Malting Barley Grain Research Articles

Quantitative and Qualitative Composition of Bacterial Communities of Malting Barley Grain and Malt during Long-Term Storage

In the grain samples of three malting barley varieties harvested in 2016, and in the malt made from them, we observed microbial changes during storage. Analyses were performed after 0, 3, 6, and 9 months of storage in floor warehouses and silos. We monitored microbial changes based on the quantitative determination of microorganisms using a plate dilution method and qualitative determination of microorganisms, where we identified a particular species of bacteria using the MALDI-TOF MS Biotyper instrument (Bruker Daltonics, Bremen, Germany). Based on the quantitative determination of microorganisms, we found that the total plate counts of microorganisms was higher in malts than in barley grains. The storage period had the greatest impact on the number of coliform bacteria, which gradually increased with the growing months in storage. The number of lactic acid bacteria in barley grains with the growing months in storage and malt produced from them decreased slightly, and the content of the sporulating bacteria in all the samples fluctuated slightly. Differences in the numbers of observed microorganisms were negligible during storage between floor warehouses and silos. In the samples of barleys, the most commonly identified species were Pantoea agglomerans, which was also present in malt samples but did not belong to the dominant species. A diverse species representation appeared in the samples, whereas predominating species belonged to the Enterobacteriaceae family.

Visual quality assessment of malting barley using color, shape and texture descriptors

An essential part of the commercialization process of malting barley is the assessment of crop quality. While a traditional indicator of quality is the moisture content, visual inspection is normally carried out as well by an expert. Some indicators of sub-par crops are broken grains, contamination by foreign objects or other agricultural products, discoloration or abnormal pigmentation. We present a complete pipeline of vision and machine learning algorithms aimed at assessing the quality of malting barley grain. Previous solutions based on computer vision have solved this problem to varying degrees, and often require the grains under inspection to be clearly separated. We compare several feature vectors, combined with a nonlinear classifier. Our results show that the Local Phase Quantization descriptor, combined with color and shape features, provides the best results even against improved local descriptors like the Median Ternary Pattern or Median Robust Extended Local Binary Pattern. Our approach is fast, tolerates touching grains and provides an assessment that complies with local industry regulations.

Natural occurrence of Alternaria mycotoxins in malting barley grains in the main producing region of Argentina.

Barley (Hordeum vulgare L.) is one of the most important cereals worldwide, and its quality is affected by fungal contamination such as species of the genus Alternaria. No information is available about the occurrence of Alternaria mycotoxins in Argentinean barley grains, which is of concern, because they can be transferred into malt and beer. The aim of this study was to analyze the occurrence of alternariol (AOH), alternariol monomethyl ether (AME) and tenuazonic acid (TeA) in malting barley grains from the main producing region of Argentina during the 2014 and 2015 growing seasons. The most frequent mycotoxin was AOH (64%), which was detected at higher levels (712 μg kg-1 ) compared with other studies, followed by TeA (37%, 1522 μg kg-1 ), while AME was present in five samples in the 2015 growing season only, with a mean of 4876 μg kg-1 . A similar frequency of mycotoxin occurrence was observed in both years (80.8 vs 85.3%), but more diverse contamination was found in 2015, which was characterized by lower accumulated precipitation. Nevertheless, AOH was more frequently found in 2014 than in 2015 (80.8 and 47.1% respectively). A negative correlation between AOH concentration and temperature was observed. The susceptibility of different barley varieties to mycotoxin accumulation varied with the mycotoxin, geographical location and meteorological conditions. The results obtained in the present work represent a tool for risk assessment of exposition to these mycotoxins and could be used by food safety authorities to determine the need for their regulation. Furthermore, the establishment of a hazard analysis and critical control point (HACCP) system to minimize fungal and mycotoxin contamination in barley from farm to processing could be apply to ensure food safety. © 2019 Society of Chemical Industry.

