Effect of malt pretreatment on phytic acid and in vitro protein digestibility of sorghum flour

Sorghum seeds of cultivar Wad Ahemed (phytate: 2.7 mg/g, tannin: 0.96% and 2 h pepsin digestion: 18%) were germinated for three days to obtain 1-, 2- and 3- days old sorghum malts. Sorghum malt was added in concentrations of 1, 2.5, 5, 7.5 or 10% to sorghum flour. The mixtures were incubated with shaking for 0, 30, 60, 90 or 120 min. Phytic acid and in vitro protein digestibility were assayed for all treatments. The results revealed that phytate content was significantly reduced. The 10% 3-day-old malt after 120 min incubation, reduced the phytate content by 83%. The in vitro protein digestibility (IVPD) was significantly improved as a result of malt pretreatment. The rate of reduction of phytate content and the rate of increment in IVPD increased with time of incubation, age and concentration of the malt.     

Investigations on winter season Sudanese sorghum cultivars: effect of sprouting on the nutritional value

Physicochemical attributes of sorghum grains of Wad Ahmed (summer season cultivar), Abu Ragaba and Abu Kunjara (winter season cultivars) were compared. Floury endosperms characterise grains of all cultivars. Grains of Abu Ragaba and Wad Ahmed are white and Abu Kunjara are coloured. Grains were sprouted for 24, 48 and 72 h and changes in nutrients, tannin, phytic acid, protein digestibility and total and extractable minerals were studied. The nutrients and antinutients contents significantly (P ≤ 0.05) varied between cultivars. High tannin characterises Abu Ragaba and Wad Ahmed. In vitro protein digestibility of the cultivars is comparable. Contents and HCl‐extractability of Ca, P and Fe are varied. Abu Ragaba had the higher HCl‐extractability of the minerals. Sprouting changed contents of the nutrients, reduced significantly (P ≤ 0.05) tannins and phytic acid and increased digestible protein in all cultivars. Reduction of tannins was the highest in Abu Ragaba. The magnitude of reduction increased as sprouting prolonged.     

Protein profile and malt activity during sorghum germination

BACKGROUND: The effect of germination time on major sorghum macromolecules was followed by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS‐PAGE), Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy. Sorghum flour was also incubated with sorghum malt to evaluate amylase and protease activities. RESULTS: The SDS‐PAGE results showed that levels of high‐molecular‐weight aggregates, β monomer and γ and α monomers increased by 120.5, 20.3 and 12.7% respectively during the first few days of germination. This behaviour shows the enhancement of prolamin extractability and concentration in sorghum as a result of starch degradation. After the third day, proteins suffered degradation by intrinsic proteases. FTIR spectroscopy showed a gradual decrease in lipid and protein levels and starch structural changes during the germination period. These modifications are due to intrinsic lipases, proteases and amylases. Sorghum flour was incubated with different malt samples resulting from 0–7 days of germination. It was found that a 5 day malt led to a sixfold increase in carbohydrate digestibility and a fourfold increase in free amino acid content. CONCLUSION: A 5 day sorghum malt is the best inoculum for porridge preparation, representing an inexpensive, effortless and culturally acceptable way to prepare weaning foods at domestic and industrial levels. Copyright © 2008 Society of Chemical Industry     

Effect of Dilute Alkaline Steeping on the Microbial Contamination,Toxicity and Diastatic Power of Sorghum Malt

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.     

Fermentation and enzyme treatment of tannin sorghum gruels: effects on phenolic compounds,phytate and in vitro accessible iron

The presence of polyphenols and phytate in cereal products has been shown to interfere with the bioavailability of minerals such as iron. In the present study, we added enzymes (wheat phytase and mushroom polyphenol oxidase) during fermentation of tannin sorghum gruels prepared from flour with or without addition of 5% flour of germinated tannin-free sorghum grains (power flour), and investigated the effects on phenolic compounds, phytate and in vitro accessible iron. Assayable phenolic compounds were significantly reduced by fermentation, with high reductions observed in gruels with added enzymes. Fermentation of the gruels with addition of enzymes reduced (on average) total phenols by 57%, catechols by 59%, galloyls by 70% and resorcinols by 73%. The phytate content was significantly reduced by fermentation (39%), with an even greater effect after addition of power flour (72%). The largest reduction of phytate (88%) was, however, obtained after addition of phytase. The in vitro accessible iron was 1.0% in the sorghum flour and it increased after fermentation with power flour and/or with enzymes. The highest in vitro accessibility of iron (3.1%) was obtained when sorghum was fermented with addition of power flour and incubated with phytase and polyphenol oxidase after the fermentation process.     

