Influence of Barley and Malt Storage on Lipoxygenase Reaction

The dioxygenation of linoleic acid (LA) by aqueous flour suspensions of barley and malting samples was studied. The rate of this lipoxygenase (LOX) reaction varied as the malting process proceeded, giving a characteristic LOX reaction profile for a malting. The differences in the profiles from one malting to another were dramatic. It also appeared that during storage of dry, intact kernel samples from a single malting, a reduction in the rate of LOX reaction always occurred, and the rates of reduction with time were dependent on the stage of malting at the time of sampling. The kinetics of this aging could roughly be divided into four categories representing different stages of malting. Consequently, greatly varying LOX reaction profiles can be obtained from a single malting depending on the time of storage of kernels before assays. The results indicate that steeping, germination and the subsequent drying render the state of kernels unstable with respect to the LOX reaction for at least two to three weeks. Homogeneity of malt quality is important in the further applications of malt, especially in the brewing industry. Therefore, the rate of LOX reaction should be considered as a quality factor of malt.     

Evolution of phenolic compounds and antioxidant activity during malting

Two barley varieties, Gan4 and Hamelin, were malted to investigate the evolution of phenolic compounds and antioxidant activity during malting. The antioxidant activity was evaluated with DPPH radical scavenging activity, ABTS radical cation scavenging activity, reducing power, and metal chelating activity. Results showed that malting had significant influences on individual and total phenolic contents as well as antioxidant activities of two barley varieties. The contents of some phenolic compounds and the antioxidant activities decreased significantly during steeping and the early stages of germination and then increased remarkably during the later stages of germination and subsequent kilning. The most phenolic compounds identified in barley were (+)-catechin and ferulic acid, which both changed significantly during malting. Moreover, results from the Pearson correlation analysis showed that there were good correlations among DPPH radical scavenging activity, ABTS radical cation scavenging activity, reducing power, total phenolic content and sum of individual phenolic contents during malting.     

Impact of low hydration of barley grain on β-glucan degradation and lipid transfer protein (LTP1) modifications during the malting process

One of the objectives of the malting industry is to reduce the energy cost during kilning without major effect on malt quality. In this study, the impact of a low hydration steeping process on lipid transfer protein (LTP1) modifications and β-glucan breakdown was evaluated in low (LH) and high (HH) hydrated malts. LTP1 modifications analyzed by MS/MS revealed acylation, glycation, and disulfide bond breakage in both LH and HH malts. LTP1 free amine content measurement and fluorescence of Maillard protein adducts revealed no significant difference between LH and HH malts. Immunolabeling of LTP1 during malting highlighted the diffusion of the protein from the aleurone layer to the endosperm at the end of steeping in both LH and HH malts. By contrast, a significant higher amount of β-glucans was measured in LH malts after five days of germination, whereas no significant difference between LH and HH malts was revealed through immunostaining of β-glucans or evaluation of the endosperm integrity after seven days of germination. The possibility to reduce the effects of a low hydration steeping process on β-glucan hydrolysis by increasing germination time was discussed.     

Germination and Malting Properties of Mutants Derived from Malting Barley cv. Triumph

Four mutants, demonstrating a range of dormancy, were derived from the malting barley cv. Triumph. Although there were environmental effects on the rate of recovery from dormancy, relative performance of the genotypes was consistent. Recovery from water sensitivity was slower than recovery from dormancy for all genotypes, but a similar ranking of genotypes was observed with two mutants germinating more readily than the parental genotype. Exposure of the grain to the plant hormone abscisic acid (ABA) at the end of each wet phase during steeping had a highly significant effect on the malting performance of all samples. However, reduction in extract levels was significantly less in the two mutants that demonstrated more rapid recovery from dormancy. None of the mutants exceeded Triumph for hot water extract level after malting in two seasons at sites in Dundee (eastern Scotland) and Lleida (northeastern Spain). However, one mutant combined rapid recovery from dormancy with high extract levels when grown and malted under Scottish conditions and subjected to unithermal hot water extraction.     

