LEVELS OF ALKALI-SOLUBLE β-D-GLUCANS IN CEREAL GRAINS

Extraction of β-D-glucans (primarily from barley grains) using sodium hydroxide solution, gave similar results to those obtained using hydrazine extraction, suggesting that the alkali is as effective as hydrazine for the extraction of β-D-glucans. Commercial growth conditions in different European countries caused limited shifts in the β-D-glucan levels of malting barley samples. Sorghum and wheat grains contained significantly less β-D-glucans than barley. Potassium bromate solution inhibited initial breakdown of β-D-glucans during the malting of barley grains. The breakdown of β-D-glucan in Sonja barley was much slower than in Golden Promise barley, during malting.     

小麦淀粉磷酸酯取代度的测定

本实验采用总磷减去游离磷的方法求出结合磷,并对总磷及游离磷的测定条件进行摸索,从而得出一个新的方法,可以简捷快速、可靠的测定淀粉磷酸酯的取代度,为指导实验室研究工作及保证生产中产品质量稳定提供依据。     

ULTRASTRUCTURE OF THE CELL WALLS OF THE TRANSPORT PATHWAY FOR GIBBERELLIC ACID IN BARLEY ALEURONE LAYER

Transmission and scanning electron microscopic studies of the scutellum-aleurone junction of barley suggest that, in the absence of plasmodesmata connections, the transport of gibberellic acid from the scutellum to the aleurone layer is effected by apoplastic transport across 3–4 μm thick cell walls. Transport of gibberellic acid along the aleurone could be apoplastic as well as symplastic because large numbers of plasmodesmata are present in the 4 μm thick cell walls, through which the hormone could pass from cell to cell. Structurally, the scutellum is separated from the starchy endosperm by a 30 μm thick layer of compressed cell wall material across which transfer of either gibberellic acid to the aleurone or small quantities of non-specific β-glucanase enzymes (E1) from the scutellum to the starchy endosperm would be restricted. No such barrier is present between the aleurone layer and the starchy endosperm, where cell wall thickness is about 4 μm, and the release of endosperm-degrading enzymes into the starchy endosperm is not restricted .     

THE PERMEABILITY OF THE SURFACE LAYERS OF CEREAL GRAINS,AND IMPLICATIONS FOR TESTS OF ABRASION IN BARLEY

The husk of barley, and the pericarps of naked, husked and ‘stripped’ barleys, of wheat and rye are more or less permeable to aqueous solutions of salts, or Eosin. The pericarps of stripped barley grains conduct aqueous solutions so that, for example, they conduct solutions of Eosin, or [¹⁴C]-gibberellic acid from the apex to the base of the grain where it accumulates in the embryo region. On the other hand the husk and pericarp are not so readily permeated by aqueous Trypan Blue. The testa/nucellar cuticle, together with the pigment strand, limits the inward penetration of salts and dyes. Gibberellic acid, and apparently water also, traversed the testae of some, but not all, decorticated barley grains, as demonstrated by the consequent modification of the starchy endosperms. However in most instances gibberellic acid solution does not traverse the surface layers of stripped grains and induce modification in their endosperms.     

洗涤剂中微量总磷含量分析方法的研究

采用硝酸－高氯酸消解、氯化亚锡还原光度法检测液体洗涤剂中总磷含量，从而建立了液体洗液剂中微量总磷分析方法。此方法操作简单、准确、快速，方法最低检出限ＤＬ＝０．００６ｍｇ／Ｌ，加标回收率１０３％，精度〈５％。该方法既有学术价值又有实用价值。     

烷基磷酸酯中单、双酯含量的测定

根据磷酸三步离解原理,采用电位滴定的方法,快速测定烷基磷酸酯中单、双酯含量.为准确控制磷酸酯合成工艺及产品质量,提供了一种简便有效的方法.     

RELATIONSHIPS BETWEEN THE DURATION OF STEEPING,GRAIN MICROBES,GRAIN MATURITY AND THE RESPONSE OF DE-EMBRYONATED GRAINS TO GIBBERELLIC ACID

After steeping, with and without antimicrobial agents in the steep liquor, for 20 h or 60 h, barley grains were degermed. α-Amylase, produced in response to a fixed dose of gibberellic acid applied to the scutellar recess, was estimated at intervals during a subsequent incubation period. When samples with similar steeping periods were compared it was seen that enzyme production was greater in those that had been steeped in the presence of antimicrobial agents. This was particularly clear in samples that had been steeped for 60 h. Furthermore, grain which had been steeped for 60 h before de-embryonation produced more α-amylase, in response to gibberellic acid, than grain which had received a 20 h steep. Sub-samples of three lots of grain were warm-stored to overcome water sensitivity. When such grains were steeped, degermed and dosed with gibberellic acid they tended to produce more a-amylase than samples of control, cool-stored grain of the same original lots similarly treated and incubated. It is concluded that microbial activity on the surface layers of the grain, ‘maturity’ of the aleurone layer (enhanced by warm storage) and the duration of the steeping period all influence the responsiveness of barley aleurone layers to a dose of gibberellic acid.     

