in honey levels from 5% to 20%, there was increase in antioxidant activity (up to 106.9%), total phenolic content (up to 90.2%) and total flavonoid content (up to 89.2%) in interaction with other extrusion cooking variables. The optimal condition corresponds to honey content of 18.86%, feed moisture of 18%, die temperature of 148.62 °C and screw speed of 209.99 rpm. The results suggest that honey can be extruded with barley flour into a healthful snack food.     

Effects of extrusion conditions on system parameters and physical properties of a chickpea flour-based snack

Response surface methodology (RSM) was used to study the effects of feed moisture content (16–18%), screw speed (250–320 rpm), and barrel temperature (150–170 °C) on extruder system parameters (product temperature, die pressure, motor torque, specific mechanical energy, SME) and physical properties (expansion, bulk density, hardness) of a chickpea flour-based snack. Second-order polynomials were used to model the extruder responses and product properties as a function of process variables. Product temperature and die pressure were affected by all three process variables, while motor torque and SME were only influenced by screw speed and barrel temperature. All three variables affected product responses significantly. Desirable products, characterized by high expansion ratio and low bulk density and hardness, were obtained at low feed moisture, high screw speed and medium to high barrel temperature. It was demonstrated that chickpeas can be used to produce nutritious snacks with desirable expansion and texture properties.     

Effect of extrusion conditions on resistant starch formation from pastry wheat flour

Pastry wheat flour was extruded under various conditions of feed moisture (20%, 40%, and 60%) and screw speed (150, 200, and 250 rpm), at constant barrel temperature profile (40, 60, 80, 100, and 120 °C, feed port to exit die). The extruded samples were stored at 4 °C for 0, 7, or 14 days, at which times resistant starch (RS) formation was analyzed. Thermal and pasting properties of extruded samples stored for 14 days were analyzed using a differential scanning calorimeter and rapid visco analyzer (RVA), respectively. The RS content increased after extrusion compared to non-extruded pastry wheat flour. High significant positive correlations of feed moisture (P < 0.01) and storage period (P < 0.05) with RS formation were observed. The RS derived from extrusion and storage showed higher thermal stability with decreasing feed moisture and screw speed. Statistically significant differences in pasting properties were observed with feed moisture or screw speed. In particular, the setback value from RVA of the sample was significantly increased with increasing feed moisture. These results indicate that feed moisture and storage time were both important factors for the formation of RS from pastry wheat flour during extrusion.     

System Parameters and Product Properties Responses During Extrusion of Fura from Millet-Soybean Mixtures

A three-factor, three-level central composite rotatable composite design (CCRD) was adopted to study the effect of feed composition (X₁), feed moisture content (X₂) and screw speed (X₃) on the system parameters (torque, pressure, and specific mechanical energy) and fura extrudate properties (expansion ratio and bulk density) from blends of pearl millet and soybean flour mixtures. The torque was influenced negatively but significantly (p < 0.05) by linear effects of feed composition and screw speed. The die pressure was also influenced negatively by the linear effects of the screw speed significantly (p < 0.05). The response surface plot showed that the specific mechanical energy SME was decreasing as screw speed increased while SME marginally decreased as feed moisture increased. The linear effects of the independent variables significantly (p < 0.05) affected the expansion ratio. The linear and quadratic effects of the independent variables significantly (p < 0.05) affected the bulk density. The CCRD was effective in explaining the effect of the process conditions on fura as influenced by feed composition, feed moisture and screw speed. The importance of process variables on system parameters and physical properties could be ranked in the following order: Feed Composition (X₁) > Feed Moisture (X₂) > Screw Speed (X₃). Response variables predicted with model equations under optimum conditions were in general agreement with experimental data. The data obtained from the study could be used for control of product characteristics and possible projection for the commercial production of fura.     

CELLULAR STRUCTURE OF PEANUT-BASED EXTRUDED SNACK PRODUCTS USING SCANNING ELECTRON MICROSCOPY

A mixture of partially defatted peanut flour (12% fat) and rice flour was extruded to produce indirectly, puffed extrudates using a corotating twin-screw extruder. Extrudates were dried to obtain half-products of 11-12% moisture content, and the half-products were expanded by deep-fat frying. The effects of three levels of peanut flour (30, 40, and 50%), screw speed (200, 300, and 400 rpm) and feed rate (4, 5, and 6 kg/h) were studied by characterizing the cellular structure of expanded snack products using Scanning Electron Microscopy (SEM). Average cell size (mm²) and the number of cells per unit area (cm²) were determined from the interior cross-section area of snack products. Those parameters were influenced mainly by the level of peanut flour followed by screw speed and feed rate. Increasing peanut flour from 40 to 50% produced less puffed final products resulting in small cell size compared to snacks of 30 - 40% peanut flour. The maximum cell size was produced in the snack products extruded with peanut flour of 30 - 40% at screw speed of 250 - 330 rpm and feed rate of 4.7 - 5.7 kg/h. While the number of cells was relatively similar regardless of screw speed and feed rate, increasing peanut flour increased the number of cells. The cell walls became thicker with increasing feed rate.     

含盐和糖的米粉的双螺杆挤压装置

研究了在使用旋转型全隔行式双螺杆挤压机时,螺杆速度、盐(0~3%)和糖(0~8%)对米粉挤压的影响。提高螺杆速度、盐分或糖分,一般来说会降低转矩和模具压力,螺杆速度是比盐分和糖分对三个重要加工变量(转矩,单位机械能和模具压力)影响更重要的因子。挤出物的直径(径向变量)只受到糖分的影响,而不受盐分或螺杆速度的影响。在螺杆速度为300r/min时,挤出物的长度(轴向延长)要高于200r/min,其长度还随含盐量和含糖量增加而增加。在添加盐和糖以及在增加螺杆速度时单位体积明显增加。挤出物的破裂强度与径向膨胀呈反比关系。螺杆速度由200r/min提高到300r/min会产生较白、不太绿的挤出物。