Quantitative study of the formation of endoproteolytic activities during malting and their stabilities to kilning

The proteinases of germinating barley (Hordeum vulgare L.) hydrolyze storage proteins into amino acids and small peptides that can be used by the growing plant or, during brewing, by yeast. They are critical for the malting and brewing processes because several aspects of brewing are affected by the amounts of protein, peptide, and amino acids that are in the wort. This study was carried out to quantitatively measure when endoproteinases form in green malt and whether they are inactivated at the high temperatures that occur during malt kilning. Little endoproteolytic activity was present in ungerminated barley, but the activities began forming 1 day into the "germination" phase of malting, and they were nearly maximal by the third germination day. Quantitative studies with azogelatin "in solution" assays showed that the green malt endoproteolytic activities were not inactivated under commercial kilning conditions that use temperatures as high as 85 degrees C but that some actually increased during the final kilning step. Qualitative (2-D, IEF x PAGE) analyses, which allow the study of individual proteases, showed that some of the enzymes were affected by heating at 68 and 85 degrees C, during the final stages of kilning. These changes obviously did not, however, decrease the overall proteolytic activity.     

Nitrogen Uptake by Malting Barley Grown under Conditions Found in Buenos Aires Province,Argentina

Abstract

There is a lack of data associated with applications of nitrogen (N) fertilizer to increase yield while not increasing seed protein to levels exceeding those acceptable for malting barley (Hordeum vulgare L.) in the Buenos Aires province of Argentina. The effect of rates and timing of N application on yield and grain N concentration of malting barley was evaluated at eight sites in 1999 and 2000. Aboveground dry matter accumulation and N‐uptake pattern through the growing season were evaluated. Dry matter production and N-uptake were measured at four sampling times: tillering, head emergence, grain filling, and maturity. The N fertilizer increased grain yield, but its response varied between sites. Under appropriate conditions, the yield increased and maintained the grain N concentration within a desirable range for malting barley. Split applications were as effective in increasing grain yield as one addition at emergence, but they invariably increased grain N concentration. The season affected the yield response to N fertilizer and its levels in the grain, but the nitrogen harvest index was not affected by the rate of N application.     

Lactobacillus plantarum and Pediococcus pentosaceus starter cultures as a tool for microflora management in malting and for enhancement of malt processability

Lactobacillus plantarum VTT E-78076 (E76) and Pediococcus pentosaceus VTT E-90390 (E390) starter cultures were added to the steeping water of normal malting barley in order to balance the microbial community and to enhance malt processability. In this study, we also investigated the effects of lactic acid-acidified MRS-spent medium (MRS-LA) on malting performance. Malting trials with five different two-row barley varieties were carried out in 25 kg pilot scale. The starter cultures promoted yeast growth during malting and restricted the growth of harmful bacteria and Fusarium fungi. Furthermore, they had positive effects on malt characteristics. Reduction in wort viscosity and beta-glucan content and enhanced xylanase and microbial beta-glucanase activities were observed. Starter cultures notably improved lautering performance. Some of the beneficial effects were due to the lactic acid and low pH, as similar effects were obtained with MRS-LA. Starter cultures offer a tool for tailoring of malt properties.     

Thermostability of Barley Malt Proteases in Western Canadian Two‐Row Malting Barley

During the malting process, barley is germinated via a carefully controlled procedure so that its components are degraded to sugars, amino acids, and other low molecular weight compounds that can be used for subsequent fermentation. One of the most important of these processes is the hydrolysis of proteins into peptides and amino acids. During seed germination, proteases hydrolyze insoluble reserve proteins into soluble peptides that are subsequently hydrolyzed into free amino acids. During kilning, green malt is initially air dried at 40–60°C, and then the temperature is gradually increased to 85–95°C. Although most proteases are denatured during kilning, the malt contains a small proportion of heat‐stable protease enzymes able to further break down protein in the subsequent mashing process. In this study, protocols were developed and standardized to measure the activity of different proteases. These protocols were then used to study protease thermostability in Canadian two‐row spring malting barley lines. We found a wide range in protease activity under controlled conditions. Upon heat treatment, several lines exhibited significant protease thermostability. These thermostable enzymes were purified by ammonium sulfate precipitation and Sephadex columns for further study.     

