DEVELOPMENT OF A CONTINUOUS METHOD FOR PUFFING AMARANTH (AMARANTHUS SPP.) SEEDS

Amaranth ( Amaranthus spp.) is a nutritionally dense pseudocereal grown mostly in South America and Asia. Traditionally amaranth seeds are puffed using a hot skillet. Besides being a batch system, in this process there is little control over the temperature and the residence time of the seeds. We have developed a continuous technique for puffing amaranth seeds using a single-screw extruder with a tapered screw without a die. With this technique we could control the temperature and the residence time for puffing the seeds. It was found that the puffing efficiency of amaranth seeds was a function of temperature and screw speed. The maximum efficiency of 86% was achieved at a barrel temperature of 290C and screw speed of 125 rpm. Sensory analyses with an untrained panel of 33 subjects using samples generated at conditions with puffing efficiency above 75% showed that the sample processed at 250C and 75 rpm was the most acceptable in terms of various sensory attributes and overall liking.

PRACTICAL APPLICATIONS

The research aims to develop a new continuous process for the puffing of amaranth seeds. The use of an extruder without a die for puffing these seeds is a novel idea. This process could possibly be used for puffing several other seeds and grains, making it a versatile technology. The sensory work conducted in this paper aims at examining the acceptance of this relatively new product among U.S. consumers.     

Effect of process parameters and soy flour concentration on quality attributes and microstructural changes in ready-to-eat potato-soy snack using high-temperature short time air puffing

High-temperature short time (HTST) air puffing has been found to be very useful process for production of potato-soy ready-to-eat snack food as it ideally produced highly porous and light texture. The process parameters considered viz. puffing temperature (185-255 °C) and puffing time (20-60 s) with constant initial moisture content of 36.74% and air velocity of 3.99 m/s for potato-soy blend with varying soy flour content from 5% to 25% were investigated using response surface methodology with central composite rotatable design (CCRD). The optimum product in terms of maximum expansion ratio (3.69), minimum hardness (2754.3 g) and maximum overall acceptability (7.3) were obtained with 10.31% soy flour blend in potato flour at the process conditions of puffing temperature (230.06 °C) and puffing time (25.46 s). Microstructural changes were evaluated at different stages (with an interval of 5 s) of HTST puffing for product obtained with the optimum processing conditions. The maximum expanded porous structures with larger cracks and smaller pits were recorded in the SEM micrographs at 20 s of HTST air puffing.     

Hot air expansion of potato starch pellets with different water contents and salt concentrations

The expansion and puffing kinetics of commercial potato starch pellets were examined using a hot air fan oven in order to determine the puffing kinetics. The time for the onset of expansion showed uni-molecular type kinetic behaviour and was modelled by an Arrhenius plot. A pseudo-activation enthalpy for pellet expansion was also determined. The initial moisture content of the commercial pellets was controlled and the changes in the extent of puffing and the pseudo-activation enthalpy were found. The effect of type and quantity of cation in the formulation was then investigated. Expansion occurred even when no cation was added although the presence of cation did improve pellet expansion. The ratio of the native and pre-gelatinized starch in the pellets was also varied and showed to have limited effect on the extent of expansion. The puffing mechanism is discussed in light of these observations.     

Effects of explosion puffing on the nutritional composition and digestibility of grains

The objective of this study was to investigate the effects of explosion puffing on the nutritional composition, physical properties, and digestibility of grains including millet, barley, black rice, rice, glutinous rice, and wheat. Explosion puffing of grains resulted in the nutritional composition with higher total sugar content and lower moisture, starch and fat contents. Although the protein content scarcely changed comparing with the untreated grains, the solubility declined significantly. Moreover, explosion puffing could significantly improve the physical properties including the water absorption index, water solubility index and gelatinization degree. The in vitro digestion experiment was employed to investigate the influences of explosion puffing on the starch hydrolysis rate and free amino acid content, and it was indicated that the digestibility of the starch and protein in grains was highly improved. The results demonstrated that explosion puffing is a suitable technique to improve the physical properties and digestibility of grains, which provided the theoretic foundation for the use of explosion puffing technology in coarse cereal processing.     

