COMPARISON OF THE MALT CHARACTERISTICS OF TRADITIONAL AND IMPROVED VARIETIES OF SORGHUM VULGARE FROM GHANA

The malt characteristics of six agronomically improved varieties of sorghum in Ghana were compared to traditionally grown local varieties. The diastatic activities of the traditional varieties were found to be better than the improved breeds. The Improved breed, Kadaga, produced extract yields comparable to the traditional varieties. Free amino nitrogen content of Nagawhite worts were also comparable to those of the traditional varieties. The malt characteristics of all the varieties tested varied remarkably, but none of the improved breeds was found to be better than the traditional varieties in terms of their potential in brewing.     

FERMENTATION OF WORTS MADE FROM 100% RAW SORGHUM AND ENZYMES

Worts made from raw sorghum and enzymes were successfully fermented even though the level of FAN present (51 mg/l) is well below that essential for fermentation of wort made from malted barley. Changes in typical fermentation parameters such as specific gravity, pH uptake of free amino nitrogen (FAN) and ammonium ions mirrored the increase in yeast cell concentration. Yeast viability remained high throughout the fermentation. Under identical fermentation conditions, malted barley worts showed typical fermentation profiles. However, malted barley worts with specific gravity maintained by the addition of D-glucose, but in which the FAN was diluted to a level similar to that found in a wort made from sorghum and enzymes, fermented more slowly and failed to attenuate fully. Five consecutive fermentations, using yeast cropped from the preceding to pitch the current fermentation were conducted. The specific gravity profiles were essentially the same in all five fermentations. Final values of pH, yeast in suspension, yeast viability and FAN were also indistinguishable. The yeast crop taken from fermentations of worts made from raw sorghum and enzymes represented a 5-fold increase over the initial pitching rate. When compared to commercial beers, the beers derived from fermentation of worts made from raw sorghum and enzymes contained lower levels of ethyl acetate, and higher levels of both 2- and 3-methyl butanol. In the beers derived from sorghum, isobutanol was always less than 20% of the total higher alcohol concentration.     

Malt characteristics of sorghum vulgare varieties from ghana

Two local varieties, a white type and a red type, of Sorghum vulgare cultivated in Ghana were malted, using a micro-malting method, and their malt characteristics studied and compared to that of a commercial barley malt. The optimal germination time, at 30°C, to produce a good malt of high diastatic power and extract from local varieties of these varieties was 4-5 days. The local varieties were also found to have high diastatic activities of between 55 and 68% of the commercial barley malt. Hot-water extracts of the well malted sorghum varieties were also found to have higher and sustainable amounts of free amino nitrogen than the commercial malt. The hot-water extracts of sorghum malts were lower than the commercial barley malt, yielding about 66-77% of the barley malt, but contained a higher glucose to malt ratio. In terms of varietal superiority, the white sorghum yielded higher malt extracts than the red type.     

Inhibitory effects of fucan sulfates on enzymatic hydrolysis of starch

The effect of fucoidan and its oversulfated derivative on starch digestibility was investigated by determining the enzymatic reaction kinetics and their inhibitory activity against α-amylase and amyloglucosidase. After the α-amylase hydrolysis, the produced reducing sugars of the buckwheat starch (BW, 2.0-3.0 g/100 mL) and those of the blends of BW with low levels of native fucoidan (NF, 0.5-1.0 g/100 mL) and oversulfated fucoidan (OSF, 0.5-1.0 g/100 mL) were in the range of 440-450 mg/g starch. The addition of NF and OSF did not significantly influence the α-amylolysis. The hydrolysis of the starch and the fucoidan blends using both α-amylase and amyloglucosidase was decreased to 12% by the addition of 1.0 g/100 mL OSF, while only 5% reduction of the starch hydrolysis by 1.0 g/100 mL NF. The inhibitory activity of NF on amyloglucosidase was negligible, but that of OSF on amyloglucosidase was considerable up to 21.2% at the concentration of 10 mg/mL with non-competitive inhibition mechanism. It was suggested that the substantial reduction of starch hydrolysis by the addition of OSF may be caused by a direct inhibition of amyloglucosidase activity, implying a possible application of OSF as an enzyme inhibitor.     

