Extrusion cooking properties of white and coloured rice varieties with different amylose content

Five white and coloured rice varieties with different AM contents (long grain rice: 34%, Thai Jasmine rice: 15%, glutinous rice: 7%, red rice: 18% and black rice: 5%) were pregelatinised using a twin‐screw extruder at a barrel temperature of 150°C and two levels of feed moisture (12 and 16%). The correlation of AM content to water absorption index (WAI), water solubility index (WSI), starting viscosity, hot viscosity and final viscosity of the five rice extrudates were determined. Total anthocyanin content (TAC), total phenolic content (TPC) and antioxidant activity of extrudates were analysed by spectrophotometric methods. AM content was positively correlated to WAI and final viscosity. High AM content of the rice varieties resulted in high WAI and high final viscosity of extrudates. In addition, higher feed moisture content (16%) increased WAI and pasting properties of rice extrudates, but decreased WSI. Extrusion cooking reduced TAC, TPC and antioxidant properties, but the remaining values were high enough to suggest a further use for (functional) food production.     

Unlocking the potential of pasting properties to predict extrudate characteristics of corn grits blends with high amylose corn starch,potato starch,or rice flour

The development of new production lines of extruded ready-to-eat (RTE) snacks often results in high losses of edible food due to the trial-and-error approach in industry. Being able to predict extrudate characteristics of new formulations before having to run trials on industrial scale would be beneficial for reducing waste and having a more efficient development process. With this study, the correlation between pasting properties of seven blends of flours/starches and extrudate characteristics was investigated (100% corn grits, 25% and 50% replacement of corn grits with high amylose starch, potato starch, and rice flour). The predictive power of pasting characteristics on extrudate's moisture content, water absorption and solubility index, sectional expansion index (SEI) and hardness was studied. Results indicated the potential of predicting SEI, water solubility index (WSI), and water absorption index (WAI) of RTE-snacks. WSI and WAI were, respectively, negatively correlated with peak temperature (R² = 0.897), and positively with peak temperature and positively with trough viscosity (R² = 0.855). One can conclude that the rheometer can be a useful tool to gain insight into the characteristics of the extrudate, although further research with enlargement of the dataset is necessary to make the rheometer effectively deployable for potentially other extrudate characteristics.     

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.     

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

Resistant 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     

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

Extrusion‐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     

Physicochemical characterisation and in vitro Starch digestion of Avocado Seed Flour (Persea americana V. Hass) and its starch and fibrous fractions

The avocado seed is considered a by-product of their pulp exploitation and today it does not present relevant food or industrial applications. In this study, we evaluate the potential use of its flour, their isolated starch and fibre fractions. After processing, the flour yielded 46.28%, and showed 6.7% of protein and low fat and ash contents (3.4, and 2.71% respectively). The starch yielded 27.28% with low-fibre content that influenced its viscosity properties; as well as their water absorption index (WAI), water solubility index (WSI) and oil absorption index (OAI), that were 2.43%, 11.22% and 0.16% respectively. The in vitro starch digestion of the different obtained fractions showed higher amounts of rapidly digestible starch (56.8%–75.36%, flour and starch respectively). The functional properties of the materials were correlated with strong molecular interactions with their apparently unique amylose structure; for this, this by-product may have different potential for food applications.     

Effects of temperature and protein content on physical properties of pasta made from rice enriched with soybean by extrusion cooking. Part I. Effect on water absorption and solubility employing response surface analysis

Rice flour was mixed with various amounts of defatted soybean flour in order to obtain a mixture with protein levels of 15, 20 and 25%. These mixtures were processed in a one-screw Brabender 20 DN extruder at temperatures of 80, 100 and 120 °C. Below 20% of protein concentration, the water absorption index (WAI) increased, with increasing extrusion temperature, and below 90 °C the WAI increased with increasing protein concentration. The water solubility index (WSI) notibly increased with increases in both temperature and protein concentration.     

马铃薯生全粉对饺子皮蒸煮特性和质构特性的影响

将不同比例(10%、20%、30%、40%和50%)马铃薯生全粉与市售高筋小麦粉复配制备饺子皮,研究马铃薯生全粉含量对饺子皮蒸煮特性、全质构特性、微观结构以及感官等方面的影响。实验结果表明,当马铃薯生全粉添加量为10%时,显著缩短了对照组饺子皮的蒸煮时间,且显著降低了饺子皮的蒸煮损失率。添加了10%马铃薯生全粉制备的饺子皮,其黏弹性、凝胶性和咀嚼性等质构指标均优于对照组饺子皮。但随着马铃薯生全粉添加量的进一步增加,饺子皮的蒸煮时间延长且吸水率和蒸煮损失率上升,其质构指标包括:硬度、弹性、凝胶性和咀嚼性降低,使得饺子皮的色泽、风味、口感和组织等感官评分降低。通过电子扫描显微镜观察也表明,造成饺子皮蒸煮特性和质构特性等劣变的原因是由于添加过多马铃薯生全粉(添加量≥20%)阻碍了饺子皮面团面筋蛋白网状结构的均匀形成。     

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.     

