Malt Samples Research Articles

Construction of a N-CDs/AuNCs@ZIF-8-assisted ratiometric fluorescent nanosensor for glyphosate detection in edible and medicinal malt

Glyphosate (Gly) is a widely-used herbicide in food production, while, the residue of which due to the long-term and excessive overspray poses serious threats to public health. The development of reliable methods for its sensitive detection is of great urgency. In this study, a novel ratiometric fluorescent nanosensor by encapsulating N-doped carbon dots (N-CDs) and gold nanoclusters (AuNCs) in zeolitic imidazole framework-8 (ZIF-8) as the dual-emissive fluorescence probes at 410 and 650 nm, respectively, was constructed for Gly detection. Due to the adsorption property of ZIF-8, the N-CDs/AuNCs@ZIF-8 nanoprobes accumulated Cu2+ to quench the red fluorescence of AuNCs, and the blue fluorescence of N-CDs was stable. While thiocholine, a product of acetylthiocholine, hydrolyzed by acetylcholinesterase could coordinate with Cu2+, resulting in significant fluorescence recovery of AuNCs. This phenomenon was utilized for the quantitation of Gly, due to its inhibitory effect on acetylcholinesterase activity. By calculating the fluorescence intensity ratio (I650/I410), Gly in real sample could be accurately determined in a concentration range of 2–100 ng/mL with a limit of detection of 1.92 ng/mL because of the anti-interference and the self-correction ability of the two fluorescence signals. The N-CDs/AuNCs@ZIF-8 nanoprobes-assisted ratiometric fluorescent nanosensor exhibited unique merits of rapid construction, simple operation, high specificity, and good accuracy for Gly in edible and medicinal malt samples with recoveries of 93.7–108.2 %. This study presents a multiple tool for the versatile sensing of trace pesticides in more food matrices, which can be extended to a full range of environmental and food safety applications.

Fast and Reliable On-Site Quality Assessment of Essential Raw Brewing Materials Using MicroNIR and Chemometrics.

The interest in the quality control of the raw materials, intermediates, and final products, as well as production methods, of beer has increased significantly in recent decades due to the needs and expectations of consumers. Increasing in the industrialization and globalization of beer supply chains led to a need for novel analytical tools suitable for the rapid and reliable characterization of the materials involved. In this study, an ultracompact instrument operating in the NIR region of the spectrum, microNIR, was tested for the chemical investigation of barley malts. The essential raw materials for brewing require careful control since they deeply affect the characteristic flavor and taste of the final products. Therefore, a robust prediction model able to classify base and specialty barley malts was developed starting from NIR measurements. Soft Independent Class Analogy (SIMCA) was selected as the chemometric technique for the optimization of two prediction models, and ground and sieved materials were investigated using spectroscopy. The microNIR/chemometric approach proposed in this study permitted the correct prediction of the malt samples included in the external validation set, providing false positive and false negative rates no higher than 3.41% and 0.25%, respectively, and confirming the feasibility of the novel analytical platform.

Two swords combination: Smartphone-assisted ratiometric fluorescent and paper sensors for dual-mode detection of glyphosate in edible malt

The long-term and excessive use of glyphosate (GLY) in diverse matrices has caused serious hazard to the human and environment. However, the ultrasensitive detection of GLY still remains challenging. In this study, the smartphone-assisted dual-signal mode ratiometric fluorescent and paper sensors based on the red-emissive gold nanoclusters (R-AuNCs) and blue-emissive carbon dots (B-CDs) were ingeniously designed accurate and sensitive detection of GLY. Upon the presence of GLY, it would quench the fluorescence of B-CDs through dynamic quenching effect, and strengthen the fluorescence response of R-AuNCs due to aggregation-induced enhancement effect. Through calculating the GLY-induced fluorescence intensity ratio of B-CDs to R-AuNCs by using a fluorescence spectrophotometer, low to 0.218 μg/mL of GLY could be detected in lab in a wide concentration range of 0.3–12 μg/mL with high recovery of 94.7–103.1% in the spiked malt samples. The smartphone-assisted ratiometric fluorescent sensor achieved in the 96-well plate could monitor 0–11 μg/mL of GLY with satisfactory recovery of 94.1–107.0% in real edible malt matrices for high-throughput analysis. In addition, a portable smartphone-assisted ratiometric paper sensor established through directly depositing the combined B-CDs/R-AuNCs probes on the test strip could realize on-site measurement of 2–8 μg/mL of GLY with good linear relationship. This study provides new insights into developing the dual-signal ratiometric sensing platforms for the in-lab sensitive detection, high-throughput analysis, and on-site portable measurement of more trace contaminants in foods, clinical and environmental samples.

