小麦淀粉与面条质量关系的研究进展

小麦淀粉品质对白盐面条的质量（尤其是煮后的感官特性）有重要影响。直链与支链淀粉的含量及比例是影响面条质量的重要因素,是造成不同小麦品种淀粉糊化和膨胀特性及面条质量差异的物质基础。较低直链淀粉含量的小麦粉具有较好的糊化和膨胀特性,制作的面条煮制时吸水率高,烹调损失低,具有较高的感官评分。优质白盐面条的直链淀粉含量应在22%左右。峰值黏度、稀懈值、峰值时间是影响面条质量的重要糊化参数,这3项参数高的小麦粉适合制作优质面条。高膨胀势或膨胀体积的小麦粉制作的面条中等偏软,光滑且富有弹性,可以作为面条用小麦的重要选择标准。一般认为,直链淀粉含量较低、峰值黏度和稀懈值高、峰值时间长、膨胀势或膨胀体积高的小麦粉适合制作优质白盐面条。其中,直链淀粉含量、峰值黏度和膨胀势是优质面条小麦评价的关键品质性状。     

Wx-1基因变异和优质HMW-GS组合对中筋小麦品质的影响

高分子量谷蛋白亚基(HMW-GS)和Wx蛋白是两个影响小麦理化品质和制成品品质的重要因素。为研究HMW-GS和Wx基因变异对小麦理化品质、面条感官评分和质构特性的影响,以镇麦9号和扬糯麦1号为亲本的2个高代系为试验材料,研究了优质HMW-GS 5+10及Wx基因缺失对小麦理化品质及面条加工品质的效应。结果表明,品系1与品系2的湿面筋含量和SDS沉淀值与镇麦9号相近,但显著好于扬糯麦1号。相较于镇麦9号,品系1与品系2的直链淀粉含量分别降低了1.5%和2.5%,其峰值黏度和稀懈值均显著高于镇麦9号,膨胀势也高于镇麦9号。5+10亚基显著提高了面条质构参数中的硬度和咀嚼性,而Wx基因缺失显著提高了面条的软硬度评分和光滑性评分。综合来看,具有5+10亚基和 Wx-D1缺失型的品系2具有较高的SDS沉淀值、面团形成时间和稳定时间、较低的直链淀粉含量、较高的峰值黏度、稀懈值和膨胀势,蛋白质和淀粉综合品质表现较好。品系2面条总评分最高,显著高于镇麦9号和扬糯麦1号,其主要体现在适中的面条软硬度和较好的光滑性。推测Wx基因缺失和优质HMW-GS聚合可显著提高小麦淀粉品质和蛋白质品质,有效改善面条的蒸煮品质和感官评分。     

Kinetics of starch digestion and functional properties of twin-screw extruded sorghum

The time-course of starch digestion in twin-screw extruded milled sorghum grain was investigated using an in-vitro procedure based on glucometry. The sorghum grains were hammer-milled, and extruded at three levels each of moisture and screw speed. Irrespective of the extrusion conditions, extruded and non-extruded milled sorghum grain exhibited monophasic digestograms, and the modified first-order kinetic and Peleg models adequately described the digestograms. Extrusion increased the rate of digestion by about ten times compared with non-extrudates. Starch gelatinisation varied in the extrudates, and microscopy revealed a mixture of raw, gelatinised and destructured starch and protein components in the extrudates. Starch digestion parameters significantly (p < 0.05) correlated with extruder response and various functional properties of the extrudates. Extrusion conditions for maximum starch gelatinisation in milled sorghum grain for fastest digestion as an efficient animal feed were interpolated, as well as the conditions for directly-expanded extrudates with potential for human food, where minimum starch digestion is desired.     

