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.     

Small-scale mashing procedure for predicting ethanol yield of sorghum grain

A small-scale mashing (SSM) procedure requiring only 300 mg of samples was investigated as a possible method of predicting ethanol yield of sorghum grain. The initial SSM procedure, which was conducted similarly to the mashing step in a traditional fermentation test, hydrolyzed just 38.5–47.2% of total sorghum starch to glucose. The initial procedure was simplified to contain only one liquefaction step, which did not influence subsequent saccharification. Thereafter, parameters such as temperature, pH, enzyme dosage, and saccharification time were optimized. Results showed that 91.2–97.5% of the total starch in 18 sorghum hybrids had been hydrolyzed to glucose using the following conditions: liquefaction at 86 °C for 90 min, 20 μL of α-amylase per 30 g of sample; pH adjustment by adding 50 μL of 2 M acetate buffer at pH 4.2 to each microtube; saccharification at 68 °C for 90 min, 200 μL of amyloglucosidase per 30 g of sample. There were strong linear correlations between completely hydrolyzed starch (CHS) from SSM and ethanol yields from both traditional (R² = 0.86) and simultaneous saccharification and fermentation (SSF, R² = 0.93) procedures. CHS was a better indicator for predicting ethanol yield in fermentation than total starch.     

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.     

Conversion into bioethanol of insect (Sitophilus zeamais Motschulsky), mold (Aspergillus flavus Link) and sprout-damaged maize (Zea mays L.) and sorghum (Sorghum bicolor L. Moench)

The bioconversion into ethanol of insect (Sitophilus zeamais), mold (Aspergillus flavus) and sprout-damaged maize and sorghum was investigated. Kernel test weight losses due to insect damage in maize were almost twice compared to sorghum (18.6 vs. 10.7%). All damaged kernels lost some of the starch and increased soluble sugars, ash and crude fiber. The mold-damaged sorghum contained approximately five times more FAN compared to the control. The sprout-damaged kernels contained the highest amounts of reducing sugars prior (11 g/L) to and at the end (146.5 g/L) of liquefaction with α-amylase. Ethanol yields based on the already damaged grain indicated that sprout-damaged kernels yielded similar amounts compared to sound kernels (381.1 vs. 382.6 L/ton and 376.6 vs. 374.8 L/ton of sorghum or maize respectively). The insect-damaged maize and sorghum have reduced ethanol yields compared with the controls (29 and 23% respectively), and this negative result was mainly due to dry matter losses during the inadequate storage. Despite differences in ethanol yield, all treatments have similar conversion efficiencies (76.1–89.9%) indicating the robustness of yeast facing biotic-damaged feedstocks. This research demonstrates that the use of already damaged insect, mold or sprouted kernels is feasible and a good alternative for biorefineries.     

茎秆高糖的能源玉米新品种选育研究

利用茎秆含糖量高的玉米自交系进行了能源玉米新品种的选育研究。结果表明:①津259、津1009、津1112、津2122、津单2号5个品种的茎秆产量、茎秆含糖量、子粒产量综合表现较好,可作为生产燃料乙醇的材料进一步试验;②玉米茎秆含糖量性状可以达到或超过甜高梁水平;③玉米各节间的含糖量变化比甜高粱相对稳定。     

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.     

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%).     

Effect of nitrogen supply on the comparative productivity of maize and sorghum in a semi-arid tropical environment III. Grain yield and nitrogen accumulation

Differences in grain yield and grain nitrogen content due to variable N supply in maize and sorghum, grown under irrigation in the semi-arid tropics, were associated with differences in their rates of accumulation and in the extent of mobilization of pre-anthesis dry matter and N. Increases in harvest index, nitrogen harvest index, and grain size during grain-filling were essentially linear, and the rates were constant under variable N supply. Differences in harvest index at maturity at different levels of applied N were small relative to differences in biomass and grain yield, and differences in grain size were small relative to differences in grain number. In effect, variation in harvest index and grain size at maturity was associated with variation in the length of the effective grain-filling period. Nitrogen supply had a greater effect on the effective duration of grain-filling in maize than in sorghum.Maximum grain yields at high levels of N uptake were greater in maize (10.0 t ha⁻¹ at 15.5% moisture) than in sorghum (7.2 t ha⁻¹ at 14% moisture). These differences were related to differences in biomass production, rate of increase in harvest index and the effective duration of grain-filling. The rate of increase in harvest index was greater, but biomass production was less and the duration of grain-filling was shorter, in sorghum than in maize.     