Improvement of malt modification by use of Rhizopus VII as starter culture

The development of a selected starter culture on malting barley and its effects on malt quality aspects were studied. Application of Rhizopus sporangiospores in a malting process resulted in increased beta-glucanase and xylanase contents of the malting barley and improved starchy endosperm cell-wall degradation. Activation of the sporangiospores and optimization of the inoculation procedure led to a further increase in enzyme levels and to larger and more consistent impacts on cell-wall modification. Whereas the main effect of the starter culture on beta-glucan degradation was observed during malting, a further decrease in beta-glucan during mashing suggests that the microbial enzymes that survived the kilning step were active during mashing. Other quality aspects that were influenced by the starter culture activity were protein modification, wort color, and wort pH. The level of microbial enzymes produced was related to the amount of barley kernels infected with the starter culture.     

两份大麦品种单倍体细胞与植株水平耐盐性的关系

为了确定盐胁迫下大麦籽粒产量和萌发期生长指标与小孢子培养阶段盐胁迫下愈伤组织产量之间是否存在一致性,以2份大麦品种为供试材料,进行了以下3项研究:(1)诱导培养基中NaCl含量对小孢子培养愈伤组织产量的影响;(2)萌发液中NaCl含量对大麦种子萌发期生长指标的影响;(3)NaCl 胁迫处理对大麦单株产量的影响.结果表明...     

Improved Methods for High-Throughput Extraction and Assay of Green Barley Malt Proteinase Activity Facilitating Examination of Proteinase Activity Across Large-Scale Barley Populations

We report efficient sample extraction and assay methods allowing quantitative determinations of proteinase activities from barley malt. The improved methods are used to assay >2,200 developmental lines of malting barley for two subsets of proteinase activity. The distributions of the resulting activities suggest differences in population structures between the two types of proteinases. Comparison of the activities of the green malt proteinases with standard malting quality measurements show highly significant correlations that differ between the proteinase subsets. The pH 4.5 hydrolysis of the artificial substrate Z-Phe-Arg-AMC correlates well with the traditional malting quality measurements, supporting the role of cysteine-class proteinases in mobilization of grain reserves during malting and mashing. Results from assays of gelatin hydrolysis at pH 6.0 suggest that these proteolytic activities may be involved in other aspects of seed C and N dynamics also linked to malting quality measurements. The differences between the pH 4.5 and 6.0 activities assayed here and their association with malting quality measurements suggest different physiological roles for the two proteinase activities in several aspects of seed germination. Either assay could be useful for population surveys, depending on the particular facet of seed metabolism under study.     

Effects of traffic on soil aeration, bulk density and growth of spring barley

This paper reports the results of field experiments on several different soils to quantify the effects of different numbers of passes of vehicular traffic on soil aeration status (measured in terms of oxygen diffusion rate, ODR and redox potential, Eh), soil bulk density and development of spring barley. In a further series of field experiments, the effects of single and dual wheels were compared and the effectiveness of a soil loosener operating behind the wheels was evaluated. Additionally, some microplot experiments are reported in which a range of known values of soil bulk density were produced and the effects on soil aeration and development of spring barley were evaluated. It is shown that repeated wheeling, even by a tractor of only about 2 tonnes weight, can produce soil conditions in which aeration can be limiting for crop growth. The use of dual wheels resulted in lower values of soil bulk density and associated greater soil aeration. The loosener alleviated the compaction produced by wheels and also improved soil aeration. For a sandy loam soil, greatest root growth and crop yield occurred at a bulk density of 1.43 Mg m⁻³. Soil aeration as a component of soil physical quality is discussed.     

