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1.
The development of a mini-column screening test for aflatoxins in sorghum malt and the finally adopted method is described. The method is based on a silica cartridge clean-up of a chloroform extract of malt followed by detection by means of an alumina/Florisil mini-column. The method is rapid, economical, more sensitive than published methods and suitable for use by semi-skilled personnel. It was deliberately designed to maximise test readings, thereby obviating false negative findings. Validation trials indicated that the method had a detection limit of approximately 3 μg aflatoxin Bt/kg and was robust enough for routine use. The method is recommended for industrial use, provided that positive samples are confirmed by conventional analysis. 相似文献
2.
Chigozie E. Ofoedu Jude O. Iwouno Nnamdi C. Ojimba James S. Chacha Damaris C. Okafor Ogechukwu M. Anwaegbu 《International Journal of Food Science & Technology》2022,57(7):4328-4336
In this study, sorghum grains were malted using different malting regimens and the malt qualities were analysed for cold water extract (CWE), hot water extract (HWE) and diastatic power (DP). Results showed that malting regimen produced sorghum malts with peak CWE, HWE and DP within the pre-determined limits of malting regimen. From this, predictive models of sorghum malt quality were developed and tested. Whilst steeping duration interacts significantly with the germination period to cause variations in CWE and HWE, only the germination period significantly influenced the DP of sorghum malts. However, the kilning temperature showed no significant impact on the parameters studied. Besides CWE, HWE and DP correlating positively with each other, the developed predictive models were significant (P < 0.05) and satisfy the quality of fit (R2 > 0.70) of the proposed models. The result demonstrated that wort for different purposes can be obtained by varying the malting operational conditions in the predictive model, thus saving time, resources, preliminary studies and research designs. Besides the promotion of a cheaper local alternative material for industrial wort production and brewing purpose, this research provides valuable insight on the brilliant prospect of variable malting regimen in predicting and adjusting the quality characteristics of sorghum malt and wort. Future studies are required to develop models for wort produced from peak CWE, HWE and DP, for predicting wort quality characteristics. 相似文献
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4.
Mathoto L. Lefyedi Gert J. Marais Michael F. Dutton John R.N. Taylor 《Journal of the Institute of Brewing》2005,111(2):190-196
Turned and unturned outdoor floor malted sorghum were studied for their total microbial contamination, nature and extent of contamination by moulds, cytotoxicity (IC50) and quality in terms of diastatic power (DP). The presence of aflatoxins, fumonisins, deoxynivalenol and zearalenone were also investigated. Total microbial counts were high (107–108 cfu/g) in both turned and unturned samples. All samples showed contamination by different moulds, with the dominant being Mucor species, Rhizopus oryzae, Fusarium moniliforme and Phoma sorghina as well as Aspergillus flavus and Alternaria alternata. The latter four are known for producing mycotoxins. Malt samples had very low cytotoxicity (IC50 from 62.5 to >1000 kg/kg), though all contained fumonisins, deoxynivalenol and zearalenone at levels of <0.25–2 μg/g, 15–20 and 10–15 μg/kg, respectively. Malt DP was generally lower in turned samples compared to unturned samples probably because the heat conserved in the latter ensured better germination conditions. Overall, turning during germination did not affect the microbial load, mould population and levels of deoxynivalenol and zearalenone in sorghum malt but decreased sorghum malt DP. Thus, alternative methods of controlling the sorghum malt microbial load should be sought. 相似文献
5.
Wisal H. Idris Samia M. AbdelRahaman Hagir B. ElMaki Elfadil E. Babiker & Abdullahi H. El Tinay 《International Journal of Food Science & Technology》2006,41(10):1229-1233
The seeds of two cultivars of Sudanese sorghum (Sorghum bicolor), namely Wad Ahmed and Tabat, were germinated for 4 days to obtain 1‐, 2‐ and 4‐day‐old malts. Sorghum malt (5% and 10%) was added to sorghum flour. The mixtures were incubated at 30 °C with shaking for 30, 60, 90 and 120 min. Malting loss was very slight for both cultivars and for all incubation periods. Phytic acid and tannin contents were assayed for all treatments. The results revealed that phytate and tannin contents were significantly (P ≤ 0.05) reduced when sorghum flour was pretreated with malt. When a mixture containing 10%, 4‐day‐old malt and sorghum flour was incubated for 120 min, it significantly (P ≤ 0.05) reduced phytate and tannin contents by 92% and 98%, respectively, for Wad Ahmed cultivar, while for Tabat they were reduced by 93% and 96%, respectively. The rate of reduction of phytate and tannin content increased with incubation time and malt age and concentration. 相似文献
6.
