小米挤压粉与小米生粉理化性质及营养品质的差异比较

为了全面分析挤压膨化处理对小米粉品质特征的影响,本文系统比较了小米挤压粉与小米生粉理化性质及营养品质的差异,结果发现:小米挤压粉的密度极显著低于小米生粉(P<0.01),而粒径(P<0.01)和静止角(P<0.01)极显著高于小米生粉。挤压膨化后,小米挤压粉亮度(L^*)减小、色泽(a^*)变暗、肉眼可观察到色泽的差异。挤压膨化过程中产生较多阈值较低,风味贡献较大的醛类、呋喃类和吡嗪类挥发性风味物质,使得小米挤压粉的风味明显优于小米生粉。醛类,尤其是己醛(其相对质量分数高达34.58%),是小米挤压粉的主要风味贡献物质。与小米生粉相比,小米挤压粉的干基脂肪含量和直链淀粉含量分别减少28.92%和28.21%,但多不饱和脂肪酸含量增加21.08%,其中亚油酸增加19.92%、亚麻酸增加63.40%。据此推测,适量添加小米挤压粉将有利于增强小米制品的风味、改善成品口感、提高成品质量。     

Functional and Nutritional Properties of Extruded Whole Pinto Bean Meal (Phaseolus Vulgaris L.)

Pinto bean meals with 18, 20, and 22% moisture were extruded at 140,160 and 180°C, using screw speeds of 150,200 and 250 rpm in a single-screw laboratory extruded. Expansion index, bulk density, water absorption and solubility indices, in vitro protein digestibility, and trypsin inhibitor activity in extrudate were measured. Temperature and feed moisture influenced (p<0.05) expansion index, bulk density, water absorption index and in vitro protein digestibility. Water solubility index was affected by temperature only. Trypsin inhibitors were inactivated completely for all conditions. Screw speed had no effect on any dependent variable. Best product was produced with 22% feed moisture at 160°C.     

Protein digestibility‐corrected amino acid scores,acceptability and storage stability of ready‐to‐eat supplementary foods for pre‐school age children in Tanzania

This study was conducted to evaluate protein quality, acceptability and storage stability of processed cereal–bean–sardine composite foods for pre‐school age children in Tanzania. Four composite products namely corn–bean–sardine meal (CBSM), bean meal (BM), sorghum–bean–sardine meal (SBSM) and rice–bean–sardine meal (RBSM) were formulated to maximize the amino acid score for pre‐school age children and were processed by extrusion, drum‐processing and conventional cooking. The products were evaluated for true protein digestibility (TPD) and protein digestibility‐corrected amino acid score (PDCAAS). The TPD and PDCAAS were highest in the extruded products. The TPD values for the products ranged from 82 to 93%. The PDCAAS values for the composite foods were 64–86% and were greater than the minimum value of 60% recommended by FAO/WHO/UNU. There were no significant (p > 0.05) variations in the amino acid contents for foods processed by extrusion, drum‐processing or conventional cooking. Threonine was most limiting in the CBSM, SBSM and RBSM while methionine + cysteine were most limiting in the BM. Sensory evaluation showed that, relative to the traditional cornmeal—Uji, the extruded CBSM and SBSM had significantly superior (p ≤ 0.05) texture and highly acceptable color and taste. Storage of the products up to 16 weeks at 38 °C resulted in a small but significant increase (p ≤ 0.05) in the malondialdehyde concentrations; nevertheless, the levels remained within the acceptable range found in processed commercial supplements. Total acids, pH and organoleptic attributes did not change significantly (p > 0.05) during storage and the foods were acceptable to the end of the storage period. Copyright © 2005 Society of Chemical Industry     

挤压膨化对大米粉糊化度及蛋白质体外消化率的影响

以大米粉为原料,采用挤压膨化法研究挤压膨化对大米粉糊化度及蛋白质体外消化率的影响,通过单因素及正交实验分析了物料含水量、螺杆转速、第五区温度对大米粉糊化度及蛋白质体外消化率的影响,分析得出挤压膨化大米粉的最佳参数为:物料含水量为18%,螺杆转速为190 r/min,第五区温度为190℃;在此实验条件下进行验证实验,糊化度为90.72%,蛋白质体外消化率为82.80%,挤压膨化后大米粉蛋白质体外消化率比未经挤压处理的大米粉蛋白质体外消化率提高了10.31%。本研究为大米精深加工提供一定的参考。      