Effect of malting and fermentation on antinutrients,and total and extractable minerals of high and low phytate corn genotypes

Two corn genotypes, Var‐113 (high phytate) and TL‐98B‐6225‐9 × TL617 (low phytate), were germinated for 6 days. The germinated grains were dried and milled. A mixture of 5% malt and 95% corn flour was fermented for 14 days. Phytic acid and polyphenol contents and hydrochloric acid (HCl) extractability of minerals from the fermented flours were determined at the intervals of 2 days during fermentation. Phytic acid and polyphenol contents decreased significantly (P ≤ 0.05) with an increase in fermentation time, with a concomitant increase in HCl‐extractable minerals. For both genotypes, the major mineral content was increased, while that of trace minerals was increased but at slow rate with fermentation time. When the grains were fermented for 14 days, TL‐98B‐6225‐9 × TL617 genotype had higher extractable calcium and Var‐113 had higher extractable phosphorus, whereas iron and manganese recorded high extractability levels in Var‐113. There was good correlation between phytate and polyphenol level reduction and the increment in extractable minerals with fermentation time.     

汽爆高粱全粉馒头的研制

目的:研究汽爆对高粱功能成分的影响以及汽爆高粱全粉添加量对面团和馒头质构特性的影响。方法:汽爆高粱以蒸汽为汽爆介质,研究0.8 MPa压力维压5 min的条件下高粱中功能成分的变化;将汽爆高粱全粉按不同比例添加到小麦面粉中制作馒头,用质构仪测定面团和馒头的质构特性,用白度仪测定馒头白度值,对馒头食用品质进行感官评价,并讨论了汽爆高粱全粉的适宜添加量。结果表明:高粱经汽爆处理后,高粱中的功能成分含量发生变化:不溶性膳食纤维和单宁含量明显下降,抗性淀粉、总多酚和总黄酮含量提高。添加适量的汽爆高粱全粉可改变小麦面团的特性及馒头的品质,在本实验中汽爆高粱全粉的适宜添加量为25%,此时硬化速率低,馒头的食用品质较好。结论:汽爆有利于降解不溶性膳食纤维和单宁含量,促进功能成分的溶出,抗性淀粉、总多酚和黄酮含量增加;汽爆高粱全粉可以添加到馒头中,可以为高粱的开发利用提供参考。     

Effects of phenolics in sorghum grain on its bitterness,astringency and other sensory properties

Despite the fact that condensed tannins are potentially important antioxidants, there is a general belief that tannins in sorghum confer objectionable sensory attributes. The objective of this study was to determine differences in the sensory attributes of sorghums containing different levels of total phenolic compounds. A trained sensory panel described and quantified the sensory attributes of different sorghums (condensed‐tannin containing and tannin‐free). All the sorghum cultivars were perceived as bitter and astringent. Bran infusions of tannin sorghums were perceived as darker, clearer, more bitter and more astringent than those of the tannin‐free sorghums, while those of tannin‐free sorghums were perceived as sweeter and cloudy. Sorghum whole‐grain rice from the tannin sorghums which had relatively soft endosperm texture (PAN 3860 and Ex Nola 97 GH) was perceived as dark, hard, chewy, bitter and astringent, while that from tannin‐free sorghums having relatively hard endosperm texture (Segaolane and Phofu) was perceived as soft, sweet and had a maize‐flavour. Surprisingly, the bitterness and astringency, as well as other sensory attributes of NS 5511 (tannin sorghum), were perceived as similar to PAN 8564 (tannin‐free sorghum) even though NS 5511 had more than twice the total phenol content of PAN 8564. This suggests not all condensed‐tannin containing sorghums have objectionable sensory attributes. Copyright © 2007 Society of Chemical Industry     

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 sorghum grain type on wort physico‐chemical and sensory quality in a whole‐grain and commercial enzyme mashing process

To determine the most suitable types of sorghum for whole‐grain adjunct in lager beer brewing, 14 cultivars of five different types: white tan‐plant, white non‐tan‐plant, red non‐tannin, white tannin (type II) and red tannin (type III) were evaluated. The effects of grain type on wort physico‐chemical and sensory quality with raw grain and malt plus commercial enzyme mashing were assessed. Tannin content correlated significantly and negatively with wort extract and fermentable sugars (p < 0.001) and free amino nitrogen (FAN; p < 0.1). This is attributable to inactivation of the exogenous enzymes by the tannins during the mashing process. However, the type II tannin sorghums had wort quality attributes closer to the non‐tannin sorghum types, probably owing to their relatively low tannin content (≤1%). Malting gave a great improvement in wort extract, fermentable sugars and FAN, but substantially influenced wort sensory properties in terms of higher sourness, bitterness and astringency, as well as the expected more malty flavour. Worts from raw red non‐tannin sorghums were similar to those of white tan‐plant sorghums in both physico‐chemical and sensory quality. Thus, red non‐tannin sorghums, in view of their better agronomic quality, have considerable potential as a whole‐grain adjunct in lager beer brewing. Copyright © 2013 The Institute of Brewing & Distilling     