Nafion-Immobilized Functionalized MWCNT-based Electrochemical Immunosensor for Aflatoxin B1 Detection.

The ubiquitous aflatoxin B1 (AFB1) contamination in foods and other complex matrices has brought great challenges for onsite monitoring. In this study, an ultrasensitive Nafion-immobilized functionalized multiwalled carbon nanotube (MWCNT)-based electrochemical (EC) immunosensor was developed for trace AFB1 detection. The introduced Nafion film could steadily stabilize functionalized MWCNTs with uniform distribution and tiling on the surface of a Au electrode. Functionalized MWCNTs with a large specific surface area, numerous active sites to couple with abundant anti-AFB1 monoclonal antibodies (mAbs), and high conductivity served as the signal amplifier for remarkably enhancing the sensing performance of the immunosensor. In the presence of AFB1, it was specifically captured by mAbs to reduce the amplified current signals, which were recorded by differential pulse voltammetry for the accurate quantitation of AFB1. Because of the synergistic effects of Nafion on the stabilization of functionalized MWCNTs as signal enhancers, the developed EC immunosensor exhibited an extremely high selectivity, excellent sensitivity with a limit of detection as low as 0.021 ng/mL, and a wide dynamic range of 0.05-100 ng/mL, besides fascinating merits of easy construction, low cost, good stability in 7 days, and good reusability. The anti-interference ability of the immunosensor was verified against three other mycotoxins, and the practicability and accuracy were confirmed by measuring AFB1 in fortified malt, lotus seed, and hirudo samples with a satisfactory recovery of 92.08-104.62%. This novel immunosensing platform could be extended to detect more mycotoxins in complex matrices to ensure food safety.

3D nanocake-like Au-MXene/Au pallet structure-based label-free electrochemical aptasensor for paraquat determination.

3D nanocake-like Au-MXene and Au pallet (Au-MXene/AuP) nanocomposite-modified screen-printed carbon electrodes (SPCEs) were utilized to construct an ultrasensitive label-free electrochemical aptasensor through a self-assembly procedure for trace paraquat (PQ) residue detection. Benefiting from the excellent electrochemical (EC) performances (e.g., high conductivity and large surface area) of Au-MXene nanocomposites and AuP substrate, the developed Apt/Au-MXene/AuP/SPCE-based EC aptasensor displayed excellent specificity and anti-interference ability, good repeatability, and stability. A linear relationship between the log value of the change in current intensity [lg (ΔI)] and the log value of the concentration of PQ [lg (CPQ)] was obtained in the range 0.05-1000 ng/mL. The limit of detection was 0.028 ng/mL, and thesensitivity was 255.5 μA/(μM·cm2). Practical applications in malt and mint samples confirmed the accuracy of the EC aptasensor in complex matrices for PQ detection, providing a universal analytical tool for othertrace pesticides in differentfood samples by simply replacing the corresponding aptamers.

Aberrant Behavior of Deoxynivalenol Production in the Malting of Fusarium Head Blight Infected Barley: Mycotoxin Accumulation and Hyphal Localization in Single Kernels

