Properties of field-sprouted sorghum and its performance in ethanol production

The objective of this research was to investigate physicochemical and biochemical characteristics of field-sprouted grain sorghum and its fermentation performance in ethanol production. Five field-sprouted grain sorghum varieties, which received abnormally high rainfall during harvest, were used in this study. Enzyme activities, microstructure, flour pasting properties, kernel hardness, kernel weight, kernel size, flour size and particle distribution of field-sprouted grain sorghum were analyzed. The effect of germination (i.e., sprouting) on conversion of grain sorghum to ethanol was determined by using a laboratory dry-grind ethanol fermentation procedure. Sprouted sorghum had increased α-amylase activity; degraded starch granules and endosperm cell walls; decreased kernel hardness, kernel weight, kernel size, and particle size; and decreased pasting temperature and peak and final viscosities compared with non-sprouted grain sorghum. The major finding is that the time required for sprouted sorghum to complete fermentation was only about half that of non-sprouted sorghum. Also, ethanol yield from sprouted sorghum was higher (416–423 L/ton) than that from non-sprouted sorghum (409 L/ton) on a 14% moisture basis.     

Production of bioethanol from steam-flaked sorghum and maize

The aim was to study the effect of steam-flaking of sorghum and maize on bioethanol production and the performance of their ground meals during liquefaction, saccharification and yeast fermentation. A bifactorial experiment with a level of confidence of P < 0.05 was designed to study differences between sorghum and maize and the effectiveness of steam-flaking. Grains were steam-flaked to increase starch bioavailability and disrupt the protein matrix that envelopes starch granules. The steam-flaked sorghum had significantly higher and faster starch hydrolysis compared to the regular kernel during liquefaction. This hydrolysate contained about 33% more reducing sugars compared to the untreated counterpart and similar amounts compared to both maize treatments. At the end of saccharification, the sorghum spent grains contained more residual starch compared to the maize counterparts. Steam-flaking significantly reduced residual starch especially in steam-flaked sorghum. The final glucose concentration in steam-flaked sorghum was similar to the concentration obtained in both maize mashes and 26.5% higher compared to the untreated sorghum. The yield of ethanol in steam-flaked sorghum was 44.2% higher compared to the untreated counterpart and similar to both maize treatments. Therefore, steam-flaking is a treatment useful to increase ethanol production especially in sorghum due to the higher starch bioavailability.     

Effect of Grain Structure and Cooking on Sorghum and Maize in vitro Protein Digestibility

Uncooked and cooked sorghum showed improvement in in vitro protein digestibility as the structural complexity of the sample reduced from whole grain flour through endosperm flour to protein body-enriched samples. This was not the case for maize. Cooking reduced protein digestibility of sorghum but not maize. Treating cooked sorghum and maize whole grain and endosperm flours with alpha -amylase to reduce sample complexity before in vitro pepsin digestion slightly improved protein digestibility. The reduction in sorghum protein digestibility on cooking was not related to the total polyphenol content of samples. Pericarp components, germ, endosperm cell walls, and gelatinised starch were identified as possible factors limiting sorghum protein digestibility. Electrophoresis of uncooked and cooked protein-body-enriched samples of sorghum and maize, and prolamin fractions of sorghum under non-reducing conditions showed oligomeric proteins with molecular weights (M_r) 45, 66 and >66 kDa and monomeric kafirins and zeins. Protein-body-enriched samples of sorghum had more 45–50 kDa oligomers than those of maize. In cooked sorghum, some of these were resistant to reduction. Pepsin-indigestible residues from protein-body-enriched samples consisted mainly of α-zein (uncooked and cooked maize) or α-kafirin (uncooked sorghum), whilst cooked sorghum had in addition, β- and γ-kafirin and reduction-resistant 45–50 kDa oligomers. Cooking appears to lead to formation of disulphide-bonded oligomeric proteins that occurs to a greater extent in sorghum than in maize. This may explain the poorer protein digestibility of cooked sorghum.     