Effect of citric acid esterification conditions on the properties of the obtained resistant starch

This study was aimed at comparing selected properties of starch citrate obtained from native or retrogrades of potato starch at various temperatures (100, 130 or 160 °C) and at various doses of reactant (10, 20 or 40 g per 100 g). Higher susceptibility to esterification was demonstrated for retrograded starch, whereas the degree of esterification of the produced esters varied considerably (1.4 to 10.0 g per 100 g preparation) and was increasing along with increasing roasting temperature and dose of citric acid. The process of pasting occurred only in the esters obtained at a temperature of 100  °C, which resulted in a significant decrease in swelling power and solubility in water of the citrates produced at higher temperatures. The resultant starch citrates were characterised by significant resistance to amylolysis (ranging from 22 to 100 g per 100 g). There was observed an increase in starch resistance along with the increase in the acid dose and roasting temperature. All analysed properties of starch citrates were not correlated with the degree of esterification, but appeared to depend on the roasting, which may point to a significant effect of this factor on the mechanism of starch cross‐linking with citric acid.     

Morphology and structural properties of high-amylose rice starch residues hydrolysed by amyloglucosidase

High-amylose starches are attracting considerable attention because of their potential health benefits and industrial uses. Enzyme hydrolysis of starch is involved in many biological and industrial processes. In this paper, starches were isolated from high-amylose transgenic rice (TRS) and its wild type rice, Te-qing (TQ). The morphological and structural changes of starch residues following Aspergillus niger amyloglucosidase (AAG) hydrolysis were investigated. AAG hydrolysed TQ starch from the granule surface, and TRS starch from the granule interior. During AAG hydrolysis, the content of amorphous structure increased, the contents of ordered structure and single helix decreased, and gelatinisation enthalpy decreased in TQ and TRS starch residues. The A-type polymorph of TRS C-type starch was hydrolysed faster than the B-type polymorph. The short-range ordered structure and B-type polymorph in the peripheral region of the subgranule and the surrounding band of TRS starch increased the resistance of TRS starch to AAG hydrolysis.     

PROPERTIES OF A GENETICALLY-ENGINEERED DEXTRIN-FERMENTING STRAIN OF BREWERS' YEAST

A dextrin-fermenting strain of brewer's yeast was obtained by transformation with a recombinant plasmid (pLHCD6) containing a DEX gene. The transformant produced five-fold more extracellular amyloglucosidase (AMG) than the strain of Saccharomyces diastaticus from which DEX was cloned. The growth rate, however, was adversely affected and, consequently, the transformant fermented wort more slowly than the parental (untransformed) strain. A mixed culture was therefore used at pilot-scale, to maintain a rate of fermentation similar to that of the parental strain. The transformant by itself was capable of superattenuating wort (original gravity 1.040) to a specific gravity of 1.0023 (compared with 1.0046 for the parental strain). This represents the expected degree of dextrin breakdown by an AMG with no “debranching” activity which can only hydrolyse alpha-1,4 linkages. A high copy number for the plasmid pLHCD6 was maintained throughout fermentation. The beers produced using the Dex+ transformants were judged to be of sound quality.     

高粱醇溶蛋白消化性研究

该文介绍高粱醇溶蛋白的提取方法,特性和消化性测定方法,并简单分析高粱醇溶蛋白发展前景。     

基于酸水解法酿酒糯高粱与粳高粱结合态香气研究

为探索糯高粱和粳高粱对酿酒品质的影响,采用固相萃取吸附前体物质、酸水解释放挥发性成分,应用HS—SPME结合GC—MS定性、定量高粱结合态香气成分。在两种高粱中共检测到21种结合态香气物质(其中3种为临时性鉴定的),包括5种醇类、7种醛酮类、5种芳香族、3种萜烯及降异戊二烯类和1种呋喃类化合物。研究发现,糯和粳高粱结合态香气化合物总量分别为7 192,6 922μg/kg,糯高粱水解后香气化合物总量比粳高粱高3.90%。含量差异较大的是醛酮类化合物,其次是萜烯及降异戊二烯类化合物。2,2,6-三甲基环己酮、TDN、异佛尔酮首次在高粱结合态香气中检测到。     

