Grain and malt quality properties of some improved Nigerian sorghum varieties

To determine their grain and malt quality properties, ten improved Nigerian sorghum varieties were subjected to several tests. The parameters that were tested included thousand corn weight, germinative energy, germinative capacity, water sensitivity, malting losses, hot and cold water extracts and free amino nitrogen (FAN). Results obtained showed variations among the sorghum varieties in most of the parameters assessed. While variety SK5912 was heaviest (40.25 g), variety Nafelen 6 had the lowest weight (22.45 g). For germinative capacity, variety KSV8 gave the highest value (97.0%), while variety ICSV400 gave the lowest value (90.5%). Variety KAT487 was the most water sensitive (5%), while four varieties simultaneously gave the lowest value. Boboje gave the lowest malting loss (13.77%), while the highest loss (37.74%) was given by White Kaura. For the extracts, variety SK5912 gave the highest value, as was the case also with FAN. Generally, there were significant differences across the different varieties of sorghum for malting loss, FAN, cold water extract and hot water extract at both p < 0.05 and p < 0.01. The results showed significant agreement with previous reports, with the key findings being that grain size mostly correlated positively with high expression of the critical malting parameters. Copyright © 2014 The Institute of Brewing & Distilling     

Current Developments in Malting and Brewing Trials with Sorghum in Nigeria: A Review

Initially, large‐scale lager beer brewing with sorghum malts proved highly intractable due to a number of biochemical problems including: high malting losses estimated at 10–30% as against 8–10% for barley; high gelatinisation temperatures which limited starch solubilisation/ hydrolysis by the amylolytic enzymes during mashing; low extract yield/low diastatic power (DP) due to inadequate hydrolytic enzyme activities especially β‐amylase; low free α‐amino nitrogen (FAN) due to inadequate proteolysis limiting yeast growth during fermentation; high wort viscosities/beer filtration problems due to low endo‐β‐1,3; 1–4‐glucanase activities on the endosperm cell walls causing the release of some β‐glucans. Strident research efforts using improved Nigerian sorghum malt varieties (SK5912, KSV8 and ICSV400) have reported some encouraging results. The knowledge of the biochemical integrity of the endo‐β‐glucanases of the sorghum malt is helping to elucidate their mode of activity in the depolymerisation of the β‐glucans. This is bound to ensure process efficiency in sorghum beer brewing, reduce beer production costs and ultimately, produce a Pilsner‐type of lager beer with 100% sorghum malt.     

Effect of malting on the protein and free amino nitrogen composition of sorghum

When sorghum is malted much of the nitrogen in the kernel is transferred to the roots and shoots. Examination of Osborne protein fractions extracted from the kernel reveals that as in the case of barley the prolamins are the major source of the nitrogen transferred. Electrophoretic prolamin bands remained unchanged during malting, indicating that prolamins are degraded directly to small peptides and amino acids. There was a general decline in the number of glutelin proteins whereas some albumin plus globulin proteins increased in quantity while others decreased. In the roots and shoots there was a considerable increase in both protein nitrogen and non-protein nitrogen as a result of the translocation of the products of storage protein breakdown from the kernel. Several-fold increases occurred in all of the nine essential amino acids determined. Quantitatively, the two most important free amino acids of sorghum malt appear to be asparagine and glutamine, as in germinated wheat and maize. This is in contrast to barley where proline is the major free amino acid.     

Barley and Malt Proteins and Proteinases: III. A Simple Method for Estimating the Combined Actions of Malt Proteinases and the Extent of Protein Degradation during Malting

The activities of barley and malt proteinases have been measured using haemoglobin and the highly degradable barley protein fraction (HDBPF) in malting and feed barley varieties. In conjunction, the barley and malt total protein and its components: hordein, glutelin, soluble proteins and free amino nitrogen (FAN) as well as Kolbach index were investigated. The comparative analysis of results revealed that the general grain modification index of Kolbach (KI), which was higher in malting varieties, was much more strongly associated with the levels of hordein degraded during malting than any other parameter investigated. The KI levels were also correlated with the increase in the levels of FAN, but not with the increase in the levels of soluble protein or changes in the glutelin component. The changes in total proteinase activity were low and cannot account for the increase in KI or the degraded hordein. The levels of total proteinase activity in both feed and malting barley varieties were similar. The results suggest that estimation of the levels of degraded hordein, during malting, is a sensitive indicator of the total proteolytic action of proteinases as well as the degradability of the reserve proteins. Therefore, we recommend measuring the amounts of hordein degraded during malting for the assessment of the impacts of grain protein and proteinases on malting barley quality of different varieties, in addition to KI and FAN.     