涌浪机在对虾养殖中的增氧作用

溶解氧是对虾正常代谢和生长中所必需的,为了探索对虾养殖增氧方式的新途径,该文进行了涌浪机在高位池凡纳滨对虾高密度养殖条件下增氧情况的研究,并进行了不同天气状况下与水车增氧机增氧效果的对比。试验表明:涌浪机在晴好天气下增氧能力远超同功率水车增氧机。在试验养殖密度约为10000kg/hm2时,0.75kW涌浪机在晴好天气白天时与同功率水车增氧机相比,使池中溶解氧质量浓度平均提高1.24mg/L,但在阴雨天和夜间涌浪机的增氧效果较差,增氧能力与同功率水车增氧机相近。因此,涌浪机在实际应用中需与其他增氧模式相结合使用,将会取得较好的增氧效果。     

Relationship Between Malting Quality Traits and Hordeins as Affected by Timing of Nitrogen Fertilizer Application

The application of nitrogen (N) fertilizer in malting barley is necessary to obtain good yield, but it also influences kernel protein content, which affects malting quality. The negative correlation between kernel protein content and malting extract is due to the hordein proteins. The aim of this study was to determine the effect of N application timing on hordein fractions and how this influences malt quality. Reversed‐phase high‐performance liquid chromatography (RP‐HPLC) was used to determine the hordein fractions in the two‐ and six‐row barley parents and their doubled‐haploid progeny, for two seasons for one location, and two locations in the second season. There were no changes in hordein level in response to timing of N application over years and locations. The two‐row parent had the lowest hordein level and the six‐row progeny had the highest. Total hordein content of the two‐row progeny and six‐row parent were similar. The supply of additional N in the form of fertilizer rather than the timing of all N applications influenced the production of all hordein fractions. There were significant correlations between hordein fractions and malting quality that also were reported in other studies. Kernel plumpness showed significant negative correlations with D, C, and B hordeins and total hordein content when half of the fertilizer was applied at planting and the other half at the six‐leaf stage. Absorption showed significant positive correlation with C hordeins and a negative correlation with the B‐to‐C ratio, also when the second half of the N was given at the six‐leaf stage.     

Detection of Incipient Germination in Malting Barley with a Starch Viscosity Method and a Proposed Ethanol Emission Method

The risk of germination loss during storage in two‐row malting barley can be reduced by identifying grain lots that have undergone incipient germination (IG) during harvest. A method based on starch viscosity that utilizes a Rapid Visco Analyzer (RVA) is currently available for IG analysis. A new potential method, based on the measurement of ethanol emission (EE) from whole barley, may be more efficient and less expensive than the RVA procedure. Three storage experiments were performed: experiments 1 and 3 at 25°C and 80% rh, and experiment 2 in unheated, uninsulated buildings. Decline in germination energy (GE) varied from <1% to about 80% during storage. In experiments 1 and 3, R² for GE loss (expressed as [weeks to 5% loss of GE]^0.2) versus EE was 0.76 in both cases, whereas R² for GE loss versus RVA viscosity was 0.64 and 0.68, respectively. In experiment 2, the greatest loss of GE was associated with high temperatures and relative humidity in July and August. EE performed as well as RVA in the prediction of germination loss in all three trials. Although further evaluation of the EE method is required, it appears to be a promising alternative to the RVA technique.     

Influence of Hydrothermal Treatment on Lipid Oxidation in Barley

A steeping process of barley grains was evaluated regarding lipid oxidation. The steeping process was evaluated with respect to the temperature during the first steep and second steep, and the lactic acid concentration of the steep solutions. The study was conducted using a central composition circumscribed design, and response surface models were estimated with the use of partial least square. The change in the concentration of hexanal was used to monitor the oxidation during processing and subsequent storage at 30°C. In all samples there was hexanal development during processing and the hexanal concentration increased considerably during storage. The results show that it is possible to optimize the process to get a lower oxidation during the subsequent storage. The temperature during the second steep in the hydrothermal process and the level of lactic acid addition were the most important factors. Both of them should be kept low to favor the oxidative stability.     

