Influence of barley variety and malting process on lipid content of malt

Integrative LC-MS and GC-MS metabolic profiling unveils dynamic changes during barley malting

Malting involves complex biochemical transformations affecting sensory and quality attributes. Despite extensive research on storage carbohydrates and proteins in malting, the lack of a detailed metabolic understanding of this process limits our ability to assess and enhance malt quality. This study employed untargeted GC-MS and LC-MS metabolite profiling across six malting timepoints to identify 4980 known metabolites, 82 % of which exhibited significant changes during the malting process. Here we identified stage-dependent metabolic shifts and dynamic chemical classes and pathways between each studied stage. These results can guide the fine-tuning of malting conditions to improve malt quality for beer production and other malt-based applications. Additionally, metabolites with antimicrobial properties were identified, underscoring the interplay between barley and microbial metabolic processes during malting. Further research into these microbial metabolites and cognate microbes may lead to novel malting assessment traits for high-quality and safe malted barley.

Characteristics of Selected Bioactive Compounds and Malting Parameters of Hemp (Cannabis sativa L.) Seeds and Malt

Hemp (Cannabis sativa L.) seeds are an interesting raw material for malting regarding its relatively high bioactive compounds concentration and proven advantageous properties in different food products and dietary supplements. In the first stage of the study, important seeds properties relevant to the malting process including moisture content, seed viability, and water absorption capacity were determined. However, a few parameters determining the seeds' usability for malt preparation, such as germination ability and water sensitivity, are different in comparison to typical malting raw materials such as barley or wheat. However, they make it possible to obtain high-quality hemp malt. In the next stage of research, spectroscopic and chromatographic analyses, including measurements of antioxidant activity and protein separation by SEC-HPLC, were conducted. The results showed that the malting process improved the total antioxidant potential of hemp seeds by 15%, leading to an increase in the concentration of lower molecular weight proteins and oligopeptides-below molecular mass of 10 kDa-responsible for this high antioxidant activity. The processing of hemp seeds reduced the phytate content while increasing phosphate fractions with fewer phosphate groups, which may have a beneficial effect on nutritional value. These results suggest that malting hemp seeds needs optimalization of the process but can increase its nutritional value as a promising raw material in the food industry.

Variation in quality of grains used in malting and brewing

Cereal grains have been domesticated largely from food grains to feed and malting grains. Barley (Hordeum vulgare L.) remains unparalleled in its success as a primary brewing grain. However, there is renewed interest in "alternative" grains for brewing (and distilling) due to attention being placed on flavor, quality, and health (i.e., gluten issues) aspects that they may offer. This review covers basic and general information on "alternative grains" for malting and brewing, as well as an in-depth look at several major biochemical aspects of these grains including starch, protein, polyphenols, and lipids. These traits are described in terms of their effects on processing and flavor, as well as the prospects for improvement through breeding. These aspects have been studied extensively in barley, but little is known about the functional properties in other crops for malting and brewing. In addition, the complex nature of malting and brewing produces a large number of brewing targets but requires extensive processing, laboratory analysis, and accompanying sensory analysis. However, if a better understanding of the potential of alternative crops that can be used in malting and brewing is needed, then significantly more research is required.

Physicochemical Characteristics of Bambara Groundnut Speciality Malts and Extract

Speciality malts and their extracts have physicochemical characteristics such as colour, flavour, and aroma sorted for in food production. Speciality malts used in food production are mostly produced from cereal grains. Hence, this study aimed to produce speciality malts from Bambara groundnut (BGN) seeds and analyse their physicochemical characteristics and metabolites. The base, toasted, caramel, and roasted malt were produced by drying at different temperatures and times. Syrups were produced isothermally from the speciality malts. The speciality malts and syrups were assessed for colour, pH, protein, α and β-amylases, total polyphenols, antioxidants, and metabolite profiling. The BGN speciality malts were assayed for fatty acid methyl esters (FAME), hydrocarbons, sugar alcohols, sugars, acids, amino acids, and volatile components using capillary gas chromatography-mass spectrometry (GC-MS) and gas chromatography with flame ionisation detection (GC-FID). The colours of the speciality malts and syrups were significantly (p = 0.000) different. The protein content of the BGN speciality malts was significantly different (p = 0.000), while the protein content of the syrups was not significantly different. The amylase activities of the BGN speciality malt decreased with the change in kilning temperatures and time. The α- and β-amylase activities for the specialty malts were 1.01, 0.21, 0.29, 0.15 CU/g and 0.11, 0.10, 0.10, 0.06 BU/g. The total polyphenols and antioxidant activities differed for all BGN speciality malts. There were twenty-nine volatiles detected in the BGN speciality malts. Fifteen amino acids consisted of seven essential amino acids, and eight non-essential amino acids were detected in the speciality malts. Fatty acid methyl esters (FAME) identified were palmitoleic, oleic, linolelaidic, linoleic, and arachidic acid. The sugars, organic acids, and sugar alcohols consisted of lactic acid, fructose, sucrose, and myo-inositol. The BGN speciality malts exhibited good physicochemical characteristics and metabolites that can make them useful as household and industrial ingredients for food production, which could be beneficial to consumers.