Effect of Malting Conditions on Pearl Millet Malt Quality

The effect of malting conditions on pearl millet malt quality in two varieties, SDMV 89004 and SDMV 91018, was investigated. Grain was steeped and germinated at four temperatures, 20°, 25°, 30° and 35°C, over 5 days. Generally, malt quality parameters (percentage of roots and shoots, diastatic power (DP), α‐ and β‐amylase activity, free α‐amino nitrogen (FAN), and malting loss) were significantly affected (P < 0.001) by germination temperature and time, as well as by variety. Malt FAN and malting loss were not affected by variety. A germination temperature of 25–30°C and germination time of 3–5 days were optimal. These conditions resulted in high DP, α‐ and β‐amylase activity, good FAN and moderate malting loss. These malting conditions and the subsequent malt quality of pearl millet are similar to those reported for sorghum. Pearl millet malt can therefore be used for the production of sorghum type beers.     

DEVELOPMENT OF A MASHING PROFILE FOR THE USE OF MICROBIAL ENZYMES IN BREWING WITH RAW SORGHUM (80%) AND MALTED BARLEY OR SORGHUM MALT (20%)

Different time and temperature programmes were used to evaluate the production of hot water extract (HWE) and free amino nitrogen (FAN) from mashes containing raw sorghum and either malted sorghum or malted barley in the presence of microbial enzymes. Two malted varieties of sorghum (SK 5912 and Zaria) were used. The former gave higher HWE but lower FAN than the latter. Sorghum malts were unable to provide enzyme activity for starch extraction and exogenous enzymes were always needed. Seventeen commercially available enzyme preparations were assessed. A double-mash process was developed. Inclusion of calcium ions (200 ppm) was beneficial but adjustment of mash pH had little effect. Raw sorghum was gelatinised at 100°C for 30–40 min in the presence of a heat-stable α-amylase followed by mixing with a malt mash (started at B0°C) to give a temperature of 65°C with a total mash time of 167 min (127 min from mixing the mashes). The inclusion of a single commercial enzyme preparation (containing both proteolytic and amylolytic activities) was sufficient to achieve satisfactory HWE and FAN. Addition of different activities or combinations of activities gave no significant advantages. To obtain levels of FAN of 100–140 mg/l however excessive amounts of enzymes were required.     

Effect of Germination Moisture and Time on Pearl Millet Malt Quality — With Respect to Its Opaque and Lager Beer Brewing Potential

The effect of germination moisture and time on pearl millet malt quality was investigated. Two pearl millet varieties SDMV 89004 and 91018 were germinated at 25°C under three different watering regimes for 5 days. As with sorghum malting, diastatic power, beta‐amylase activity, free α‐amino nitrogen (FAN), hot water extract and malting loss all increased with level of watering. However, pearl millet malt had a much higher level of beta‐amylase and higher FAN than sorghum malt and a similar level of extract. Malting losses were similar or lower than with sorghum. Thus, it appears that pearl millet malt has perhaps even better potential than sorghum malt in lager beer brewing, at least as a barley malt extender, especially in areas where these grains are cultivated and barley cannot be economically cultivated. Also, its increased use in commercial opaque beer brewing, where sorghum malt is currently used, could be beneficial.     

Relationship between some Sorghum Malt Quality Characteristics and Nature of Alkaline Steep Liquor

Two Nigerian sorghum cultivars, SK5912 and ICSV400 were used to evaluate the relationships between nature of alkaline steep liquor and some malt quality characteristics over a five day germination period. Patterns of development of the malt quality indices examined were significantly influenced by the nature of alkaline steep liquor, cultivar and duration of germination, plus all their possible interactions at p<0.001. Maximum diastatic activity development was attained in ICSV400 and SK5912 when grains were steeped in NaOH and Ca(OH)₂ respectively. Ca(OH)₂ treatment seemed to cause significant enhancement of diastatic enzyme development in SK5912 compared to other treatments presumably due to Ca²⁺ stabilisation of α-amylase. Mean malt cold water extract (CWE) and hot water extract (HWE) were generally similar within both cultivars for the treatments except for ICSV400 where CWE appeared to be remarkably enhanced by NaOH treatment. Data on cold water soluble carbohydrates (CWS-Carbohydrates), CWS — Carbohydrate/CWE and CWS — Carbohydrate/HWE ratios showed that solubilised carbohydrate matter produced during malting constituted significantly higher proportion of total HWE in ICSV400 in contrast to SK5912.     

