STRUCTURAL ANALYSIS ON THE AMYLOPECTIN OF WAXY-BARLEY LARGE STARCH GRANULES

The hydrolysis of waxy-barley starch by the α-amylase of B. subtilis was followed by gel chromatography on Sepharose CL 6B. A range of intermediate dextrins were initially produced, and at later stages dextrins with a degree of polymerization in the range 100–200 accumulated. Maltohexaose was produced simultaneously from the external chains. The hydrolysis of the amylopectin β-limit dextrin followed a similar pattern, though smaller amounts of the low-molecular weight material were formed. The sizes of the more resistant products in the hydrolysis mixtures suggested that the amylopectin contained two types of unit clusters with d.p. for the β-limit dextrins of 65 and 85. A regular model for the structure of the amylopectin that shows the possible mode of interconnection of the unit clusters is presented .     

AMYLOLYSIS OF LARGE STARCH GRANULES FROM BARLEYS IN RELATION TO THEIR GELATINISATION TEMPERATURES

Large starch granules, prepared from a range of barley samples, show considerable variation in their susceptibility to attack by α-amylase at 65°C. Susceptibility is not correlated with their protein content, amylose/amylopectin ratio or gelatinisation temperature as measured by loss of birefringence. It does correlate with gelatinisation as measured by swelling of the granules or their staining with Congo Red. When granular expansion is taken as the measure of gelatinisation, the more resistant starches show gelatinisation curves displaced to higher temperatures.     

THE IN VIVO AND IN VITRO DEGRADATION OF BARLEY AND MALT STARCH GRANULES

The susceptibilities to amylolytic hydrolysis of the two different types of starch granule in barley and malt have been investigated. The large and small granules from both germinated and ungerminated grain were subjected to the sole action of malt α-amylase under conditions which otherwise simulated those of a conventional infusion mash. Large starch granules from barley are hydrolysed at a slower rate than those from malt. The faster conversion of the latter is attributed to prior modification of the starch granule structure during germination. The small granules from barley are extremely resistant to attack by α-amylase and even pre-cooking does not appreciably increase their susceptibility to amylase attack. Although the small starch granules from malt are less susceptible than the corresponding large granule fraction, they can be hydrolysed to a greater extent than can the small granules from barley. The increased susceptibility of small granules from malt is probably due to the partial removal of their protecting surface layer of protein. Although during malting the small granules of barley are hydrolysed more rapidly than the large granules, the situation is reversed during mashing. Very little loss of extract can be attributed to the enzymic resistance of small starch granules in all-malt mashes. If raw barley is used in the grist, substantial amounts of small starch granules may remain in the mash.     

INITIAL STAGES IN α-AMYLOLYSIS OF BARLEY STARCH

The initial stages in α-amylolysis of large and small barley starch granules were followed by gel chromatography. Hydrolysis of gelatinised large and small granules is very similar, indicating a similar structure of the individual components in the two starches. Amylolysis of intact large granules is quite different from that of intact small granules, suggesting differences in the mode of packing of the starch components within the granules. It is concluded that α-amylolysis is of a non-random nature, probably due to the amylopectin component of the starch. On the basis of the intermediate products obtained, a possible structure for the amylopectin molecule is presented, based on a unit cluster with a molecular weight of 3 × 10⁴.     

LIPOLYTIC AND OXIDATIVE CHANGES OF BARLEY LIPIDS DURING MALTING AND MASHING

Lipolytic and oxidative changes of barley lipids were studied during malting and mashing. The amount of lipid decreased by 23% during malting and changes in the composition of lipid classes were minor. On the other hand, during mashing the amount of free fatty acids (FFA) increased which indicated, that lipid hydrolysis had occurred. The same phenomenon was seen when malt flour was soaked in water at 23°C. The triglyceride (TG) and polar lipid (PL) contents were reduced and the proportion of FFA in total lipids was increased. Following similar soaking of barley flour, TG and PL were reduced but the accumulation of FFA and especially linoleic acid (LA) was slight. The results were consistent with the data on lipoxygenase activity (LOX) during malting. During steeping LOX decreased and was 15–20% of the activity of raw barley at the beginning of germination. The activity remained low during germination but rose sharply in the middle of kilning only to decrease again to a very low level at the end of kilning (5%). This in combination with the fact that the proportion of FFA remained high in the soaked malt samples suggests that the oxidation by LOX is negligible in the malt samples. However, the data suggest that mashing of barley, but not that of malt, includes the potential for the formation of highly polar lipid oxidation products.     