Study of the puffing process of amaranth seeds by dielectric spectroscopy

Amaranth (Amaranth spp) is considered a pseudocereal with valuable nutritional characteristics. Amaranth grain is commonly used in cereal industry as expanded product obtained from the puffing operation. In this work, the puffing process of amaranth seeds with different water content was studied. Moreover, the seeds and puffed kernels were analyzed by Differential Scanning Calorimetry (DSC), image analysis, dielectric spectroscopy and Cryo-SEM. The results of the study allowed identifying different levels of water retention in amaranth seeds. Moreover, the expansion process was modeled determining the critical points, obtaining the state variables and the final product conditions. It was also performed a structural study of the amaranth seed and the puffed product. The dielectric properties were also measured for determining the optimal time for the puffing operation.     

Quality Attributes of High Temperature Short Time Air Puffed Ready-to-eat Potato Snacks

The effects of process parameters for high temperature short time (HTST) air puffing viz. puffing temperature (175–275°C), puffing time (15–75s), moisture content (30–40%), and air velocity (2.4–4.8m/s) on quality attributes such as expansion ratio (ER), bulk density (BD), colour (L-value), and texture (hardness) of ready-to-eat (RTE) potato snacks were investigated, based on central composite design. Increasing puffing temperature resulted in potato snack with a higher ER, lower hardness, lower BD, and lower L-value. Increasing puffing time produced lower hardness and lower L-value but no significant effect on the ER and BD. Higher moisture content increased ER and L-value but reduced hardness and no significant effect on the BD. Increasing air velocity resulted in potato snack with a higher ER, higher L-value, lower BD and lower hardness.     

EXTRUSION COOKING OF RICE: EFFECT OF AMYLOSE CONTENT AND BARREL TEMPERATURE ON PRODUCT PROFILE

The effect of amylose content (5.0–28.6%) of rice and barrel temperature (80–120C) on extrusion system parameters torque and net specific mechanical energy and extrudate characteristics extrudate bulk density (ED), water solubility index, expansion ratio (ER) and Warner–Bratzler shear stress were studied using a twin‐screw extruder. The feed rate (15 kgh^?1), moisture content (20.0% ± 0.2) of feed and the screw speed (400 rpm) were kept constant. ED and ER of the product suggested that a barrel temperature of 120C was desirable to generate an expanded extrudate rice product from low‐amylose rice cultivar. Experimental data on system parameters and extrudate characteristics fit to second‐degree polynomial regression equations (r ≥ 0.904, P ≤ 0.01) with the amylose content of rice and barrel temperature of the extruder.     

玉米膨化食品加工参数研究

以玉米糁为材料，采用DSE-25型双螺杆挤压膨化实验室工作站为加工设备，分析了加工温度和物料含水量对扭矩、压力、膨化率和产品含水量的影响。结果表明，在试验设计的加工温度和物料含水量范围内，加工温度和物料含水量对螺杆扭矩、第4区压力、第5区压力、产品膨化率和含水量都有极显著影响。加工温度对第4区压力影响较大；物料含水量对扭矩、第5区压力、产品膨化率和含水量影响较大。随着加工温度上升，物料含水量增加，扭矩、压力、产品膨化率降低；随着加工温度升高，物料含水量下降，产品含水量降低。     

葛根黑豆挤压膨化工艺研究

以葛根粉和黑豆粉为主要原料,研究葛根粉与黑豆粉质量比、混合物料含水率、机筒Ⅲ区温度、螺杆主轴转速等因素对产品感官和糊化度的影响。通过单因素和正交试验优化葛根黑豆膨化食品的加工工艺,得到最佳工艺参数为机筒Ⅲ区温度150℃、螺杆主轴转速160 r/min、混合物料含水率17%、葛根粉与黑豆粉质量比1∶5,在该条件下生产出的产品具有较好的感官品质和糊化度。     

Effects of extrusion variables on the properties of waxy hulless barley extrudates