温度对普通玉米和高油玉米挤压产品品质的影响

以膨化率、淀粉糊化度、蛋白溶解度和有效赖氨酸为指标评价了挤压膨化过程中温度对普通玉米和高油玉米营养价值的影响．试验结果表明：与普通玉米相比，膨化高油玉米能够得到更高的膨化率，其更容易进行膨化加工；温度升高，提高了两种玉米的淀粉糊化度水平，要得到相似的淀粉糊化度，高油玉米需要更高的膨化温度，高温膨化对高油玉米蛋白质溶解性的不利影响要小于普通玉米，而对氨基酸品质的不利影响则刚好相反。综合考虑以上几个评价指标，结合膨化加工过程中的能量消耗，建议膨化腔内达到90℃来膨化普通玉米，用135℃温度膨化高油玉米。     

Nutritional and anti-nutritional characteristics of mucuna (Mucuna utilis) bean seeds

Some nutritional and anti-nutritional characteristics of mucuna (Mucuna utilis (Wight) Burck) bean seeds were studied. The mature seeds contained 264 g crude protein, 63 g crude fibre, 41 g crude fat, 37 g ash and 595 g carbohydrates kg^?1 DM. The essential amino acid profile compared well with the FAO/WHO scoring pattern except for a deficiency of sulphur-containing amino acids. Mineral composition was similar to those reported for most tropical grain legumes. Raw mucuna seed samples contained moderately high levels of anti-tryptic activity (2170 trypsin units inhibited g^?1 DM), but this was completely destroyed by cooking. The other anti-nutritional factors (phytate, cyanide and tannins) are probably of little nutritional significance provided that the beans are properly processed. The in-vitro protein digestibility of raw and cooked beans were 71·5 and 80·3 %, respectively. In view of the high L-DOPA contents reported in some mucuna cultivars, overconsumption of mucuna beans should be viewed with some caution until suitable processing methods are developed.     

微生物固态发酵菜籽粕营养特性的研究

以普通菜籽粕为原料,选用枯草芽孢杆菌、地衣芽孢杆菌、植物乳杆菌、啤酒酵母、季也蒙毕赤酵母及黑曲霉等菌种,通过单菌株与混菌株发酵试验,研究发酵对菜籽粕中粗蛋白和抗营养因子含量的影响。结果表明,芽孢杆菌的蛋白酶活性高于其他菌株;混菌株发酵效果明显优于单菌株发酵;混菌株发酵中枯草芽孢杆菌、植物乳杆菌和啤酒酵母三菌种组合发酵能较好地提高菜籽粕作为饲料蛋白的品质,此时其粗蛋白质增加率和硫代葡萄糖苷(硫苷)、唑烷硫酮(OZT)、单宁、植酸降解率分别为5.37、93.44、99.99、34.86、18.15%(干基)。     

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.     

挤压剪切活化对添加耐高温α-淀粉酶脱胚玉米淀粉结构和理化特性的影响

本研究通过偏光显微镜、扫描电子显微镜、热台显微镜、X射线衍射、差示扫描量热分析、傅里叶变换红 外光谱分析等手段,研究原脱胚玉米、挤压脱胚玉米和添加耐高温α-淀粉酶挤压脱胚玉米的淀粉结构及性质变化, 并探究其相互关系,揭示挤压剪切活化对脱胚玉米的淀粉颗粒机械力化学效应。研究表明：与原脱胚玉米和挤压脱 胚玉米相比较,挤压处理对添加耐高温α-淀粉酶脱胚玉米的淀粉结构及性质产生显著影响,酶解力和糊化度增大,碘 蓝值、直链淀粉含量减小。添加耐高温α-淀粉酶挤压脱胚玉米淀粉颗粒形貌破坏,偏光十字破坏,结晶度变小;升温糊 化过程中,焓变降低;挤压使淀粉颗粒的结晶结构破坏,淀粉颗粒发生聚集,破损淀粉颗粒易糊化和裂解。     

瓜尔豆胶对马铃薯淀粉消化性和糊化特性的影响

研究瓜尔豆胶对马铃薯淀粉消化性和糊化特性的影响,采用体外模拟消化性实验测定淀粉的消化性,比较与不同质量比(0:100、1:80、1:40、1:20)的瓜尔豆胶与马铃薯淀粉间糊化特性、热力学特性、结晶结构及微观结构的差异,从而探索瓜尔豆胶对马铃薯淀粉消化性影响的本质原理。研究结果显示:当瓜尔豆胶添加量较低时复配体系经糊化后冷却至37 ℃的体系较易被酶解,抗性淀粉含量低;随着瓜尔豆胶添加量的增大,瓜尔豆胶与淀粉颗粒缠结形成空间位阻从而抑制酶解,复配体系经糊化后冷却至37 ℃的体系不易被酶解,抗性淀粉含量较高。添加瓜尔豆胶增大了马铃薯淀粉的起始糊化温度和峰值温度,提升了马铃薯淀粉的吸热焓,延长糊化过程,增加吸热量。观察复配体系的结晶结构发现加入胶体后复配体系并没有新基团产生,胶体与淀粉间仅为物理作用,同时微观结构观察表明胶体与淀粉作用所形成空间位阻使得淀粉颗粒分布均匀,复配体系呈现出更加均一稳定的结构。     