Phosphorus seed coating as starter fertilization for spring malting barley

Abstract

Experiments were conducted with malting barley (Hordeum vulgare L.) cultivars in 2003 and 2004 in central, western and southern Lithuania to test phosphorus (P) availability at early seedling growth stage with P seed coating. Phosphorus seed coating resulted in alteration to plant stand structure traits. Despite the fact that seedling emergence sometimes decreased, the number of total and productive stems, number of grains per ear and 1000-grain weight increased. The positive effect of P seed coating on grain yield was revealed when the growth conditions during post-anthesis were favourable for exploiting the potential that was obtained during the pre-anthesis phase. In our experiment favourable conditions were considered those that generated a grain yield over 6 t ha^?1. According to path coefficients analyses the significant positive effect of P seed coating on malting barley yield increase was related to seed weight increase. Although P seed coating slightly increased single grain N concentration and thus grain protein concentration, grain protein concentration ranged from 8.6% to 10.2% and met the quality standard requirements for malting barley in all trials and treatments.     

The effect of mashing on malt endoproteolytic activities

During malting and mashing, the proteinases of barley (Hordeum vulgare L.) and malt partially hydrolyze their storage proteins. These enzymes are critical because several aspects of the brewing process are affected by the soluble proteins, peptides and/or amino acids that they release. To develop improved malting barleys and/or malting and brewing methods, it is imperative to know whether and when the green malt endoproteinases are inactivated during malting and mashing. These enzyme activities are totally preserved during kilning and, in this study, we have determined when they were inactivated during mashing. Samples were removed from experimental mashes that mirrored those used in commercial breweries and their endoproteolytic activities were analyzed. The malt endoproteinases were stable through the 38 degrees C protein rest phase, but were quickly inactivated when the mash temperature was raised to 72 degrees C for the conversion step. All of the proteinase activities were inactivated at about the same rate. These findings indicate that the soluble protein levels of worts can be varied by adjusting the protein rest phase of mashing, but not by altering the conversion time. The rates of hydrolysis of individual malt proteins probably cannot be changed by altering the mash temperature schedule, since the main enzymes that solubilize these proteins are affected similarly by temperature.     

Starch Lipids of Barley and Malt

Barley and malt starches were compared with respect to their lipid content and composition. The starch lipids were first fractionated into internal and surface lipid fractions followed by lipid class and fatty acid analyses of each fraction. Barley starch contained 13 mg/g lipids, of which 9.3 mg were internal lipids and 3.7 mg were surface lipids. The total lipid content of malt starches varied between 11 and 13 mg/g of starch. However, malt starch contained only 1 mg of surface lipids; therefore, the internal lipid contents were as high as or even higher than those in the corresponding fraction of barley starch. Lipid class analyses suggested that the ability for hydrolysis of starch surface lipids was increased in malt. The hydrolysis occurred during the malting or the isolation process, resulting in reduced surface lipid content in malt starch. However, no reduction in the portion of polyunsaturated fatty acids was seen; therefore, lipid oxidation could not have been responsible for the lower content of malt starch surface lipids. Also, not only was the content of starch internal lipids higher in malt, but the composition of these lipids was different when compared to barley starch. The increase in starch internal lipids during malting may be due to transportation and reacylation of free fatty acids that had been liberated by hydrolysis from surface lipids.     

Placement of nitrogen,phosphorus and potassium fertilizers by drilling in spring barley grown for malt without use of pesticides

Abstract

The increasing consumer demand for food products that are produced without the use of pesticides are reflected in action plans to reduce the use of pesticides in agriculture. Most of the barley (Hordeum vulgare L.) produced is used for pig feed but some is used for malting – the primary step in the production of beer. The effects of fertilizer application method, type and rate on yield and grain quality were investigated in a malting barley crop without the use of pesticides. Twelve treatments where single and multiple nutrient fertilizers were either broadcast or placed in bands by drilling, were compared in a field experiment at two sites in Denmark during 1993–96. Weeds were controlled mechanically in all treatments, and chemical control of foliar fungal diseases and insects was only carried out in two treatments.

The placement of a compound NPK-fertilizer increased the grain yield and the quality parameters grain size and grading when weeds are controlled mechanically by harrowing. The effect of fertilizer placement on grain yield and quality decreased in the order NPK > NP > N>P. Herbicide-free growing of malting barley may be possible using fertilizer placement, but the use of chemical control of foliar fungal diseases and insects may be critical when pests exceed certain thresholds as they significantly reduce grain yield, grain size and grading. The aim of growing malting barley satisfactorily without the use of pesticides was only partly met.