Malting Barley Grain Quality and Yield Response to Nitrogen Fertilization in the Arsi Highlands of Ethiopia

The malting industry in Ethiopia is often challenged by the availability of barley that meets the quality and quantity requirements set by the industry. Field experiments were conducted to evaluate (i) the effects of nitrogen (N) fertilization rate, variety and growing season on grain yield and grain characteristics of malting barley, and (ii) to determine the N rate that optimize grain yield and quality of malting barley. The treatments studied were five N levels (0, 23, 46, 69, and 92 kg ha−1) and two malting barley varieties (Holker and Miscal-21) over three growing seasons (2012, 2013, and 2014). The results showed that as N rates increased, malting barley grain yield, grain and straw N concentration, grain protein content, 1000-kernel weight and kernel plumpness increased, but N rates had no effect on hectoliter weight. Grain yield, grain N concentration, grain protein content, kernel plumpness and 1000-kernel weight were greater in Miscal-21, whilst straw N concentration and hectoliter weight were greater in Holker. Grain yield and hectoliter weight were affected by seasonal conditions, but grain and straw N concentration, grain protein content, kernel plumpness, and 1000-kernel weight were not affected. Although both grain yield and protein content increased with increased N rates, based on the regression equation, application of 48 kg N ha−1 gave the highest net benefit and marginal rate of return with acceptable grain quality (protein content 85 g kg−1). Application of N beyond 48 kg ha-1 did not increase net benefit, but instead increased cost of production. In conclusion, to improve the likelihood that barley will be acceptable for malting, growers should limit N application and select varieties with low protein content.

Nitrogen Uptake and Utilization Efficiency of Malting Barley as Influenced by Variety and Nitrogen Level

Nitrogen (N) is the primary driver of crop production and it is heavily used in modern agriculture to maximize yield. However, the effectiveness with which N is used by cereals has become increasingly important because of both financial and environmental costs to N fertilization. The aims of this study were to determine the effects of N fertilization rate, variety, and growing season on grain yield, N uptake, and N-efficiency traits of malting barley at Bekoji, southeastern Ethiopia. The treatments studied were five N levels (0, 23, 46, 69, and 92 kg ha-1) and two malting barley varieties (Miscal-21 and Holker) over three seasons (2012, 2013, and 2014). The results showed that as N rates increased, malting barley grain yield, grain, straw, and total N uptakes increased, but N-harvest index, N-use efficiency, N-recovery efficiency, and N-utilization efficiency decreased. Grain yield, grain, and total N uptake, N-harvest index, N-use efficiency, N-recovery efficiency, and N-utilization efficiency were greater in Miscal-21, whilst straw N uptake were greater in Holker. Grain yield, grain, straw, and total N uptake, N-recovery efficiency, and N-harvest index were greater in 2012 than in 2013 and 2014, but growing season had no effect on N-use efficiency and N-utilization efficiency. Grain yield was positively correlated with N-efficiency traits, but the role of N-recovery efficiency in enhancing grain yield was larger than the role of N-utilization efficiency.

Detection of volatile organic compounds in the headspace above mold fungi by GC-soft X-radiation-based APCI-MS.

Mold fungi on malting barley grains cause major economic loss in malting and brewery facilities. Possible proxies for their detection are volatile and semivolatile metabolites. Among those substances, characteristic marker compounds have to be identified for a confident detection of mold fungi in varying surroundings. The analytical determination is usually performed through passive sampling with solid phase microextraction, gas chromatographic separation, and detection by electron ionization mass spectrometry (EI-MS), which often does not allow a confident determination due to the absence of molecular ions. An alternative is GC-APCI-MS, generally, allowing the determination of protonated molecular ions. Commercial atmospheric pressure chemical ionization (APCI) sources are based on corona discharges, which are often unspecific due to the occurrence of several side reactions and produce complex product ion spectra. To overcome this issue, an APCI source based on soft X-radiation is used here. This source facilitates a more specific ionization by proton transfer reactions only. In the first part, the APCI source is characterized with representative volatile fungus metabolites. Depending on the proton affinity of the metabolites, the limits of detection are up to 2 orders of magnitude below those of EI-MS. In the second part, the volatile metabolites of the mold fungus species Aspergillus, Alternaria, Fusarium, and Penicillium are investigated. In total, 86 compounds were found with GC-EI/APCI-MS. The metabolites identified belong to the substance classes of alcohols, aldehydes, ketones, carboxylic acids, esters, substituted aromatic compounds, terpenes, and sesquiterpenes. In addition to substances unspecific for the individual fungus species, characteristic patterns of metabolites, allowing their confident discrimination, were found for each of the 4 fungus species. Sixty-seven of the 86 metabolites are detected by X-ray-based APCI-MS alone. The discrimination of the fungus species based on these metabolites alone was possible. Therefore, APCI-MS in combination with collision induced dissociation alone could be used as a supervision method for the detection of mold fungi.