Carotenoid bioaccessibility from whole grain and decorticated yellow endosperm sorghum porridge

Sorghum is a staple crop and a potential dietary source of carotenoids in semi-arid regions of Africa, but information on the bioavailability of these pigments is limited. This study aimed at exploring the effects of agronomic manipulation on sorghum carotenoid contents at selected stages of kernel development and maturation and assessing carotenoid bioaccessibility from matured yellow-endosperm sorghum varieties (P88 and P1222), by comparing porridge made from sorghum whole and decorticated milled grains. Carotenoid content of sorghum milled fractions ranged from 2.90 to 7.22 mg/kg in P88 unbagged decorticated flour, at 50 and 30 days after half bloom (DAHB) respectively, to 9.87-13.69 mg/kg in bagged decorticated bran fractions in P88, at 50 and 30 DAHB respectively. Maize milled fractions were significantly (P < 0.05) higher in carotenoid content than all sorghum products. Bagging increased sorghum carotenoid content by 8-184% vs. unbagged panicles. Carotenoid bioaccessibility was generally higher from sorghum (63-81%) compared to maize (45-47%). Micellarization of xanthophylls (75%) was more efficient than carotenes (52%) in sorghum, while they were similar in maize (40-49%). These results suggest that the higher bioaccessibility of sorghum carotenoids combined with efforts to enhance sorghum carotenoid content may allow for sorghum to provide similar levels of bioaccessible carotenoid pigments as common yellow maize.     

Ethanol production from supercritical-fluid-extrusion cooked sorghum

Sorghum (Sorghum bicolor (L.) Moench) is a starch-rich grain similar to maize (Zea mays L.), but sorghum has been underutilized for biobased products and bioenergy. This study was designed to investigate the effects of supercritical-fluid-extrusion (SCFX) of sorghum on ethanol production. Morphology, chemical composition, and thermal properties of extruded sorghum were characterized. Analysis of extruded sorghum showed increased measurable starch content, free sugar content, and high levels of gelatinized starch. SCFX cooked and non-extruded sorghum were further liquefied, saccharified, and fermented to ethanol by using Saccharomyces cervisiae. The ethanol yield increased as sorghum concentration increased from 20 to 40% for both extruded and non-extruded sorghum. Ethanol yields from SCFX cooked sorghum were significantly greater than that from non-extruded sorghum (>5%).     

国内外高粱深加工研究现状与发展前景

高粱既可直接食用、饲用，又可加工利用。近年来，国内外高粱深加工研究发展很快，除传统的用高粱作主食、酿制白酒、啤酒、做饲料等外，还对高粱的多种加工用途进行了有益的探索。如：用甜高粱茎秆造酒，用饲草高粱作青贮和青饲料，用高粱生产酒精，用高粱壳提取色素，用高粱籽粒提取淀粉，生产高粱面包、高粱甜点等等。高粱深加工发展前景看好。     

Relationship between the corneous and floury endosperm content and the popped sorghum quality

Popcorn is a healthy snack suggested by nutritionists. However, some countries in Europe, Asia, and South America have evaluated the use of sorghum as a popped cereal. Therefore, this study aims to evaluate the content of corneous and floury endosperm of sorghum and its influence in the popped sorghum quality. Five red varieties and three white varieties were evaluated. The physical and microstructural characteristics of the raw varieties were evaluated. The correlation matrix showed that physical properties such as the pericarp thickness, the hectoliter weight, and the type of endosperm are crucial to obtain popped sorghum. A high percentage of corneous endosperm and the size distribution of starch granules in the floury endosperm determine the popping ability of sorghum. The analysis of the principal components showed that the Paloma variety was the most suitable to obtain popped sorghum.     