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.     

AMYLOLYSIS OF SORGHUM STARCH AS INFLUENCED BY CULTIVAR,GERMINATION TIME AND GELATINISATION TEMPERATURE

The susceptibility to amylolysis of starches derived from two improved Nigerian sorghum cultivars were evaluated at assay temperatures between 50°C and 75°C. Enhancement of gelatinisation rates at temperatures up to 65°C was not significant inspite of the apparent grain modification due to germination for four days. Greater starch gelatinisation rates (20–22%) were achieved in this study compared to previously reported values, suggesting possible roles for cultivar and malting methods. There was a statistical correlation between starch gelatinisation rates over the temperature range 65°C–75°C and the duration of grain germination (r=0.91 for KSV8 and r=0.5 for SK5912 starches). Gelatinisation rate and temperature were affected significantly by assay pH. The occurrence of two pH related maxima of starch gelatinisation for both cultivera at all temperatures examined indicates the possible presence of two sets of “binding forces” within the starch granules and features of starch retrogradation .     

A CRITICAL EXAMINATION OF PROCEDURES FOR THE ISOLATION OF BARLEY STARCH

A study has been made of the methods available for isolating and purifying barley starch granules. A detailed examination involving light and scanning electron microscopy and Coulter counter analysis has indicated that discarding the brown protein layer, which appears on top of centrifuged suspensions of crude starch, results in severe loss of small granules. A protocol is suggested whereby this brown layer is purified separately and then added back to the white layer to give representative starch granule preparations without loss of small granules.     

A RAPID AND SIMPLE METHOD FOR THE DETERMINATION OF STARCH AND β-GLUCAN IN BARLEY AND MALT

A simple and precise method suitable for the routine determination of starch and β-glucan in barley and malt is described. Perchloric acid (50 mM) was used to effect rapid (3 min) and exhaustive extraction of both glucans which were then measured directly from this single extract by specific enzymic hydrolysis of the individual glucans to glucose. The glucose was also measured enzymically. Little or no acid hydrolysis of starch or β-glucan was observed under the extraction conditions used; most or all of the free glucose could be attributed to hydrolysis of sucrose. Complete solubilisation of the gum and hemicellulosic components of β-glucan was achieved. Preincubation of the acid extracts with protease prior to amyloglucosidase digestion resulted in higher measurements (approximately 4% w/w) of starch. The method was used to measure the levels of starch and β-glucan in five varieties of barley with contrasting malting quality, in micro-malts prepared from these samples and in commercial lager and ale malts.     

STARCH DEGRADATION IN ENDOSPERMS OF DEVELOPING BARLEY KERNELS*

Shortly after anthesis, empty endosperm cells adjacent to the embryo were crushed between the developing embryo and endosperm tissues to form the crushed cell layer. Starch granules in cells adjacent to this layer were hydrolysed and the empty cells were added to the crushed layer. In this way, the crushed layer increased in thickness throughout kernel development. α-Amylase 2 was detected in the crushed cell layer region of barley endosperms during the period that starch granule hydrolysis was occurring.     

EFFECTS OF GAMMA IRRADIATION OF BARLEY AND MALT ON MALTING QUALITY

Two two-rowed barley cultivars, Tokak and Clerine, were irradiated at two different dose ranges (0.05–0.75 kGy and 0.5–5.0 kGy) using a ⁶⁰Co source. Irradiation of barley at the medium levels before malting had detrimental effects on most of the malt quality criteria. The detrimental effects of irradiation was lower at doses up to 0.25 kGy. Irradiation of malt samples caused either slight or no deterioration of quality characteristics .     

