基于挤压蒸煮的荞麦粉加工品质改良及其机制研究

文章分析了挤压蒸煮对荞麦粉室温黏度和凝胶特性的影响,并利用体积排阻色谱测定了淀粉的分子量分布,探讨预糊化处理改善荞麦粉凝胶特性的机制;基于面带质地评价方法,优化预糊化荞麦粉在50%荞麦挂面中的添加比例。结果表明:荞麦粉经挤压蒸煮后,常温水中可形成凝胶;室温黏度显著增加;在主区温度200℃,水分含量18%,螺杆转速220r/min的条件下,所得预糊化荞麦粉中聚合度(DP)为6～50的支链淀粉分子最多,且此时凝胶强度最大。当预糊化荞麦粉添加量为10%时,面带抗拉能力最佳,黏附能力适中。由此可见,预糊化荞麦粉中特定链长的支链淀粉分子(DP 6～50)与凝胶品质呈正相关;50%荞麦挂面中添加适量预糊化粉可显著改善挂面的加工性能。     

改良挤压法制备铁营养强化大米的研究

以早籼米碎米为原料,使用乙二胺四乙酸铁钠（NaFeEDTA）做铁营养强化剂,通过改良挤压法制备铁营养强化大米。采用响应面法考察改良挤压法加工参数,（物料含水率、螺杆转速、机筒温度）的变化对铁营养强化大米质构特性的影响,并且以市售晚籼米质构特性为参考指标,优化铁营养强化大米的制备工艺。得到接近晚籼米质构的最佳工艺条件为湿基物料含水率34％,螺杆转速25r／min,机筒四区温度为102℃,其余四个加热区的温度分别为50、65、90、95℃。此条件下制备的营养强化大米硬度为6062g,粘附力为-1175．21g·s,弹性为0．72,内聚性为0．61,接近市售晚籼米的质构;铁含量为36．95mg／kg,远高于晚籼米的7．21mg／kg,并且淘洗蒸煮损失较小,为其他营养强化米的生产提供理论参考。     

Fate of Fusarium mycotoxins in maize flour and grits during extrusion cooking

Extrusion technology is used widely in the manufacture of a range of breakfast cereals and snacks for human consumption and animal feeds. To minimise consumer exposure to mycotoxins, the levels of deoxynivalenol (DON) and zearalenone (ZON) in cereals/cereal products and fumonisins B₁ and B₂ (FB₁ and FB₂) in maize are controlled by European Union legislation. Relatively few studies, however, have examined the loss of Fusarium mycotoxins during processing. The behaviour of FB₁, FB₂ and fumonisin B₃ (FB₃), DON and ZON during extrusion of naturally contaminated maize flour and maize grits is examined using pilot-scale equipment. DON and ZON are relatively stable during extrusion cooking but the fumonisins are lost to varying degrees. There is some loss of ZON when present in low concentrations and extruded at higher moisture contents. The presence of additives, such as reducing sugars and sodium chloride, can also affect mycotoxin levels. Moisture content of the cereal feed during extrusion is important and has a greater effect than temperature, particularly on the loss of fumonisins at the lower moistures. The effects are complex and not easy to explain, although more energy input to the extruder is required for drier materials. However, on the basis of these studies, the relationship between the concentration of Fusarium toxins in the raw and finished product is toxin- and process-dependent.     

Effect of extrusion on nutritional quality of maize and Lima bean flour blends

Maize flour (Zea mays) (M), Lima bean flour (Phaseolus lunatus) (B) and blends of these in proportions of 75M/25B, 50M/50B and 25M/75B (w/w) were extruded and their nutritional quality evaluated. Extrusion was done with a single screw extruder at 160 °C, 100 rpm and 15.5% moisture. In vitro protein digestibility (87%) was higher in the extruded products. Available lysine and resistant starch were highest in 50M/50B raw flour (59.5 g kg⁻¹ protein, 67.9 g kg⁻¹, respectively) but decreased after extrusion (45.5 g kg⁻¹ protein, 16.6 g kg⁻¹, respectively). The same treatment had the lowest available starch (561.6 g kg⁻¹ flour, 507.9 g kg⁻¹ extrudate). Total dietary fiber in the 50M/50B raw flour blend was 144 g kg⁻¹ versus 176 g kg⁻¹ in its extrudate. This was most noticeable for soluble dietary fiber, which increased from 10.6 g kg⁻¹ to 79.4 g kg⁻¹ after processing. Extrusion of blends is feasible up to a 50% bean inclusion level, which improves the nutritional value of the expanded product.Copyright © 2006 Society of Chemical Industry     