The objective of this research was to investigate the extrudability of waxy hulless barley flour under various extrusion conditions. Waxy hulless barley flour was processed in a laboratory-scale corotating twin-screw extruder with different levels of feed moisture content (22.3, 26.8, and 30.7%) and die temperature (130, 150, and 170 degrees C) to develop a snack food with high beta-glucan content. The effects of extrusion condition variables (screw configuration, moisture, and temperature) on the system variables (pressure and specific mechanical energy), the extrudate physical properties (sectional expansion index, bulk density), starch gelatinization, pasting properties (cold peak viscosity, trough viscosity, and final viscosity), and beta-glucan contents were determined. Results were evaluated by using response surface methodology. Increased extrusion temperature and feed moisture content resulted in decreases in exit die pressure and specific mechanical energy values. For extrudates extruded under low shear screw configuration (LS), increased barrel temperature decreased sectional expansion index (SEI) values at both low and high moisture contents. The feed moisture seems to have an inverse relationship with SEI over the range studied. Bulk density was higher at higher moisture contents, for both low and high barrel temperatures, for samples extruded under high shear screw configuration (HS) and LS. Cold peak viscosities (CV) were observed in all samples. The CV increased with the increase in extrusion temperature and feed moisture content. Although beta-glucan contents of the LS extrudates were comparable to that of barley flour sample, HS samples had generally lower beta-glucan contents. The extrusion cooking technique seems to be promising for the production of snack foods with high beta-glucan content, especially using LS conditions.     

低脂青稞膨化米卷加工工艺及其品质

试验对含有青稞全麦粉的物料进行挤压膨化,采用果胶脂肪替代物为注芯材料,研制出一种低脂肪含量的青稞米卷。影响青稞米卷膨化度的因素主次为:膨化温度>物料水添加量>膨松剂添加量>果胶脂肪替代物。影响青稞米卷酥脆性因素主次为:膨化温度>膨松剂比例>物料水添加量>果胶脂肪替代物添加量。具体试验结果为:青稞粉添加量为6%,果胶替代物添加比例为10%,水添加量为6%,膨松剂添加比例为0.7%,三段温区温度设置:Ⅰ区70℃、Ⅱ区130℃、Ⅲ区150℃,固体粉末喂料机转动频率为12 Hz,双螺杆挤压机主轴转动频率为30 Hz;对最佳工艺条件的米卷理化指标进行检测、质构分析和感官评价,结果表明果胶脂肪替代物作为注芯材料研制的青稞膨化米卷品质优良,脂肪含量为24.48%,能够有效降低膨化米卷脂肪用量。     

超微粉碎后粒径对大麦全粉品质特性的影响

本研究主要以大麦为主要原料,探究不同粒径对超微粉碎大麦粉品质特性的影响.研究结果表明,随着粒径的降低,大麦全粉水分、淀粉含量、溶解性、亮度值及白度值显著增加(P<0.05),而膨润力、吸油性、持水性、峰值黏度和回生值则显著降低(P<0.05).微观结构结果表明,随着粒径的降低,大麦全粉粉体的颗粒形状由圆形或椭圆形转为不...     

枣的变温压差膨化干燥工艺研究

利用变温压差膨化干燥技术开发枣加工新产品。通过研究,枣变温压差膨化干燥的关键影响因素,确定最佳工艺条件为预干燥水分40%,膨化温度105℃,膨化压差-0.08 MPa,干燥时间160 min,干燥温度75℃。采用以上工艺条件生产的枣膨化产品品质佳,酥脆可口。     

Optimization of oven toasting for improving crispness and other quality attributes of ready to eat potato-soy snack using response surface methodology

Ready-to-eat potato-soy snacks were developed with high temperature short time air puffing process followed by oven toasting for increasing crispness. Oven toasting experiments were conducted with varying temperature (85.86–114.14 °C) and time (12.69–35.31 min) based on central composite rotatable design. The final product was evaluated in terms of quality attributes such as crispness, moisture content, ascorbic acid loss, colour (L and ΔE) values and overall acceptability. The optimum product qualities in terms of crispness (38.7), moisture content (3.35%, db), ascorbic acid loss (20.87%, db), L value (52.03), ΔE (8.60) and overall acceptability (7.8) were obtained at temperature of 104.4 °C and time of 27.9 min.     

挤压花生蛋白品质特性的加工因素研究

基于Box-Behnken响应面模型,研究花生蛋白挤压过程中挤压参数（机筒温度、螺杆转速、物料水分）对产品品质（膨胀率、吸水性指数、氮溶解指数、硬度）的影响,并根据标准型原理分析单因素对产品品质的贡献率。结果表明,随着机筒温度、螺杆转速、物料水分的上升,产品膨胀率不断增加;机筒温度和螺杆转速对产品的吸水性指数影响显著;高温、高湿、高剪切力使产品的氮溶解指数和硬度处于较低的水平。利用转化为标准型的回归方程计算出机筒温度对膨胀率的贡献率为59.3%,螺杆转速对硬度贡献率为54.5%。物料水分对吸水性指数和氮溶解指数具有决定性的作用。通过调整挤压操作参数,可以一定范围内控制挤压蛋白产品品质。     