高梁种质资源的创新和利用

高梁品种遗传改良取得的成果很大程度上取决于占有的高梁种质资源的数量,以及对其主要性状的鉴定、创新和利用。在高粱育种史上,品种改良的突破性进展,往往都是由于找到并利用了具有关键基因的种质。目前,已创造和选育出7种不同细胞质雄性不育系,其育性反应各不一样。除A．细胞质不育系组配的杂交种得到广泛应用外,A：细胞质不育系的杂交种在生产上应用,A,细胞质不育系在甜高粱杂交种上应用。籽粒优质、茎秆高糖、低氰氢酸、抗病虫、抗杂草、抗干旱等抗性种质资源也得到了创新利用。     

3种生长延缓剂对甜高粱幼苗生长和生理特性的影响

采用不同浓度的多效唑、矮壮素、比久对甜高粱种子进行浸种处理,结果表明,3种生长延缓剂中,多效唑对甜高粱幼苗生长的抑制作用最强;0.1～0.2 g/L的多效唑浸种处理可以提高种子的发芽势和发芽率,但幼苗生长受到过度抑制而表现不正常;5g/L和10g/L的矮壮素和比九处理可以延缓甜高粱幼苗生长,使叶片缩短、厚度增加,具有提高幼苗可溶性糖、可溶性蛋白质和叶绿素含量的作用,促进了幼苗对干物质的合成和积累,使幼苗十物质重显著提高,有利于培育壮苗.其中,10g/L矮壮素浸种处理效果最佳.     

Influence of processing conditions on the nutritive value of Ogi-baba,a Nigerian fermented sorghum gruel

The effect of germination, cowpea fortification and fermentation on thechemical and amino acid composition of ogi-baba, a Nigerian fermented sorghum gruelwas investigated. The lowest protein value of 1.4% was obtained in the traditionally preparedsample, while samples prepared from germinated, fortified sorghum had 13%. The ash ranged from 0.9% to above 2%, while the fat was in the range of 1.2% to2.8%. Generally, fortification, in addition to germination, improved the chemicalcomposition of ogi-baba relative to the control sample. There was improvement in the amino acidprofile of all the ogi-baba samples compared to the unprocessed sorghum grains.Lysine, a limiting amino acid in sorghum, increased more than 50% in ogi-baba. However, samples prepared using germinated sorghum without the addition of cowpeas hada lower lysine content.     

Farmers’ perceptions and management practices of insect pests on stored sorghum in southwestern Ethiopia

Surveys were undertaken in six districts of southwestern Ethiopia from July to October 2003 to investigate farmers’ perceptions and management practices of insect pests on traditionally stored sorghum. The survey involved 138 randomly selected farmers who were interviewed using a semi-structured questionnaire. Storage insect pests were perceived as the major insect pests of sorghum. The majority of the farmers estimated sorghum yield losses of up to 50% due to insect damage during storage. High temperature and lack of storage hygiene were cited as the major factors resulting in insect infestation of stored sorghum. Infestations of stored sorghum insect pests were common on different forms of sorghum, which stored in various types of farm storage. Farmers classified sorghum varieties according to the level of resistance to stored sorghum insect pests. Only about 32% of the farmers had access to chemical insecticides for the control of stored sorghum insect pests, while the majority of them used cultural practices and locally available plant materials as storage protectants.     

Application of very high gravity technology to the cofermentation of sweet stem sorghum juice and sorghum grain

Ethanol production from mixtures of sweet stem sorghum juice and sorghum grain was investigated under normal and very high gravity (VHG) fermentation conditions. Fermentation was carried out using Saccharomyces cerevisiae yeast strain N96 at 30°C. For VHG fermentation, sucrose was added to the sweet sorghum juice to obtain a concentration of 34 g per 100 ml of dissolved solids. Fermentation was carried out for 96 h using malted and unmalted milled sorghum grain from sorghum cultivars DC-75 and SV-2. Under VHG conditions, maximum ethanol levels were about 16.8% (v/v) and 11% (v/v) for media containing malted and unmalted milled sorghum grain, respectively. Although fermentation did not occur to completion, levels of ethanol obtained under VHG conditions were three times higher than the levels obtained under normal fermentation conditions. Under VHG conditions, about 8 g/100 ml of dissolved solids remained in the fermentation media after ethanol production had ceased while under normal fermentation conditions, about 4 g/100 ml of dissolved solids remained unused in the fermentation media. There was an initial decline in free amino nitrogen (FAN) levels up to 34 h followed by an increase up to 96 h under VHG fermentation conditions. Levels of assayable proanthocyanidins (PAs) from sorghum cultivar DC-75 were reduced during fermentation.     