全谷物重组速煮糙米的理化性质和蒸煮品质研究

本研究以低值早籼稻糙米为原料,采用挤压质构重组技术,研究开发速煮糙米产品,攻克了糙米难以煮制、口感粗糙及食用不方便等难题,并对产品的理化性质和蒸煮、食用品质进行了分析研究。结果显示:重组糙米的B族维生素等各项营养指标与天然糙米接近。在30、40℃下重组糙米的吸水率高于原料糙米和精白米,50℃时吸水率介于原糙米和精白米之间;重组糙米糊化温度低于原糙米和精白米,糊化时间减少。衰减值降低,表明糙米重组后不易发生回生。质构和感官测试表明重组糙米色泽淡黄,外观光滑,透明度高,蒸煮8min即达到完全熟化,其硬度低于精白米和原糙米。产品货架期超过6个月。      

Nutritional,physicochemical, and textural properties of gluten-free extruded snacks containing cowpea and whey protein concentrate

Ready-to-eat extruded snacks with high protein and fibre were developed from a composite flour comprising rice flour, cowpea flour and whey protein concentrate (WPC). Nutritional, physicochemical, and textural properties of extrudates were evaluated, at five ratios of cowpea: WPC (10:0, 15:05, 20:10, 25:15, 30:20); rice flour was used as a control. The protein and fibre content in the extrudates significantly increased (P ≤ 0.05) with cowpea (10%–30%) and WPC (5%–20%) incorporation compared to the control. The extrudates with higher levels of cowpea and WPC showed a significant increase in bulk density and hardness. A slight decrease of 12% was observed in the expansion of 15% cowpea and 5% WPC fortified extrudates compared to the control. The number of peaks during compression increased with incorporations of cowpea and WPC. All cowpea and WPC containing snacks were darker than the control. Significant correlations were found between the protein, fibre, colour values and textural properties. The essential and non-essential amino acid profiles increased in the extrudates, proportionally to the cowpea and WPC fortification.     

挤压温度对膨化豆粕品质及蛋白质结构的影响

采用挤压膨化法对高温脱溶豆粕进行处理,分析探讨挤压温度对膨化豆粕品质及蛋白质结构的影响。结果表明:随着挤压温度的升高,膨化豆粕的氮溶解指数和蛋白质分散指数先增大后减小,而胰蛋白酶抑制活性不断降低;当挤压温度为60℃时,膨化豆粕蛋白的二级结构稍有变化,蛋白质部分变性,此时氮溶解指数和蛋白质分散指数最大,表明蛋白质适当变性有利于提高豆粕品质;随着挤压温度的升高,膨化豆粕蛋白的荧光强度逐渐增加而后稍有降低,当挤压温度为60℃时,色氨酸残基的微环境极性增加,蛋白质的三级结构变得更加疏松。     

挤压蒸煮改性黄精粉的制备及品质评价

目的:提高黄精食用及功能品质。方法:以冻干鲜黄精粉为原料对照品,九蒸九晒黄精粉为工艺对照品,分析比较挤压蒸煮黄精粉的人体感官、电子感官、色度、流动性、冲调性、浸出物、总多糖和总皂苷含量等质量特性。结果:挤压蒸煮可有效消除鲜黄精的不良口感,改善黄精粉的色泽和流动性。与九蒸九晒黄精粉相比,挤压蒸煮黄精粉的总多糖和总皂苷含量显著增加,增幅分别为49.27%,69.10%。结论:挤压蒸煮能有效改善黄精的食用品质和功能特性,提高工艺的可控性和稳定性。     

