Malted Grain Research Articles

SOME RELATIONSHIPS BETWEEN THE PROTEIN NITROGEN OF BARLEY AND THE PRODUCTION OF AMYLOLYTIC ENZYMES DURING MALTING

Barleys studied (Chariot and Delibes) contained different levels of extractable β-amylase enzymes. The potential levels of β-amylase enzymes of the two varieties studied were similar at 1.4 to 1.7% total nitrogen. Higher values of potential β-amylase enzyme were observed in the Delibes barley of higher total nitrogen of 1.9%. The higher level of β-amylase found in the barleys with the highest total nitrogen was not reflected in the protein banding patterns as revealed by SDS-PAGE protein fractionation. Extraction of barley proteins was largely influenced by the different extractants used. The alcohol soluble proteins, M r 97 kDa (D-hordeins), were only extracted when mercaptoethanol was included in the extracting solution. Although barleys with the highest nitrogen (1.9%) had the highest apparent potential to develop β-amylase enzymes, the better modified low nitrogen barleys produced higher levels of β-amylase and α-amylase when malted. Dehusking revealed that the high nitrogen barleys contained more steely grains. In contrast, the low nitrogen barleys contained more mealy grains. Steely grains contained more nitrogen than mealy grains and had the greater potential to develop β-amylase. Notwithstanding, the results of this study suggested that the proteins of the lower nitrogen barleys (1.4-1.7%) were capable of producing higher levels of β-amylase and α-amylase than the higher nitrogen barleys (1.9%) over comparable periods of malting. The high apparent β-amylase potential of the barley was linked to high nitrogen levels and associated high levels of steeliness, whilst the corresponding high β-amylase levels of malt were linked to the efficiency of endosperm modification of the malted grain.

Mycotoxins Transmitted into Beer from Contaminated Grains During Brewing

Studies with aflatoxin B1, ochratoxin A, zearalenone, deoxynivalenol, and fumonisins B1 and B2 added at various stages of the brewing process show that these mycotoxins (or metabolites) may be transmitted from contaminated grains into beer. Citrinin does not survive the mashing step. Mycotoxins in beer could originate from the malted grain or from adjuncts. Although high incidences and concentrations of aflatoxins and zearalenone have been found in local beers brewed in Africa, aflatoxins have not been detected in European beers. Zearalenone and alpha- or beta-zearalenol (the metabolite likely to occur) have not been found in Canadian and European beers, except for one sample analyzed by thin-layer chromatography only. Ochratoxin A rarely has been detected at > 1 ng/mL in beer; liquid chromatographic methods with a 0.05-0.1 ng/mL detection limit, however, have shown moderately high incidences of trace levels. Deoxynivalenol, which survives the brewing process, has been found with high incidence in Canadian and European beers, with concentration of > 200 ng/mL reported in several German beers. Fumonisins B1 and B2 occur to a limited extent in beer.

Traces of a possible Celtic brewery in Eberdingen-Hochdorf, Kreis Ludwigsburg, southwest Germany

A large number of weakly germinated hulled barley grains was found during archaeobotanical analyses from the early Celtic settlement excavations at Eberdingen-Hochdorf in southwest Germany (ca. 600 – 400 BC). These grains seem to represent deliberate germination, due to the purity of the find and its unusual archaeological context. The possibility of deliberate malting which could be connected with beer brewing is discussed. Recent germination and charring experiments show that the consistently weak traces of germination on the charred subfossil grains from Hochdorf are enough to indicate malted grains. A comparison of the archaeobotanical remains with the written and archaeological sources shows that evidence of beer brewing from excavations is very scarce. There is practically no clear proof of brewing, while written sources and indirect suggestions are abundant. Neither archaeological finds nor either written or iconographic sources give exact details about the prehistoric brewing technology of the early Celts. The archaeological finds from Hochdorf seem to be the result of deliberate malting of hulled barley for the purpose of Celtic beer brewing.

The Effect of Malting on the Extractability of Proteins and its Relationship to Diastatic Activity in Sorghum

Diastatic activity, total protein content, water-extractable protein and water-extractable contents in malted grains of several sorghum cultivars showed wide variation. Protein fractionation studies of malted grain of selected cultivars showed that cultivars with high diastatic activity exhibited high amounts of albumin-globulin fraction in malted sorghum. Diastatic activity was significantly and positively correlated with the water-extractable protein and the water-extractables contents of malted grain. The data indicate that the water-extractable components are good indicators for predicting diastatic activity and indirectly the malting quality. Water-extractable protein and water-extractable determinations are simple and rapid methods that can be used to screen a large number of sorghum cultivars for malting quality.