The malting industry faces a dilemma in which barley, initially containing low deoxynivalenol levels, occasionally exhibits an unexpected increase in deoxynivalenol levels during malting. In the current study, we investigated mycotoxin accumulation and hyphal localization in single kernels from Fusarium head blight infected barley and malt samples which showed an aberrant behavior of deoxynivalenol increases during malting. While deoxynivalenol levels in these bulk barley samples already ranged from <0.20 to 1.27 µg/g, they further increased on average by approximately 500% after malting, along with Fusarium growth. In addition, deoxynivalenol-3-glucoside and 3-acetyl deoxynivalenol levels increased from <0.20 µg/g to the mean levels of 2.47 µg/g and 1.03 µg/g in the bulk malt, respectively. In the investigation of single kernels, results showed that only 7% of barley single kernels (n = 385) had deoxynivalenol >1.00 μg/g, with the maximum level of 35.97 μg/g. However, 31% of malt single kernels contained deoxynivalenol >1.00 μg/g and up to 255.43 μg/g. Deoxynivalenol-3-glucoside and 3-acetyl deoxynivalenol were found in 40% of malt single kernels. Fungal hyphae were observed in the aleurone layer and embryo of barley kernels with deoxynivalenol >10.00 μg/g, in addition to the husk and vascular bundles of kernels with deoxynivalenol <1.00 μg/g. Hyphae spread largely in these tissues following malting, and even into the endosperm and pericarp cavities of extremely high deoxynivalenol kernels (i.e., >100.00 μg/g).

Impact of malt concentration in solid substrate on mycelial growth and network connectivity in Ganoderma species

With its distinctive material properties, fungal mycelium has emerged as an innovative material with a diverse array of applications across various industries. This study focuses on how the growth strategies of wood fungi adapt to nutrient availability. The effect of malt extract concentration in the growth medium on radial growth kinetics, morphology, mycelium network connectivity, and mechanical characteristics of mycelium from two Ganoderma species were investigated. While an evident pattern of radial growth rate enhancement with malt concentrations was not apparent, there was a discernible trend towards denser mycelium network characteristics as revealed by spectrophotometry. Increased malt extract contents corresponded to elevated optical density measurements and were visually confirmed by denser mycelium networks in photographic images. Investigating the mechanical characteristics of mycelium cultivated on varying solid substrate concentrations, the Young’s modulus exhibited a substantial difference between mycelium grown on 5 wt% malt substrate and samples cultivated on 2 wt% and 0.4 wt% malt substrates. The obtained results represent a new understanding of how malt availability influences mycelial growth of two Ganoderma species, a crucial insight for potentially refining mycelium cultivation across diverse applications, including meat alternatives, smart building materials, and alternative leather.

Proteome Changes Resulting from Malting in Hordein-Reduced Barley Lines.

Hordeum vulgare L., commonly known as barley, is primarily used for animal feed and malting. The major storage proteins in barley are hordeins, known triggers of celiac disease (CD). Here, sequential window acquisition of all theoretical mass spectra (SWATH)-MS proteomics was employed to investigate the proteome profile of grain and malt samples from the malting barley cultivar Sloop and single-, double-, and triple hordein-reduced lines bred in a Sloop background. Using a discovery proteomics approach, 2688 and 3034 proteins were detected from the grain and malt samples, respectively. By utilizing label-free relative quantitation through SWATH-MS, a total of 2654 proteins have been quantified from grain and malt. The comparative analyses between the barley grain and malt samples revealed that the C-hordein-reduced lines have a more significant impact on proteome level changes due to malting than B- and D-hordein-reduced lines. Upregulated proteins in C-hordein-reduced lines were primarily involved in the tricarboxylic acid cycle and fatty acid peroxidation processes to provide more energy for seed germination during malting. By applying proteomics approaches after malting in hordein-reduced barley lines, we uncovered additional changes in the proteome driven by the genetic background that were not apparent in the sound grain. Our findings offer valuable insights for barley breeders and maltsters seeking to understand and optimize the performance of gluten-free grains in malt products.

From grain to malt: Tracking changes of ultra-low-gluten barley storage proteins after malting

Barley (Hordeum vulgare L.) is a major cereal crop produced globally. Hordeins, the major storage proteins in barley, can trigger immune responses leading to celiac disease or symptoms associated with food allergy. Here, proteomics approaches were employed to investigate the proteome level changes of grain and malt from the malting barley cultivar, Sloop, and single-, double- and triple hordein-reduced lines. The triple hordein-reduced line is an ultra-low gluten barley cultivar, Kebari®. Using discovery proteomics, 2,688 and 3,034 proteins in the barley and malt samples were detected respectively. Through the application of targeted proteomics, a significant reduction in the quantity of B-, D-, and γ-hordeins, as well as avenin-like proteins, was observed in the ultra-low gluten malt sample. A compensation mechanism was observed evidenced by increased biosynthesis of seed storage globulins, specifically vicilin-like globulins. Overall, this study has provided insights into protein compositional changes after malting in celiac-friendly barley varieties.