干燥温度对改良挤压法制备的全谷物质构米品质的影响

研究干燥温度(40～80℃)对改良挤压法制备的全谷物质构米的营养特性、食用品质和热力学特性的影响。结果表明:干燥温度在40～80℃,全谷物质构米的粗脂肪和脂肪酸含量随温度升高而降低,对其他营养素无明显影响;当干燥温度低于50℃时,全谷物质构大米样品具有易消解、米饭较软、黏弹性大、口感较好的食味品质;同时,DSC的试验数据表明干燥温度低于50℃时,全谷物质构米具有起始糊化温度略低,糊化时间更短,糊化焓更小的热力学特性。     

挤压工艺参数对犬粮产品质量影响的研究

以鸡肉、大米为制备犬粮的主要原料,研究机筒温度、物料水分含量、螺杆转速对挤压膨化犬粮品质指标（蛋白消化率、糊化度）的影响。本研究首先以挤压参数为双螺杆挤压机的机筒温度、物料水分含量和螺杆转速进行单因素实验。进而根据单因素实验结果进行正交实验,并确定出最佳工艺参数。研究得出的三个参数的最佳组合为:机筒温度为80-100-130-140℃;物料水分含量为26%;螺杆转速为150r/min。本研究结果对于应用双螺杆技术控制犬粮生产加工的产品质量方面具有一定的理论指导作用。      

螺杆挤压工艺对米粉品质的改良作用

对螺杆挤压工艺的圆条米粉(TDM、XMM)和土豆粉丝(TFS),以及传统工艺圆条米粉(WFM)的品质特性进行比较分析,并观察其煮熟后的微观组织结构。结果表明:从煮熟前的质构特性看,TDM、XMM的硬度、压缩功、断裂变形等主要指标介于TFS与WFM之间,但TDM几乎接近TFS;从煮熟后的理化特性看,TDM与XMM具有相似性,且与TFS相近,离WFM较远。煮熟米粉(或粉丝)的微观组织均表现为无规则多边形的蜂窝状微室结构,微室直径约为0.5~2.0μm。说明螺杆挤压工艺不仅仅是简便、节能、高效,且对米粉的品质特性有较大的改良作用。     

In-vitro iron dialysability from legumes: Influence of phytate and extrusion cooking

In-vitro iron dialysability from five Italian legumes (mottled bean, white bean, faba bean, chickpea, lentil) and the influence of phytate and extrusion cooking on it were evaluated. Iron dialysability was 2·3 and 2·4% in mottled and white bean respectively, 1·2% infaba bean, 2·7% in chickpea and 1·1% in lentil. After extrusion cooking the flours showed a marked iron contamination and a decrease in iron dialysability, but these changes were significant only for mottled bean. Enzymic phytate removal induced an increase in iron dialysability > 100% in all the raw legumes except mottled bean which showed an increase of only 57%. This finding indicates that, although phytate consistently modifies iron dialysability, it is difficult to identify a quantitative relationship between phytate content and iron dialysability.     

Physical properties, molecular structures, and protein quality of texturized whey protein isolate: effect of extrusion moisture content

To explore the complex relationship between processing conditions and functional and nutritional properties of food products containing whey protein isolate (WPI), we investigated the effect of extrusion texturization at various temperatures (50, 75, and 100°C) and varying moisture levels of the feed (20, 30, 40, and 50%) on changes in the composition, molecular structure, and protein quality of the extrudates. Bradford assay methods were used to determine protein solubility of the extruded WPI as a function of changing level of moisture. Protein compositional changes as a function of extrusion conditions were quantitatively characterized and analyzed by sodium dodecyl sulfate-PAGE and reversed-phase-HPLC techniques. We showed that at a given temperature, increasing the extrusion moisture content resulted in a slight increase in the overall protein water solubility (at 50 and 75°C), averaging approximately 5% per 10% increase in moisture content. A reduction in β-lactoglobulin content was observed at 50°C with increasing moisture content, indicative of the sensitive nature of β-lactoglobulin to extrusion treatment, whereas the amount of α-lactalbumin remained unchanged at all moisture contents used at a set temperature. The protein quality of the extruded WPI, determined chemically by available sulfhydryl and primary and secondary amines, remained relatively unchanged as a function of moisture level. Circular dichroism and intrinsic tryptophan fluorescence spectroscopic studies revealed considerable structural changes, both at the secondary structural level and the tertiary contacts as a function of increasing temperature, and higher moisture levels can slightly preserve secondary structures but not the tertiary contacts of the protein molecules. Atomic force microscopy provided direct visualization of the fine difference of the protein particles caused by changing extrusion moisture contents, which is in close agreement with the results obtained using other techniques in this work.     