Zinc Source Influences Zinc Retention in Hair and Hair Growth in the Dog

Zinc absorption has been shown to vary as a func tion of the source of the zinc in the diet (Ho and Hdiroglou 1977, Ashmead et al. 1985, Wedekind and Baker 1990, Wedekind et al. 1990) and, in dogs, as a function of the presence or absence of dietary antag onists (Robertson and Burns 1963). Zinc absorption also varies as a function of the ac tual quantity of zinc in the diet (Mejborn 1990), the effect being with respect to the absolute amount of zinc absorbed with increasing dietary zinc, in contrast to the percentage absorption that may remain un changed. Problems may, however, arise as a result of increas ing the zinc content of a diet in an attempt to increase zinc absorption form the gut. The increase in zinc content of the diet may result in interaction with an other mineral causing a reduction in absorption of that mineral. Increasing dietary zinc above the minimum recommended, however, remains common practice to counteract antagonist effects on zinc absorption (NRC 1985) in many commercial diets. It has been suggested that when dietary zinc is sup plied in the form of a chelate with amino acids, rather than from inorganic sources, a greater proportion of zinc is absorbed. Depending on the amino acids used to chelate the zinc, the retention of zinc in tissues may be increased (Ashmead et al. 1989) and the undesirable effects that dietary antagonists exert on zinc absorp tion may be negated. Thus the inclusion of a zinc chelate in a diet for dogs may allow for the improvement of zinc absorp tion irrespective of the presence of dietary antagonists without the need to increase the total zinc supply in the diet. The purpose of this study was to compare two sources of zinc, zinc-amino acid chelate (2 mol metgly:l mol Zn) containing 20% Zn (ZM) and a zincpolysaccharide complex consisting of zinc sulphate complexed with alkali-modified brewers wort (the liq uid portion of malted grain), 16.7% Zn (ZP) as a re placement for Zn from zinc oxide when added to a commercial diet formulation. Materials and methods. Each zinc source was added to a typical commercial diet formulation (Table 1) that contained no added zinc. An equivalent of an additional 50 mg Zn • kg'1 as either ZO, ZM or ZP was

Properties of endosperm cell walls isolated from unmalted and malted grains of barley and sorghum

Enzymic breakdown of the endosperm cell walls occurred faster in germinated (malting) barley than in the corresponding grains of sorghum. Pentosans were the main polysaccharide lost from the endosperm cell walls of malting sorghum, whereas the main polymers lost from the cell walls of malted barley were β- d-glucans. The cell wall of malted barley showed a release and degradation pattern for β- d-glucan which did not occur in the cell walls of sorghum. The peak viscosity of the cell walls of malting barley occurred at day 2 growth, suggesting that the β- d-glucans releasing enzymes were very active during the first day of growth of the malting grain. Enzyme extracts from germinated (malted) barley were more effective than the corresponding extracts from malted sorghum in degrading endosperm cell walls isolated from either barley or sorghum. The release and degradation pattern of β- d-glucans in malting barley may be an important feature of grain quality and a part of the controlling mechanism by which the endosperm food reserves are degraded (modified) enzymically during the process of germination and seedling growth (malting).

Production of purple pigment from green malt and dry malt grains by fermentation without steaming

A large amount of high-molecular-mass anthocyanin pigment was produced by fermentation of malt grains without steaming, in which the malts were used as raw materials. The formation of a purple pigment from green malt was the most prominent from all malt grains tested. The precursor of the purple pigment was presumed to be a polyphenol (proanthocyanidin). When malt was used as the raw material, it allowed the production of pigment without using the glucoamylase preparation that is used for the fermentation of barley bran. In addition, the pigment was produced even from dry malt that had been treated with heat (80°C).

Enzymic degradation of the endosperm cell walls of germinated sorghum

Evidence derived from scanning electron microscope studies of the cell walls of germinated (malted) and unmalted sorghum grains suggests that portals (holes) develop in the endosperm cell walls during mobilization of the food reserves. It is proposed that amylolytic and proteolytic enzymes enter the endosperm cells through these portals and hyrolyse starch granules and associated storage proteins. Limited protease, pentosanase and/orβ-glucanase activities during malting may be responsible for the development of these portals in the endosperm cell walls. The latter persist in the malted grain.

Malted sorghum bicolor grains and physiology of associated microfungi

AbstractCertain aspects of the physiology of 2 microfungi associated with degradation of malted grains of Sorghum bicolor are studied. Isolated organisms are Fusarium pallidoroseum and Alternaria tenuissima. Fusarium utilized nitrogen free extract more than Alternaria in an acid medium, temperature of 20°C and 50°C enhanced protease production in Fusarium and Alternaria respectively, and both fungi preferred a substrate of malt extract agar. Both fungi have an enhanced growth in the presence of sulphur.