Congress mashing of malted wheat cultivars from Thailand provide adequate malt extract physicochemical properties suitable for brewing purposes

AbstractBackground and ObjectiveThe use of wheat for brewing is associated with its influence on protein content, phenolic compounds, and organoleptic properties, such as mouth feel, haze, and foaming intensity in malt‐based beverages. The quest for alternate malt materials other than barley malt and the exponential growth of micro‐breweries in Thailand have intensified the search for appropriate wheat cultivars suitable for brewing purpose. In this study, four imported commercial wheat malts and three malted wheat cultivars from Thailand (Samerng‐2, Phrae‐60, and Fahng‐60) were compared in terms of their physicochemical characteristics. Malt quality was based on α‐amylase, β‐amylase, antioxidant activities, the contents of free amino acid (FAN), fermentable sugars, total reducing sugar (TRS), and total polyphenol (TPC) of the malt extract samples produced by congress mashing.FindingsThe levels of α‐amylase activity were lower than that for β‐amylase activity in all malt samples. The malt extract (wort) yield was 83.7% weight per weight (w/w), 83.9% w/w, and 83.3% w/w in Samerng‐2, Phrae‐60, and Fahng‐60, respectively. The FAN contents in wort from the three Thai wheat malts were in the range of 155.2–183.4 mg/L. When used as an adjunct at 30% w/w or 50% w/w, the FAN contents were in the ranges 197.5–203.9 and 140.9–173 mg/L, respectively. Sucrose, glucose, maltose, and maltotriose were in the ranges 0.37–1.17, 2.8–4.3, 37.9–48.8, and 7.3–9.68 g/L, respectively. Wort produced contained contents of TRS, total carbohydrate, and TPC of 56.3–57.4, 79.4–88.9, and 116.4–18.2 mg/L, respectively. The antioxidant activity level based on 2,2‐di(4‐tert‐octylphenyl)‐1picrylhydrazyl and 2,2‐azino‐bis (3‐ethylbenzothiazoline‐6‐sulfonic acid) diammonium salt assays was within 61.0–125.4 and 1259–1413 µmol TE/L, respectively.ConclusionThese physicochemical attributes of the Thai malted wheat cultivars were similar to the commercial imported wheat malt samples. Consequently, the Thai cultivar would be suitable as raw brewing material.Significance and NoveltyThis preliminary study is limited to laboratory experimental design. Different conditions and processes could lead to different experimental results. Notwithstanding, this study provides the first report on some physicochemical properties of malted Thai wheat cultivars as the base raw material and adjunct for brewing purposes, which are critical in selecting cultivars for brewing purposes. This will intend to promote the cultivation of local wheat cultivars to meet the demand of local craft breweries.

Evolution of Alternaria toxins during the brewing process and the usability of optical sorting methods to reduce mycotoxin concentrations in beer

To assess the impact of black-colored grain on Alternaria mycotoxin concentrations in different stages of the brewing process, brewing experiments were conducted in a microscale brewhouse. Different mixtures of visually unaffected and black-colored batches of two malt samples were used, which were obtained by an optical sorting device. The 13 Alternaria mycotoxins alternariol (AOH), alternariol monomethyl ether (AME), tenuazonic acid (TeA), tentoxin (TEN), alterperylenol (ALTP), altertoxins I and II (ATX I and II), altenuene (ALT) as well as the modified forms AOH-3-glucoside (AOH-3-G), AOH-9-glucoside (AOH-9-G), AME-3-gluoside (AME-3-G), AOH-3-sulfate (AOH-3-S) and AME-3-sulfate (AME-3-S) were analyzed in each processing step by liquid chromatography–tandem mass spectrometry (LC–MS/MS), and the toxin concentrations were balanced over the whole brewing process. Fungal DNA content in the starting material (mixtures) was determined by quantitative real-time polymerase chain reaction (qPCR). In this study, TeA was the only toxin to migrate into the final beer, while the AOH, AME, TEN, ALTP and ATX I toxins were mainly found in the spent grains. The observance of AOH-3-S and AME-3-S in some processing steps also showed the possibility of modification reactions during brewing. Furthermore, no distinct correlations between the fungal DNA and the analyzed mycotoxins could be observed in the starting material, while the amount of black colored grains only impacted toxin concentrations in one of the two used malt samples. Nevertheless, it was shown that optical sorting of malt batches might be a useful tool for the malting and brewing industry to prevent elevated mycotoxin concentrations.