马铃薯全粉添加量对小麦粉及其挂面品质特性的影响

在小麦粉中添加不同比例马铃薯全粉,测定其粉质特性、糊化特性及其挂面的烹煮和质构品质,探讨马铃薯全粉对小麦粉及其挂面品质的影响。结果表明:随着马铃薯全粉添加量的增加,马铃薯小麦混合粉的峰值黏度、谷值黏度、衰减值、最终黏度和回生值均降低;面团形成时间、稳定时间、弱化度先降低后升高,吸水率呈线性增加;马铃薯挂面的烹调损失率变大,最佳烹煮时间变长,硬度和弹性逐渐减小。当马铃薯全粉添加量≤20%时,所制作的挂面品质较好。马铃薯全粉的添加量、马铃薯小麦混合粉的粉质特性、糊化特性与马铃薯挂面的品质特性有显著的相关性。     

预糊化时间对即食冲调米粉品质的影响

以碎米为主要原料,采用湿热方法对原料进行预糊化,再应用滚筒干燥制备成即食冲调米粉,通过分析即食冲调米粉的吸水性指数、水溶性指数、流变特性、微观结构、消化特性,研究预糊化时间对样品的影响.结果表明:预糊化处理后的米粉冲调特性和消化性质得到显著改善,相对于未进行预糊化处理组样品,经过30min预糊化后,吸水性指数和水溶性指...     

挤压处理对苦荞粉理化特性及全苦荞挂面品质的影响

为提高全苦荞挂面的加工适应性、蒸煮和质构品质,对苦荞粉进行挤压预处理后与苦荞生粉混合制作全苦荞挂面,探究了挤压处理对苦荞粉的冷糊黏度及凝胶强度的影响,并结合面带、面条的质构品质及面条蒸煮特性探究挤压处理对全苦荞挂面加工性能及食用品质的影响。结果表明,经过挤压后苦荞粉的吸水性指数和水溶性指数分别增加了102.7%和87.5%以上,冷糊黏度显著增加（p<0.05）,挤压后苦荞粉在冷水中可形成凝胶,凝胶强度随挤压加水量的增加或温度的降低而升高;添加挤压苦荞粉促进了面带成型,面带的表面黏附力随苦荞粉冷糊黏度的增加而显著增加（p<0.05）,随挤压苦荞粉凝胶强度的增加,面带的抗拉伸力及面条的硬度和咀嚼性显著增加（p<0.05）,蒸煮损失率及断条率显著下降（p<0.05）。     

主要几种配料对挤压膨化早餐谷物挤压特性的影响

采用双螺杆连续挤压机生产早餐谷物食品的经典工艺，选用大米为挤压基料，探讨了糖、油脂、蛋白质、膳食纤维及品质改良剂等配料对谷物挤压特性的影响。研究结果表明：1％-5％还原糖即可使产品组织结构变得均匀细密、产品色泽加深、风味加强、膨化度和水溶性指数加大、吸水指数变化不大；加入蔗糖在8％以上时，即可抑制挤压谷物产品的膨化度，提高产品脆度，降低其吸水指数，对产品水溶性指数影响不大。加入少量的油脂、大豆蛋白和膳食纤维可改善产品的感官指标，提高产品营养；大豆磷脂和碳酸钙可作为挤压谷物产品品质改良剂。     

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.     

Physicochemical characterisation of corn extrudates prepared with varying levels of beetroot (Beta vulgaris) at different extrusion temperatures

This study examines the effect of beetroot powder (BRP) incorporation (0%, 5%, 10% and 15%) at different extrusion temperatures (125, 150 and 175 °C) on the physicochemical, antioxidant and sensory properties of corn grit (CG) extrudates. BRP showed higher values of total phenolic content (TPC = 9095 μg GAE g^?1) and free radical inhibition (ABTS = 6.5 μm trolox mg^?1 and DPPH = 7.9 μm trolox mg^?1) than CG (1346 μg GAE g^?1, 1.5 μm trolox mg^?1 and 2.2 μm trolox mg^?1, respectively). Pasting viscosity (peak, breakdown and final) decreased, while pasting temperature of CG increased with the level of BRP incorporation. Analyses of the extrudates showed an increase in redness, bulk density, hardness, TPC, free radical inhibition, total dietary fibre (TDF) and a decrease in water absorption index (WAI), water solubility index (WSI), expansion ratio and oil uptake with the increase in the level of BRP incorporation. On the other hand, higher extrusion temperature increased porosity, WAI, WSI, oil uptake but decreased redness, bulk density, hardness and TPC.     

Starch Phosphates Produced by Extrusion: Physical Properties and Influence on Yogurt Stability

Starch phosphorylation with sodium tripolyphosphate (STP) was performed using a single‐screw extrusion process. The extrusion variables studied were temperature (from 99.5°C to 200.4°C), water content (16.3% to 19.7%, w/w), and STP content (0.82% to 4.18%, w/w). The resulting phosphorylated starch was evaluated with respect to expansion, water solubility index (WSI), water absorption index (WAI), degree of substitution (DS), and viscosity. The phosphorylated starch was tested as a stabilizing additive in yogurt formulations, with respect to the syneresis index (SI) and the syneresis susceptibility coefficient (SSC). The results show that the expansion increases with increasing STP content, and decreases with increasing temperature and water content employed in the process. Increasing extrusion temperatures and decreasing water content resulted in increasing WSI and decreasing WAI. The DS was dependent on STP content, increasing as STP content increased, but appeared to be insensitive to changes in water content (between 16% and 20%, w/w). The highest level of yogurt stability, as measured by the syneresis index (SI) and the syneresis susceptibility coefficient (SSC), were obtained when the yogurt was formulated with the starch of the highest DS (0.018), which had been obtained at 150°C, 18% water content, and 4.12% (w/w) of STP.     