Time-Course Comparative Metabolome Analysis of Different Barley Varieties during Malting

Malt production is one of the important uses of barley, and its quality differs greatly depending on the barley varieties used. In this study, ultraperformance liquid chromatography coupled to quadrupole time-of-flight mass spectrometry technology was used to investigate the temporal changes of metabolites during malting in two barley varieties: Franklin (malt barley) and Yerong (non-malt barley). Also, differences in metabolite profiles were compared in the kilned malt between two other malt barley varieties (Copeland and Planet) and two non-malt varieties (ZD10 and Hua30). Results showed that degradation of trisaccharide and accumulation of UDP-glucose and mannose-1-phosphate are the key metabolic events during steeping, with Franklin showing earlier and greater changes. Earlier increase of sugars and amino acids in Franklin is associated with its faster germination rate. Comparative metabolome analysis of kilned malt from the different barley varieties indicated that malt barley accumulated more sugars, hordatine-glucoside, and oxoproline, and non-malt barley accumulated more polyphenols and monogalactosylmonoacylglycerol. These results improved the understanding of the genotypic difference in the formation of malt quality at the metabolomic level.

Effect of malting on nutritional and antioxidant properties of the seeds of two industrial hemp (Cannabis sativa L.) cultivars

The impact of malting on antioxidant, nutritional, and antinutritional features of two industrial hemp cultivars was investigated. The seeds were steeped (5 h; RT), germinated (3-days; 24 °C), and kilned at different temperatures (6 h; 50 °C or 70 °C). The following determinations were performed on malted and unmalted samples: total phenolic content, polyphenol profile, total antioxidant capacity, tocopherol composition, proximate analysis, fatty acids profile, trypsin inhibitors and phytate content. The results showed that malting increased the protein content up to 9%, without affecting the fat amount, and the fatty acids profile. Total phenolic content, tocopherol profile and total antioxidant capacity were also improved. 70 °C kilning temperature resulted effective to reduce the trypsin inhibitors (up to -27%), increase the reducing power and the level of N-trans-caffeoyltyramine and cannabisin A. Based on this, malting using 3 germination days and 70 °C as kilning temperature could be considered suitable transformation process for improving hempseeds quality.

The Impact of Terroir on the Flavour of Single Malt Whisk(e)y New Make Spirit

The impact of barley variety and its geographical growth location (environment) on the flavour of new make spirit was investigated to determine if "terroir" can be applied in the production of single malt whisk(e)y. New make spirits were produced at laboratory scale under controlled conditions from two different barley varieties (Olympus and Laureate) grown at two distinct environments (Athy, Co Kildare and Bunclody, Co Wexford) in Ireland over two consecutive seasons (2017 and 2018). The spirit samples were analysed by gas chromatography mass spectrometry olfactometry and descriptive sensory analysis. Forty-two volatiles were detected with eight deemed as very influential and fifteen deemed as influential to the aroma of new make spirit. Sensory attributes were influenced by barley variety, environment, and the interactions thereof over both seasons, with environment and the interaction of variety x environment having a greater impact than variety alone. Chemometric analysis of the olfactometry and sensory data found that both environment and season had a greater impact on the aromatic sensory perception of the new make spirits than variety alone. Therefore, this study clearly demonstrates a "terroir" impact on the flavour of new make spirit and highlights its potential importance especially in relation to single malt whisk(e)y.

Total, Neutral, and Polar Lipids of Brewing Ingredients, By-Products and Beer: Evaluation of Antithrombotic Activities

The in vitro antithrombotic properties of polar lipid constituents of malted grain (MG), pelleted hops (PH), brewer’s spent grain (BSG), spent hops (SH), wort, and bottled beer from the same production line were assessed in human platelets. The total lipids (TL) were extracted according to the Bligh and Dyer method and further separated into the total neutral lipids (TNL) and total polar lipids (TPL) extracts by counter-current distribution. The TL, TNL, and TPL extracts of all samples were assessed for their ability to inhibit platelet-activating factor (PAF) and thrombin-induced human platelet aggregation. The raw materials, by-products, wort, and beer lipid extracts all exhibited antithrombotic properties against PAF and thrombin. However, the beer TPL exhibited the lowest IC₅₀ values against PAF-induced (7.8 ± 3.9 µg) and thrombin-induced (4.3 ± 3.0 µg) platelet aggregation indicating that these polar lipids were the most antithrombotic. The lipid extracts tended to be more bioactive against the thrombin pathway. The fatty acid content of all the TPL extracts were assessed using GC-MS. The fatty acid composition of the most bioactive TPL extracts, the wort and the beer, shared similar fatty acid profiles. Indeed, it was noted that fermentation seems to play a role in increasing the antithrombotic properties of polar lipids against PAF and thrombin by moderately altering the polar lipid fatty acid composition. Furthermore, the use of brewing by-products as a source of functional cardioprotective lipids warrants further investigation and valorisation.