中国粉丝与日常食品中抗性淀粉含量的比较研究

为消除消费者对中国传统食品资源--粉丝的认识误区,从抗性淀粉的角度对粉丝与日常食品做对比分析。结果显示：普通食品中的抗性淀粉含量分别为：热米饭0.27%、凉馒头1.99%、饼干1.16%、方便面1.64%,粉丝中抗性淀粉的含量明显高于普通食品如：甘薯粉丝3.69%、绿豆粉丝6.21%。     

Modeling Thermal and Mechanical Effects on Retention of Thiamin in Extruded Foods

ABSTRACT: A model was proposed to predict separate thermal and mechanical effects of extrusion cooking on thiamin retention. Thermal effects were determined by heating small samples of wheat flour mixed with 0.30% (wt/ wt) thiamin hydrochloride isothermally at 140 °C, 151 °C, and 161 °C for different times. The calculated activation energy and rate constants at each temperature were 67.28 kJ/g mol and 0.00869/min, 0.0145/min, and 0.0224/min, respectively. The "extruder constant" was estimated as 27.7/rev, based on a matching-viscosity method. Wheat flour with 0.30% (wt/wt) thiamin was extruded at different screw speeds. Mechanical effects caused 89.7% to 94.4% of total thiamin loss. This research provides a generalized method to "fingerprint" the extrusion process.     

挤压处理对豌豆淀粉的流变特性和体外消化率的影响

目的:研究挤压条件(豌豆淀粉水分质量分数:25％、35％、40％、45％和55％;剪切温度:50、60、70、80?℃和90?℃;螺杆转速:100、120、140、160?r/min和180?r/min)对豌豆淀粉的体外消化率和流变特性的影响.方法:采用体外消化法测定了豌豆淀粉的水解度,并通过稳态剪切实验、频率扫描实验...     

Rapid Liquid Chromatographic Assay of Vitamin E and Retinyl Palmitate in Extruded Weaning Foods

Extruded weaning foods were produced using cowpea + corn + soybean + soybean oil (35:50:10:5, w/w) and cowpea + corn + peanut (42:43:15, w/w) by twin screw extrusion and fortified with vitamin premix. A direct solvent extraction method was used to assay fortified α-tocopheryl acetate as the ester to differentiate it from the naturally occurring alcohol for accurate assessment of total vitamin E activity. The fortified retinyl palmitate was assayed from the same extraction and assayed as the more stable ester with the same LC conditions after changing the detection wavelengths. Using direct solvent extraction, analytical values of vitamin E homologs in extruded products were higher than those values from saponification.     

Impact of Guar and Wheat Bran on the Physical and Nutritional Quality of Extruded Breakfast Cereals

Two non‐starch polysaccharides, guar gum and wheat bran, were used at 15% replacement level in a cereal base to produce an extruded breakfast cereal product from both wholemeal and high‐ratio wheat flour mixes. The inclusion of the non‐starch polysaccharides into the flour bases had no significant effect on the expansion ratio of the products. However, the product density and bulk density of the extruded products increased with guar gum and wheat bran addition. The pasting properties of the raw flour and polysaccharide base as well as the extruded products were altered with the incorporation of polysaccharides, with guar gum‐enriched products showing elevated peak and final viscosity readings. This appeared to be related to moisture manipulation and hence the regulation of gelatinisation. In vitro starch hydrolysis of the raw bases and the extruded samples illustrated that the extrusion process significantly increased the availability of carbohydrates for digestion. Additionally, the inclusion of non‐starch polysaccharides in the raw bases significantly reduced the rate and extent of carbohydrate hydrolysis. This potentially glycaemic reducing action was also evident in the extruded products where the incorporation of guar gum at 15% yielded a reduction of starch hydrolysis of 36% in the wholemeal base and 32% in the high‐ratio white wheat flour base.     