直接挤出制备米粉(线)工艺的优化

为了获得直接挤压制备米粉(线)的最适工艺参数,采用响应面(RSM)方法设计试验方案,对挤压机挤压制作米粉的工艺参数进行优化分析。研究原料含水量、机筒温度、螺杆转速对米粉糊化度的影响。结果表明:3个因素对糊化度影响大小依次为机筒Ⅲ区温度>螺杆转速>原料含水量。通过响应面分析得出挤压米粉最佳工艺:原料含水量35.1%,Ⅲ区温度102℃,螺杆转速117 r/min。在此条件下,米粉糊化度为92.1。与3种市售产品对比,自制米粉在硬度、糊化度、咀嚼性和感官品质方面达到了市售产品平均水平。     

Impact of ripening stages of banana flour on the quality of extruded products

The study investigated the physical, nutritional and sensory properties of different ripening stages of banana during extrusion processing in combination with rice flour to develop quality snack products. Dehydrated banana flours at ripening stages 4, 5 and 6 (peel colour) were mixed separately at 40% banana to 60% rice flour levels. The mixtures were extruded through a twin-screw extruder at 120 °C barrel temperature, 220 and 260 r.p.m, screw speed and 12% feed moisture. Increase in ripeness indicated negative effect on expansion and water absorption capacity while increasing the water solubility index and moisture retention (wet basis) of the products. Protein and mineral (except for zinc and copper) content of the products were significantly different ( P  < 0.05) from 4 to 6 of the ripening stages. Most of the essential amino acids in the extruded products increased significantly ( P  < 0.05) at the ripening stage of 6. All the products were within the acceptable range in the 9-point Hedonic scale showing the best texture and flavour scores for stage 4 and 6, respectively. The extruded products show potential as snack products because of their nutritional quality and sensory acceptability.     

微波膨化果蔬小食品的研究

探讨了微波膨化技术在山药和胡萝卜脆片加工中的应用。以膨化率为指标,结合感官评价,实验了添加不同比例的淀粉原料对山药及胡萝卜脆片膨化效果的影响,并讨论了样品初始水分含量、样品的厚度以及微波功率和时间对膨化率的影响,且通过正交实验确定了最佳膨化工艺条件。     

大豆蛋白高水分挤压组织化过程中工艺参数对系统压力和扭矩的影响

以食用脱脂低温豆粕为原料,用响应面分析法,研究了DSE-25型双螺杆挤压机在大豆蛋白高水分挤压组织化过程中工艺参数对系统压力和扭矩的影响。结果表明,机筒温度、物料水分含量、喂料速度和螺杆转速等操作参数对挤压机系统压力和扭矩均具有显著的影响。系统压力随着机筒温度和物料水分含量的升高而降低,随着喂料速度的增加而增加,螺杆转速对其影响较小;扭矩随物料水分含量的增加而降低,随着机筒温度和螺杆转速的升高均表现出先升后降的趋势,随喂料速度的增加则表现出先降后升的趋势。依据逐步回归分析法建立的双螺杆挤压机系统参数的统计模型,具有较高的预测精度,可用于挤压过程的控制和挤压结果的预测。     

Toasting of corn flakes: Product characteristics as a function of processing conditions

Toasting of corn flake is an important processing step that dictates the attributes of the finished product with particular reference to consumer acceptability. The effect of important toasting variables such as moisture content, temperature and time of toasting of corn flakes on quality attributes has been investigated employing response surface methodology (RSM). A central composite experimental design consisting of five coded levels (−1.682, −1, 0, 1 and 1.682) of each independent variables has been employed. The response functions are thickness of flake, bulk density, puncture force, colour parameters and the sensory overall acceptability. Further, the changes in the microstructure of the flakes have been monitored. The energy expenditure during the toasting process was also determined, and 721–746 J g⁻¹ of energy was required to have properly toasted flakes. These response functions can be correlated (r  0.82, p  0.01) with the independent variables by second order polynomials consisting of linear, quadratic and interaction terms. The effect of temperature and time usually dominates over the moisture content for toasting of corn flakes. Optimum conditions for achieving best puffing and overall acceptability have been obtained.