Effect of chemical treatments on the micro-organisms associated with malting of sorghum grains and sorghum malt

The effect of five chemical preservatives on the micro-organisms associated with sorghum grain and malts was investigated. Sorbic acid, sodium benzoate, nisin, formaldehyde and lime at concentrations up to 500, 100, 1000, 1500 and 2000 ppm, respectively did not adversely affect the malting properties of sorghum grain. Only HCHO and Ca(OH)2, each of which prevented bacteria and mould growth at 500 and 2000 ppm, respectively, were sufficiently effective at maximum practicable concentrations to control microbial contamination during malting.     

Enzymic degradation of the endosperm cell walls of germinated sorghum

Evidence derived from scanning electron microscope studies of the cell walls of germinated (malted) and unmalted sorghum grains suggests that portals (holes) develop in the endosperm cell walls during mobilization of the food reserves. It is proposed that amylolytic and proteolytic enzymes enter the endosperm cells through these portals and hyrolyse starch granules and associated storage proteins. Limited protease, pentosanase and/or-glucanase activities during malting may be responsible for the development of these portals in the endosperm cell walls. The latter persist in the malted grain.     

Nitrogen metabolism as affected by hexavalent chromium in sorghum (Sorghum bicolor L.)

A pot experiment was conducted to determine the effects of varying Cr (VI) levels (0–4 ppm in the form of potassium dichromate) on the key enzymes of nitrogen metabolism in sorghum. Total as well as specific enzyme activity of nitrate reductase, nitrite reductase, glutamine synthetase, glutamate dehydrogenase (GDH) and urease in various plant organs at different growth stages decreased with an increase in Cr (VI) levels from 0 to 4.0 ppm. In general, the enzyme activitiy increased with advancement of growth to reach maximum at 50% flowering stage (70 DAS) and thereafter decreased at grain filling stage (90 DAS). However, nitrite reductase activity in shoot increased continuously till grain filling stage. It is concluded that Cr (VI) at higher doses adversely affects the key enzymes of nitrogen metabolism in forage sorghum (Sorghum bicolor L.).     

Developments in the malting and brewing trials with sorghum

A comparative study of sorghum and barley grains reveals structural and physiological differences in their aleurone, embryo and starchy endosperm cells. These differences are responsible for the observed differences in their malting characteristics. Reports on brewing trials with sorghum favour its use as an adjunct to barley malt. Nevertheless, a recent successful resolution of the incompatibility of the gelatinization and saccharification temperatures of sorghum starch through the adoption of a new mashing technique has greatly improved its extract yield. A similar report on the discovery of a Nigerian-grown sorghum variety with improved β-amylase activity as well as high diastatic power will obviously ensure better fermentable extracts. Further research on the development and trial of new sorghum varieties is strongly recommended. The purpose of this review, however, is to highlight research efforts aimed at alleviating the problems of sorghum as a brewing material.     

Fungi associated with sorghum grain from Argentina

Sorghum (Sorghum bicolor (L.) Moench) is an important cereal produced in and exported from Argentina. The risk of contamination by mycotoxins is related to the mycoflora associated with the sorghum grain. This paper reports on the identification of internal mycoflora of sorghum grain harvested in Argentina in 1991, 1992 and 1993, years with different total rainfall levels. A mycological survey was carried out on sorghum samples, from a location at the humid Argentinian pampa, using a Fusarium/dematiaceous fungi selective medium. The relative density of the prevalent fungal genera were statistically compared. Genus Fusarium was the most prevalent component of the internal seedborne mycoflora in the three harvest seasons. Genera Alternaria, Phoma, Penicillium and Aspergillus were also isolated. The predominant Fusarium was F. moniliforme and the most frequently isolated species of Alternaria, Phoma, Penicillium and Aspergillus were Alt. alternata, Pho. sorghima, Pen. funiculosum and Asp. flavus, respectively. This is the first report of the isolation of Fusarium napiforme in sorghum grain in Argentina. This revised version was published online in June 2006 with corrections to the Cover Date.     

