Effect of malt pretreatment on phytate and tannin level of two sorghum (Sorghum bicolor) cultivars

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.     

Effect of preincubation of sorghum flour with enzymes on the digestibility of sorghum gruel

A low-tannin sorghum cultivar M-35-1 was used in this study. Sorghum was germinated for 6 days and protease and amylase activities were measured every 24 h. Results showed that the 5th day germinated sorghum had a higher protease activity and a lower amylase activity. Sorghum flour was incubated for 30 min with the extract from germinated sorghum or with 0.01, 0.05 or 0.1 mg ml⁻¹ papain or trypsin prior to cooking in water. Results showed increase in in vitro protein digestibility (IVPD) with the 5th day germination extract. Pretreatment of sorghum flour with small amounts of papain or trypsin (0.01 mg ml⁻¹) improved the IVPD without affecting the paste viscosity, whereas the germinated sorghum extract led to very low paste viscosity. ©     

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     

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.     

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).     

PROCESSING OF FOXTAIL MILLET FOR IMPROVED NUTRIENT AVAILABILITY

Foxtail millet grains were soaked in distilled water (1:5, w/v) for 12 h at room temperature, dehulled; dehulled and soaked; and dehulled, soaked and cooked in distilled water (1:3, w/v), and the effects of removal of polyphenols and phytate on the in vitro protein digestibility (IVPD) and availability of iron and zinc were measured. The results showed that polyphenols and phytate were decreased significantly up to 50.92 and 49.89%, respectively. The IVPD, however, increased up to 38.71%. The iron and zinc contents decreased up to 18.79 and 18.61%, respectively, but the ionizable iron and zinc were increased up to 55.45 and 80.18%, respectively. This indicated the suitability of simple processing techniques for improvement of availability of nutrients from foxtail millet.     

Potential for improvement in yeast nutrition in raw whole grain sorghum and maize lager brewing and bioethanol production through grain genetic modification and phytase treatment

Brewing and bioethanol production with raw grain and exogenous enzymes produces wort with satisfactory hot water extract (HWE). However, the free amino nitrogen (FAN) and mineral content can be too low, owing to low protein digestibility (PD) and phytate–mineral chelation, respectively. This study evaluated the potential for improvement in yeast nutrition in raw whole sorghum and maize brewing and bioethanol production by genetic modification (GM) of sorghum to improve PD and reduce phytate content, and by treatment with exogenous phytase. While phytase addition decreased sorghum spent grain phytate content (88%) and content of minerals (17 to 59%; i.e. increased wort mineral content), it did not affect maize phytate spent grain mineral content or HWE significantly. However, phytase addition did increase maize wort FAN (20%), sorghum HWE (2.8 percentage points) and wort FAN (23%). GM sorghum gave reduced spent grain mineral contents (11–38%), increased HWE (5.5 percentage points) and wort FAN (71%). Hence, genetic modification of sorghum to improve PD and reduce phytate content has considerable potential in raw grain brewing and bioethanol production to improve yeast nutrition. Copyright © 2012 The Institute of Brewing & Distilling     

Effects of various phytase sources on phytic acid content,mineral extractability and protein digestibility of tarhana

Changes in phytic acid (PA), HCl-extractability (HCl-E) of some minerals and in vitro protein digestibility (IVPD) during the production of tarhana prepared with the addition of different phytase sources (bakers’ yeast, barley malt flour and microbial phytase) were investigated. PA content of tarhana decreased significantly (p < 0.01) after addition of the yeast, malt and phytase. With respect to wheat flour used as raw material, PA content of tarhana decreased by 95.3%. After tarhana production, average values of HCl-E of Ca, Mg, Zn and K, and also IVPD of tarhana increased up to 80.2%, 86.4%, 73.9% and 92.6%, and 91.9%, respectively. Significant negative correlation coefficients were found between the PA and HCl-E of the minerals, and also IVPD. Tarhana production processes, including fermentation, drying and grinding, were able to remove the antinutritional effects of PA. Each one of the phytase sources used alone decreased the PA content to a limited extend. The results show that tarhana has good potential in the total amounts and bioavailability of the minerals and proteins.     