Special Buckwheat Malt Obtaining and Quality Evaluating

Recently, a man has been actively working to obtain new types of malts that are used as raw materials for food production. The study aim is to develop methods for obtain ing malts from buckwheat grain. The study objects are five malt samples obtained from buckwheat grain: light (control), two caramel (subtypes I and II) and two dark (subtypes I and II). The manufacture methods of colored malts differed in the use of conversion procedures for dark and conversion and fermentation procedures for caramel, as well as thermal load level during drying. There are indicators of buckwheat malt: moisture mass fraction, extract and protein substances, Kohlbach number, amine nitrogen content, color, viscosity, titrated acidity. The thesis consists of technological schemes for obtaining light and dark malts from buckwheat. The types of malt obtained differed in organoleptic and physico-chemical properties. Caramel malt samples had a weak malt aroma and a sweet taste with a nutty taste, more pronounced in subtype II. Dark malt samples had the ab sence of a nutty taste. Higher extractivity, lower Kohlbach number and amine nitrogen levels, and higher chromaticity for caramel II and dark II compared to the control sample led to the main differences in physico-chemical parameters. The results showed that the viscosity of buckwheat malt samples 3 and 5 was 1.12 and 1.03 mPa∙s. The resulting malt from buckwheat can be recommended for the gluten-free food products (kvass, malt and low-alcohol fermented beverages, confectionery, etc.) manufacture in order to improve their flavor characteristics.

Gold Nanoclusters and Silica-Coated Carbon Dots-Assisted Ratiometric Fluorescent Nanosensors for Ultrasensitive Detection of Glyphosate

In this work, a novel ratiometric fluorescent nanosensor by coupling mesoporous silica spheres-coated nitrogen-doped carbon dots (N-CDs@SiO2) and bovine serum albumin-stabilized gold nanoclusters (BSA-AuNCs) was developed for sensitive detection of glyphosate. BSA-AuNCs nanocomposites were covalently connected onto the surface of amino-functionalized N-CDs@SiO2 nanospheres, causing the core-satellite probes with two fluorescence emissions at 436 and 651 nm, respectively, under a single excitation of 360 nm. The N-CDs@SiO2@BSA-AuNCs “signal on–off–on” ratiometric fluorescent probes could realize highly selective differentiation and accurate detection of glyphosate based on the fluorescence quenching of Cu2+ on BSA-AuNCs and glyphosate-induced fluorescence recovery due to the strong complexation of glyphosate toward Cu2+. The developed ratiometric fluorescent nanosensor exhibited excellent selectivity to glyphosate, wide detectability in a concentration range of 5–100 ng/mL, high sensitivity with a low detection limit of 3.4 ng/mL, as well as fascinating reliability and practicability in real malt samples with recoveries of 94.81–101.61%. This study provides a universal platform for versatile sensing of more trace analytes in complex matrices and can be extended for wide application in the environment and food safety fields.

Intrinsic and extrinsic factors drive differences in the gelatinisation behaviour of barley and malt starch

We studied the impact of malting on barley starch gelatinisation properties and whether observed differences are due to changes in extrinsic or intrinsic factors. We isolated the total starch and large and small starch granules fractions from barley and malt samples and subjected them to DSC. The peak gelatinisation temperature for malt starch was, on average, 1.2 °C higher than for barley starch. The malting process and endosperm breakdown products were each responsible for half of this difference. The presence of water-extractable, non-starch components (sugars, minerals, protein and starch hydrolysis products,…) increased the intrinsic starch gelatinisation temperatures by 2.2–4.7 °C for barley and 3.6–5.3 °C for malt. The small starch granule fractions from barley had a 3.1 °C higher peak gelatinisation temperature than large granule fractions. No effect of malting was observed here. These findings indicate that matrix effects and starch granule size must be considered when addressing starch conversion during brewing.