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.     

Evaluation of drought and heat stressed grain sorghum (Sorghum bicolor) for ethanol production

Sorghum is one of the most drought-tolerant grain crops and is used in biofuel production. Since sorghum is often exposed to drought and high temperature (heat) stress, this study investigated the effect of stress applied at different phenological stages of crop development on the glucose levels in grain and subsequent ethanol production. Short season sorghum hybrid DK-28E grown under controlled environment was exposed to drought and heat stress at five different stages of growth, namely: (1) pre-flowering (boot leaf emergence) to flowering, (2) flower to seed-set, (3) seed-set to early seed-fill, (4) early seed-fill to mid seed-fill, and (5) mid seed-fill to late seed-fill stage. Drought stress at any of the growth stages did not statistically affect either the glucose content or the ethanol production compared to the control (337 mg/g), although the ethanol yield increased up to 4.5% (352 mg/g) in flowering to seed-set stage. Heat stress, on the other hand, significantly reduced the glucose release and ethanol yield compared to the control (322 mg/g). Marginal ethanol yield reduction by 9% (293 mg/g) and 8.3% (295 mg/g) was seen in plants stressed during early seed-fill to mid seed-fill and mid seed-fill to late seed-fill stages, respectively. The results suggest that the phenological stage when sorghum is exposed to stress affects the ethanol yield. Overall, from the point of ethanol yield, it appears that grain sorghum cultivated in semi-arid regions where heat and drought stress are prevalent can be used for biofuel production. However, economic viability of ethanol production, especially of grain sorghum from high temperature stress needs to be investigated.     

Sorghum silage quality as determined by chemical–nutritional factors

Sorghum [Sorghum bicolor (L.) Moench] is an ensilable tropical plant known as a good alternative to maize crops in regions with scarce rainfall. The objective of this trial was to obtain prediction models based on nutritional contents and end products of sorghum silage fermentation as related to the dry-matter composition of fresh plants before ensiling. Eleven different sorghum cultivars (including silage, graniferous and sweet types) were used. Twenty-five sorghum plots were harvested between 80 and 120 days of growth. Fifty plastic buckets were used as experimental microsilos and opened between 60 and 90 days of storage. Statistical modelling was used to create a prediction equation that could explain the impact of fresh sorghum composition on the chemical and nutritional composition of its silage. A complex model was detected by stepwise multiple regression to predict the difference of in vitro dry-matter digestibility (IVDMD) before and after ensiling, but a simpler model, which involved only the sum of water-soluble carbohydrate (fWSC) and hemicellulose (fHemi) concentrations in the dry matter of fresh forage, was considered to more usable. It had an acceptable coefficient of determination (0.51). The higher amount of WSC and Hemi in fresh sorghum linearly decreased the difference between IVDMD before and after the ensiling process. A WSC concentration of 125.4 g/kg DM in fresh sorghum is recommended for an ideal silage fermentation when considering pH and lactic acid levels, although ethanol levels continued to increase.     