Effect of reducing agents on the in vitro protein and starch digestibilities of cooked sorghum

A low-tannin sorghum cultivar M-35-1 was used in this study. Investigation showed that the in vitro protein digestibility (IVPD) decreased considerably when sorghum flour was cooked in water, while it increased when cysteine, sodium metabisulphite, or ascorbic acid were added to the cooking medium. The increase in the IVPD was significantly higher with increasing concentrations of cysteine up to 0.25 M and it continued to increase to 0.5 M for sodium metabisulphite; with ascorbic acid it increased up to 0.1 M then decreased. The in vitro starch digestibility (IVSD) of the treated gruel initially increased in the presence of either cysteine, sodium metabisulphite or ascorbic acid. The increase was parallel to that shown by IVPD; however, at high levels of cysteine or sodium metabisulphite the IVSD was low. Removal of cysteine from the gruel by alcohol gave higher IVSD. Altered viscosity patterns for all the treatments led to increase in the gelatinization temperature, peak viscosity and breakdown. However, the setback decreased in all treatments. Cysteine and ascorbic acid gave a negative setback but when the pH was adjusted to 4.5 or 7.0 a normal setback was obtained. ©     

Determination of formulation and processing factors affecting slowly digestible starch,protein digestibility and antioxidant capacity of extruded sorghum–maize composite flour

High‐temperature high‐pressure extrusion of sorghum–maize composite flour, of potential for healthy food manufacture, was investigated by factorial experimental design to determine the effect of level of sorghum in dry mix (15–60%); final barrel zone temperature (120–150 °C); total moisture in barrel (21.4–25.8%); total input rate (2.3–6.8 kg h^?1); and screw speed (250–450 rpm) on extrudate slowly digestible starch (SDS), phenolic content, antioxidant capacity, protein digestibility, density and expansion ratio. Extrudate SDS increased with increasing sorghum level and decreased as the barrel temperature increased. Total phenolic content and antioxidant capacity were positively associated with sorghum level. Protein digestibility was associated negatively with sorghum level and positively with barrel temperature. Extrudate density was associated positively with total moisture and negatively with barrel temperature and input rate. Sorghum in dry mix, final barrel zone temperature and total moisture in barrel were the three most significant independent variables influencing extrudate dependant variables.     

高梁威士忌酒的生产工艺

报道高梁威士忌酒的中试研究内容．用5l％高梁，38％麦芽，6％玉米，5％豌豆芽配比，酿制“高粱威士忌酒”。生产工艺为麦芽糖化，威士忌酵母和生香酵母双菌种液态发酵，壶氏蒸馏器和填充泡盖蒸馏塔二次蒸馏，橡木桶老熟陈酿。原粮出酒率为59.2％，成品酒度38％。     

高粱威士忌酒的生产工艺

报道高粱威士忌酒的中试研究内容．用５１％高粱,３８％麦芽,６％玉米．５％豌豆芽配比,酿制“高粱威士忌酒”。生产工艺为麦芽糖化,威士忌酵母和生香酵母双菌种液态发酵,壶氏蒸馏器和填充泡盖蒸馏塔二次蒸馏,橡木桶老熟陈酿。原粮出酒率为５９．２％,成品酒度３８％。     

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.     

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.     

Nutrient content of complementary foods based on processed and fermented sorghum, groundnut, spinach, and mango

BACKGROUND: Many African mothers use gruels made of maize and sorghum as complementary foods for their infants because they cannot afford the cost of nutritionally superior commercial weaning foods. OBJECTIVE: To improve the nutritional quality of traditional sorghum gruels used as complementary foods for children between six months and five years in the northern part of Cameroon. METHODS: Sorghum grains were processed by dehulling, sprouting, dehulling and cooking, and sprouting and cooking, then fermented using Saccharomyces cerevisae and tested for nutritional quality. The processed samples were analyzed for their nutrient composition and the digestibility of proteins and carbohydrates. RESULTS: The resulting products showed a significant reduction in antinutritional factors (e.g., phenolic compounds and phytates). In addition, germination improved the in vitro digestibility of proteins and carbohydrates. These effects were enhanced by fermentation of the resulting sorghum flour, regardless of how grains were pretreated, although the protein and mineral content remained low. Use of a composite flour made from pretreated sorghum, groundnut, spinach, and mango improved the protein, mineral, and vitamin A and C content of the gruels. Fermentation of composite flours resulted in an improvement in the protein content. CONCLUSIONS: This study, conducted under local conditions and using local technology, describes an opportunity for improving the quality of complementary foods using local ingredients.     