Effect of ensilage method on storage dry matter loss and feeding value of malt distillers grains (draff)

Operation of whisky distilling plants throughout the year produces considerable quantities of by-products malt distillers grains (draff) during the summer months. Draff is traditionally used as a ruminant feedstuff with the greatest demand being in winter. Competitive prices during summer make draff a very attractive buy and summer purchase, with subsequent storage on the farm for winter feeding is now a widely accepted, practice. However,, there is little information about the consequencies of long term draff storage or a detailed evaluation of different ensilage methods. This investigation examined the effects of three different storage methods on dry matter losses in the silo, and evaluated the recovered feedstuff using young steers.Storage methods - Each storage method was examined in duplicated sleeper walled silos, each containing approximately 6 tonnes of draff. The silos were roofed and had individual effluent tanks. For method 1 draff was tipped into the pits and a top sheet was held in place by an incomplete surface covering of sandbags.

ENDOSPERM BREAKDOWN IN DECORTICATED BARLEY GRAINS GROWN AT 25°C ON A WET SUBSTRATUM

When decorticated grains are grown at 25°C, in the dark and on a wet substratum the starchy endosperm is progressively dissolved and the residue is surrounded by a fluid filled space. The pattern of endosperm liquefaction is described. Attention is called to the important differences which exist between malted grains and those which have been grown ‘wet and warm’.

PATTERNS OF MODIFICATION IN MALTING BARLEY

The modified regions of the starch endosperms of malted grains were fragile and, in thin sections, the cell walls in these regions did not stain readily with Congo Red or Trypan Blue, although scanning electron microscopy demonstrated some cell-wall material remained. Initially the enzymes causing modification came from the scutellum, but later more came from the aleurone layer. Patterns of modification in different grains differed significantly, but usually resembled those recorded previously6 except that often modification had advanced further by the nucellar sheaf cells. In grains treated with gibberellic acid modification advanced faster, particularly beneath the aleurone layer, after two days germination. In tumbled or commercially abraded grains, malted with gibberellic acid, modification was even more rapid, but in more than 99% of the grains the same patterns of modification occurred. Two-way modification was a rare event. Rapid, general sub-aleurone modification occurred in grains cut at the apex and dosed with gibberellic acid. Decorticated grains modified exceptionally quickly and, when treated with gibberellic acid, massive subaleurone modification occurred. The cell walls of the tissues that resisted modification fluoresced strongly in ultra-violet light, in contrast to those of the starchy endosperm.

Mineral composition, ionisable iron and soluble zine in malted grains of pearl millet and ragi

Grain samples of nine varieties of pearl millet (P. typhoides) and six varieties of ragi (E. coracona) were analysed before and after malting for total ash, phosphorus, phytin phosphorus, calcium, magnesium, iron, zinc, manganese, copper and chromium contents. Pearl millet alone varietal differences were significant for iron, manganese and chromium contents. Significant nutrient losses in malting were, in pearl millet: iron and manganese, 40%; copper, 30%, and phosphorus, 25% and, in ragi: calcium, 40%; zinc, 30% and copper 25%. As judged by an in vitro method, the availability of iron and zinc in millets improved several fold on malting. The values for ionizable iron (mg per 100 g of raw and malted grains) were 0·64 and 2·70 in pearl millet and 0·29 and 2·98 in ragi. Soluble zinc contents per 100 g of raw and malted grains, respectively were 2·04 and 5·25 mg in pearl millet and 2·15 and 3·24 mg in ragi. Reduction in phytin phosphorus on malting of these millets partly explained the improved availability of iron and zinc.

Content of (+)‐catechin and proanthocyanidins in barley and malt grain

AbstractAcetone:water (3:1) extracts of milled barley grains contained simple monomeric, dimeric and trimeric flavanols in addition to higher molecular weight flavanoid tannins. Whereas (+)‐catechin and the simple individual oligomeric proanthocyanidins were readily separated by h.p.l.c. and t.l.c. fine resolution of the tanning components was not accomplished. Adsorption chromatography on Sephadex LH‐20 permitted group separation and measurement of tanning components which were characterised as polymers of (+)‐catechin and (+)‐gallocatechin. Using h.p.l.c. little change in the contents of simple flavanols was detected during the malting of barley, neither were there substantial differences in flavanol contents between five different varieties of barley. The tannins appeared to be formed in the grain prior to harvesting, possibly by oxidation of simple flavanols, and were not artefacts of post‐extraction treatments.