Quality Assessment of Different Sorghum Varieties for Their Brewing Potential

Four sorghum varieties (SK 5912, KSV 4, KSV 8, ICSV 400) were malted and extracted under similar conditions to assess their quality for brewing. The results showed that, in general, the sorghum varieties had high malting loss which was attributed to the high germination temperature used. The sorghum varieties also developed low levels of amylolytic activity (α‐amylase and β‐amylase), and with similar ratios. When the sorghum malts were mashed at different temperatures with the aid of commercial enzyme preparations, it was observed that mashing temperatures were more important in sugar release than additions of commercial enzymes. This was because at the lower mashing temperature, sorghum starch was not adequately gelatinised. However, when commercial enzyme preparations were added, low levels of enzymes were very effective in reducing wort viscosity and producing free amino nitrogen (FAN). Although, both commercial enzyme preparation and mashing temperature influenced sugar production, the malts produced glucose and maltose at similar ratios. Therefore good quality malts can be produced from sorghum, however mashing will employ commercial enzymes and mashing regimes are not yet optimised.     

Variety and germination time effect on total β‐glucan,water‐insoluble β‐glucan,water‐soluble β‐glucan components and β‐glucanase levels in improved sorghum varieties SK5912, KSV8 and ICSV400 before and after malting and their relationships to wort viscosity

The effects of variety and germination time on β‐glucan components – total β‐glucan (TBG), water insoluble β‐glucan (WIBG) and water soluble β‐glucan (WSBG) and β‐glucanase (BG) levels – before and after malting in improved sorghum varieties SK5912, KSV8 and ICSV400 and their relationships to wort specific viscosity (SV) were studied. This study was part of efforts to aid local malting and brewing industries in the application of sorghum varieties that are abundantly available to reduce costs. At the fifth day of germination, variety ICSV400 had the lowest TBG, WIBG and WSBG levels in its raw and malt samples. Variety SK5912 had the highest TBG, WIBG and WSBG levels in its raw samples, while variety KSV8 had the highest levels of TBG, WIBG and WSBG in its malt samples. Similarly, variety ICSV400 malts developed the highest BG levels, while the KSV8 malts gave the lowest level. The effect of variety, germination time and variety × germination time interaction was significant (p < 0.05) on the TBG, WIBG and BG levels and was not significant on the WSBG levels. Weak and significant correlation of TBG levels with SV (0.25, p < 0.05 for SK5912; 0.24, p < 0.05 for KSV8; and 0.31, p < 0.05 for ICSV400) was observed in all the samples, suggesting that the low β‐glucan levels may not be primarily and solely responsible for any viscosity impediments associated with sorghum worts during run‐off. With improvement in the effective utilization of sorghum, ICSV400 appeared the most suitable variety for malting and brewing in Nigeria.Copyright © 2016 The Institute of Brewing & Distilling     

萝卜籽粕蛋白质的组成及功能性质

以萝卜籽粕为原料,提取了其中的蛋白质;根据溶解性,萝卜籽粕蛋白中的清、球、谷、醇溶蛋白被分 离;用氨基酸自动分析仪测定了萝卜籽粕蛋白的氨基酸组成;物理化学方法测定萝卜籽粕蛋白的功能性质以及体外 清除1,1-二苯基-2-三硝基苯肼自由基、?OH、NO2 －、H2O2的能力。结果表明：萝卜籽粕蛋白中球、谷、清和醇溶蛋 白含量分别占总蛋白质的44%、33%、21%和2%;萝卜籽粕蛋白含18 种氨基酸,第一限制氨基酸为蛋氨酸,其氨基 酸评分为57。萝卜籽粕蛋白具有很好的功能性质及抗氧化能力,表明有很高的开发价值。     

Extractability and Chromatographic Characterization of Wheat (Triticum aestivum L.) Bran Protein

About 70% of the protein for human consumption is derived from plants, with cereals as the most important source. Wheat bran protein has a more balanced amino acid profile than that of flour. We here for the first time report the amino acid, size exclusion, and SDS‐PAGE profiles of bran Osborne protein fractions (OPFs). Moreover, we also investigated how OPFs are affected when physical barriers which entrap proteins in bran tissues are removed. Albumin/globulin is the most abundant OPF. It is richer in lysine and asparagine/aspartic acid than other OPF. Most bran albumin/globulin proteins have a molecular weight (MW) lower than 30 k and their chromatographic profiles differ from those of flour. The prolamin has high levels of proline and glutamine/glutamic acid. It is rich in proteins with a MW of 30 to 45 k and about 66 k reflecting contamination with gliadin from endosperm. The glutelin has high levels of glycine, proline, and glutamine/glutamic acid. Its protein is of intermediate and high MW with little protein with MW lower than 30 k. The high (MWs from 80 to 120 k) and low (MW around 45 k) MW glutenin subunits of flour are also present in bran. The glutelin of wheat endosperm is named glutenin. Ball milling releases albumin/globulin and glutelin but not prolamin. Not all glutelin was endosperm glutenin as a substantial part was entrapped in the aleurone cells.     