Control of microbes on barley grains using peroxyacetic acid and electrolysed water as antimicrobial agents

The extent and type of microbial growth on barley grain is a key determinant of malt quality for beer production, as problematic microbial products can persist into the brewing process and impact beer quality. Microbial composition on malting barley grain are influenced by field growth, storage and malting conditions. The present study investigated the efficacy of electrolysed water (EW) with free chlorine concentrations of 5, 50, 100 and 500 ppm, as well as peroxyacetic acid (PAA) at 100 and 500 ppm, as pre-steep treatments to control microbes on grains during the malting process. The research determined the reduction in the load of Pseudomonas spp., heterotrophic bacteria, yeasts and filamentous fungi on weathered and on non-weathered grains. Pseudomonas spp., heterotrophic bacteria and yeasts were significantly reduced up to 4 logs when treated with 500 ppm PAA. PAA reduced filamentous fungi but 500 ppm free chlorine EW showed greater reductions. None of the treatments had detrimental effect on grain germination. The variation in antimicrobial efficacy among treatments can be attributed to variations in microbial susceptibility as well as differences in anti-microbial mechanisms specific to each antimicrobial agent.

Evaluation of critical points of mould growth and mycotoxin production in the stored barley ecosystem with a hazardous initial microbiological state of grain

The development of effective control systems for post-harvest preservation and storage processes seems to be one of the best ways to reduce the activity of fungi and thus the risk of mycotoxin contamination of grain during its storage. A crucial step towards developing such a system requires the understanding of ecological relationships between environmental factors, fungal development and mycotoxin production in bulk of grain treated as holistic systems. The aim of this study was to estimate the critical points associated with mould development and mycotoxin production in the ecosystem of malting barley grain with a hazardous initial microbiological state (provided by the inoculation of naturally contaminated grain with Aspergillus ochraceus and Penicillium verrucosum) stored in different temperature and water activity conditions (t = 12–30 °C and aw = 0.78–0.96, where aw corresponds to equilibrium relative air humidity in inter-grain spaces). The most intensive fungal growth occurred in the ecosystems of barley grain with aw = 0.91–0.93 stored at 24 and 30 °C. The biosynthesis of ochratoxin A (OTA) was observed at 0.91–0.95 aw at 18–30 °C, whilst penicillic acid and citrinin were detected only at temperatures of 24 and 30 °C. The toxicogenic ability of fungi at 12–24 °C and aw≤0.80 was significantly limited. In the ecosystem of barley grain, the threshold of fungal concentration (expressed in colony forming units of moulds, CFU g−1), for which the amount of OTA exceeded binding limits, was 105 CFU g−1 of grain. The study indicates that the duration of the lag phase of fungal development (comprising spores germination and the beginning of exponential mould growth), which in all tested ecosystems was shorter than the time, after which admissible levels of OTA were exceeded, may be used to evaluate the safe period, at which grain should be subjected to preservation processes.

Fungal community, Fusarium head blight complex and secondary metabolites associated with malting barley grains harvested in Umbria, central Italy