Chemical changes and diastatic activity in grains of sorghum (Sorghum bicolor) cultivars during germination

Grain samples from nine sorghum (Sorghum bicolor (L) Moench) cultivars were germinated for 16, 48, 96 and 144 h, and changes in their diastatic activity, protein, starch, soluble sugars, tannin and total phenols contents were studied. The diastatic activity increased up to 96 h of germination and decreased at 144 h. Diastatic activity showed significant variation among cultivars, which ranged from 10.0 to 88.3 units at 48 h and from 20.0 to 150.4 units at 96 h germination. In general, starch content decreased while soluble sugars increased during germination. Variation in protein content during germination was appreciable among the cultivars.     

几种高粱粉挤压特性的研究

选取辽宁白高粱、辽宁红高粱、内蒙白高梁三种具有地方代表性的高粱栽培品种,分析了高粱粉的基本化学组成,比较了其挤压加工特性,及其挤压前后单宁酸含量的变化.结果表明:双螺杆挤压技术是一种较好的改善高粱品质的加工方式,三种高粱粉经挤压处理均能形成细致多孔的海绵体,糊化度、吸水指数、水溶性指数、蛋白消化率比挤压前均大幅度增加,产品中单宁酸含量比挤压前降低了50%以上.比较三种高粱粉挤压产品的质量,辽宁白高粱挤压产品具有最小容重,具备一定的膨化度和硬度,其水溶性、蛋白体外消化率均明显高于内蒙白高粱挤压产品(P<0.05),经感官评定,与其他两种高粱挤压产品相比具有更好的可接受性,因此辽宁白高粱更适合挤压加工.     

QUALITY CHARACTERISTICS OF GLUTEN‐FREE CHICKEN NUGGETS EXTENDED WITH SORGHUM FLOUR

ABSTRACT

Application of coarse cereal flours is recommended to replace wheat gluten in meat products and to avoid gluten allergy in susceptible populations. Sorghum flour is a good source of dietary fiber and provides nonglutinous flours and scope for making gluten‐free meat products. Keeping this in view, the present research was envisaged to evaluate the different quality characteristic of gluten‐free chicken nuggets prepared with sorghum flour. Three types of chicken nuggets viz., Control chicken nuggets (CCNs), gluten‐free nuggets (GFN1 with 5% sorghum flour and GFN2 with 10% sorghum flour) were compared for different physicochemical, instrumental texture, color and sensory characteristics. Use of sorghum flour significantly (P < 0.05) increased the product yield and dietary fiber content in GFN1 and GFN2 as compared with CCN. Instrumental color results showed that lightness (L* value) and redness (a*) values were significantly (P < 0.05) lower in GFN1 and GFN2 as compared with CCN. Texture profile analysis indicated that incorporation of sorghum flour significantly (P < 0.05) improved hardness, gumminess and chewiness. Sensory scores of GFN1 and CCN were significantly (P < 0.05) higher than GFN2. It was concluded that that 5% sorghum flour is optimum to prepare gluten‐free chicken nuggets.

PRACTICAL APPLICATIONS

Sorghum is coarse millet and a popular staple diet in many developing countries. The results of this study support that sorghum flour can serve as a functional ingredient in developing healthy meat products. Use of sorghum flour in the formulation of wheat free meat products is an alternative to avoid gluten allergy. These gluten‐free meat products have potential to reach the niche markets and will be highly acceptable to gluten allergic consumers who demand gluten‐free products. Therefore, sorghum based food products can be marketed as health/functional products.     

Improving the quality of sorghum injera by decortication and compositing with tef

Injera is an Ethiopian fermented pancake‐like bread made from cereals, with tef being preferred. Decortication and compositing with tef were evaluated as methods to improve the injera‐making quality of red tannin‐free and tannin‐containing sorghums. Both decortication and compositing improved sorghum injera quality. Concerning decortication, mechanical abrasion was found to be more effective than hand pounding because acceptable injera was obtained with lower milling loss. Good quality injera was produced at an extraction rate of 540 g kg^?1 for tannin‐containing and 830 g kg^?1 for tannin‐free sorghum. With compositing, good quality injera was produced with a 50:50 (w/w) composite of whole tannin‐containing sorghum and tef. Both processes reduced the tannin content of the flours, which appeared to relieve the inhibiting effects of tannins on the fermentation. Decortication also seemed to improve sorghum flour injera‐making quality by improving flour pasting as a result of reducing the level of interfering substances such as lipids and proteins. In contrast, the improvement brought about by compositing with tef seemed to be due to inherent differences between tef and sorghum starch granules and an increase in the water solubility index of the flour. Compositing seems to be a more useful method of improving sorghum injera quality than decorticating as it avoids the grain loss associated with decortication. Copyright © 2005 Society of Chemical Industry     

Enzyme inhibition by polyphenols of sorghum grain and malt

Enzyme 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.     