In vitro starch digestibility,degree of gelatinization and functional properties of twin screw prepared cereal-legume pasta

The investigation explores the possibility of utilizing legume flour (pigeon pea:10–30%) and brown rice flour (35–45%) for production of pasta using twin screw extruder. RSM was used to analyse the effect of feed moisture (28–36%), barrel temperature (70–110 °C) and legume:brown rice ratio on quality responses (in vitro starch and protein digestibility, degree of starch gelatinization, cooking quality, pasting properties, color and textural properties) of pasta. Extrusion processing significantly enhanced in vitro starch and protein digestibility of prepared pasta. The in vitro starch and protein digestibility of pasta ranged between 15.00 and 26.77 g/100 g and 50.34–84.82 g/100 g respectively. Addition of brown rice flour and pigeon pea flour exhibited dominating positive effect on cooking quality of the pasta. Degree of gelatinization of prepared pasta was found in range of 52.13–90.10 per cent. Color characteristics viz. luminosity, redness and yellowness of pasta enhanced with feed moisture. Pasting properties revealed lower peak and final viscosity at higher processing conditions. Firmness of cooked pasta elevated with an increase in the barrel temperature. Acceptability score of health based pasta on the basis of sensory attributes was 8 as inferred from 9 point hedonic scale.     

Variation in amylose concentration to enhance wheat flour extrudability

Composition and functionality of five waxy wheat (Triticum aestivum L.) genotypes were elaborately investigated and related to end-product attributes of extrudates. As such, the interaction between starch biopolymers and protein in extrusion processing could be studied. Furthermore, the effect of an increasing amylose-concentration was studied by the use of blends. Waxy genotypes absorbed more water, gave rise to stiffer doughs and had higher onset and peak gelatinization temperature. In contrast, a lower pasting temperature and final viscosity and higher peak viscosity and breakdown could be observed. The volume percentage of small starch granules showed to be negatively correlated with peak temperature and positively with final viscosity and holding strength as well as with extrudate hardness. This was also positively correlated with amylose concentration. Expansion index was highest at a slightly decreased amylose concentration of 16.6%. Markedly higher moisture content for all amylose-free extrudates was attributed to a combination of increased solubility of amylopectin and reduced water evaporation at die emergence. It was hypothesized that an interplay with protein content and composition was laying at the basis of the observed differences. Moreover, the altered pasting behavior of waxy wheat may enhance the extrudability of gluten containing wheat flour.Starch granule size distribution is related to extrudate texture. Amylose content affects expansion index, water absorption and texture of extrudates. Interaction between starch content and protein composition and quality was observed. Waxy genotypes are strongly varying in their protein composition and functionality. Maximum expansion was obtained for blends containing 25% waxy flour.     

Effects of selected extrusion parameters on physicochemical properties and in vitro starch digestibility and β-glucan extractability of whole grain oats

Whole grain oat flour was extruded under different moisture contents (15%, 18%, 21%), barrel temperatures (100 °C, 130 °C), and screw speeds (160 rpm, 300 rpm, 450 rpm), and selected physicochemical properties, in vitro starch digestibility, and β-glucan extractability of the extrudates were analyzed. An increase in screw speed resulted in an increase in radial expansion index, water absorption index, and water solubility index. Screw speed significantly affected slowly and rapidly digestible starch. Moderate screw speed (300 rpm) led to higher slowly digestible starch with an accompanying decrease in rapidly digestible starch. Low moisture conditions (15%) resulted in the highest resistant starch and water-extractable β-glucan. Under the conditions used in this study, extrusion did not result in changes in water-extractable β-glucan molecular weight. Thus, extrusion might be beneficial in improving functionality and consumer acceptability by affecting physicochemical properties, in vitro starch digestibility, and β-glucan extractability of oat extrudates.     