Clement Djameh Firibu Kwesi Saalia Emmanuel Sinayobye Agnes Budu Gloria Essilfie Henry Mensah‐Brown Samuel Sefa‐Dedeh 《Journal of the Institute of Brewing》2015,121(1):106-112
Pito is an alcoholic beverage obtained through a yeast (Saccharomyces cerevisiae) fermentation of wort extracted from sorghum (Sorghum bicolor L. Moench) malt. The malting conditions of sorghum are thought to influence the quality characteristics of the malt, and subsequently the quality of the pito obtained from it. Studies were carried out on a local sorghum cultivar grown in Ghana – chireh, to optimize the conditions for malting conditions for pito production in Ghana. A 33 full factorial experimental design was replicated with steeping times of 12, 16 and 22 h, germination times of 3, 4 and 5 days, and malt drying temperatures of 30, 40 and 50 °C as factors. Diastatic power, extract yield, attenuation limit and free amino nitrogen were determined. Germination duration significantly affected diastatic power and free amino nitrogen (p < 0.001). Extract yield was also significantly influenced by germination duration (p = 0.001). The germination time, steeping time and drying temperature had no significant effect on the attenuation limit. The optimal conditions for malting this specific cultivar grown in Ghana to obtain critical malt quality indices are 12.0–12.5 h steeping, 5 days of germination at 30 °C and drying at 40 °C. Free amino nitrogen levels in all treatments were higher than the minimum requirement for good yeast nutrition and fermentation. Copyright © 2015 The Institute of Brewing & Distilling 相似文献
7.
The effects of two extractants on the activities of carboxypeptidase and proteinase enzymes from three sorghum varieties germinated for 3 and 5 days were studied. In all three varieties, cysteine hydrochloride (Cyst. HCl) proved a better extractant than 2‐mercaptoethanol (2‐ME) as shown by the increase in carboxypeptidase and proteinase activities with 5‐day malts. A three‐way analysis of variance (ANOVA) on the effect of germination time, extractant and variety on the carboxypeptidase activities of the three malts showed that all the factors plus their possible four‐way interactions highly significantly (P < 0.001) affected the extractability/activity of the enzyme. However, while the three factors had a highly significant (P < 0.001) effect on the proteinase activity, one of their four‐way interactions, specifically, extractant/variety, had no significant effect. This suggests that, unlike the carboxypeptidase enzyme, the effectiveness of the extractants in enhancing the extractability/activity of the proteinase enzyme in all the sorghum malt samples was amongst other factors, not variety‐dependent. 相似文献
8.
An investigation into factors influencing beta-amylase activity in sorghum malt confirmed that ungerminated sorghum grain exhibited essentially no beta-amylase activity. Malted sorghum had beta-amylase activity less than 25% of the level in barley malt. Neither reducing agents nor papain affected beta-amylase activity in sorghum, indicating that the enzyme is not in a bound form, unlike in barley. Isoelectric focusing indicated that sorghum beta-amylase comprises just one major and one minor isozyme of pl approximately 4.4–4.5, unlike the many isozymes all of higher pl in barley. However, like barley, sorghum beta-amylase was more temperature-labile than its alpha-amylase. Beta-amylase activity in sorghum malt was increased by germination time, high germination moisture and over the germination temperature range investigated (24–32°C), 24°C gave the highest activity. The beta-amylase activity of sorghum malts was significantly correlated with malt diastatic power, despite the fact that alpha-amylase and not beta-amylase is the predominant diastatic enzyme in sorghum malt. 相似文献
9.