ENZYME DEVELOPMENT IN THE ALEURONE AND EMBRYOS OF GALANT AND TRIUMPH BARLEYS

The aleurone layer of the pro-anthocyanidin free barley, galant, produced less endo-beta-(1–3, 1–4) glucanase and alpha-amylase than the aleurone of triumph. The slower rate of endosperm breakdown (modification) of galant is associated with its reduced potential to produce the cell-wall-degrading enzyme, endo-beta-(1–3, 1–4) glucanase.     

THE DETERMINATION OF GERMINATED GRAINS IN BARLEY

A method for determining germinated grains in barley by detecting the presence of α-amylase activity in individual corns is recommended.     

DETERMINATION OF MOISTURE,TOTAL AVAILABLE EXTRACT AND SOLUBLE EXTRACT IN SPENT GRAINS

The methods for the determination of moisture⁴, total available^3,4 and soluble extracts⁴ in spent grains have been collaboratively tested by members of the Analysis Committee of the European Brewery Convention to obtain repeatability (r₉₅) and reproducibility (R₉₅) values . Repeatability and reproducibility values of 0.1 and 0.67 respectively were obtained for spent grain moisture's ranging between 4 and 8% m/m in pre-dried and pro-milled samples. In a pro-dried and unmilled sample containing 3.4% m/m moisture the values obtained were 0.3 and 1.5 respectively . For total available extract (MEBAK) these values were 0.5 and (2.2+0.045 m) respectively, with total available extract ranging from 9 to 42% m/m dry matter, where m refers to the actual value. The values for the pre-dried and unmilled sample containing an extract of 41.2% m/m were 0.5 and 4.6 respectively . The precision values for soluble extract were dependent on the extract level of the sample over the range 6 to 40% m/m dry matter. A repeatability value of 0.13+0.007 m and a reproducibility value of 0.2+0.06 m were obtained over this range. Values for the same pre-dried and unmilled sample with a soluble extract of 38.7% m/m were 1.3 and 3.8% m/m respectively .     

THE INFLUENCE OF LIPIDS DERIVED FROM MALT SPENT GRAINS ON YEAST METABOLISM AND FERMENTATION

The addition to wort of lipids derived from malt spent grains had a pronounced effect on yeast metabolism. The lipids allowed the fermentation of de-oxygenated wort and also stimulated yeast growth and the corresponding rate and extent of fermentation of air-saturated wort by yeast strains having a high oxygen requirement. The lipids increased the fusel alcohols content of beer and decreased the content of esters and medium chain-length fatty acids. The yeast incorporated sitosterol and unsaturated fatty acids from the spent grain lipids and the unsaturated fatty acids changed the pattern of fatty acids and sterols synthesized by the yeast. The fatty acids were present in the spent grain lipids mainly as triglycerides, free fatty acids and phospholipids. Using pure lipid compounds it was shown that the triglycerides were inactive and that the spent grain lipids exerted their effect on fermentation through the synergistic action of free unsaturated fatty acids, sitosterol and phospholipid. Phospholipid could be replaced by the detergent, Triton X-100. The effect of the lipids on the synthesis of esters, fusel alcohols and medium chain fatty acids could be explained solely by their content of unsaturated fatty acids.     

QUANTITATIVE CHANGES IN THE CONCENTRATIONS OF THE MAJOR COMPONENTS OF FOUR GENOTYPES OF BARLEY GRAINS DURING MALTING AND MASHING

Four genotypes of barley, including good and poor malting varieties, were sampled as grain, green malt, kilned malt and spent grains. Each of these samples were analysed for total protein, aggregated protein, total and soluble β-glucan, starch and husk contents. Protein sub-units were separated using sodium dodecyl sulphate polyacrylamide electrophoresis. Activities of β-glucanase, endopeptidase and α-amylase were measured and starch from each sample was purified and separated into large and small granules, and analysed for total protein and sub-unit protein content. Results calculated as % of dry weight and as a proportion of the weight of dry grain showed quantitatively the changes which occurred in the components of the grain during malting and mashing. Comparisons of the composition of the genotypes at the various stages showed that the best malting variety studied, Ark Royal, was better because of moderate superiority in several characters rather than a fundamental difference in a single attribute and supports the thesis that to further improve malting quality plant breeders should select for several characters which are independently inherited.     

THE RELATIONSHIP OF DIMETHYL SULPHIDE LEVELS IN MALT,WORT AND BEER

The half-life for the conversion of malt dimethyl sulphide (DMS) precursor to free DMS has been determined at various temperatures and pH values. At pH 5·2 the half-life of the precursor in wort (S.G. 1·060) at its boiling point is 38 min, and is doubled for each 6°C fall in temperature. At pH 5·5 the half-life at the boiling point is 32·5 min. Knowing the stability of the precursor at the various temperatures in the brewing process, the extent of conversion to free DMS in wort at pitching can be predicted for malt of a given precursor content and for a given set of process conditions. The results of DMS analyses of samples taken during brewery trials are in reasonable agreement with the predicted values. This work involved infusion mashing only, but the same principles apply to decoction mashing. The fate of precursor and free DMS during fermentation and conditioning has been followed on a production scale. With some brews, where high levels of free DMS were present at pitching, much free DMS was lost during fermentation. Also, precursor DMS reappeared in the beer after a few days and there was some increase in the level of free DMS. The DMS precursor in green malt has been isolated by ion-exchange and gel-filtration chromatography. A preparation has been obtained which has 0·6 mol potential DMS per mol amino nitrogen. Thin layer chromatography showed that the preparation and its hydrolysis product had the same R_f values as S-methylmethionine and homoserine respectively.     