Development of weaning food formulations based on malting and roller drying of sorghum and cowpea

Sorghum and cowpea were steeped in water for 16 h, allowed to germinate for 72 and 24 h respectively, then dried to about 14% moisture. Roots and shoots of sorghum sprouts were cleaned off and the devegetated malt was kilned at 70°C, moistened with 3% added water, heaped for about 10 min, milled and sieved to obtain debranned malt flour. Cowpea sprouts were split, dehusked, kilned at 85°C and milled. Malted sorghum and malted cowpea flours were blended in the proportion of 70:30 to prepare the malted weaning food (MWF). A precooked weaning food (RDF) was prepared by roller drying a cold water slurry consisting of 70% pearled sorghum flour and 30% toasted cowpea flour. The cooked paste viscosity of MWF was considerably lower than that of RDF and the blend of raw sorghum (70%) and cowpea (30%), at all comparable slurry concentrations. The protein content of MWF was 13.4% and that of RDF was 13.0%, but the available lysine content of MWF protein was 3.85% and that of RDF protein was 2.95%. The protein efficiency ratio for MWF (2.26) was significantly higher than that for RDF (1.87).     

125th Anniversary Review: The science of the tropical cereals sorghum,maize and rice in relation to lager beer brewing

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     

Phytate and tannin content of amaranth

The phytate and tannin contents of eight varieties of amaranth were determined. The phytate content of amaranth (0·52–0·61%) was higher than that of rice and millet, but lower than that of corn and wheat. Phytate is distributed throughout kernels of amaranth. Phytate content cannot be reduced by removal of the seed coat.Tannin levels of amaranth (0·043–0·116% catechin equivalent) were small in comparison with those in sorghum and millet. Tannin levels in the seed coat of amaranth are higher than those in the starchy perisperm.     

Influence of PROP taster status on the consumer acceptability of food made from tannin sorghums

BACKGROUND: Condensed tannins in sorghum are powerful antioxidants, beneficial for health. However, tannin sorghums are believed to be unpalatable. The objective was to determine the influence of 6‐n‐propylthiouracil (PROP) taster status on consumer acceptability of food from tannin sorghums. Consumers (n = 194) classified by PROP taster status (super, medium and non) evaluated the appearance, flavour, overall liking and texture of sorghum rice from two tannin‐free sorghums, PAN 8564 and Phofu, and two tannin sorghums, PAN 3860 (82 g catechin equivalents (CE) kg^?1) and NS 5511 (18 g CE kg^?1), with high antioxidant activity. RESULTS: The PROP tasters could distinguish differences among the sorghum cultivars varying in tannin content levels, finding PAN 3860 less acceptable than the other sorghums. The non tasters preferred all the cultivars equally, presumably because they could not detect taste (bitter and astringent) differences between the sorghums. With the exception of appearance, tannin sorghum NS 5511 was generally equally preferred by PROP tasters to tannin‐free sorghums. CONCLUSION: There appear to some tannin sorghums that are palatable, even to PROP tasters, because the level of tannins is below a sensitivity threshold (ca 20 g CE kg^?1). Hence such tannin sorghums could be used to produce acceptable high‐antioxidant activity foods. Copyright © 2009 Society of Chemical Industry     

Malt characteristics of sorghum vulgare varieties from ghana

Two local varieties, a white type and a red type, of Sorghum vulgare cultivated in Ghana were malted, using a micro-malting method, and their malt characteristics studied and compared to that of a commercial barley malt. The optimal germination time, at 30°C, to produce a good malt of high diastatic power and extract from local varieties of these varieties was 4-5 days. The local varieties were also found to have high diastatic activities of between 55 and 68% of the commercial barley malt. Hot-water extracts of the well malted sorghum varieties were also found to have higher and sustainable amounts of free amino nitrogen than the commercial malt. The hot-water extracts of sorghum malts were lower than the commercial barley malt, yielding about 66-77% of the barley malt, but contained a higher glucose to malt ratio. In terms of varietal superiority, the white sorghum yielded higher malt extracts than the red type.