Millet Malt Research Articles

Biochemical changes occurring during the application of high gravity fermentation technology to the brewing of Zimbabwean traditional opaque beer

Three types of opaque beer were produced, differentiated according to the varieties and ratios of raw materials used in the initial stage of beer preparation. Beer 1 contained sorghum meal and sorghum malt in the ratio 2:1, beer 2 contained sorghum meal and finger millet malt in the ratio 2:1 and beer 3 contained sorghum meal, maize meal and finger millet malt in the ratio 1:2:2. Beers 1, 2 and 3 were prepared under normal and high gravity (HG) fermentation conditions. The time taken to attain the desired sourness and final products varied according to the raw materials used for beer preparation. The pH values of the brews and dissolved solid contents decreased during the preparation process for all the beers. Higher ethanol levels were obtained for the HG beers compared with the normal beers, the maximum ethanol level recorded being 4.74% (v/v) for HG beer 3. Generally, higher free amino nitrogen (FAN) and organic acid levels were obtained in the HG beers as compared with the corresponding normal beers. A sensory evaluation carried out to assess the overall acceptability of the beers revealed HG beers 2 and 3 as having the highest overall acceptability of 82% while HG beer 1 had the lowest overall acceptability of 27%.

Effect of milling and mashing procedures on millet ( Pennisetum maiwa) malt wort properties

Millet ( Pennisetum maiwa) was malted for 5 days and mashed using the infusion, double-decoction and decantation mashing methods. Highest extract recovery was obtained in the decantation mashing system because in this mashing procedure, the enzymes of millet malt were protected and the starch adequately gelatinised. The decoction or decantation mashing method however, produced wort with lower values of soluble nitrogen and free amino nitrogen (FAN) products than the infusion mashing method because the proteins were partly denatured during the cooking process of the decoction or decantation mashing methods. The decantation mashing, in particular, produced wort that filtered more slowly. The wort also had a darker colour because of a greater degree of Maillard reaction. Wet milling marginally produced extracts with higher values of the parameters tested than dry milling, but both the wet and dry milling procedures maintained a constant mass balance of the soluble nitrogen and FAN products.

Combination of malted cereals and cassava starch in the production of sugar syrup

The relative capacity of malted cereals and their optimum conditions of temperature and pH in the hydrolysis of starch were studied. Malted cereals prepared from rice, maize, sorghum and millet were used to degrade cassava starch to produce sugar syrup. Effect of pH and temperature on the level of dextrose equivalent produced indicated that the combination of malted maize, rice and sorghum with cassava starch at pH 5 in 0.015M citrate buffer and pH 5.5 for malted millet produced relatively high amounts of sugar at temperatures of 60oC for malted maize, millet and sorghum and 55oC for malted rice. The combination of malted rice and cassava starch produced the highest amount of sugar syrup among the various cereals studied. JOURNAL OF THE GHANA SCIENCE ASSOCIATION Volume 2 No. 1 (2000) pp. 87-92

Diastatic Power and α-Amylase Activity in Millet, Sorghum, and Barley Grains and Malts

The purpose of this study was to evaluate the α-amylase, diastatic power, and saccharification rates of malts from different types of grains after different germination temperature and time treatments. A total of 22 grains were placed in five groups: U.S.-grown barley, Kenyan-grown barley, U.S.-grown millet, Kenyan-grown sorghum, and Kenyan-grown millet. Grains were germinated for two, four, and six days at 14, 18, and 22°C and malts were made from each treatment (198 total). Grains and malts were analyzed for diastatic power, α-amylase activity, and saccharification rates. The grain groups 5(22)*1 and malt groups 5(22)*3*3 were analyzed using statistcal procedures. Of the grains, barley had the highest diastatic power and α-amylase activity, followed by millet, and then sorghum. For malts, the diastatic power of the barley groups (116.50 diastatic power degrees [DP]° ASBC) was much greater than that of the millet groups (13.22 DP° ASBC) and the sorghum group (4.37 DP° ASBC), which were all different (P < 0.05). The sorghum group malt α-amylase activity was low (4.63 dextrinizing units [DU]) compared to that of the millet groups (23.00 DU) and barley groups (44.36 DU). Saccharification times for all millets and sorghums were >20 min, while barley malts had more favorable times of <15 min.