The chemical profiling of fatty acids during the brewing process

BACKGROUND

Although fatty acids have a beneficial effect on yeast growth during fermentation, their effect on foam and sensory stability of beer is negative. In general, long-chain fatty acids originate from raw materials, whereas short-chain acids are produced by yeast during fermentation. If the concentration of short-chain fatty acids, especially isovaleric and butyric acid, overreaches a sensory threshold, then an unpleasant aroma, such as cheesy or sweaty feet, can be formed in beer.

RESULTS

The distribution of fatty acids, from the preparation of sweet wort to the final beer, was studied using chemometric evaluation. Differences were observed between the decoction and infusion system using four barley varieties. Attention was paid to the behavior of short-chain fatty acids, namely isovaleric acid. The concentration of isovaleric acid in commercial beers brewed in infusion and decoction systems was approximately 1.4 and 1.0 mg L^-1 , respectively. The same trend was observed in experimental samples (1.3 and 0.5 mg L^-1 , respectively). This phenomenon was confirmed experimentally; based on the results, this possibly explains why, during the fermentation, isovaleric acid is coupled with the redox state of yeast cell, which is given by the wort composition (i.e. by the mashing process).

CONCLUSION

The formation of isovaleric acid is not only caused by microbiology infection or by oxidized hops, but also is influenced by the mashing process. © 2018 Society of Chemical Industry.

A Review on the Source of Lipids and Their Interactions during Beer Fermentation that Affect Beer Quality

The presence of lipids in wort and beer are important due to their influence on yeast metabolism and beer quality. Barley lipids have long been considered to have adverse effects on beer quality where some long-chain fatty acids are associated with high flavour potential. In addition, beer foam stability can be influenced by the concentration of lipids as well as other factors such as hop acids (e.g., iso-α-acids), proteins, polysaccharides and the presence of metal ions (e.g., nickel). Lipids can also influence yeast protease activity as well as the production of ethanol. This review provides an overview of the effect of climate change on the chemical composition of barley in relation to lipids and the influence of lipids in the process of this raw material in order to produce beer.

Effect of malt process steps on bioactive properties and fatty acid composition of barley, green malt and malt grains

In this study, the effect of barley malt process on antioxidant activity, carotenoid content, oil yield, phenolic compounds and fatty acid composition of barley, green malt and malt was investigated. The highest antioxidant activity (79.80%) and total phenolic content (122.43 mg/100 g) was observed in green malt. Carotenoid content of green malt (1.71 µg/g) was higher than those of barley and malt. Green malt had the maximum (+)-catechin (69.06 mg/100 g), 1,2-dihydroxybenzene (37.21 mg/100 g), quercetin (30.78 mg/100 g) and isorhamnetin (22.44 mg/100 g) content. Oil contents of samples ranged from 1.73 to 2.13% and showed increase with malting process. While barley lipids contained 18.53% palmitic, 19.94% oleic and 51.74% linoleic acids, malt oil contained 17.33% palmitic, 15.62% oleic and 56.56% linoleic acids. Linoleic acid content increased during malting process while oleic and palmitic acid content decreased.

Gluten-Free Sources of Fermentable Extract: Effect of Temperature and Germination Time on Quality Attributes of Teff [Eragrostis tef (zucc.) Trotter] Malt and Wort

This study was conducted to evaluate the behavior of a white teff variety called Witkop during malting by using different parameters (germination temperature and duration) and to identify the best malting program. Samples were evaluated for standard quality malt and wort attributes, pasting characteristics, β-glucan and arabinoxylan content, and sugar profile. It was concluded that malting teff at 24 °C for 6 days produced acceptable malt in terms of quality attributes and sugar profile for brewing. The main attributes were 80.4% extract, 80.9% fermentability, 1.53 mPa s viscosity, 7.4 EBC-U color, 129 mg/L FAN, and 72.1 g/L of total fermentable sugars. Statistical analysis showed that pasting characteristics of teff malt were negatively correlated with some malt quality attributes, such as extract and fermentability. Witkop teff appeared to be a promising raw material for malting and brewing. However, the small grain size may lead to difficulties in handling malting process, and a bespoke brewhouse plant should be developed for the production at industrial scale.