Effect of maize type and extrusion‐cooking conditions on starch digestibility profiles

This study aimed at evaluating the influence of screw speed (250–600 rpm), barrel temperature (100–160 °C) and water content (16.4–22.5%) on rapidly digestible (RDS), slowly digestible (SDS) and resistant (RS) starch levels of waxy, normal and high‐amylose maize starches. In native starches, an increase in amylose content was correlated with lower SDS content. After extrusion, this trend was reversed. Both waxy and normal maize starches became rapidly digested. However, for normal maize starch, some SDS fraction remained. In contrast, the high‐amylose maize starch showed a significant increase in digestibility and an increase in SDS content from 20.4% in the native starch up to 27.5% after extrusion. This high level of SDS may be attributed to the presence of some remaining granular structures and formation of crystalline orders, which have slow digestion properties.     

The effect of extrusion cooking using different water feed rates on the quality of ready-to-eat snacks made from food by-products

The effect of different levels of feed moisture (12–17%) during extrusion cooking, using a co-rotating twin-screw extruder on selected nutritional and physical properties of extruded products was investigated. Four different formulations were used based on wheat flour and corn starch with the addition of 10% brewer’s spent grain (BSG) and red cabbage (RC) trimming reducing the flour and starch. The samples were: wheat flour + BSG (WBSG), corn starch + BSG (CBSG), wheat flour + red cabbage (WRC) and corn starch + red cabbage (CRC). Process conditions utilised were: constant feed rate of 25 kg/h, screw speed 200 rpm and barrel temperature of 80 and 120 °C. The results indicated that increasing the water feed to 15% increased the level of total dietary fibre (TDF) in all the extrudates while extrusion processing increased the level of TDF in WBSG, CBSG and CRC but decreased in WRC products. Extrusion cooking increased the level of total antioxidant capacity (TAC) and total phenolic compounds (TPC) in WRC and CRC. In addition to water feed level affecting the TDF of the extrudates, also affected were the expansion ratio, bulk density, hardness, WSI, SME and colour. The protein level of the products and hardness of extrudates were related to the different formulations.     

Effect of extrusion cooking on structure and functional properties of pea and kidney bean proteins

Pea (Pisum sativum L cv Ballet) and kidney bean (Phaseolus vulgaris L cv Pinto) seeds were extruded at 148 and 156 °C respectively. Protein solubility at various pH values and in various solvents was determined and analysis of protein fractions was carried out by SDS‐PAGE. Also, sulphhydryl and disulphide groups, water‐holding capacity (WHC), water solubility index (WSI) and oil absorption capacity (OAC) were determined. No changes in total nitrogen content of pea and kidney bean seeds occurred as a result of thermal treatment. Protein solubility from raw and extruded legumes was significantly higher in saline solutions than in water in the pH range 2–10. The solubility of proteins from extruded pea and kidney bean flours was greatly decreased with respect to native flours when extraction was in buffer (pH 7.0) alone. Extraction with buffer containing 2‐mercaptoethanol (2‐ME) or sodium dodecyl sulphate (SDS), alone or in combination, greatly increased protein extractability. As a result, the relative solubility was nearly 100% in buffer with SDS and 2‐ME for both raw and extruded samples. Total and free sulphhydryl group and disulphide contents decreased significantly (P < 0.05) after extrusion cooking. Moreover, extrusion treatment caused major changes in the band patterns of the albumin and globulin fractions obtained by SDS‐PAGE. WHC and WSI of extrudates increased significantly in both peas and kidney beans. A significant reduction in OAC was observed in extruded kidney bean flour. © 2000 Society of Chemical Industry