Effect of polyphenol content on the hydrolysis and fermentation of grain sorghum starch

The high polyphenol content of birdproff grain sorghum has been associated with impaired nutritional quality of the grain and with reduced brewing value of birdproof grain sorghum malt due to enzyme inhibition. In this investigation, high polyphenol grain sorghum was evaluated as a feedstock for fermentation ethanol production using NaOH pretreatment to inactivate the polyphenolic compounds prior to hydrolysis with commercial amylases. The polyphenolic inhibition of starch hydrolysis was minimal at a grain sorghum slurry concentration of 20% dry solids, but became pronounced at slurry concentrations of 28% and higher. At these high slurry concentrations the liquefaction and subsequent saccharification and fermentation were markedly improved by alkaline pretreatment. The highest ethanol concentration (12·3%, vol/vol), coupled with the best starch conversion efficiency to ethanol (83·5%), was obtained with a 28% grain sorghum slurry using a partial simultaneous saccharification and fermentation procedure. The residual fermented solids had a crude protein content of 45·4%. Tannic acid decreased yeast cell viability in synthetic media, but had no effect on the hydrolysis or fermentation of grain sorghum starch.     

Comparative studies of the development of endosperm-degrading enzymes in malting sorghum and barley

The endosperm cell walls of barley are degraded extensively during malting whilst those of sorghum are not. Malting barley produced endo--1,3:1,4-glucanase, endo--1,3-glucanase and pentosanase in large quantities. In contrast, malting sorghum developed mainly endo--1,3-glucanase and pentosanase. Although the limited break-down of the endosperm cell walls of sorghum may reflect sub-optimal activities of -glucanases, such as endo--1,3:1,4-glucanases, it is possible that the highly intractable nature of the cell walls and their high protein content (approx. 60%) may contribute to the low susceptibility of sorghum endosperm cell walls to enzymic degradation during malting.

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Résumé Les parois cellulaires endospermiques de l'orge sont fortement dégradées pendant le maltage, tandis que celles du sorghum ne le sont pas. L'orge en maltage produit l'endo--1,3:1,4-glucanase, l'endo--1,3-glucanase et la pentosanase en grandes quantités. Par contre, le sorghum en maltage dévéloppe principalement l'endo--1,3-glucanase et la pentosanase. Bien que la destruction limitée des parois cellulaires endospermiques puisse réflecter des activités sub-optimales des -glucanases, comme l'endo--1,3:1,4-glucanase, il n'en est pas molns possible que la nature hautement intractile des parols cellulaires et leur contenu élevé en protéines (approximativement 60%) pulsse contribuer à la faible susceptibilite des parois cellulaires endospermiques du sorghum à la dégradation enzymatique durant le maltage.

     

Influence of Potassium Bromate on Some Malting Properties of Nigerian Sorghum (Sorghum bicolor)

The effect of various concentrations of potassium bromate (a malting additive) was studied on malting sorghum. Potassium bromate at concentrations of 50-125 mg/litre sprinkled on germinating sorghum (28°C ± 1°C) at steep out increased the filtration rate and cold and hot extract values after four days of germination. There was no significant decrease in malting loss at the low concentrations (50-125 mg/litre) of the additive. A higher dose, of 150 mg/litre, decreased the malting loss, while at a concentration of 125 mg/litre a significant increase was observed for the diastatic power after four days of germination.     

Nitrogen assimilation in opaque and normal sorghum during grain development

Activity of key nitrogen assimilating enzymes was studied in developing grains of high-lysine opaque sorghum P-721 and normal sorghum CSV-5. The higher percentage of protein in opaque sorghum was mainly due to lower starch content since protein per grain was less than in CSV-5. During grain development, albufn and globulin decreased while prolafne and glutelin increased. Prolafne content in CSV-5 was higher than in opaque sorghum. Average nitrate reductase activity in flag and long leaf were similar in both the varieties. The nitrate reductase activity decreased during grain development. Glutamate dehydrogenase activity was higher during early development and lower at later stages in opaque sorghum than in CSV-5. Glutamate oxaloacetate transaminase activity was higher and glutamine synthetase lower in opaque sorghum than in CSV-5 grains during development. Glutamate synthase activity was higher in opaque sorghum up to day 20 and lower thereafter than in CSV-5. It is suggested that reduced activities of glutamine synthetase as well as glutamate synthase in opaque sorghum as compared to CSV-5 during later stages of development may restrict protein accumulation in the former.     