带状复合种植对玉米和大豆光合特性及籽粒产量的影响

为比较带状复合种植和清种种植模式下玉米和大豆光合特性以及产量的差异,2015年和2016年进行大田试验,研究了玉米和大豆2∶4带状复合种植模式及清种种植对玉米和大豆光合特性及籽粒产量的影响。结果表明:(1)与清种玉米相比,对于高秆品种(垦丰41),带状复合种植提高了玉米净光合速率、蒸腾速率、气孔导度、胞间CO2浓度和水分利用效率;对于矮秆品种(垦丰40),2015年带状复合种植净光合速率等指标略小于清种玉米,但水分利用效率和胞间CO2浓度均大于清种玉米,有利于玉米籽粒内含物质的积累,而2016年净光合速率和蒸腾速率等指标均大于清种玉米;(2)对于高秆品种(垦丰41),除叶绿素含量略小外,清种大豆的各光合生理指标均大于带状复合种植;对于矮秆品种(垦丰40),带状复合种植净光合速率、气孔导度和叶绿素均大于清种大豆,且净光合速率均达到极显著差异水平;(3)带状复合种植增加了玉米穗粒数、穗重、籽粒重,虽产量较清种略有降低,但总经济效益高于清种;(4)带状复合种植大豆较清种大豆单株荚数、单株粒数、单株粒重和百粒重均有所降低,且产量明显下降,但总体经济效益高于清种经济效益。综合分析认为:玉米大豆带状复合种植增加了玉米光合生理特性,且对于增加玉米和大豆总产量和总体经济效益具有重要意义。     

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.     

玉米子粒主要营养成分合成调控研究进展

玉米具有广泛的用途,玉米不仅可以作为食品,同时也是重要的加工原料。淀粉、蛋白质、脂肪是玉米子粒中最主要的3种营养物质。三者之间在含量及机构上相互影响,不仅影响玉米子粒产量,同时影响玉米的营养品质。因此,深入了解玉米子粒不同的化学成分含量及其相互关系,可以为玉米品种选育提供理论依据。本研究系统阐述玉米子粒中淀粉、蛋白质、脂肪的结构组成和合成途径以及相关功能基因的研究进展,为玉米子粒品质研究提供参考。     

东北春玉米区不同耕作方式对玉米磷素积累分配的影响

以先玉335为试验材料,在大田条件下设置4种耕作方式处理,研究耕作方式对春玉米产量及各器官磷含量、磷素吸收、积累和利用的影响。结果表明,苗带紧、行间松型耕作方式下玉米的产量最高,苗带松、行间紧型耕作方式次之,苗带、行间全松型耕作方式产量最低。开花期,苗带紧、行间松型耕作方式下根系磷含量和磷积累量均最高;成熟期,苗带紧、行间松型耕作方式下根系、茎秆和子粒的磷含量及磷积累量显著高于其他处理。苗带紧、行间松型耕作方式下玉米的磷素吸收效率、磷素偏生产力、磷素贡献率和磷素转移效率显著高于其他处理,磷素干物质生产效率和磷素子粒生产效率显著低于苗带、行间全松和苗带、行间全紧处理。相关分析表明,粒重与磷素子粒生产效率、磷素吸收效率、整株干物重、磷素收获指数显著正相关,与磷素偏生产力、磷贡献率极显著正相关。     

不同品种酿酒高粱在盐碱地种植的适应性研究

盐碱地适盐种植是目前发展盐碱地产业的重要模式。以3个酿酒高粱品种为研究对象,通过测定并分析酿酒高粱的农艺性状、产量及籽粒品质等指标,筛选出耐盐、优质高产的酿酒高粱品种以丰富河套灌区作物的种植结构,降低因长年种植葵花引起各种病虫害的发生,并提供优质酿酒原料。研究结果表明:1)吉杂127的产量最高,为10 832.0 kg/hm^2,其次是辽杂19的10 429.8 kg/hm^2;2)辽杂19农艺性状、产量及籽粒淀粉、蛋白质含量和容重等指标优于其他品种,为最佳酿酒高粱品种;3)相比于种植葵花,种植高粱具有机械化程度高、便于轮作倒茬等优点,提高种植户的净收入约5070元/hm^2,并能提供优质酿酒原材料。     