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 相似文献
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John R. N. Taylor Bhekisisa C. Dlamini Johanita Kruger 《Journal of the Institute of Brewing》2013,119(1-2):1-14
Mainstream lager beer brewing using the tropical cereals sorghum, maize and rice, either as malt or as raw grain plus commercial enzymes, is becoming widespread. This review examines the differences in composition between these tropical cereals and barley and their impact on brewing processes and beer quality. All of these cereals have a starch gelatinization temperature some 10 °C higher than barley. The sorghum prolamin proteins are particularly resistant to proteolysis owing to disulphide cross‐linking involving γ‐kafirin. Unlike barley, the major endosperm cell wall components in sorghum and maize are arabinoxylans, which persist during malting. The rice cell walls also seem to contain pectic substances. Notably, certain sorghum varieties, the tannin‐type sorghums, contain considerable levels of condensed tannins (proanthocyanidins), which can substantially inhibit amylases, and probably also other brewing enzymes. Tropical cereal malts exhibit a similar complement of enzymic activities to barley malt, with the notable exception of β‐amylase, which is much lower and essentially is absent in their raw grain. Concerning beer flavour, it is probable that condensed tannins, where present in sorghum, could contribute to bitterness and astringency. The compound 2‐acetyl‐1‐pyrroline, responsible for the popcorn aroma of maize and also the major aroma compound in rice, presumably affects beer flavour. However, much more research is needed into tropical cereals and beer flavour. Other future directions should include improving hydrolysis of prolamins into free amino nitrogen, possibly using prolyl carboxypeptidases and investigating tropical cereal lines with useful novel traits such as high amylopectin, high protein digestibility and low phytate. Copyright © 2013 The Institute of Brewing & Distilling 相似文献
12.
B.N. Okolo O.C. Amadi A.N. Moneke T.N. Nwagu C.I. Nnamchi 《Journal of the Institute of Brewing》2020,126(1):46-52
The sugar profile of wort from laboratory malted barley, malted sorghum, unmalted barley and unmalted sorghum grains mashed with commercial enzyme preparations were studied. Similar levels of glucose to maltose (1:7) were observed in wort of malted barley and malted sorghum. Mashing barley or sorghum grains with commercial enzymes changed the glucose to maltose ratio in both worts, with a greater change in wort from sorghum grains. Although hydrolysis with commercial enzymes released more glucose from maltose in sorghum wort, the same treatment retained more maltose in barley wort. Adding malted barley to sorghum grains mashed with commercial enzymes restored the glucose to maltose ratio in sorghum mash. Fermentation of wort produced from all barley malt (ABM) mash and commercial enzyme/barley malt/sorghum adjunct (CEBMSA) mash of similar wort gravity was also studied. ABM and CEBMSA worts exhibited similar glucose to maltose ratios and similar amino acid spectra. However, ABM released more individual amino acids and five times more proline than wort from commercial enzyme/barley malt/sorghum adjunct. ABM produced 27% more glucose and 7% more maltose than CEBMSA. After fermentation, ABM mash produced 9.45% ABV whilst commercial enzyme/barley malt/sorghum adjunct mash produced 9.06% ABV. Restoration of the glucose/maltose ratio in the CEBMSA mash produced wort with a sugar balance required for high gravity brewing. © 2020 The Institute of Brewing & Distilling 相似文献
13.
Okokon U. Etok Akpan 《Journal of the Institute of Brewing》2004,110(3):189-192
The diastatic power of the freshly kilned sorghum malt at 68.1°WK had a 29% drop after six months of storage. Freshly kilned sorghum malt displayed high wort turbidity (4.9 EBC) which dropped to 0.95 EBC and 1 EBC after 2 and 6 months of storage respectively. The colour of the malt worts faded slightly over the trial period from 7.6 EBC in freshly kilned malt to 6.8 EBC after six months. Extract remained fairly steady throughout the study period most likely due to the use of external amylolytic enzymes during mashing. The protein in extract/protein in grain fluctuated between 46.6% in the freshly kilned malt to 43.2% at the end of six months. The apparent extract after final attenuation (AEFA) indicates more fermentability beginning from two months after storage. Free α‐amino nitrogen (FAN) dropped from 238 mg/L to 194 mg/L after six months of storage. Mash filtration with a micro‐mash filter remained prolonged (86–93 min) throughout the six months of storage. 相似文献
14.