In recent years, due to the negative impact of toxigenic mycobiota and of the accumulation of their secondary metabolites in malting barley grains, monitoring the evolution of fungal communities in a certain cultivation area as well as detecting the different mycotoxins present in the raw material prior to malting and brewing processes have become increasingly important. In this study, a survey was carried out on malting barley samples collected after their harvest in the Umbria region (central Italy). Samples were analyzed to determine the composition of the fungal community, to identify the isolated Fusarium species, to quantify fungal secondary metabolites in the grains and to characterize the in vitro mycotoxigenic profile of a subset of the isolated Fusarium strains. The fungal community of barley grains was mainly composed of microorganisms belonging to the genus Alternaria (77%), followed by those belonging to the genus Fusarium (27%). The Fusarium head blight (FHB) complex was represented by nine species with the predominance of Fusarium poae (37%), followed by Fusarium avenaceum (23%), Fusarium graminearum (22%) and Fusarium tricinctum (7%). Secondary metabolites biosynthesized by Alternaria and Fusarium species were present in the analyzed grains. Among those biosynthesized by Fusarium species, nivalenol and enniatins were the most prevalent ones. Type A trichothecenes (T-2 and HT-2 toxins) as well as beauvericin were also present with a high incidence. Conversely, the number of samples contaminated with deoxynivalenol was low. Conjugated forms, such as deoxynivalenol-3-glucoside and HT-2-glucoside, were detected for the first time in malting barley grains cultivated in the surveyed area. In addition, strains of F. avenaceum and F. tricinctum showed the ability to biosynthesize in vitro high concentrations of enniatins. The analysis of fungal secondary metabolites, both in the grains and in vitro, revealed also the presence of other compounds, for which further investigations will be required. The combination of microbiological analyses, of molecular biology assays and of multi-mycotoxin screening shed light on the complexity of the fungal community and its secondary metabolites released in malting barley.

Natural Contamination with Mycotoxins Produced by Fusarium graminearum and Fusarium poae in Malting Barley in Argentina.

Two of the most common species of toxin-producing Fusarium contaminating small cereal grains are Fusarium graminearum and F. poae; with both elaborating diverse toxins, especially deoxynivalenol (DON) and nivalenol (NIV), respectively. The objective of our work during the 2012–2014 growing seasons was to screen crops for the most commonly isolated Fusarium species and to quantify DON and NIV toxins in natural malting-barley samples from different producing areas of Argentina. We identified 1180 Fusarium isolates in the 119 samples analyzed, with 51.2% being F. graminearum, 26.2% F. poae and 22.6% other species. We found high concentrations of mycotoxins, at maximum values of 12 μg/g of DON and 7.71 μg/g of NIV. Of the samples, 23% exhibited DON at an average of 2.36 μg/g, with 44% exceeding the maximum limits (average of 5.24 μg/g); 29% contained NIV at an average of 2.36 μg/g; 7% contained both DON and NIV; and 55% were without DON or NIV. Finally, we report the mycotoxin contamination of the grain samples produced by F. graminearum and F. poae, those being the most frequent Fusarium species present. We identified the main Fusarium species affecting natural malting-barley grains in Argentina and documented the presence of many samples with elevated concentrations of DON and NIV. To our knowledge, the investigation reported here was the first to quantify the contamination by Fusarium and its toxins in natural samples of malting barley in Argentina.

Fungi in malting barley grain and malt production

Contamination of malting barley grain with microscopic fungi during different periods was investigated from 2012 to 2014. Grain samples of malting barley were taken directly from the field before harvesting and from a storage silo; malted grain was taken from two malt producers in Lithuania. The fungi were isolated and identified in barley grain before the malting and after steeping and germination during the malting process. The total count of fungi was done in these barley samples during the mentioned phases. Most attention was given to widely distributed fungi known as producers of toxins: Aspergillus, Penicillium, and Fusarium. Abilities of some of these fungi to produce secondary toxic metabolites cause a possible hazard to people consuming the contaminated products. The aim of this work was to investigate changes in fungi composition and in their total count in barley grain, the raw material for the production of malt.

Kvalita zrna sladovnického ječmene v České republice, sklizeň 2016

Kvalita zrna sladovnického ječmene v České republice, sklizeň 2016

Evaluation of total phenolic content and antioxidant activity of malting and hulless barley grain and malt extracts

Nine malting and six hulless barley varieties were evaluated for their grain characteristics, β-glucans, total phenolic contents, and corresponding antioxidant activities determined by DPPH radical scavenging method. Samples were malted to compare malt quality properties between hulled and hulless types of barley and to estimate the influence of malting process on total phenolics. The highest levels of total phenolics and antioxidant activity were observed in the hulless barley lines GZ-191 and GZ-186. Malts were found to have higher antioxidant activity and contents of total phenolics than their corresponding barley. Results from the present study showed that hulless barley lines had on average higher protein, starch, β-glucan, malt extract content, and wort viscosity, but lower Kolbach Index and malt friability when compared to hulled malting varieties. The analysis of fifteen different barley samples shows that the barley type has an influence on both the total phenolic content and the antioxidant activity, as well as on the malting performance of hulless and hulled barley.