PROMOTING SORGHUM RESERVE PROTEIN MOBILISATION BY STEEPING IN ALKALINE LIQUOR

Mobilisation of sorghum storage reserve proteins by steeping in alkaline liquor for 48 h under four different regimes was evaluated. Germination was for 4 days at 30°C. Cold water soluble protein (CWS-protein), CWS-protein modification index, total non protein nitrogen (TNPN), peptide accumulation, FAN, endo- and exo-protease activities—all key indicators of protein mobilisation were highly significantly affected by steep regime, steep liquor and cultivar as well as their pairwise interactions. Mean FAN and TNPN were significantly higher (P < 0.0005) for malts derived from alkaline steep liquor except for KSV 8 which exhibited significant inhibition of TNPN development. Similarly, alkaline steeping promoted protein solubilisation and CWS-protein modification. While parallel improvements in amylolysis and proteolysis were recorded for ICSV 400, proteolysis in KSV 8 and SK 5912 seemed more enhanced except for SK 5912 exposed to air rest cycles. Steeping in alkaline liquor also caused significant repression of the proteases in KSV 8. Conversely, steeping SK 5912 under similar conditions promoted rather than inhibited development of these enzymes. Poor correlation between protein degradation products and enzyme development suggest major roles for factors other than proteolysis in sorghum reserve protein mobilisation.     

热变性大米蛋白的结构和性质研究Ⅰ米蛋白加热前后的溶解特性和氨基酸变化

为探讨热变性米蛋白的性质与结构关系,分析了大米蛋白加热前后的溶解性能和氨基酸组成变化。结果表明,米渣中各种蛋白质的含量大大低于未受高温处理的原料大米;米渣蛋白中胱氨酸含量比大米谷蛋白提高83%,说明大米醇溶蛋白、球蛋白和清蛋白等受热后也存在于米渣中;米渣谷蛋白胱氨酸含量比米渣蛋白降低23%,说明胱氨酸是影响米渣蛋白溶解的重要因素。     

Walnuts (Juglans regia L): proximate composition,protein solubility,protein amino acid composition and protein in vitro digestibility

Walnuts contained 16.66% protein and 66.90% lipids on a dry weight basis. Non‐protein nitrogen values ranged from 6.24 to 8.45% of the total nitrogen when the trichloroacetic acid concentration was varied within the range 0.25–1.0 M . Albumin, globulin, prolamin and glutelin respectively accounted for 6.81, 17.57, 5.33 and 70.11% of the total walnut proteins. Walnut proteins were minimally soluble at pH 4.0. The majority of total walnut protein polypeptides had estimated molecular weights in the range 12 000–67 000. The Stokes radius of the major protein in walnuts (glutelin fraction) was 66.44 ± 1.39 Å. Lysine was the first limiting essential amino acid in total walnut proteins as well as in the globulin and glutelin fractions. Leucine and methionine plus cysteine were the second limiting essential amino acids respectively for the prolamin and albumin fractions. Hydrophobic and acidic amino acids dominated the amino acid composition in all protein fractions. Native and heat‐denatured walnut glutelins were easily hydrolysed by trypsin, chymotrypsin and pepsin in vitro. © 2000 Society of Chemical Industry     

INFLUENCE OF CULTIVAR AND STEEP REGIME ON SOME PROTEIN RELATED PROPERTIES OF SORGHUM MALTS

Cold water extract (CWE), cold water soluble protein (CWS-protein), CWS-protein modification and free alpha amino nitrogen (FAN) were determined for three improved Nigerian sorghum cultivars malted under four different steep conditions. The levels of these variables in the sorghum malts differed significantly when malted under identical steep regimes. This indicates that soluble protein accumulation and modification in these grains are cultivar dependent. Grains exposed to a combination of air rest cycles and final warm steeping gave highest values of cold water solubles, CWS-protein modification and FAN. Amylolytic activity was enhanced over the rate of proteolysis when grains were steeped under regimes incorporating final warm steep. Cultivar SK 5912 with highest soluble protein solubilisation activity showed lowest FAN accumulation under all steep regimes suggesting roles for factors other than proteolysis in FAN accumulation.     