QTL mapping of stay-green in two sorghum recombinant inbred populations

The stay-green trait is a reported component of tolerance to terminal drought stress in sorghum. To map quantitative trait loci (QTLs) for stay-green, two sorghum recombinant inbred populations (RIPs) of 226 F(3:5) lines each were developed from crosses (1) IS9830 x E36-1 and (2) N13 x E36-1. The common parental line, E36-1 of Ethiopian origin, was the stay-green trait source. The genetic map of RIP 1 had a total length of 1,291 cM, with 128 markers (AFLPs, RFLPs, SSRs and RAPDs) distributed over ten linkage groups. The map of RIP 2 spanned 1,438 cM and contained 146 markers in 12 linkage groups. The two RIPs were evaluated during post-rainy seasons at Patancheru, India, in 1999/2000 (RIP 2) and 2000/2001 (RIP 1). The measures of stay-green mapped were the green leaf area percentages at 15, 30 and 45 days after flowering (% GL15, % GL30 and % GL45, respectively). Estimated repeatabilities for % GL15, % GL30 and % GL45 amounted to 0.89, 0.81 and 0.78 in RIP 1, and 0.91, 0.88 and 0.85 in RIP 2, respectively. The number of QTLs for the three traits detected by composite interval mapping ranged from 5 to 8, explaining 31% to 42% of the genetic variance. In both RIPs, both parent lines contributed stay-green alleles. Across the three measures of the stay-green trait, three QTLs on linkage groups A, E and G were common to both RIPs, with the stay-green alleles originating from E36-1. These QTLs were therefore consistent across the tested genetic backgrounds and years. After QTL validation across sites and verification of the general benefit of the stay-green trait for grain yield performance and stability in the target areas, the corresponding chromosomal regions could be candidates for marker-assisted transfer of stay-green into elite materials.     

Grain sorghum (Sorghum bicolor Pers.) responses to organic iron on calcareous soils

Effects of Fe-EDDHA (Sequestrene 138), Fe-polyflavonoid (Rayplex), and an experimental iron lignosulfonate on dry matter yields, Fe content, and plant chlorosis of grain sorghum were studied under controlled conditions, using a normal and an Fe-deficient soil (DTPA extract). Application rates of 20, 40, and 80 ppm Fe were employed. Dry matter yields increased due to Fe applications. The lignosulfonate (Fe-LS) produced maximum dry matter yields followed by Fe-EDDHA and the polyflavonoid (Fe-PF) material. At the 80 ppm rate Fe-EDDHA and Fe-PF produced moderate and slight toxic effects, respectively. No toxic effect was noted with the Fe-LS material. Fe-EDDHA was found to be the most effective for correcting iron chlorosis, while the other two sources were similar in this respect. Except for the Fe-LS applied to the normal soil, all other treatments increased Fe content of plant shoots. In the Fe-deficient soil, Fe application lowered the Ca, Mg, Zn, and Mn concentrations in the plants. In the case of the normal soil, concentrations of these elements increased at the 20 ppm rate and underwent no further changes with higher rates. Treatments did not influence K and P concentrations of plants.Additional index words: Micronutrients, Iron compounds.     

Optimization of proteolytic activities in malting sorghum

The effects of malting conditions on proteolytic activities in three improved sorghum varieties: ICSV400, SK5912 and KSV8 were studied. Grains were steeped for 45 h using 6 h wet and 3 h dry cycles and germinated for 8 days. Moisture contents and their effects on proteolytic activity were monitored at various intervals using standard methods. Significant positive correlations existed between moisture content and carboxypeptidase and proteinase activities during steeping. Optimum carboxypeptidase and proteinase enzyme activities were consistently recorded in both ICSV400 and SK5912 at the 40th h of steeping while those of KSV8 occurred on the 45th h. This suggests that protein hydrolysis of KSV8 is different from that of ICSV400 and SK5912. Similarly, optimum proteolytic activities occurred in all the sorghum varieties on the 5th day of germination suggesting optimum germination time for optimum protein modification. Variety and steeping time affected both carboxypeptidase and proteinase activities significantly (P<0.001) during germination. Significant positive correlations existed in the sorghum varieties ICSV400 and SK5912 between free amino nitrogen (FAN) contents and carboxypeptidase activities during both steeping and germination. In contrast, variety KSV8 showed no significant correlation between FAN contents and carboxypeptidase activities during either steeping or germination. On the other hand, while there was a highly significant positive correlation between CWS-P development and proteinase activities in all the sorghum varieties during steeping, no such relationship existed during germination.     

