Extrusion processing characteristics of quinoa (Chenopodium quinoa Willd.) var. Cherry Vanilla

Extrusion processing characteristics of Cherry Vanilla quinoa flour (Chenopodium quinoa Willd) were investigated using a three factor response surface design to assess the impact of feed moisture, temperature, and screw speed on the physicochemical properties of quinoa extrudates. Specific mechanical energy (SME) required to extrude this quinoa variety was higher (250–500 kJ/kg) than previously reported for quinoa. The following characteristics of the extrudates were observed: expansion ratio (1.17–1.55 g/cm³), unit density (0.45–1.02 g/cm³), water absorption index (WAI) (2.33–3.05 g/g), and water solubility index (WSI) (14.5–15.87%). This quinoa flour had relatively low direct expansion compared to cereal grains such as corn or wheat, suggesting that it is not well suited for the making of direct expanded products. The study further suggests that there is a need to understand the processing characteristics of new quinoa varieties for cultivation. Understanding extrusion and other quality traits in advance will help to select the appropriate varieties that would allow food processors to meet consumer needs.     

Rheological properties of starches with different amylose/amylopectin ratios

The rheological properties of corn starches with different amylose/amylopectin ratios (80/20, 50/50, 23/77, and 0/100) were systematically studied by Haake rheometry. The starches were initially pre-compounded with water to designated moisture content levels using a twin-screw extruder. A single-screw extruder with a slit capillary die was then used to characterize the shear stress and melt viscosity characteristics of sample pellets, as a function of both moisture content (19–27%) and extrusion temperature (110–140 °C). The melts exhibited shear thinning behavior under all conditions, with the power law index (0 < n < 1) increasing with increasing temperature and moisture content in the majority of cases. The higher the amylose content, the higher is the viscosity (for example, η increases from 277 Pa s to 1254 Pa s when amylose content increases from 0% to 80% under a certain condition), which is opposite to the sequence of molecular weight; amylopectin-rich starches exhibited increased Newtonian behavior. These rheological behaviors are attributed to the higher gelatinization temperature of amylose-rich starches, and in particular the multiphase transitions that occur in these starches at higher temperatures, and the gel-ball structure of gelatinized amylopectin.     

膨化食品表面质量的自动检测

利用图像处理方法,对膨化玉米表面质量进行了研究。结果表明,膨化玉米的颜色和体积是反映产品质量的重要信息,直接受物料喂入量和含水量的影响,通过伴样本图像的统计分析可知,ＲＧＢ,ＣＭＹ模型比ＨＳＩ模型更适用于膨化玉米,用图像处理方法自动检测多膨化食品表面质量可避免手工检测和内部结构图像分析时破坏样本,减少了损失,是在线自动检测膨化食品质量的新途径。     

Effects of formulation and extrusion cooking conditions on furfural and hydroxymethylfurfural content

The objective of this research was to investigate the effects of different ingredients (reducing sugars, leavening agents, citric acid), processing conditions (feed moisture content, exit die temperature), and extrusion cooking methods (with/without CO₂ injection) on furfural and 5-hydroxymethylfurfural (HMF) formation in corn-based extrudates. The decrease in furfural levels was 16% upon addition of sodium-bicarbonate, while the increase was 12% upon addition of ammonium-bicarbonate for extrudates produced at 150 °C and feed moisture content of 22%. The furfural concentration of extrudates produced at 150 °C and feed moisture content of 22% without leavening agents was 810 μg/100 g and increased to 11,901 μg/100 g upon citric acid addition (about a 15-fold increase). Furthermore, both low feed moisture and high exit die temperature had promoting effects on furfural and HMF contents. The CO₂ injection method did not have considerable effect on furfural and HMF levels of the extrudates; however, it positively affected the physical properties of extrudates.     

Effect of concentrate extrusion and castration on diet digestion and performance of intensively reared male calves

Fifty-six male Friesian calves, half of them castrated, were used to study the effects of concentrate extrusion and animal castration on diet digestibility and performance in two different growth phases (from 91 to 250 and from 250 to 400 kg live weight). Diets consisted of a compound meal, extruded or nonextruded, and barley straw, both of them fed ad libitum. Half of the animals were slaughtered at 250 kg and the remaining at 400 kg live weight. Extrusion increased the gelatinization grade, resulting in a higher (p<0.01) fermentation rate, and reduced nitrogen solubility and degradation after 12 h of rumen incubation (p<0.05). Calves receiving the extruded meal showed a lower rumen ammonia concentration just before the first meal (p<0.001), the differences disappearing afterwards. Neither the pH nor the total VFA concentrations were affected, although butyrate, isobutyrate and isovalerate proportions before the first meal decreased with the extruded diet. Concentrate extrusion did not affect the apparent OM digestibility of total diet but caused a reduction of NDF (p<0.01) and CF (p<0.05) digestibility. In the first growth phase, concentrate and total DM intake decreased with extrusion (p<0.001), without affecting the average daily gain (ADG). Consequently, the concentrate and total feed conversion ratios were significantly lower (p<0.001 and p<0.01, respectively) with the extruded meal. Bulls showed a higher ADG than steers (p<0.001), resulting in lower feed conversion ratios (p<0.01) given that intake was not affected by castration. In the second growth phase, extrusion did not affect any of the performance parameters, however bulls showed a higher DM intake and ADG (p<0.05), but no differences in the feed conversion ratio were found between entire and castrated animals.     