淀粉微球的研究与开发进展

淀粉微球是一种新型的可生物降解材料,诸多优良特性使其应用在医药、食品、化工等领域.对淀粉微球的性能、制备方法和应用进行概述,并提出淀粉微球今后的发展方向.     

微波提取荔枝多糖及冲剂的研制

采用正交试验法优化了微波提取荔枝多糖的条件,研究了多糖冲剂制备工艺,并用苯酚-硫酸法对荔枝多糖冲剂中多糖含量进行测定.结果表明,以水为溶剂,荔枝多糖最佳提取条件为:提取时间10min,微波功率为640 W,液料比为9∶1.荔枝多糖冲剂配方为:粗多糖∶可溶性淀粉∶甜蜜素为1∶4∶0.04,冲剂中多糖含量为6.226%.     

NON-STARCH POLYSACCHARIDES FROM BARLEY: STRUCTURAL FEATURES AND BREAKDOWN DURING MALTING

An extraction procedure is described for the complete solubilisation and fractionation of non-starch polysaccharides (NSP) from barley and malt, using ethanol, water and 4-methylmorpholine-N-oxide. Important structural features of the NSP are preserved with this non-destructive procedure. The fractionation method enables the investigation of structural features of NSP fractions and of NSP breakdown during malting.     

A GEL FILTRATION STUDY ON THE ACTION OF BARLEY α-AMYLASE ISOENZYMES ON GRANULAR STARCH

Small starch granules are hydrolysed better than large granules by barley α-amylase isoenzymes. The major isoenzyme in barley is less active against both types of granules than the minor isoenzyme. Molecular weight distribution analysis of the hydrolysates shows that the action pattern of the two enzymes is almost identical. Though minor differences in the intermediate products are obtained, the major product from both starches is dextrins with a degree of polymerisation of 6–8.     

INFLUENCE OF SOIL NUTRIENT LEVELS ON HARVEST YIELD AND MALTING QUALITY OF BREWING BARLEY

Four levels of N, P and K nutrition (poor, moderate, satisfactory and high) and all their possible combinations with 64 treatments in two replications (128 plots) were studied in a long term field trial on barley yield and malting quality. A standard East-European spring barley “Opal” (bred in Czechoslovakia) was grown in 1986, 13th year of the agricultural experiment, involving various crops in previous years, on a calcareous loamy chernozem soil. The optimum fertility levels for yield enhancement resulted in the poorest malting quality: low modification and extract but long saccharification time and high protein. To solve this problem the brewing industry will have to apply the well-known technological methods available since growers are not likely to give up their fertilizers. Applying soil and plant analysis data, having knowledge about both soil and plant optimum values, the danger of the excessive use of fertilizers can be realized and decreased.     

小麦淀粉与谷朊粉生产

指出了小麦淀粉与谷朊粉生产的重要性；简要叙述了小麦淀粉与谷朊粉生产的历史、典型工艺及最新动态。着重介绍了韦斯伐里亚公司的三相卧螺工艺，并对新旧工艺进行对比，指出了小麦淀粉与谷朊粉生产中的关键问题，并进行了探讨。     

大麦的营养价值及在食品业中的利用

简述了大麦的营养成分、提取物及其功能，并指出了大麦在食品工业中的应用现状，以及发展前景。     

EVALUATION OF THE INFRAALYZER 400 FOR THE ANALYSIS OF BARLEY AND MALT

A collaborative study is described of the use of infra-red reflectance for the evaluation of the analytical characteristics of barley and malt. Transfer of centrally-prepared calibrations to other reflectance machines was found to be possible for moisture content and protein content in barley and malt but not for malt extract or malt modification. The examination of infra-red reflectance results, obtained at different wavelengths, by step-wise ascending regression rather than step-wise descending regression showed that the former was more satisfactory, especially in being more rapid in execution.