Nutrient composition, amino acid and vitamin contents of malted sorghum, pearl millet, finger millet and their rootlets

Sorghum, pearl millet and finger millet were allowed to germinate up to 96 h and samples were withdrawn from the germinating bed at every 24 h intervals, dried at 50°C and derooted to prepare the malt. The native and the malt samples were analysed for the proximate principles, and amino acids, thiamine, riboflavin, niacin and ascorbic acid contents. Protein, fat, ash and crude fibre contents of the rootlets separated from the malt were also determined. Protein content of finger millet malt was considerably less than the native millet, but the protein, fat and mineral contents of native and malted sorghum and pearl millet were almost the same. A noticeable increase in lysine content and decrease in sulphur-containing amino acids were also recorded only in the case of finger millet on malting. Malting enhanced riboflavin, niacin and ascorbic acid contents but slightly reduced the thiamine content of sorghum as well as both the millets. The SEM photomicrographs of the endosperm portion of sorghum and pearl millet exhibited visible pitting of starch granules, but contrary to this in the case of finger millet, only surface erosion was noticed. The rootlets from sorghum as well as the millets were rich sources of protein and the essential amino acids.

Assessment of cyanogenic glucoside (cyanide) residues in Mbege: an opaque traditional Tanzanian beer

Levels of cyanide in two varieties of malted millet, spent grain (Machicha) and opaque beer (Mbege) were determined. Protein content and amino acid composition of the malt, Mbege and Machicha were determined. Mbege was made in the laboratory using an improved method. The cyanide content of millet, malt, spent grain and Mbege were 40.6, 513.4, 18.9 and 8.1 ppm, respectively for the Moshi local millet variety. For Sumbawanga-2 millet variety the cyanide content was found to be 41.2, 489.2, 17.8 and 6.8 ppm for the millet, malt, spent grain and Mbege, respectively. The cyanide content increased linearly as the number of days of germination of the millet grain increased and the highest values of cyanide were attained on the third day of germination. Cyanogenic glucosides in the millet were enzymetically hydrolysed to respective cyanohydrins and volatile hydrogen cyanide due to low pH level of the Mbege which was 4. Malting of the millet increased the protein content by 5%. Lysine, the most limiting amino acid in millet, increased by 20%. It was concluded that the fermentation process of the millet malt into Mbege is efficient in reducing the levels of cyanogenic glucosides below levels considered toxic and therefore rendering the product safe.

THE BREWING POTENTIAL OF “ACHA” (DIGITARIA EXILIS) MALT COMPARED WITH PEARL MILLET (PENNISETUM TYPHOIDES) MALTS AND SORGHUM (SORGHUM BICOLOR) MALTS

The malting and brewing characteristics of millets (Pennisetum typhoides and Digitaria exilis) and sorghum (Sorghum bicolor) were compared. Diastase, α-amylase, amyloglucosidase and proteases increased with malting time and the increase was associated with the modification. Development of hydrolytic enzymes was significantly higher in pearl millet and Digitaria exilis (“acha”) than in sorghum at P ≥ 0.01. The major starch degrading enzyme in the three varieties of pearl millet (SE composite, SE.13 and SE 2124) was α-amylase. On the other hand, β-amylase was the major starch degrading enzyme in “acha” (Digitaria exilis) which is similar to the pattern in barley. Gibberellic acid had a stimulating effect on the diastatic activity of pearl millets, Digitaria exilis (“acha”) and sorghum (KSV-4), but inhibited the diastatic activities of sorghum (Farafara). Gibbereltic acid inhibited the proteolytic activities in all the pearl millet varieties, Digitaria exilis and sorghum varieties. Potassium bromate had little or no effect in the reduction of malting losses. Although “acha” (Digitaria exilis) had a high β-amylase content, a high malting loss makes it uneconomical to brew with “acha” mart. A blend of “acha” malt with pearl millet malt or sorghum malt (composite malt) will produce a malt of the same profile as barley malt and this will enhance the quality of sorghum and pearl millet malt during the mashing process. Wort quality of all the samples was suitable for brewing conventional beer.