Sorghum: a cereal with lager beer brewing potential

The potential of sorghum as an alternative substrate for lager beer brewing was recognized over five decades ago. Factors which appear to influence brewing with sorghum include: the variety of sorghum, storage time, steep period, germination time, duration and levels of temperature-time sequence of the kilning cycle and temperature-time regimes during mashing. Malts from sorghum varieties that have high diastatic power, amylase and starch contents are desirable. Soluble and insoluble amylases in grain sorghum contribute towards the hydrolysis of grain constituents during mashing. Optimizing conditions for malting, mashing and fermentation are therefore necessary for the production of acceptable sorghum lager beer. This review aims to update research results on lager beer brewing with sorghum.     

Field inoculation of sorghum and rice withAzospirillum spp. andHerbaspirillum seropedicae

Two field experiments were carried out at the UAPNPBS experimental station, Seropédica, with two sorghum and one rice cultivars. The establishment, and inoculation effects, ofAzospirillum spp. andHerbaspirillum strains marked with antibiotic resistance were investigated. One grain sorghum (BR 300) and one sugar sorghum (Br 505) cultivar were used.Azospirillum lipoferum strain S82 (isolated from surface sterilized roots of sorghum) established in both cultivars and comprised 40 to 80% of theAzospirillum spp. population in roots and stems 60 days after plant emergence (DAE).Azospirillum amazonense strain AmS91 (isolated from surface-sterilized roots of sorghum) reached only 50%. At 90 DAE, S82 almost disappeared (less than 30% of establishment) while the establishment of AmS91 remained constant in roots and stems. No establishment ofH. seropedicae strain H25 (isolated from surface-sterilized roots of sorghum) orA. lipoferum strain S65 (isolated from the root surface of sorghum) could be observed on inoculated roots. Inoculation with S82, AmS91 or S65 but not withH. seropedicae H25, increased plant dry weight of both cultivars and total N in grain of the grain sorghum. In rice,A. lipoferum Al 121 andA. brasilense Sp 245 (isolated from surface sterilized rice and wheat roots respectively) established in the roots but there was no increase inAzospirillum spp. numbers due to inoculation. None of the strains affected plant growth or rice grain yield.Azospirillum amazonense, A82 andH. seropedicae Z95, which did not establish in roots, significantly enhanced seed germination.     

Activated carbons prepared from phosphoric acid activation of grain sorghum.

The production of activated carbons from grain sorghum with phosphoric acid activation has been studied by means of two processes, i.e., one-stage and two-stage. The former comprises simultaneous carbonization and activation after impregnation; the latter, the carbonization of the precursor at 300 degrees C for 15 min, followed by the activation of the resultant char after impregnation with phosphoric acid. The preparation conditions, e.g., activation duration, phosphoric acid concentration, and activation temperature, have been varied to determine the optimal processing conditions. The optimal activation conditions for the highest surface areas have been determined to be 600 and 500 degrees C with a phosphoric acid concentration of 35% for the one-stage and two-stage processes, respectively. The two-stage process has been found to greatly enhance the porosity development, especially the microporosity.     

高粱穗部主要性状的配合力分析

以4个高粱不育系13163A、1358A、128A和407A,以及6个恢复系9.1R、213R、272R、381R、矮182R和早21R为试验材料,按照不完全双列杂交设计(NCII),对其F1的穗部主要性状进行配合力分析。结果表明:亲本穗部主要性状存在显著的遗传差异,主要表现为加性基因效应遗传的性状有:穗长、一级枝梗数、二级枝梗数、穗粒数;狭义遗传力大小顺序分别为:二级枝梗数一级枝梗数穗长穗粒数穗粒重千粒重。不同亲本的一般配合力(GCA)和特殊配合力(SCA)在不同穗部性状间存在较大差异。不育系407A和恢复系早21R、9.1R是综合性状较好的亲本材料,利用它们可组配出产量较高的杂交组合。恢复系272R组配的杂交种具有穗粒数较多、千粒重较小的特点,能满足市场上对小粒高粱的需求。深入分析高粱杂交亲本穗部主要性状表现,有利于对亲本材料的进一步了解和利用。     