Enzymic modification of sorghum endosperm during seedling growth and malting

AbstractModification in the sorghum grain endosperm during seedling growth and malting was found to be associated mainly with increased activities of α‐amylase, endo‐β‐glucanase, limit dextrinase and endoprotease. The major starch‐degrading enzyme was α‐amylase. The activities of endo‐β‐glucanase, limit dextrinase and endoprotease were comparatively higher in the endosperm than in the embryo during seedling growth. Endo‐β‐glucanase activity appeared to be relatively low during seedling growth. The low activity of this enzyme might be partially responsible for the limited degradation of the cell walls in the endosperm of the malted grain.

HORDEIN POLYPEPTIDE PATTERN IN RELATION TO MALTING QUALITY AND THE VARIETAL IDENTIFICATION OF MALTED BARLEY GRAIN

A procedure is described for the extraction of hordein fractions from single seeds of barley and determination of their polypeptide composition by SDS-PAGE. Varietal differences in the hordein polypeptide pattern occur, and on the basis of this character the 28 varieties which are most widely grown in the U.K. can be divided into 11 groups. Whereas several of these groups contain varieties with similar malting quality, other groups contain both good and poor quality varieties. Examination of pilot scale malts and germinating seeds showed little change in the hordein polypeptide pattern during malting or the early stages of germination. Thus the procedure is suitable for use in the identification of malted grain as well as dry seed.

Enzyme inhibition by polyphenols of sorghum grain and malt

AbstractEnzyme production and activity in malt produced from birdproof sorghum cultivars were unaffected by the endogenous polyphenols present in the testa and nucellar layer of the grain. When the rigid segregation of tissues and substances in the malt grain is disrupted by milling, the polyphenols inhibit the endogenous enzymes in aqueous suspensions and reduce the brewing value of the ground malt. Sorghum beer made from malt of birdproof cultivars did not taste bitter. Bird‐proof sorghum cultivars differ widely in content and quality of polyphenols inhibiting enzymes. Enzymatic methods are proposed to determine the inhibiting fractions of the polyphenols in sorghum grain. The results of these methods correlate well with DMF‐extractable polyphenols assayed by ferric ammonium citrate in alkaline medium. The merits of enzymatic and chemical methods to determine biologically active polyphenols are discussed. Suggestions to protect the brewing industry against unsuitable grain sorghum cultivars of the birdproof class are made.

The production of pito, a Nigerian fermented beverage

Summary. The traditional method for preparing pito, a Nigerian fermented beverage, from maize, sorghum or a mixture of both, is described. Pito was prepared from maize in the laboratory and microbiological aspects of the process investigated. the conversion of starch to sugars during steeping and malting appears to be due partly to enzymes in the grain and partly to moulds (Penicillium spp., Rhizopus oryzae and Aspergillus sp.) present on the surface of the grain. the first stage of fermentation of the extract from the malted grain, souring, is dependent upon micro‐organisms from the atmosphere and a second stage, after boiling to concentrate, on the addition of a ‘starter’ from a previous brew. Candida sp., Geotrichum candidum and Lacto‐bacillus sp. appear to be important in both stages, and result in the production of lactic acid and about 3% alcohol. the production of alcohol and organic acids by inoculation of sterile extracts of malted grain by pure cultures of the above organisms was demonstrated.

麦芽根飼料より分離せる有毒物質産生糸状菌の研究 (第4報)

The fungus grew parasitically on sugar-containing medium or malt grains and produces a toxic substance (C7H6O4) as a metabolic product in early stages. The domestic animals which take the fungus with their feed falls prey to poisoning or succumbs by poison. Pathological dissection of these animals revealed the cause of death to be due to brain hemorrhage.

麦芽根飼料より分離せる有毒物質産生糸状菌の研究 (第1報)

A strain of hyphomycetes that produces a toxic substance was isolated from a fungus that was parasitically growing on the malt feed responsible for mass death of milking cows. The fungus penetrates into malt grains from an injured section, causes morbid change in the starch and aleuron layers, to brown the tissues, and produces a metabolic products that causes marked toxicity in animals. The fungus was found to grow on a medium with a wide variety of carbon source. The morphology of the fungus on the Czapek culture medium is as follows: Vegetative mycelium, 3-5×18μ; aerial mycelium, 2μ diam.; conidiophore, 3.0-4.5×400-500μ; metulae, 3.0-5.2×6.0-10.4μ; sterigmata, 2.3-2.7×6.0-6.7μ; conidia, 2.5×3.2μ. Since the morphology and other properties of this fungus are identical with the description for Penicillium urticae Bainier in the classification by Thom (“A Manual of the Penicillia” (1949)), the fungus is now determined as that strain.