Comparative Study of Experimental Beers Brewed from Millet, Sorghum and Barley Malts

Comparative Study of Experimental Beers Brewed from Millet, Sorghum and Barley Malts

Combined mashing of millet ( Pennisetum maiwa) malts prepared with potassium bromate and gibberellic acid (GA 3) as additives

Millet, Pennisetum maiwa, was malted using 125 mg/litre potassium bromate, 0·20 mg/litre gibberellic acid and a combination of both solutions in equal volumes as additives by sprinkling the solutions at steep out. Germination which lasted for 5 days was carried out at 28°C. Both potassium bromate and gibberellic acid improved the values of the parameters analysed, but the influence was more pronounced with malt prepared using potassium bromate than with gibberillic acid. The influence of the combined additive on the properties of the wort was lower than those of the respective additives, but it was better than with water control.

Effect of potassium bromate on diastase, cellulase and hemicellulase development in Nigerian malted millet ( Pennisetum maiwa)

The influence of varying concentrations (0–150 mg/litre) of potassium bromate on enzyme development in Nigerian millet ( Pennisetum maiwa) during sprouting and growth was assessed. Optimum diastatic, cellulolytic and hemicellulolytic activities were observed on the fifth day of germination at 28°C when 125 mg/litre of potassium bromate was applied.

Isolation and utilization of indigenous yeast strain for brewing of millet beer (OYOKPO)

Three yeast strains were isolated from a spontaneously fermented native millet (Pennisetum typhoideum) malt beer (Oyokpo). One of the yeast isolates found to have the most highly fermenting capacity was characterised and identified as a strain of Saccharomyces cerevisiae. The yeast was then utilised as the pitching yeast in a subsequent controlled fermentation of millet wort at 20°C for 120 hours. Bitter leaf (Vernonia amagdalina) extract was used as the bittering and flavouring agent. The Oyokpo beer sample produced under these conditions was found to possess both chemical and organoleptic qualities comparable to some extent, to the conventional barley malt beer. At the end of fermentation, the pH, specific gravity, alcohol content, reducing sugar content and protein content of the beer were 4.11, 1.0308, 2.81% (v/v), 4.00 (mg/ml) and 0.84 (mg/ml) respectively.

Microbiology of ‘obiolor’: a Nigerian fermented non‐alcoholic beverage

Obiolor is an acidic non-alcoholic beverage prepared by fermenting sorghum and millet malts. The traditional process for the production and microbiological characteristics of the beverage were investigated. Bacillus spp., Lactobacillus plantarum and Streptococcus lactis were the associated micro-organisms most actively involved. Yeasts were present in low numbers towards the end of the fermentation. Other micro-organisms isolated did not appear to play a role in the fermentation process. Variations in the important microbial groups involved and their metabolic products were studied. Titratable acidity increased gradually until the end of the fermentation while the total soluble solids and pH declined. Acetobacter spp. were probably responsible for the unacceptability of the product after 24 h.