Physical,Predictive Glycaemic Response and Antioxidative Properties of Black Ear Mushroom (<Emphasis Type="Italic">Auricularia auricula</Emphasis>) Extrudates

Black ear mushroom (Auricularia auricula) is an important genus of cultivated mushroom, which contains health benefits. Incorporating black ear (BE) mushroom into brown rice by extrusion changed the physicochemical, and more importantly, the nutritional characteristics of the extrudates. With increased incorporation of BE mushroom in the extrudates in vitro starch digestion of the different extrudates revealed significantly reduced starch digestion, suggesting a lower glycaemic index. In addition, incorporation of BE in brown rice extrudates increased the total phenolic concentration of the samples, which led to higher % scavenging effect against free-radicals in DPPH assay. In the ORAC assay for anti-oxidant activity, BE powder exhibited the highest anti-oxidant activity, followed by 10% BE and 15% BE, and 5% BE extruded products. The extruded brown rice control exhibited the lowest antioxidant activity. Inclusion of black ear mushroom was shown to improve the nutritional qualities of the food product illustrating the connection between plant bioactive ingredients and human health.     

糯小麦配粉对普通小麦品质性状和鲜切面条品质的影响

为了明确糯麦配粉对小麦品质的影响,利用中国北部和黄淮冬麦区的三个小麦主栽品种京411、豫麦49和豫麦34,研究了添加10%、15%、20%、25%和30%不同比例的糯小麦面粉后其蛋白质、淀粉特性及面条品质的变化.结果表明,随着添加比例的提高,面粉蛋白质含量和沉淀值有所增加,和面时间和衰落势无显著变化.直链淀粉含量随添加量的增加而逐渐降低,高峰粘度和反弹值则均有所下降.直链淀粉含量与面条的粘弹性、光滑性和总评分呈二次曲线关系,直链淀粉含量为24%～25%时,面条的粘弹性、光滑性和总评分最好,添加15%～20%的糯小麦面粉即可达到这一效果.添加糯小麦面粉对面条色泽和表观状况无显著影响.     

Physical Properties of Extruded Products from Three Mexican Common Beans (Phaseolus vulgaris L.) Cultivars

The physical properties of extruded products from three Mexican common bean cultivars were investigated. Common bean cultivars Flor de Mayo, Pinto Villa and Bayo Victoria from the same harvesting season (2006) were used in this work. Beans were milled and the flour was hydrated to 24, 26 and 28 g of water/100 g of dry weight. Two temperatures, 130 degrees C and 165 degrees C at the end of the extruder barrel without die, were experimented. Common bean flour extrudates were evaluated for water absorption index (WAI), water absorption capacity (WAC), oil absorption capacity (OAC), and emulsifying capacity (EC). Flor de Mayo extrudates showed the highest WAC and WAI values. Thus starch from Flor de Mayo beans showed minor restricted water availability. In all cases, the OAC of extruded products was lower than the crude bean flour. The EC for Bayo Victoria flour increased as a consequence of the extrusion process. The EC for Flor de Mayo was higher at lower temperature and lower moisture content than Pinto Villa and Bayo Victoria beans. EC behavior of Pinto Villa was similar to Bayo cultivar. These results indicate that it is possible to produce new extruded products with good physical properties from these common bean cultivars.     

Wheat Bread Quality as Influenced by the Substitution of Waxy and Regular Barley Flours in Their Native and Extruded Forms

The substitution of wheat flour with barley flour (i.e. native or pretreated/extruded) reduced the loaf volume. Depending on the barley variety and flour pretreatments, the colour and firmness/texture of the bread loaves were altered. Amongst the barley breads prepared from native flours (at 15% barley flour substitution level), Phoenix had higher loaf volume and lower crumb firmness than Candle. However, amongst the barley breads prepared from extruded flours, CDC-Candle had higher loaf volume and lower crumb firmness than Phoenix. The lower loaf volume and firmer crumb texture of barley breads as compared with wheat bread may be attributed to gluten dilution. Also, the physicochemical properties of barley flour components, especially that of β-glucan, can affect bread volume and texture. β-glucan in barley flour, when added to wheat flour during bread making, could tightly bind to appreciable amounts of water in the dough, suppressing the availability of water for the development of the gluten network. An underdeveloped gluten network can lead to reduced loaf volume and increased bread firmness. Furthermore, in yeast leavened bread systems, in addition to CO₂, steam is an important leavening agent. Due to its high affinity for water, β-glucan could suppress the amount of steam generated, resulting in reduced loaf volume and greater firmness. In the present study, breads made with 15% HTHM CDC-Candle flour had highly acceptable properties (loaf volume, firmness and colour) and it indicated that the use of extruded barley flours would be an effective way to increase the dietary fibre content of barley breads.     