施氮量对玉米产量和氮素利用效率及土壤硝态氮累积的影响

采用田间试验研究不同施氮量对两个玉米品种子粒产量、土壤硝态氮累积量及氮素利用率的影响。结果表明,玉米产量随施氮量增加显著提高,当施氮量高于200kg/hm2时玉米产量不再增加,高氮处理地上部分秸秆生物量出现下降趋势。0～100cm土层硝态氮累积量随氮素输入量的增加显著增加。不同玉米品种对氮素的吸收利用影响硝态氮在土壤中的累积,植株氮积累量存在差异。密植型玉米先玉335总吸氮量高于平展型玉米辽单28,土壤硝态氮的累积量也显著低于后者。不同氮肥水平的氮肥利用率为28.38%～35.33%,高氮处理氮肥利用率最低。本试验条件下,中氮处理水平基本能够满足作物生长的需求。综合产量、氮肥利用效率和土壤硝态氮累积情况,确定合理施氮量应控制在200kg/hm2左右。     

Effect of processing on the phenolic contents,antioxidant activity and volatile compounds of sorghum grain tea

Sorghum grain is rich in phenolic compounds and may be used to develop functional tea beverages. This work investigated the effect of processing techniques on the phenolic contents, antioxidant activity, and volatile compounds of a white colour sorghum (Liberty) grain tea. Significant (P ≤ 0.05) increase of total phenolic content, total flavonoid content and condensed tannin content were observed during the processing, whereas the antioxidant activity was not statistically enhanced. A total of 63 volatile compounds were detected including 5 alcohols, 13 alkanes, 2 aldehydes, 2 carboxylic acids, 15 esters, 4 ketones, 3 pyrazines and 1 phenylenediamine, which were affected by the processing techniques. The sorghum tea made from powder form infusion had more abundant volatile compounds compared to whole grain form infusion. The findings of this research have potential to expand human consumption of sorghum grain in the new form of grain tea.     

Small-scale farmer perceptions of diatomaceous earth products as potential stored grain protectants in Zimbabwe

Farmers repeated prioritisation of the need for improved methods of controlling insect damage to stored commodities in Zimbabwe led to the search for alternative grain protectants to the locally available organophosphate-based pesticides. In field trials the diatomaceous earth (DE) products, Protect-It^® and Dryacide^®, gave good protection to threshed maize, sorghum and cowpea from insect attack during 8 months storage, enabling households to increase both their food security and control over grain sales. However the initial trials, although on-farm, were researcher-managed and only evaluated by farmers at the end of the storage period. No information existed on how effective DEs were under real farmer management.

At the start of the 1999/2000 storage season, farmers in Buhera and Binga districts set up trials in their own granaries using their own maize and sorghum grain, respectively. During a 7 months storage period they evaluated the application of 0.1% w/w Protect-It^® compared to their typical grain protection methods. At 5 and 7 months storage, farmers compared the treatments using the parameters they view as important such as insect damage, expected ‘sadza’ yield and quality and sale price. The DE treatments outscored other practices for all parameters and farmers were keen to purchase DEs to protect their future harvests. Grain samples from the same trial were also analysed in the laboratory at 5 and 7 months for insect populations, damage and moisture content. Although grain damage and insect numbers were higher in the typical grain protection treatment than the DE treatment, the differences were not statistically significant.     

Nutritional components and antioxidant properties of seven kinds of cereals fermented by the basidiomycete Agaricus blazei

The aim of this work was to evaluate the effects of solid-state fermentation (SSF) by basidiomycete Agaricus blazei Murrill (ABM) on the nutritional components and antioxidant properties of wheat, rice, oat, corn, millet, broomcorn millet and sorghum.The results showed that the contents of nutritional components in the fermented cereals varied with the fermentation time. After SSF of ABM, the enhancement rates of millet in total phenols, amino acid nitrogen and water-soluble protein content were the highest, which were respectively 4.03, 12.04 and 10.37 times higher than that of the control; the enhancement rates of wheat in total protein and reducing sugar content were the highest, which were 0.32 and 100.77 times higher than that of control. According to 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging capacity, reducing power, ferrous ion chelating ability and superoxide anion radical scavenging ability of ethanolic extracts from the fermented cereals, it was shown that the antioxidant properties of the cereals were significantly stronger than that of control after fermented by ABM. The improvement degrees of sorghum in DPPH radical scavenging capacity and superoxide anion radical scavenging ability were the highest, the improvement degrees of wheat in reducing power and ferrous ion chelating ability were the highest.