FLOW BEHAVIOR AND FUNCTIONAL PROPERTIES OF MALT EXTRACT CONCENTRATES

Flow characteristics and functional properties of malt extract concentrates were investigated. Flow behavior was studied using a coaxial viscometer over shear rates of 0.6–145.8 s‐1. The shear rate‐shear stress data followed the power law, Casson, Herschel‐Bulkley and Bingham plastic models. Herschel‐Bulkley values for flow behavior index which ranged from 0.73–0.94, and presence of yield stress indicated the Bingham plastic nature of malt extract concentrates. The activation energy of flow for various concentrates was in the range of 14.8–17.7 kcal/gmole. Magnitudes of Reynold numbers (0.0–49.9) for all concentrates were lower than 2100. Temperature, yield stress and plastic viscosity considerably influenced the flow of concentrates in straight pipes. The pressure drop and power requirements for flow of concentrates in pipes at 50°–60°C were lower than those at 30°C, but negligibly different from those at 80°C. Coefficients of correlation between the Bingham plastic values for pressure drop and yield stress (r = 0.86, P &lt; 0.01), and plastic viscosity (r = 0.97, P &lt; 0.01) were highly significant. Hulled barley and corn concentrates containing high amounts of reducing sugars, showed low viscosities and yield stresses, and required desirably low power for flow in pipes at 50°–60°C. The high protein concentrates of wheat and triticale malts showed high whip volume and good foam stability. Wheat concentrate was superior in fermentability. Hulless barley and finger millet malts produced concentrates with high viscosities which might facilitate their utilization in gums, candies and other such products.

Malting of Finger Millet: Factors Influencing α-Amylase Activity and Wort Characteristics

The effect of germination temperature and duration and application of gibberellic acid on α-amylase activity and some wort characteristics of finger millet malt was studied. Two samples of finger millet were steeped to 33% moisture and germinated at 20, 25, 30, and 35° C for 48 and 96 hr with and without gibberellic acid (0.1 mg/kg). α-Amylase of the malts increased in response to higher germination temperatures (30-35° C). The α-amylase activity showed substantial decrease at the maximum mashing temperature of 70° C. The extract yield varied from 42.7 to 73.5% depending on malting conditions. The worts were light in color, low in soluble nitrogen, and filtered slowly. Reducing sugars were higher in the worts prepared from malts germinated at 30-35° C than those germinated at lower temperatures (20-25° C). Desirable free α-amino nitrogen levels (120-150 mg/L) in the worts were obtained from the malts germinated at higher temperatures for 48-96 hr. Malts treated with gibberellic acid and germinated at 30-35° C for 48 hr produced worts comparable to those of control malts germinated for 96 hr. Response to exogenous gibberellic acid was higher in the malts germinated at 30-35° C than in those germinated at 20-25° C

STUDIES ON COMPARATIVE MALTING CHARACTERISTICS OF SOME TROPICAL CEREALS AND MILLETS

Malts prepared from some of the tropical cereals and millets were evaluated for their suitability in weaning food formulations. Pearl millet and finger millet malts exhibited high α-amylase activity within 2–3 days of germination, while maize, sorghum, wheat and triticale malts showed high enzyme activity after 4–5 days of germination. Malting drastically lowered the paste viscosity of cereal flours especially millet. Finger millet malt had desirable flavour and taste besides high amylase activity. Wheat and triticale malts also had acceptable flavour. Rice malt was bitter and pearl millet malt developed rancid odour and bitterness within a week after preparation.

Evaluation of nigerian millet (pennisetum typhoideum) as a raw material for beer production

AbstractMillet (Pennisetum typhoideum) its malt and wort were evaluated to ascertain the suitability of the grain for beer production. Thousand grain weight was 8.03 g while foreign material and broken cernels represented 3.23%. Germination energy, germination capacity and moisture content of the grain were 75.67, 92.33 and 10.43%, respectively, while the carbohydrate, total nitrogen and protein contents were 53.88, 1.34 and 8.40%, respectively. Millet malt had a moisture content of 5.03% while its carbohydrate, total nitrogen, protein content and malting loss were 48.47, 1.87, 11.7 and 8.3%. pH and specific gravity of the worth were 5.70 and 1.5927, respectively; its protein content was negligible while % titratable acidity was 1.35. The low nitrogen and protein contents of the grain as well as the low malting loss make millet an attractive alternative cereal for beer production in Nigeria.