Reginald C. Agu 《Journal of the Institute of Brewing》2011,117(2):206-211
A sorghum variety was supplied as commercial malt and as an unmalted cereal by a maltster. The commercial sample had been malted in a tropical country. Sub‐samples of the unmalted cereal were malted in the laboratory under controlled germination temperatures of 28°C and 30°C. Laboratory and commercially malted sorghum were studied for their brewing qualities. The α‐amylase development in sorghum malt was enhanced when germination was carried out at the higher temperature of 30°C rather than at 28°C. Hot water extract (HWE) was more variable. With infusion mashing, results showed a significant difference for germination time (3–6 days), but no significant difference relating to germination temperature. With the decantation mashing method the reverse was observed. The low numerical values of HWE obtained from sorghum malt in the infusion mashing process confirmed that this process is not suitable to produce optimal extract development from malted sorghum. The 28°C germinated sorghum released more FAN products into the worts than the 30°C malt, using both the infusion and decantation methods. With regard to the parameters tested, commercially malted sorghum gave lower analytical values than laboratory malted sorghum. It was also observed that variations in malting temperatures and mashing processes can cause unexpected variations in the analyses of sorghum malt. These findings suggest that careful process control is required during the malting and mashing of sorghum. 相似文献
15.
Jean‐Claude Bwanganga Tawaba François Béra Philippe Thonart 《Journal of the Institute of Brewing》2012,118(3):295-304
Previous work has shown that Bacillus subtilis‐S499‐based biocontrol treatments applied without aeration at the steeping stage of red sorghum malting offer good mould reduction, but yield malts with low levels of key hydrolytic enzymes. Thus we attempted to raise these levels by aerating the steeping liquor, varying the steeping time (from 8 to 40 h) and temperature (from 25 to 35 °C), and combining a biocontrol treatment with prior steeping in 0.2% NaOH. Aeration proved particularly important whenever B. subtilis cells were present in the steep liquor. The optimal temperatures for α‐ and β‐amylase were 30 and 25 °C, respectively. By increasing the steeping time, it was possible to improve the α‐amylase activity, but the β‐amylase activity peaked sharply between 16 and 20 h, depending on the steeping medium. A good compromise was steeping in a biocontrol medium for 14–16 h at 30 °C. Combination steeping treatments (0.2% NaOH for 8 h followed by biocontrol for 8 h) yielded malts of a quality approaching that afforded by dilute alkaline treatment. Copyright © 2012 The Institute of Brewing & Distilling 相似文献
16.
C. F. Ndubisi E. T. Okafor O. C. Amadi T. N. Nwagu B. N. Okolo A. N. Moneke F. J. C. Odibo P. M. Okoro R. C. Agu 《Journal of the Institute of Brewing》2016,122(1):156-161
Preliminary microbiological studies carried out on sorghum grains showed that the major microorganisms found were mainly bacteria and that aflatoxin‐producing fungi were not found. The effect of added commercial enzyme preparations and different infusion mashing temperatures on extract yield, from sorghum malted at 30 °C, was studied. The infusion mashing method (65 °C) developed for mashing well‐modified barley malt produces poor extract yields with sorghum malt. The extract yield from the sorghum malt in this study was very low with infusion mashing at 65 °C, without the addition of commercial enzyme preparations. A higher extract yield was obtained from the sorghum malt, without the commercial enzyme addition, when using infusion mashing at 85 °C. Both infusion mashing temperatures (65 and 85 °C) showed an improved extract yield over the control malt when commercial enzyme preparations were used during mashing of the sorghum malt. The added enzyme preparations resulted in a higher extract yield from the germinated sorghum when infusion mashing was performed at 65 °C over mashing at 85 °C. The use of individual commercial enzymes (α‐amylase, β‐glucanase, protease, xylanase, saccharifying enzyme and combinations of some hydrolytic enzyme) increased extract yields, when complemented with the enzymes that had developed in the sorghum malt. Copyright © 2016 The Institute of Brewing & Distilling 相似文献
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Pilot scale (1000 L) brews were carried out with a grist comprising of unmalted sorghum (50% of total wet weight of grain) (South African variety) and malted barley (50% of total wet weight of grain) grist using a mashing program with rests at 50°C, 95°C and 60°C. Mashes were supplemented with a high heat stable bacterial α‐amylase, a bacterial neutral protease and a fungal α‐amylase. A control brew containing 100% malted barley was also carried out. Saccharification difficulties were encountered during mashing, and extraction of the grist was lower for the sorghum mashes. The sorghum mashes showed comparable lautering behaviour to that of the control mash. At mashing off the sorghum worts were starch positive. Apparent degree of fermentation of the sorghum gyles were less than the control gyles. Green beer filtration proved unproblematic. The sorghum beers compared quite closely with the control beer with regard to colour, pH and colloidal stability. Foam stability deficiencies were apparent with the sorghum beer. However, the fermentability of the sorghum worts were lower. Hence the sorghum beers were lower in total alcohol. Sensory analysis indicated that no significant differences existed between the sorghum beer and both the control beer and a commercial malted barley beer with regard to aroma, mouth‐feel, after‐taste and clarity. However, the sorghum beer was found to be significantly different to both of the other beers with regard to colour, initial taste and foam stability. 相似文献
18.