Unusual Profile of Thiol Precursors in Special Malts: First Evidence of Chemical Glutathione-/γGluCys- and CysGly-/Cys- Conversions

Polyfunctional thiols (PFTs) present in beers or in wines are known to be released by yeast, during fermentation, from bound forms originally found in raw materials. In the brewing field, huge amounts of S-conjugates have been evidenced in several dual-purpose hop varieties. Malt, however, being the major raw material of beer, could also be a significant contributor of PFTs to beer (cysteinylated, Cys- and glutathionylated, G- precursors of 3SHol already identified in a few samples of barley and malt). Forty-two barley malts from 2 to 1500 EBC and five other malted cereals were screened to characterize their thiol precursor profile (G- and Cys- as well as dipeptidic bound CysGly- and γGluCys- forms of 3SHol). First, it was confirmed that G-3SHol was ubiquitous reaching up to 320 µg/kg in some samples, whereas Cys-3SHol remained at a trace level of up to 13 µg/ kg. Moreover, for the first time, dipeptidic bound forms of 3SHol were evidenced in malt (up to 10 and 11 µg/kg for CysGly-3SHol and γGluCys-3SHol, respectively). In pale malts, the level of the CysGly- form was shown to be proportional to that of G-3SHol (in situ γGT during the malting process). This appeared to be no longer true for special malts (ranging from 5 to 45°EBC), whose CysGly-3SHol level correlated instead with Cys-3SHol (suspected chemical conversion from the dipeptide conjugate). As for γGluCys-3SHol, it was only found in the special barley malts (indicating another chemical break of the Cys-Gly bond, here on G-3SHol) and in malted rye, spelt, and wheat. No precursors were found in roasted malt.

Ultrasensitive electrochemical aptasensor with Nafion-stabilized f-MWCNTs as signal enhancers for OTA detection

In this study, an ultrasensitive electrochemical (EC) aptasensor with Nafion-stabilized functionalized multi-walled carbon nanotubes (f-MWCNTs) as signal enhancers was established for ochratoxin A (OTA) determination. Herein, f-MWCNTs were prepared through functionalization with nitric acid. The incorporation of Nafion promoted a good dispersion of f-MWCNTs and prevented their leaching on the electrode, making a robust stability of the aptasensor. The Nafion-f-MWCNTs composites were used as the sensing substrates to largely enhance the electroactive surface area and the conductivity of the electrode, realizing a significant signal amplification. Carboxyl groups on the surface of f-MWCNTs readily exposed from Nafion membrane to couple with streptavidin, facilitating the immobilization of biotinylated aptamers to achieve selective recognition towards OTA. When OTA existed, aptamers preferentially combined with it, causing a noticeable decline in the current response. Under optimum conditions, a good linear relationship between the current changes and the logarithm of OTA concentration was observed from 0.005 ng/mL to 10 ng/mL, with a limit of detection low to 1 pg/mL for OTA. The specific, sensitive, and reproducible aptasensor succeeded in application in malt samples, confirming a great promise for more contaminants and providing a universal platform in complex matrices by simply replacing the corresponding aptamers.

Quality Characteristics and Sensory Attributes of Dough and Bread Fortified by Carob, Malt and Soybean Flours

Background: The objective of this study was to evaluate the effect of the partial replacement of wheat flour by carob, malt and soybean flours on the characteristics of dough’s and breads. Methods: For preparation of basic dough, wheat flour was blended with water, sodium chloride and dried yeast. The samples were subjected to the operations of mixing, proofing and baking. The carob, soybean and malt flours were used in increasing ratio 1-5%. Result: Physicochemical properties of composite flours showed that the proteins level (for soybean), ash, fat, fatty acids and starch were increased with increase level of flours substitution. Composite flours prepared with carob and soybean displayed higher amounts of dry and wet gluten, Zeleny number and lower value of failing number. For sensory characteristics, carob and soybean breads received higher liking scores compared to the malt and wheat samples. For malt, only 1% was able to improve the color, section shapes and texture of bread. This study demonstrated the potential use of carob, soybean and malt flours to improve the overall characteristics of the dough’s and breads.