High (1→3,1→4)-β-Glucan Barley Fractions in Bread Making and their Effects on Human Glycemic Response

Barley flour (BF) from whole naked grain and two (1→3,1→4)-β-glucan-enriched fractions, a sieved fraction (SF) and a water-extracted fraction (WF), were produced and mixed with bread wheat flour (BW), for bread-making quality evaluation. Bread was baked in a pilot plant and analysed for sensory properties, proximate composition and (1→3,1→4)-β-glucan content. Four kinds of bread were produced from different mixtures of barley ingredients and bread wheat flour: a 100% BW ((1→3,1→4)-β-glucan content: total, 0·1%; soluble, 0·1%); a 50% BW and 50% BF (2·4%; 2·0%); a 50% BW and 50% SF (4·2%; 2·8%); an 80% BW and 20% WF (6·3%; 5·7%). Eight adults were fed test meals of each of the four breads, containing the same amount (50 g) of available carbohydrate, and glycemic indices calculated from finger-prick capillary blood samples. A linear decrease in glycemic index was found for increasing (1→3,1→4)-β-glucan content. The 20% WF bread had a 28% lower glycemic index than the plain BW and also showed the best scores for sensory attributes. This research confirms the effectiveness of viscous (1→3,1→4)-β-glucan in reducing postprandial blood glucose levels, even in foods with a high glycemic index. The enrichment technique, and water extraction/freeze-drying technique, could enable the use of barley as a source of a high-value fibre for reducing the glycemic index of traditional wheat-based foods such as bread, without negatively affecting their sensory characteristics.     

燕麦粉对强筋面粉品质特性及其面包品质的影响

面包逐渐成为中国人营养早餐的选择,但面包中膳食纤维含量较低。燕麦是一种食疗兼备的特色杂粮作物,富含膳食纤维。为拓宽燕麦的应用范围、提高面包的营养价值,以优质强筋小麦品种藁优2018和燕麦粉为材料,研究了燕麦粉对小麦面粉面团流变学特性及淀粉糊化特性的影响,并进行了燕麦面包实验室制作和质构分析。结果表明,随着燕麦粉添加比例的增加,面团吸水率逐渐增加,面团稳定时间和粉质质量指数先减小后增加;面团拉伸能量、拉伸长度、拉伸阻力、最大拉伸阻力均逐渐减小。说明燕麦粉对面团拉伸特性各参数均有弱化作用。在藁优2018小麦面粉中添加10%的燕麦粉,既能保证面包的感官品质,又能满足面包营养最大化。     

Phytic Acid Level in Wheat Flours

The phytic acid content of refined (hand-made and factory-made) and whole (factory-made) wheat flours, much consumed in the Canary Islands, have been determined in this study. A total of 200 samples of flours from different types (100 refined and 100 whole) were analysed. The method proposed by Garcı́a-Villanova et al. (1982) was used for determination of phytic acid content in wheat flours. Most of the phytic acid concentrations are within the range 2–4 mg/g for the refined flours and 6–10 mg/g for the whole ones. The arithmetic mean obtained from all the samples studied is 3·77 mg/g for hand-made, refined flours, 2·96 mg/g for factory-made refined flours and 8·50 mg/g for the whole ones. On analysing the phytic acid content in all the flour samples, significant differences were observed for the different types of flour. Refined flours had a content lower than whole ones.     