Lewis I. Ezeogu Bartholomew N. Okolo James C. Ogbonna 《Journal of the Institute of Brewing》2001,107(6):337-343
The effects of method of hydrolysis and source of sorghum sprout (sorghum cultivar) on the nitrogen and mineral contents of acid digests from three commercial malting varieties of sorghum were assessed. The mineral and nitrogen contents and constituents of the digests varied significantly (p < 0.05) with respect to the method of digestion, sprout source and the pair-wise interaction of the two factors. Higher digest nitrogen, in both ICSV 400 and SK 5912, was supported by acid digestion in the autoclave while reflux digestion produced higher nitrogen in KSV 8. Of all the digests, those from ICSV 400 (both reflux and autoclave) displayed the best balance of yeast-essential acids as well as superior growth-promoting activity. In their growth-producing activity, the digests also compared very favourably with seven commercial nitrogenous bases used industrially for yeast cultivation. Results suggest that sorghum sprout acid digests are good alternative sources for nitrogen and mineral nutrients in media for microbial cultivation. 相似文献
19.
Steeping in dilute alkali was investigated with the primary aim of reducing the moulds, coliforms, and preventing toxicity of sorghum malt. Red tannin‐free sorghum cultivars NK 283 and PAN 8546 were steeped in 0.1, 0.2 and 0.3% NaOH and 0.1, 0.3 and 0.5% Ca(OH)2. The effects of these solutions on aerobic plate count, lactic acid bacteria, yeasts, moulds, coliforms, the presence of some mycotoxins (aflatoxins, fumonisins, deoxynivalenol and zearalenone), the cytotoxicity and diastatic power (DP) of sorghum malt was evaluated. Steeping NK 283 in 0.1% Ca(OH)2 increased the DP from 10.5 to 16 Sorghum Diastatic Units (SDU)/g. However, it did not reduce the general levels of malt microflora. Steeping in dilute NaOH reduced the microflora on the malt. Steeping both grain cultivars with 0.2% NaOH resulted in malts with the moulds and coliforms reduced to approximately 3.5 and 2.0 log colony forming units/g, respectively and the percentages of some mould species to very low or undetectable levels. The DP of the 0.2% NaOH steeped malts increased to 16.2 and 26.9 SDU/g in the NK 283 and PAN 8546, respectively. There were no detectable amounts of mycotoxins and no indication of cytotoxicity in the 0.2% NaOH steeped samples. Steeping sorghum grains in food‐grade 0.2% NaOH is recommended as a method for the control of bacterial and fungal contamination during sorghum malting. 相似文献
20.
R. C. Agu 《Journal of the Institute of Brewing》2002,108(1):19-22
Sorghum and maize adjunct, at a 5 to 20% level, resulted in a decrease of extract recovery, solubilisation of nitrogen, and production of free amino nitrogen and peptide nitrogen progressively. Both sorghum and maize adjuncts released higher levels of FAN and peptide nitrogen in their extracts than barley adjuncts, but the peptide levels were higher in sorghum than maize and barley adjuncts. The solubilisation of nitrogen and hydrolysis of the soluble nitrogen were higher for high nitrogen barley adjunct than for low nitrogen barley. Although maize adjunct is used extensively in brewing, the results of this study showed that sorghum has the potential to release higher levels of peptides than maize. This difference may influence fermentation potential. 相似文献