Characterization of the aroma compounds in crystal malt

Crystal malt, the most popular type of specialty malt used in beer brewing, plays a vital role in forming complex flavor and color. Nevertheless, crystal malt is only defined based on the malting process, and there is not any standard to evaluate its quality. In the current study, the volatile aroma constituents of commercial crystal malt samples were analyzed with headspace solid-phase microextraction combined with gas chromatography-mass spectrometry, in order to explore the characteristic aroma compounds of crystal malt. The average concentration of volatile aroma compounds in 10 crystal malt samples is 587µgL-1 , ranging from 347 to 1265µgL-1 . A total of 38 aroma compounds were identified, 47% of which were existed in all the 10 samples. Based on principal component analysis and odor activity value, isobutyraldehyde, 2-methylbutanal, furfural, 2-acetyl-1H-pyrrole, oct-1-en-3-ol, 4-methyl-2-phenyl-2-pentenal, and (2E)-2-isopropyl-5-methyl-2-hexenal could be considered the characteristic aroma compounds of crystal malt. The results of this present study would help to establish a standard to assess the quality traits of crystal malt sample.

Physicochemical Properties and Antioxidant Activity of Portuguese Craft Beers and Raw Materials.

There is an increase in the popularity of craft beer, which is produced by small, independent, and traditional breweries. Since craft beer popularity is rising in Portugal this research focused on assessing physicochemical parameters, total phenolic content (TPC) and the antioxidant capacity of Portuguese craft beers and raw materials used in beer production. In this experimental study, 19 beer samples were analyzed. Parameters such as pH, Total Acidity, Reducing Sugar Content and TPC were evaluated. For the determination of antioxidant activity, DPPH scavenging activity and metal chelating activity (MCA) were analyzed in all samples. Craft beers demonstrated a high phenolic content (ranging from 343.78 mg GAE/L to 2172.49 mg GAE/L), significantly different from industrial beers. Craft beers demonstrated a higher inhibition of DPPH radicals and higher MCA than the raw materials. DPPH inhibition ranged from 36.5% to 96.0% for malt and 64.7% to 79.6% in hops samples. MCA also varied between the different samples, with results of 12.0% to 24.8% in malt samples and 3.8% to 23.5% in hops. Raw materials can potentially influence the antioxidant activity of the resulting beer. Positive correlations between TPC and physicochemical properties can be useful to help consumers choose beers with added value for health.

QUALITY ASSESSMENT OF SPRING BARLEY VARIETIES INTENDED FOR MALTING PROCESS

The suitability of a barley grain for malt production depends upon a large number of quality parameters that are crucial for the identification of high-quality malt varieties. The grain and malt technological quality parameters of five samples of four spring malting barley varieties were studied in order to estimate their malting potential. Selected barley varieties proved to be of satisfactory malting quality in terms of analyzed technological parameters. First-class grain percentage in the analyzed samples ranged from 84.9 to 94.6 %. Hectoliter weight reached values from 634.2 to 737.1 g.dm-3. Barley samples also contained a relatively high starch content of 63 to 68 %. Nitrogenous substances ranged from 9.9 to 11.3 % and all tested varieties met the requirement for nitrogen content. These samples were micro-malted and resulting malt was analyzed. All tested malt samples achieved high and satisfactory extract content of 82.4 - 84.3 %. Statistically significant (p&lt;0.05) the highest extract content was confirmed in variety LG Tosca (84.3 %) which was found to be relatively the best technological quality also for its kernel size and optimal starch and protein content. The average value of friability was 98 %. The intensity of proteolytic modification among varieties was satisfactory (Kolbach index 39.18 - 47.17 %). The viscosity of the wort reached values from 1.41 to 1.47 mPa.s-1, varieties provided clear wort in all cases. Based on the results of grain and malt quality parameters it can be concluded that all tested spring barley varieties are suitable for malting process.