Effect of extrusion pretreatment on extraction,quality and antioxidant capacity of oat (Avena Sativa L.) bran oil

Extrusion is an alternative pretreatment for oil extraction from cereal resource. The objective of this study was to assess the feasibility of extrusion pretreatment of oat bran for oil extraction. The effects of extrusion conditions including feed moisture content, screw speed and die temperature on the extraction, quality and antioxidant capacity of oat bran oil were investigated. The results showed that the extraction yield of oat bran oil varied from 3.93% to 8.43% under different extrusion conditions. A feed moisture content of 25% had an important effect on the extraction of oil from oat bran. Extrusion pretreatment could increase oil extraction efficiency by increasing expansion index and porosity of oat bran extrudates. Extrusion processing had no positive or adverse effect on the fatty acid compositions, and acid, peroxide and iodine values. Meanwhile, extrusion processing did not affect the phytochemical components and antioxidant capacity of oat bran oil. But refining process could result in decrease of phytochemical components and antioxidant capacity of oat bran oil. These results indicated that extrusion is a feasible and potential pretreatment procedure for oil extraction from oat bran.     

Effect of extrusion treatment on enzymatic hydrolysis of wheat bran

Although, wheat bran is a good source of dietary fibre (DF), it has certain disadvantages due relatively lower levels of soluble DF. Therefore, in the current study, the effect of extrusion treatment on microstructure and enzymatic hydrolysis of wheat bran was investigated. Extrusion treatment increased fibre solubility at all process conditions and the screw speed was found to be the most effective parameter. Physicochemical properties of bran were affected from extrusion treatments. While the water-binding capacities of extruded brans were lower than that of non-extruded wheat bran, their water solubilities were higher. Enzymatic hydrolysis increased the soluble DF content of the bran samples as compared to those of respective samples at the beginning of incubation. The results showed that extrusion treatment can be used to disrupt the wheat bran microstructure and thus to increase the soluble fibre content. Enzymatic hydrolysis can also be used for increasing solubility further. The outcomes of this study can be utilized for improving the technological functionality of cereal fibres to develop high fibre ingredients for food applications.     

Effect of extrusion cooking on chemical structure,morphology, crystallinity and thermal properties of sorghum flour extrudates

The effect of feed moisture content (10, 14 and 18%) and die temperature (110 and 160 °C) on functional properties, specific mechanical energy (SME), morphology, thermal properties, X-ray diffraction pattern (XRD), Fourier transform infrared spectroscopy (FTIR) and amylose-lipid complex formation of extruded sorghum flour was investigated. Results showed that the extrusion cooking significantly changed the functional properties of extruded sorghum flour. Increasing feed moisture increased the peak gelatinization temperature (T_p), the degree of gelatinization (%) and starch crystallinity (%) while it decreased the gelatinization temperature ranges (T_c - T₀), starch gelatinization enthalpy (ΔH_G) and amylose-lipid complex (%) formation. With increasing die temperature, the degree of gelatinization and amylose-lipid complex formation increased and the starch T_p, T_c-T₀, ΔH_G and crystallinity decreased. The FTIR spectra also showed that the extrusion cooking did not create new functional groups or eliminate them in sorghum protein, whereas the sorghum extrudate protein had random coil conformation.     

玉米籽粒品质性状与挤压膨化特性的关系

 以黄淮海平原玉米主产区53份玉米品种为材料，以德国布拉本德食品仪器公司DSE-25型双螺杆挤压膨化实验室工作站为膨化设备，研究了玉米籽粒品质性状与挤压膨化特性的关系。结果表明，在相同挤压膨化工艺条件下，不同玉米品种挤压膨化物的径向膨化率、容积密度、水溶性指数、吸水性指数、硬度差异较大。与夏玉米品种相比，春玉米品种挤压膨化物具有较高的径向膨化率、吸水性指数和产量，较低的水溶性指数和机械能耗。玉米容重与挤压膨化物质量指标之间无显著相关性，而百粒重、百粒体积与径向膨化率、扭矩、五区压力以及产量呈显著或极显著负相关。淀粉含量高、蛋白质含量和脂肪含量低的玉米品种，其挤压膨化物有较大径向膨化率，较小容积密度和硬度，挤压膨化时的扭矩、五区压力以及机械能耗较大。玉米品种的糊化特性与挤压膨化特性之间有相关性。糊化参数可用来预测挤压膨化物的质量。     

花生蛋白高水分挤压组织化过程中的化学键变化

 【目的】从挤压产品微观结构、化学键变化和蛋白质酰化改性等方面，探讨花生蛋白高水分挤压组织化结构的形成机理。【方法】采用扫描电子显微镜观察挤压产品的微观结构，利用物性测定仪分析挤压产品的质构特性，用化学分析方法对蛋白质中的总巯基和二硫键含量进行分析，采用琥珀酰化的方法对花生蛋白进行酰化处理。【结果】蛋白质溶解度试验结果显示，随挤压温度的升高，花生蛋白的溶解度迅速降低，在含2%SDS和2%SDS+2%2-ME缓冲液中的溶解度显著增加，最高达76.89%（140℃），说明挤压产品中以非共价键结合的蛋白质含量显著增加。随挤压温度的增加，二硫键含量在140～150℃范围内呈缓慢下降趋势，在155℃时显著降低。花生蛋白质酰化后，挤压产品的硬度、咀嚼度和组织化度等显著降低，相应的微观结构也显示出显著的变化。【结论】在花生蛋白高水分挤压组织化过程中，疏水作用和氢键起主要作用，其次是二硫键。在挤压过程中，花生蛋白分子内原有的二硫键含量降低，可能发生了部分断裂，高温会加速该反应的进行。酰化改性明显干扰了蛋白质分子间的相互作用，不利于挤压产品良好组织化结构的形成。