十二种中国高粱的高粱蜡和高级烷醇含量分析

从全国各主产区采集12种有代表性的高粱样品,测定高粱籽粒中蜡和高级烷醇的含量,结果显示,高粱籽粒中蜡含量在0.2050%～0.3700%之间,其中内杂5号、白杂8号和辽杂1号等品种的高粱蜡含量较高。高粱籽粒中二十八烷醇含量为0.0304%～0.0778%,吉林吉杂97、吉林四杂1号和天津杂交高粱等为二十八烷醇含量较高的品种。高粱籽粒中含有三十烷醇0.0351%～0.0922%,其中吉杂97、四杂25号和辽杂1号等为三十烷醇含量较高的品种。     

Purification and characterization of a novel glucoamylase from Fusarium solani

Thermostable enzymes are currently being investigated to improve industrial processes of starch saccharification. A novel glucoamylase was purified to electrophoretic homogeneity from the culture supernatant of Fusarium solani on a fast protein liquid chromatographic system (FPLC). The recovery of glucoamylase after gel filtration on FPLC was 31.8% with 26.2-fold increase in specific activity. The enzyme had a molecular mass of 40 kDa by SDS-PAGE and 41 kDa by gel filtration. The glucoamylase exhibited optimum activity at pH 4.5. The K_cat and K_m were 441/min and 1.9 mg/ml, respectively, for soluble starch, specificity constant (K_cat/K_m) was 232. The enzyme was thermally stable at 50 °C and retained 79% activity after 60 min at this temperature. The half-life of the enzyme was 26 min at 60°C. The enzyme was slightly stimulated by Cu²⁺ and Mg²⁺ and strongly inhibited by Hg²⁺, Pb²⁺, Zn²⁺, Ni²⁺ and Fe³⁺.     

Aflatoxins,ochratoxins and zearalenone in sorghum and sorghum products in Sudan

This survey examined 60 samples of sorghum and 30 samples of sorghum products from three states (Khartoum, Kordofan and Gadarif) of Sudan for aflatoxin B1, B2, G1 and G2 (AFB1, AFB2, AFG1, AFG2), ochratoxin A and B (OTA, OTB) and zearalenone (ZEN), using high performance liquid chromatography with fluorescence detection. The limits of detection and limits of quantification were in the range 0.01–0.6 µg kg^–1 and 0.03–2.0 µg kg^?1, respectively. The frequency of contaminated samples with AFB1 from Khartoum, Gadarif and Kordofan state was 38.1%, 22.2% and 23.8%, respectively. Only two samples of sorghum from Khartoum state were contaminated with OTA (3.3%). Concentrations of OTA and OTB were low and may not cause problems. No sample of sorghum or sorghum products was contaminated with ZEN. Some sorghum samples contained AFB1 concentrations above the European Union regulatory limits. The highest contaminated samples were found in Khartoum state.     

基于GC-IMS技术的高粱米风味分析

高粱米自古就是我国人民的口粮。以高粱米作为研究材料,尝试利用气相色谱-离子迁移谱（GC-IMS）技术分析高粱米在蒸煮过程中挥发性物质的变化。结果表明：高粱米中的挥发性物质以酮类、醛类、酯类化合物为主,高粱米饭的呈香物质有苯乙醛、己醛、2-戊基呋喃、乙酸己酯等。在蒸煮过程中,蒸煮40~60 min时香气最为浓厚,检测出挥发性物质种类最多,可作为最佳加工时间。对数据进行方差分析发现：蒸煮后的高粱米饭样品能表征更多风味信息,若采用挥发性物质对高粱米进行判别分析,可优先选择将高粱米蒸煮后对高粱米饭进行分析,以提高分辨率。     

REGULATION OF AMYLOGLUCOSIDASE PRODUCTION BY SACCHAROMYCES DIASTATICUS

In wort fermentations, production of extracellular amyloglucosidase (AMG) by Saccharomyces diastaticus was greatest, and initiated earliest, when the requirement of yeast for oxygen or unsaturated lipid was incompletely satisfied. During such fermentations, maltotriose disappeared before maltose, glucose, the product of AMG action, accumulated and the wort was inadequately attenuated. In all circumstances examined, commencement of dextrin breakdown coincided with initiation of AMG excretion. Prior to excretion, active enzyme was associated with yeast cells but was located externally to the plasma-membrane. Dextrin or starch was not required to induce AMG production which is initiated, we conclude, when the carbon and energy-source becomes growth-limiting. S. diastaticus strains hydrolysed only a small proportion of wort dextrine and AMG produced in beer was unable to release glucose from pullulan. For production of low carbohydrate beer, strains which (i) synthesise significant amounts of a ‘debranching’ enzyme and (ii) are catabolite-derepressed for AMG production would be advantageous.     