Occurrence of Fusarium spp. on Malting Barley Grains in the Czech Republic During 2011-2013

During 2011-2013, the frequency of occurrence and species spectrum of Fusarium fungi occurring on grains of five malting varieties of spring barley (Aksamit, Bojos, Malz, Radegast, and Kangoo) were monitored at two locations (Kroměřiž and Žabcice, Czech Republic). The effect of three fungicide treatment variants on Fusarium species suppression was also evaluated. During the monitored period, five species were detected: F. poae, F. culmorum, F. graminearum, F. avenaceum, and F. tricinctum. The most frequently isolated species was F. poae. Radegast had the highest frequency of naturally occurring Fusarium fungi, while Kangoo was the least infected variety at both locations. The greatest fungicide effectiveness against Fusarium spp. occurrence on ears was recorded after the variant with application of Hutton at BBCH 39 and Prosaro 250 EC at BBCH 65. During the monitored years, Žabcice had a higher rate of infection by Fusarium fungi. The rates of barley infection by Fusarium pathogens differed among individual years, with the highest rate occurring in 2011 (16-17 %) and the lowest rate in 2012 (1-2 %).

Application of Hyperspectral Imaging for Cultivar Discrimination of Malting Barley Grains

Abstract The aim of this study was to perform and evaluate the accuracy of classification of grains of different cultivars of malting barley. The grains of eight cultivars: Blask, Bor do, Con chita, Kormoran, Mercada, Serwal, Signora, Victoriana, with three moisture content: 12, 14, 16% were examined. The selected parameters of the surface texture of grain mass obtained from images taken using the techniques of hyperspectral imaging were determined. The accuracy of grains discrimination carried out using different methods of selection and classification of data was compared. The pairwise comparison and comparison of three, four and eight cultivars of malting barley were carried out. The most accurate discrimination was determined in the case of the pairwise comparison. Victoriana cultivar was the most different from the others. The most similar texture of grain mass was found in the comparison of cultivars: Blask and Mercada. In the case of eight examined cultivars of malting barley, the most accurate discrimination (classification error – 55%) was obtained for images taken at the moisture content of 14% and at a wavelength of 750 nm, for the attributes selection performed with the use of probability of error and average correlation coefficient (POE+ACC) method and the discrimination carried out using the linear discriminant analysis (LDA).

Vplyv dlhodob�ho skladovania na kvalitu zrna sladovn�ckeho jacmena a sladu

In the grain samples of five malting barley varieties harvested in 2011, the amount of basic components as well as physiological characteristics of barley were determined. These samples were micromalted and resulting malt was analyzed mainly according to the European Brewery Convention (EBC) and the Mitteleuropaische Brautechnische Analysenkommission (MEBAK) methodologies. The same samples of malting barley grain and also samples of malt were placed in polyethylene bags, from which the air was exhausted and they were further stored at 4 °C until 2016. In 2016, grain and malt samples were subjected to the same analyses as in 2011. Results were statistically evaluated by t-test of dependent samples. Most of the monitored parameters has remained at the same level as in 2011 or has slightly improved. The exception was statistically very highly significant decrease (P ≤ 0.001) of friability and increase of amount of whole and partly unmodified grains. Under conditions described, long-term storage of malting barley grain has not significantly negatively affected its germination. Long-term storage of malt has had not a significant negative impact on its quality too.