蜂窝陶瓷固定化酵母细胞啤酒连续后发酵工艺的研究

将蜂窝陶瓷用作酵母细胞固定化的载体，进行啤酒连续后发酵试验研究。应用均匀试验设计法来安排试验．对试验数据进行统计分析及最优化处理，并通过验证试验，获得优化的工艺条件为：发酵温度13～14℃，稀释率0．142h^-1。啤酒主要理化指标的测定和口味品评结果表明：与传统工艺相比，采用蜂窝陶瓷固定化酵母细胞啤酒连续后发酵工艺不会影响啤酒的品质，而后发酵时间可大为缩短。     

ISOLATION AND PARTIAL CHARACTERIZATION OF THE DIMETHYL SULPHIDE PRECURSOR IN GREEN MALT,AND ITS EFFECT ON BEER DIMETHYL SULPHIDE LEVELS

The component from which dimethyl sulphide (DMS) is produced when green malt worts are heated has been purified and its effects on wort and beer DMS levels studied. The green malt precursor can be split into S-methylmethionine and an as-yet uncharacterized ninhydrin-positive component. When the purified precursor is added to worts derived from kilned malts, it is rapidly taken up by yeast, but there is no resulting increase in DMS production. DMS production during fermentation occurs with worts made from kilned malts but not with worts from green malt; however, this difference is not due to an inhibitor being present in green malt worts. The evidence suggests that malt kilning affects the nature as well as the amount of DMS precursor in malts.     

国产PS版的现状和发展概述

我国商业性生产PS版开始于1978年,计算我国历年PS版的年产量,则1992年国内PS版的年产量相当于前十年总和。我国的PS版制造业在短短的十多年中,取得令人瞩目的成绩,得到了飞速发展。1989年,我国PS版年产量首次突破500万M~2,成为我国新崛起的印刷器材业生产业——PS版制造业。     

ON THE DIFFERING RATES OF FRUCTOSE AND GLUCOSE UTILISATION IN SACCHAROMYCES CEREVISIAE

Fructose is utilised slower than glucose when the two sugars are fermented separately. This phenomenon occurs in a growth promoting medium as well as in brewers wort when using the brewing yeast Saccharomyces cerevisiae. The use of a fructose adjunct in wort at concentrations of 2% w/v and above, may result in residual concentrations of fructose to remain at the end of fermentation and consequently taint the beer with a sweet off-flavour. Glucose and fructose have no effect on maltose utilisation. Thus they do not exert catabolite repression on the maltose membrane transport system in the particular brewing strain of S. cerevisiae under investigation, when fermented in brewers wort.     

THE PRESENCE OF TWO DIMETHYL SULPHIDE PRECURSORS IN MALT,THEIR CONTROL BY MALT KILNING CONDITIONS,AND THEIR EFFECT ON BEER DMS LEVELS

The precursor of dimethyl sulphide (DMS) which is formed during barley germination and is present in green malt differs from that present in malt kilned at high (> ～75°C) temperatures in that it cannot be metabolized to DMS by yeast. It is therefore termed ‘inactive’ precursor to distinguish it from the ‘active’ precursor present in kilned malt, which is metabolized to DMS by yeast. During malt kilning, inactive precursor is changed into the active form, but only at temperatures at which destruction of both precursors is also taking place. Therefore, for any kiln there is an optimum temperature range over which maximum conversion of inactive to active precursor can be combined with minimum destruction of both precursors. The DMS in beers brewed from green malt or malts kilned only at low (< ～70°C) temperatures is almost entirely the result of precursor destruction during wort boiling, final levels being governed not only by the conditions of boiling, but also by the extent of losses during fermentation and subsequent processing. In contrast, the DMS in beers brewed from malts kilned at higher temperatures is mostly formed during fermentation, and since beer DMS levels can be related to wort and beer DMS precursor levels, they can be better predicted and controlled. The method used for the measurement of total DMS precursor levels in malts is described in detail.     

AN ENZYMIC METHOD FOR THE MEASUREMENT OF TOTAL AND WATER-SOLUBLE β-GLUCAN IN BARLEY

Crude cellulase preparations from Trichoderma reesei, freed of amyloglucosidase by heating, will completely hydrolyse barley β-glucan to glucose. Apparent non-quantitative recovery of glucose is due to its adsorption by the high levels of protein present. Methods are given for the measurement of total and water-soluble β-glucan. Dehusking does not lower the amount of β-glucan which is measured.