甜高粱茎秆糖分及发酵制取乙醇研究进展

甜高粱作为能源植物主要是利用其茎秆中的糖分制取乙醇.对甜高粱茎秆糖分积累以及利用糖分发酵制取燃料乙醇两个方面的研究进行了综述,同时对如何进一步提高甜高粱的产量和糖分含量进行了探讨.     

Effect of extrusion cooking of sorghum flour on rheology,morphology and heating rate of sorghum–wheat composite dough

Addition of a gluten-free flour such as sorghum has negative impact on the quality of wheat dough for bread making. One of the methods which can be used to promote the quality of sorghum-wheat composite dough is to extrude the sorghum flour before incorporation. In this regard, to produce a dough with appropriate bakery properties sorghum flour was extruded at 110 °C and 160 °C die temperature with 10%, 14% and 18% feed moisture. The effect of extruded sorghum flour incorporation (10%) on rheological (farinography and stress relaxation behavior), morphological and temperature profile of sorghum-wheat composite dough were evaluated. Extrusion cooking altered the sorghum-wheat composite dough properties through partial gelatinization of starch granules. Addition of extruded sorghum flour increased the water absorption and dough development time but it decreased the dough stability. Native sorghum-wheat composite dough showed viscoelastic liquid-like behavior whereas addition of sorghum flour extrudate changed dough to a more viscoelastic solid-like structure. Maxwell model was more appropriate than Peleg model to describe the viscoelasticity of the sorghum-wheat composite dough. Extrusion cooking decreased composite dough elasticity and viscosity. Sorghum extrudate increased the heating rate of composite dough crumb during baking. Addition of extruded sorghum flour formed a non-uniform and less compact dough structure. As a result, dough containing extruded sorghum flour had a good potential for producing a high-yielding bread in a short time of baking.     

Effects of endosperm texture and cooking conditions on the in vitro starch digestibility of sorghum and maize flours

The effects of endosperm vitreousness, cooking time and temperature on sorghum and maize starch digestion in vitro were studied using floury and vitreous endosperm flours. Starch digestion was significantly higher in floury sorghum endosperm than vitreous endosperm, but similar floury and vitreous endosperm of maize. Cooking with 2-mercaptoethanol increased starch digestion in both sorghum and maize, but more with sorghum, and more with vitreous endosperm flours. Increasing cooking time progressively reduced starch digestion in vitreous sorghum endosperm but improved digestibility in the other flours. Pressure-cooking increased starch digestion in all flours, but markedly more in vitreous sorghum flour; probably through physical disruption of the protein matrix enveloping the starch. Irrespective of vitreousness or cooking condition, the alpha-amylase kinetic constant (k) for both sorghum and maize flours remained similar, indicating that differences in their starch digestion were due to factors extrinsic to the starches. SDS-PAGE indicated that the higher proportion of disulphide bond-cross-linked prolamin proteins and more extensive polymerisation of the prolamins on cooking, resulting in polymers of M_r>100k, were responsible for the lower starch digestibility of the vitreous sorghum endosperm flour.     

Acceptability of wheat-sorghum composite flour products: An assessment

The acceptability of sorghum as human food has been a problem in Tanzania even in regions showing promising potential for its production and utilization. Reasons given for low acceptability of sorghum products as human foods include unpleasant colour, aroma, mouthfeel, taste, unpleasant aftertaste and stomachfeel. An acceptability test of selected sorghum products was, therefore, conducted in the Department of Food Science and Technology, Sokoine University of Agriculture, Morogoro, Tanzania. The objective of the test was to determine consumers' preference for the following wheat-sorghum composite flour products: bread and buns or maandazi. The products were prepared using sorghum flour composited with wheat flour in the following proportions: 100% brown sorghum flour (standard products); and 80:20%; 60:40%; 40:60% and 20:80% for wheat/sorghum (white and brown) composite flours. Results indicated that in the case of composite flour bread, preference for the product improved as the amount of sorghum flour decreased. In the case of buns or maandazi the 100% sorghum flour products of both white and brown were equally preferred. Buns prepared from 100% sorghum flour of white and brown varieties showed promising potential in the improvement of the acceptability of sorghum products. Taking advantage of such products, especially in villages, could enhance sorghum utilization in rural communities.     