The effect of germination time on malt quality of six sorghum (Sorghum bicolor) varieties grown at Melkassa,Ethiopia

The effect of germination time (48, 96 and 144 h) on malt quality of six sorghum varieties was investigated to determine the potential of grain sorghum cultivars in the local brewery industry. Six sorghum varieties (Gambella 1107, Macia, Meko, Red‐Swazi, Teshale and 76 T1#23) were evaluated in a randomized complete block design with three replications. The results showed that both germination time and variety had a significant effect (p ≤ 0.05) on sorghum malt quality. The hectolitre weight (kg hL^?1 at 12.5% moisture), germination energy (%), crude protein (%) and flour starch amylose content (%) were: 75.8–82.9, 96–99, 7.0 ? 11.9 and 16.0 ? 23.0, respectively. The sorghum malt diastatic power (DP, °L), free amino nitrogen (FAN, mg L^?1), hot water extract (HWE, %) and malting loss (%) were: 18.96 ? 31.39, 185.67 ? 343.29, 41.85 ? 85.08 and 8.68 ? 27.56, respectively. Malting loss, HWE and FAN increased with germination time. The DP increased as the germination duration increased from 48 to 96 h, but the difference between 96 and 144 h was not significant. Considering the excessive malting loss and marginal increase in HWE beyond 96 h, this study suggests that the optimum malting duration would be around 96 h. Among the varieties tested, Teshale and Gambella 1107 produced the better malt quality. Copyright © 2012 The Institute of Brewing & Distilling     

Influence of High Protein Digestibility Sorghums on Free Amino Nitrogen (FAN) Production during Malting and Mashing

In sorghum brewing, obtaining sufficient Free Amino Nitrogen (FAN) for rapid and complete fermentation remains a problem due to the high proportions of unmalted sorghum used and the poor digestibility of wet‐heat treated sorghum protein. Sorghum mutant lines with high protein digestibility have been developed through breeding. These high protein digestibility sorghums (HPDS) have protein bodies with villi‐like borders that apparently facilitate protease access. This work investigated FAN production from HPDS when malted and mashed, to assess their potential for use in sorghum brewing to improve wort FAN levels. When malted, HPDS contained substantially higher levels of FAN than normal protein digestibility sorghums (NPDS), 32 mg/100 g malt more. However, when the HPDS were mashed either as malt, or as grain or malt plus exogenous proteases, FAN production during mashing was not substantially higher than with NPDS subjected to the same treatments, only 6, 6–18 and 9–13 mg/100 g grain or malt, respectively. This is probably due to wet‐heat induced cross‐linking of the kafirin proteins reducing their susceptibility to proteolysis. Notwithstanding this, HPDS could be very useful for improving FAN levels in sorghum brewing if they are malted.     

苦荞麸皮蛋白的提取分离及清除自由基作用研究

以苦荞二道荞麸为原料,进行复合蛋白提取和蛋白质Osborne分级分离,并对各蛋白组分进行清除自由基能力研究。结果表明,苦荞麸皮中最主要的蛋白组分为清蛋白,占蛋白总量的51.22%;其次为球蛋白和谷蛋白,分别占13.69%和17.07%;最少的为醇溶蛋白,占8.83%。苦荞麸皮复合蛋白及各蛋白组分均有体外清除自由基作用,其中水溶性清蛋白和球蛋白清除自由基能力高于醇溶蛋白和碱溶蛋白,且在低浓度范围内,随蛋白质浓度增加,清除能力呈线性提高,但在高浓度时却无明显量效关系。     

MICRO-SCALE MALTING AND BREWING STUDIES OF SOME SORGHUM VARIETIES

The malting and brewing characteristics of three sorghum varieties were investigated in a micromalting and microbrewing plant. The optimum malting conditions for Sorghum vulgare c.v. Fara Fara (Australia), Sorghum bicolor (South Africa) and Sorghum vulgare c.v. SK5912 (Nigeria) were found to consist of steeping for 21 h, at 30°C, initial germination at 30°C for 24 h, followed by a further germination period of 4 days at 25°C. Kilning temperatures of 50°C and 82°C were investigated. Evidence of the presence of hydrocyanic acid was found. The extent of modification in all malts was markedly irregular with the kernels showing brown coloration on the outer layers. The brewing trials with 100% sorghum malt showed a slow and incomplete saccharification, slow lauter tun filtrations and very difficult beer filtrations. By supplementing commercial enzymes in the mash only the speed of lauter tun filtration improved significantly.