Components of resistance to the sorghum midge, Contarinia sorghicola

Studies were conducted on components of resistance to sorghum midge on four resistant (DJ 6514, AF 28, TAM 2566 and IS 15107) and two susceptible cultivars (CSH 1 and Swarna). Data were recorded on the numbers of eggs, larvae, emerged adults and grain damage in panicles of different genotypes infested with 60 midge females/panicle under no-choice conditions. The size of floral parts (glume, lemma, palea, lodicule, stigma, style, ovary and anther), rate of grain development and tannin content of grain were measured. The lengths of glume gl and 82, lemma L1 and L2, palea, lodicule, anther, style and stigma were positively associated with susceptibility to sorghum midge. Rate of grain development (between 3rd and 7th day after anthesis) was negatively associated with susceptibility to sorghum. Tannin content of grain was also negatively correlated with midge susceptibility, although there were distinct exceptions (e.g. DJ 6514 is highly resistant bur has a low tannin content).     

Quantification of yield losses caused by leaf anthracnose on sorghum in Brazil

The leaf anthracnose disease in sorghum, caused by Colletotrichum sublineolum (Henn. ex Sacc. & Trotter), is widely distributed throughout its Brazilian cultivation areas. The disease can cause significant losses in grain yield and quality. This study aimed to quantify the effects of leaf anthracnose on grain yield of different sorghum genotypes. Two elite inbred lines of sorghum, BR009 (susceptible) and BR008 (moderately resistant), and the hybrids, BR304 and MR43 (susceptible), BRS310 and DKB599 (moderately resistant) and BRS308 and AG1060 (resistant), were planted in a complete randomized block design with three replicates. The disease severity (DS) was evaluated weekly, starting from the onset of the first foliar symptoms, and yield losses were estimated using linear regression analysis. Leaf anthracnose significantly reduced sorghum yields in the susceptible genotypes. The highest yield loss of 86% was observed in the inbred line BR009, when the disease severity reached 100%. For the hybrids, the grain yield loss varied from 35% (BRS310) to 72% (BRS308). According to the adjusted model, a grain yield reduction of 23.48 kg/ha for BR304, 14.57 kg/ha for BRS310 and 15.91 kg/ha for DKB599 was observed for every 1% increase in disease severity. We demonstrate for the first time the effect of leaf anthracnose disease on grain sorghum yields under Brazilian conditions. The results from this study provide a starting point for developing new strategies for the integrated disease management of sorghum anthracnose.     

Relationships between tristimulus colour values and digestibility of grain sorghum by swine

Fourteen grain sorghum cultivars were used to study the degree of relationship between energy and protein digestion coefficients and tristimulus colour values of grain sorghum. Colour values from whole grain, ground dry and ground blended samples of each cultivar were used. Colour values of the ground blended samples were more highly associated with digestibility and nitrogen retention than were colour values of either whole grain or ground dry grain sorghum. Although close relationships were shown by simple correlation coefficients, valid prediction equations could not be developed (P < 0.05) from combinations of these three colour observations. These data indicate that colour difference meter values can be used to develop linear regression equations that would assist in screening grain sorghum cultivars for nutritive value in swine.     

Genetic transformation of sweet sorghum

Sweet sorghum has substantial potential as a biofuel feedstock, with advantages in some environments over alternatives such as sugarcane or maize. Gene technologies are likely to be important to achieve yields sufficient for food, fuel and fibre production from available global croplands, but sorghum has proven difficult to transform. Tissue culture recalcitrance and poor reproducibility of transformation protocols remain major challenges for grain sorghum, and there has been no reported success for sweet sorghum. Here we describe a repeatable transformation system for sweet sorghum, based on (1) optimized tissue culture conditions for embryogenic callus production with >90% regenerability in 12-week-old calli, and (2) an effective selection regimen for hygromycin resistance conferred by a Ubi-hpt transgene following particle bombardment. Using this method, we have produced sixteen independent transgenic lines from multiple batches at an overall efficiency of 0.09% transformants per excised immature embryo. Co-expression frequency of a non-selected luciferase reporter was 62.5%. Transgene integration and expression were confirmed in T₀ and T₁ plants by Southern analysis and luciferase assays. This success using the major international sweet sorghum cultivar Ramada provides a foundation for molecular improvement of sweet sorghum through the use of transgenes. Factors likely to be important for success with other sweet sorghum cultivars are identified.