Effect of germination time and temperature on the functionality and protein solubility of sorghum flour

Sorghum was germinated for different time (12, 24, 36 and 48 h) at different temperatures (25, 30 and 35 °C) and the changes in their nutritional and functional properties of germinated sorghum flour were assessed and compared with native sorghum flour. Germination inversely affects the crude protein, fat, fibre and ash content. A decrease in water absorption and swelling power and increase in oil absorption capacity was observed due to enzymatic starch modification as the germination duration progressed. Germination of sorghum increased the gel consistency while paste clarity was decreased as compared to native flour. Proteins were modified by action of enzymes during higher germination time and temperature conditions, which results in significantly higher protein solubility of germinated sorghum flour, which also result in enhancing the foaming and emulsifying properties of the flour. Lowest % synersis value and least gelation concentrations were observed in native sorghum has, which increased during germination and were highest in sorghum germinated for 48 h at 35 °C. Germination in overall can be used as low cost natural bio-processing technique for the preparation of modified flour with enhanced function properties without chemical modification or genetic engineering.     

高粱新品种沈杂10号

沈杂10号是沈阳市农业科学院于2005年以自选不育系7-02A为母本,自选恢复系F0018为父本杂交选育而成的高粱新品种。2007—2008年参加全国高粱品种春播晚熟组区域试验,平均产量8 838.0 kg/hm2,居第1位,2008年参加全国高粱品种春播晚熟组生产试验,平均产量9 033.0 kg/hm2,居第1位,并于2010年通过国家鉴定。具有高产、抗病、抗逆等特点。     

Comparison of sorghum and maize raw distillates: Factors affecting ethanol efficiency and volatile by-product profile

The potential of sorghum grain in the production of bioethanol was determined in comparison to maize and as an alternative to it. The effects of the raw materials, the raw material cultivars, and the fermentation process on ethanol efficiency and volatile compound profile of the raw distillates were investigated. The ethanol yield proved to be strongly determined by the variety of the raw material and by the fermentation method. The SSF method with a weight to water ratio of 1:4 proved to be the most effective for ethanol production in the case of both maize and sorghum. The highest ethanol yield at 86.94% of the theoretical value, was obtained from maize; the value from sorghum was 80.15%. The fermentation method, though not the grain cultivar, had a significant effect on the volatile compound profile of the raw distillates. The raw distillates obtained using the SSF method at a ground grain to water ratio of 1:4 had the lowest concentration of esters and aldehydes. The average content of volatile compounds in the sorghum distillates was lower than in the maize distillates. This study emphasizes the great potential of sorghum, a maize alternative, as an energy plant in the distillery.     

Evaluation of sorghum flour as extender in plywood adhesives for sprayline coaters or foam extrusion

This study was conducted to evaluate sorghum flour as protein extender in phenol-formaldehyde-based plywood adhesive for sprayline coaters or foam extrusion. Defatted sorghum flour, containing 0.2% (db) residual oil and 12.0% (db) crude protein, was analyzed for solubility and foaming properties. Sorghum flour proteins were least soluble (≤12%) under acidic pH, most soluble (72%) at pH 10, and produced substantial and highly stable foam at pH 10. Sorghum flour was substituted (on protein content basis) for wheat flour in the standard glue mix. Mixing properties and bond strength of the sorghum-based glue were compared with those of the industry standard glue. The sorghum flour-based adhesive had mixing properties and appearance that were superior to those of the standard wheat flour-based plywood glue, but its viscosity and bond strength were markedly less. Doubling the amount of protein contributed by sorghum flour in the glue mix markedly improved both viscosity (1104 cP) and adhesion strength (1.37 MPa) of the sorghum-based plywood glue to acceptable levels. The modified sorghum flour-based plywood glue also produced foam that remained stable up to 3 h. These results demonstrated that sorghum flour is a viable extender in plywood glues for sprayline coater or foam extrusion.