High Lysine Extruded Products of Quality Protein Maize

Extrusion-cooking is used by several food industries to produce expanded snack foods, ready-to-eat cereals and pet foods from corn meal. A snack food utilising normal maize and quality protein maize (QPM) as its main ingredient was developed and characterised. The extrusion process was performed in a Mapimpianti single cooker extruder. Processing conditions were single screw with a screw speed of 150 rpm, and a die with 20 die-nozzle orifices with openings of 2 mm of diameter. The die head zone was heated at 110°C by electrical resistance. Compressed air was circulated around the barrel to maintain precise control of the temperature. Moisture content of samples were 150 and 200 g kg⁻¹. The extruded products showed low density and high expansion degree. Optimum expansion index was obtained with flours processed at 150 g kg⁻¹ of moisture content in both maize samples with better characteristics for QPM extrudates. The white colour values were highest for QPM compared to H-128 extruded products.     

Determination of formulation and processing factors affecting slowly digestible starch,protein digestibility and antioxidant capacity of extruded sorghum–maize composite flour

High‐temperature high‐pressure extrusion of sorghum–maize composite flour, of potential for healthy food manufacture, was investigated by factorial experimental design to determine the effect of level of sorghum in dry mix (15–60%); final barrel zone temperature (120–150 °C); total moisture in barrel (21.4–25.8%); total input rate (2.3–6.8 kg h^?1); and screw speed (250–450 rpm) on extrudate slowly digestible starch (SDS), phenolic content, antioxidant capacity, protein digestibility, density and expansion ratio. Extrudate SDS increased with increasing sorghum level and decreased as the barrel temperature increased. Total phenolic content and antioxidant capacity were positively associated with sorghum level. Protein digestibility was associated negatively with sorghum level and positively with barrel temperature. Extrudate density was associated positively with total moisture and negatively with barrel temperature and input rate. Sorghum in dry mix, final barrel zone temperature and total moisture in barrel were the three most significant independent variables influencing extrudate dependant variables.     

Cereal processing and glycaemic response

Cereals are processed into diverse products using techniques that range from thermal to biotechnological, with different degrees of mechanical and pressure effects, in various moisture systems. Amongst others, cereal processing gelatinises starch, influences its digestibility and modulates glycaemia, and this review concentrates on recent developments on how cereal processing conditions affect these properties. In vitro and in vivo starch digestions are discussed, so also are types of digestible starches and glycaemic indices (GIs) of cereal products. Modelling of in vitro starch digestograms and estimated GIs of processing effects are highlighted. Extrusion moisture of and fermentation time‐dependent acidity in cereal products reduce GIs, and their lipid components can enhance amylose–lipid complexation to reduce starch digestibility. Cereal types and varieties differ in starch characteristics, micronutrients, amylase inhibitors and nonstarch components. This review explores how these endogenous factors, in association with exogenous factors, can assist in combining cereal processing conditions for desirable glycaemic outcomes.     

Microwave irradiation of guar seed flour: Effect on anti-nutritional factors,phytochemicals, in vitro protein digestibility,thermo-pasting,structural, and functional attributes

Guar seed flour (GSF) has a high amount of carbohydrates, proteins, phytochemicals, and anti-nutritional factors (ANFs), which limits its use. To address this issue, the current study was undertaken to understand the effect of microwave (MW) irradiation on ANFs, phytochemicals, in vitro protein digestibility (IVPD), and functional attributes of GSF at varying power density (P_d: 1–3 W/g) and duration (3–9 min). The ANFs were determined using a colorimetric assay and a Fourier transform infrared spectrum. At 3 P_d-9 min, the maximum reduction in ANFs (tannin, phytic acid, saponin, and trypsin inhibitor activity) was observed. Higher P_d and treatment duration increased antioxidant activity and total phenolic content, except for total flavonoid content. Furthermore, compared to the control sample (78.38%), the IVPD of the GSF samples increased to 3.28% (3 P_d-9 min). An increase in P_d and duration of MW treatment improved the thermal and pasting properties of GSF samples up to 2 P_d-9 min. Due to inter- and intramolecular hydrogen bonding degradation, the relative crystallinity of the 3 P_d-9 min treated GSF sample was 30.58%, which was lower than that of the control (40.08%). In MW-treated samples, SEM images revealed smaller clusters with rough and porous structures. However, no noticeable color (ΔE) changes were observed in MW-treated samples. Aside from water absorption capacity and water solubility index, MW treatment reduced oil absorption capacity, foaming capacity, and emulsifying capacity. As demonstrated by principal component analysis, MW irradiation with moderate P_d (2–3) was more effective in reducing ANFs, retaining nutritional contents, and improving the digestible properties of GSF, which could be a potential ingredient for developing gluten-free products.