Malt Barley Yield and Quality Affected by Irrigation, Tillage, Crop Rotation, and Nitrogen Fertilization

Little is known about the comparison of management practices on malt barley (Hordeum vulgare L.) yield and quality in irrigated and non‐irrigated cropping systems. We evaluated the effects of irrigation, tillage, cropping system, and N fertilization on malt barley yield and quality in a sandy loam soil from 2005 to 2011 in croplands converted from Conservation Reserve Program in western North Dakota. Treatments were two irrigation practices (irrigated vs. non‐irrigated) and five cropping systems (conventional till malt barley with nitrogen fertilizer [CTBN], conventional till malt barley without nitrogen fertilizer [CTBO], no‐till malt barley–pea [Pisum sativum L.] with nitrogen fertilizer [NTB–P], no‐till malt barley with nitrogen fertilizer [NTBN], and no‐till malt barley without nitrogen fertilizer [NTBO]). Malt barley biomass and grain yields were greater with NTB–P, CTBN, and NTBN than CTBO and NTBO in the irrigated and non‐irrigated practices. Compared with CTBO and NTBO, grain protein concentration was greater with CTBN in the irrigated practice and greater with NTB‐P in the non‐irrigated practice. Grain plumpness was greater with CTBO than CTBN in the irrigated practice and greater with CTBN than NTB–P in the non‐irrigated practice. Plant stand and test weight were greater with CTBO than CTBN in the irrigated practice and harvest index greater with NTBO than other treatments in the non‐irrigated practice. Because of similar or superior yield and quality, NTB–P may be used to sustain malt barley yield and quality compared with the traditional CTBN in the irrigated condition and during years with adequate precipitation in the non‐irrigated condition.

Effect of fungicide treatment on Fusarium culmorum and Tri genes transcription in barley malt

Malting barley grains are essential components in the beer production. Fusarium infection can have severe effects on malt and beer, because it may inhibit the enzymatic activity in malt and may induce the occurrence of gushing and changes in the colour and flavour of the finished beer. We examined the growth of the filamentous fungi Fusarium culmorum in artificially infected and non-infected barley malting grains during the first steps of the malting process and under the effects of fungicide pretreatment (Hutton and Prosaro 250 EC) of barley plants. Our study focused on the fungi growth in two distinct barley malting cultivars Bojos and Malz. Fusarium growth was investigated by quantitative real-time PCR using TagMan MGB probes. Furthermore, we focused on the Tri5 and Tri6 genes because they play the most important roles in trichothecene biosynthesis. Surprisingly, the higher transcription activity of the Tri genes was found in the fungicide-treated cultivar Malz as compared with untreated cultivars.

Relationship between grain yield and agronomic traits in winter barley

Grain yield is one of the most important and complex traits in cereal breeding and depends upon a combination of different plant traits. Therefore, an effective breeding program requires a proper understanding of the relationships between grain yield and agronomic traits. The objectives of this study were the evaluation of two-rowed winter malting barley genotypes and the perceiving of relationships among grain yield and their agronomic and quality traits. The trials with 19 two-rowed winter malting barley genotypes were conducted during three years. The relationships among plant lodging, height, thousand kernel weight, hectolitre mass, grain protein content and grain yield, were studied by PCA biplot analysis. The results showed that the influence of year, genotype and genotype by year interaction on barley grain yield were significant. Further, results indicate that two-rowed winter malting barley grain yield can be improved by selecting plants of average plant height with thousand kernel weight above 41.0 g and grain protein content of about 11.0 g 100-1g dm.

In vitro gas production and dry matter digestibility of malting barley grain sown with different seeding and nitrogen fertilization rates in Canada

Two malting barley varieties, AC Metcalfe and CDC Copeland, were grown at seven sites in Canada with varying seeding rates (SR; 200 and 400 seeds/m2) and nitrogen fertilization rates (NR; 0, 30, 60, 90, and 120kg/ha) and were assessed for variation in chemical composition, gas production (GP), and dry matter digestibility (DMD) after 24h of batch culture. The variety affected (P<0.01) the crude protein (CP) content of malting barley grain and interacted with SR or NR on DMD. The increase in NR quadratically increased (P<0.01) CP and fiber content but linearly (P<0.01) decreased starch content of malting barley grain. Variety, SR, and NR had limited impact on in vitro GP and DMD. This study showed substantial variation in CP content and DMD among samples and that the chemical composition of malting barley grain and its potential feed value could be altered by NR.