Influence of wheat flour substitution with potato pulp on dough rheology,microstructure and noodle quality

The effects of potato pulp (0–40%) on dough rheology and microstructures, as well as noodle quality, were investigated in this study. Substitution of wheat flour with potato pulp led to a decrease in β-sheet content, an increase in α-helix and unordered content for protein in dough, as well as a drop of the storage and loss modulus, which was mainly caused by the weakening of dough gluten strength. Scanning electron microscopy confirmed that the gluten–starch network could no longer to be observed for the formulated dough containing 30–40% potato pulp. Structural damage of dough induced the increases in optimal cooking time, cooking loss and adhesiveness, and a decrease in cohesiveness of cooked noodles. However, the samples with 20% potato pulp addition showed higher values in water absorption, hardness, springiness and chewiness, indicating that noodles with potato pulp content below 20% were acceptable.     

莲子淀粉重组米制备工艺优化

以不同比例莲子淀粉与碎米粉进行混合后挤压制备重组米,通过对混合粉的糊化特性和重组米的感官品质、质构特性及蒸煮损失率的分析,确定了莲子淀粉重组米的配比。以物料含水量、模头温度、螺杆转速为影响因素,采用响应面试验优化了莲子淀粉重组米挤压的最佳工艺条件。结果表明:随着莲子淀粉添加量的增加,混合粉的峰值黏度、谷值黏度、崩解值、最终黏度及回生值等均逐渐增加;感官评分先增大后减小,在莲子淀粉添加量为30%时较高;质构特性中硬度逐渐增大,弹性、咀嚼性、黏聚性先增大后减小,在莲子淀粉添加量为30%时最大;蒸煮损失率逐渐增大。综合分析,重组米品质在莲子淀粉添加量为30%时达到最佳。重组米的最佳挤压条件为:物料含水量40%、螺杆转速210 r/min、模头温度95 ℃时,重组米评分为69.13分。     

Effect of Extrusion Cooking on Functional Properties and in vitro Starch Digestibility of Barley-Based Extrudates from Fruit and Vegetable By-Products

ABSTRACT:  Barley flour and barley flour–pomace (tomato, grape) blends were extruded through a co-rotating twin-screw extruder. The aim of the present study was to investigate the effects of die temperature, screw speed, and pomace level on water absorption index (WAI), water solubility index (WSI), degree of starch gelatinization, and in vitro starch digestibility using a response surface methodology. The selected extrudate samples were examined further using differential scanning calorimetry (DSC) and polarized light microscopy, respectively. The WAI of barley–pomace extrudates was affected by increasing pomace level. Temperature had significant effect on all types of extrudate but screw speed had significant linear effect only on barley and barley–grape pomace extrudates on degree of starch gelatinization. Although no gelatinization peak was detected, an endotherm was observed on all selected extrudates. In general, extrusion cooking significantly increased in vitro starch digestibility of extrudates. However, increasing level of both tomato and grape pomace led to reduction in starch digestibility.     

马铃薯抗性淀粉对韧性饼干品质及消化性能的控制

目的 研究马铃薯抗性淀粉对韧性饼干消化性能及品质的影响规律, 为评价和提高马铃薯抗性淀粉韧性饼干的品质奠定基础。方法 通过将马铃薯抗性淀粉作为膳食纤维成分, 按照不同比例替代面粉, 制作成韧性饼干, 对韧性饼干的延展性、色泽、感官、质构特性、表观结构等物理特性、营养成分及消化性能进行测定, 研究马铃薯抗性淀粉对韧性饼干品质及消化性能的影响。结果 随着马铃薯抗性淀粉的增加, 韧性饼干的延展性总体呈增长趋势,蛋白质和脂肪含量逐渐减少,水分和灰分含量差异不显著。在马铃薯抗性淀粉添加为20%时饼干色泽均匀,硬度、脆性和咀嚼性均较好, 感官评分最高, 为82.6分。SEM观察发现随着马铃薯抗性淀粉的添加饼干结构显示暴露在油脂外的淀粉颗粒逐渐增加。马铃薯抗性淀粉的加入降低系统中淀粉的水解速率, 进而调节饼干的体外消化率, 降低血糖指数, 添加30%马铃薯抗性淀粉时, 血糖指数为62.06, 已达到中等血糖指数。结论 适量的马铃薯抗性淀粉添加到韧性饼干中可以改善饼干品质, 随着马铃薯抗性淀粉含量的增加, 饼干血糖指数降低。为抗性淀粉饼干的开发提供理论基础。