Effect of thermal processing and storage on digestibility of starch in whole wheat grains

Gelatinisation and retrogradation of starch in wheat flour systems and whole wheat grains were studied using DSC and the impact of these events on starch digestibility was investigated. Gelatinisation of starch was possible in wheat flours with more than 60% moisture content (dwb) and gelatinised samples had higher digestibility values. Retrogradation of starch was studied with partially and fully cooked (boiled at 100 °C for 12 min and 32 min, respectively) wheat grains that were subjected to storage at 22 °C for 48 h. Stored samples had lower digestibility values when compared to the freshly cooked counterparts. The effect of moisture on retrogradation was studied with fully cooked wheat grains that were dried to a range of moisture contents (14.6–35.9%, wwb) and stored at 20 °C for 24 h. Retrogradation enthalpy increased with increasing moisture content; however, digestibility values did not reflect the changes in retrogradation enthalpy. The possibility of estimating the degree of retrogradation in fully cooked grains (32 min cooking) was investigated using a wheat flour-water system. The retrogradation enthalpy of fully cooked grains was slightly higher than the wheat flour-water system (at a moisture content of 49%, wwb) during the course of storage at 22 °C.     

Physicochemical characterization and in-vitro digestibility of extruded rice noodles with different amylose contents based on rheological approaches

The physicochemical properties and in-vitro digestibility of extruded rice noodles with different amylose contents were characterized from a rheological point of view. Thermo-mechanical measurements showed that the rice flour with higher amylose contents exhibited greater stability to dual-mixing and higher degrees of starch gelatinization and retrogradation. In addition, greater elastic properties were clearly observed in the high amylose rice samples. The use of high amylose rice flour produced noodles with a harder texture, consequently contributing to reduced cooking loss. Furthermore, the rheological changes of extruded rice noodles were monitored in real time during the in-vitro starch digestion. The rice noodle digesta with higher amylose contents exhibited greater viscosities throughout the simulated oral-gastric-intestinal digestion steps. The flow behaviors of the rice noodle digesta consisted of the Power-law region and infinite shear plateau that were satisfactorily characterized by the Sisko model (R² > 0.99).     

Development of anIn VitroEnzymic Digestion Method for Removal of Starch and Protein and Assessment of its Performance Using Rye andWheat Breads

The development of anin vitroenzymic batch method for pretreatment of cereal samples prior toin vitrofermentation is presented. A statistical experimental design is described and the importance of bile and pepsin for the digestibility of starch was investigated. Day-to-day variation was studied by measuring glucose released and total starch in the digestion residue of rye flour. Four samples, wholemeal rye flour and bread, wholemeal and white wheat breads, were tested to evaluate the performance of the digestion procedure. Pepsin and bile enhanced the hydrolysis of slowly digestible starch. The extent of starch hydrolysis in rye and wheat breads (93–95%) was reproducible and about the same as using thermostablealpha-amylase. More soluble fibres were released from the wholemeal rye bread than from the wholemeal wheat bread. The procedure is an efficient method for the removal of starch and protein under physiological conditions prior toin vitrofermentation. The method can also be used as a tool for studying the solubility of dietary fibre (DF).     

The recycling of brewer's processing by-product into ready-to-eat snacks using extrusion technology

Brewer's spent grain (BSG) is the main by-product of the brewing industry. The incorporation of BSG into ready-to-eat expanded products and its effects on the textural and functional properties of extrudates have been studied. Dried and milled BSG at levels of 10–30% was added to the formulation mix made of wheat flour, corn starch and other ingredients. The results obtained from the analysis of the extrudates are discussed in terms of the interaction between the ingredients and effects of processing conditions. The samples were processed in a twin-screw extruder with a combination of parameters including constant feeding rate of 25 kg/h, process temperatures 80–120 °C and screw speeds of 150–350 rpm. Pressure, torque and material temperature during extrusion were recorded. The extrudate properties of nutritional and textural characteristics were measured. Image technique investigations provided useful information on internal structure of the extruded products, total cell area, and their contribution to the appearance and texture. It was found that addition of BSG significantly increased protein content, phytic acid and bulk density, decreased sectional expansion index, individual area and total area of the cells. The higher level of BSG resulted in cells with thicker walls with a rougher surface.