THE CARBOHYDRATES OF BARLEY GRAINS — A REVIEW

The carbohydrate composition of barley grains and the structure of barley carbohydrates is described and related to their influence on grain quality and utility. The adequacy of methods used for the analysis of barley carbohydrates is also critically evaluated. Low molecular weight carbohydrates, glucose, fructose, sucrose, maltose, fructosylsucrose and raffinose; non-structural polysaccharides, fructans and starch; and cell wall polysaccharides, including beta-glucans and arabinoxylans are included.     

单粮发酵和多粮混合发酵对比试验研究

对高粱和大米混合发酵与单纯高粱发酵所得原酒进行对比分析研究。结果表明,采用高粱和大米混合发酵所得原酒总酯高于单纯高粱发酵,且其中己酸乙酯、乙酸乙酯、乳酸乙酯及丁酸乙酯含量也较高;但单纯高粱发酵总酸含量高于高粱和大米混合发酵,尤其是丁酸和己酸。通过感官品评发现,高粱和大米混合发酵所产原酒感官品评略优于单纯高粱发酵,完全符合浓香型白酒香、绵、甜、净、长及香味谐调的特点。这为多粮代替单粮发酵生产高炉家酒提供了实验依据,也为进一步扩大生产奠定理论基础。     

粳高粱和糯高粱酿造的川法小曲白酒风味物质差异分析

目的 解析粳高粱和糯高粱酿造的川法小曲白酒风味物质差异。方法 对发酵过程酒醅理化指标和出酒率进行了检测分析,利用顶空固相微萃取气相色谱质谱联用法(headspacesolidphasemicroextraction coupled with gas chromatography-mass spectrometry, HS-SPME-GC-MS)、氢火焰气相色谱法(gas chromatography flame ionization detector, GC-FID)、偏最小二乘判别分析(partial least squares discriminant analysis, PLS-DA)结合感官评定分析了基酒挥发性风味物质。结果糯高粱原料出酒率极显著高于粳高粱(P<0.01);HS-SPME-GC-MS共检测出39种物质,主要为酯类和醇类物质;粳高粱发酵基酒中异丁醇、异戊醇和乙醛含量显著高于糯高粱发酵基酒(P<0.05,P<0.01),糯高粱发酵基酒中乙酸乙酯和乙酸含量显著高于粳高粱发酵基酒(P<0.05, P<0.01)。结论 出酒率和主要风味物质的...     

单粮发酵和多粮混合发酵对比试验研究

试验对高粱和大米混合发酵与单纯高粱发酵所得原酒进行对比分析,结果得出,采用高粱和大米混合发酵所得原酒总酯高于单纯高粱发酵,且其中己酸乙酯、乙酸乙酯、乳酸乙酯及丁酸乙酯含量也均高于单纯高粱发酵;但单纯高粱发酵总酸含量高于高粱和大米混合发酵,尤其是丁酸和己酸含量均显著高于高粱和大米混合发酵。通过感官品评,结果发现高粱和大米混合发酵所产原酒感官品评略优于单纯高粱发酵,完全符合浓香型白酒香、绵、甜、净、长及香味谐调的特点。这为多粮代替单粮发酵生产高炉家酒提供可能。     

粳糯高粱的酿酒工艺参数研究

研究了粳高粱和糯高粱的酿酒工艺参数,结果表明,糯高粱具有吸水量小、吸水速率快、吸水膨胀率小、糊化温度高等特点;而粳高粱则与此相反。因此,在酿酒生产上,要根据不同类型高粱的酿酒品质特性,适当调整生产工艺。