The effect of cooking on proteins from acha (Digitaria exilis) and durum wheat

The effect of cooking on proteins from acha and durum wheat was assessed from an analysis of protein extractability, gel electrophoretic profiles, in-vitro protein digestibility (IVPD) and the amino acid compositions of wholemeal flour and residue proteins. Heating wholemeal flour samples at 100–140°C (t = 10–40 min) resulted in 0–30% and 45–55% decreases in acha and durum protein solubility, respectively. In general, high molecular weight (30–70 k Da) protein subunits were more susceptible to heat damage. For both cereals, sodium dodecyl sulphate (SDS; 10 g litre^?1) and/or dithiothrcitol (DTT; 10 mM ) increased protein solubility in unheated and heated samples. The IVPD index was 90–91% and was not significantly altered by cooking (100–120°C, t = 40 min). Cooking at extreme temperatures (140°C, t = 40 min) reduced the IVPD by 8% (P = 0.05). Osborne fractionation resulted in a durum or acha residue level of 7.8% or 55.2%. Treatment with solvent containing propanol, SDS and/or DTT at room temperature followed by SDS-polyacrylamide gel electrophoresis of non-solubilised proteins showed that the glutelin fraction of acha, with the exception of a 65 kDa subunit, was insoluble owing to strong inter-subunit hydrophobic and disulphide interactions. Wholemeal acha flour and residue protein showed a significantly greater level of hydrophobic and sulphur amino acids as well as glutamine which is associated with H-bonding. The possibility that cereal protein solubility is also dependent on protein-carbohydrate links is discussed.     

Mathematical models for maximum improvement of in vitro protein digestibility of high dietary fibre cookies

Via substituting with wheat flour some high dietary fibre cookies were prepared (with 6, 12, 18 and 24%) from cereal industry by-products: corn bran (CB), rice bran (RB) and barley husk (BH). In vitro protein digestibility assay was used to examine the effect of substituting on protein digestibility. The applied nonlinear mathematical models indicated a higher determination coefficient between experimental and predicted data (R2 ≥ 0.999). A maximum in vitro protein digestibility (IVPD) of 88.4, 84.1, 85.2% was obtained when using optimum level substituting with wheat flour (7.9, 9.3 or 5.2%) in the CB, RB or BH respectively for producing cookies. The maximum improvement or minimum reducing IVPD by using fibre sources in producing cookies ranged from ?0.25% in RB to 4.9% in CB.     

Study of chemical compositions,anti-nutritional contents and digestibility of electron beam irradiated sorghum grains

Effects of electron beam irradiation at doses of 10, 15, 20, 25 and 30 kGy on chemical composition, phytate and tannin contents, and in vivo digestibility of sorghum grain were investigated. Irradiation had no effect (p > 0.05) on chemical compositions. Tannin content was reduced (p < 0.05) by 28%, 30%, 42%, 83% and 86% and phytate content reduced (p < 0.05) by 39%, 49%, 66%, 79% and 90% in electron beam irradiated compared to control, respectively. Irradiation improved (p < 0.05) in vivo digestibilities of dry matter, crude protein, true protein and gross energy. Based upon these results, electron beam irradiation was judged to be a useful processing method for reducing the anti-nutritional compounds and therefore, improving nutritive value of sorghum grain.     

Effect of soaking and heat processing on the levels of antinutrients and digestible proteins in seeds of Vigna aconitifolia and Vigna sinensis

The effect of soaking, cooking and autoclaving on the levels of total free phenolics, tannins, phytic acid and in vitro protein digestibility (IVPD) were studied in Vigna aconitifolia and Vigna sinensis. Though soaking significantly reduced the content of tannins alone in V. aconitifolia, both total free phenolics and tannins were markedly reduced in V. sinensis. Greater loss of total free phenolics as well as tannins occurred under autoclaving compared to soaking and cooking in both the legumes investigated. In V. aconitifolia, soaking in distilled water for 6 h and cooking for 30 min reduced the phytic acid content by up to 43%. Maximum reduction in the level of phytic acid (36%) was observed under distilled water soaking compared to cooking and autoclaving in V. sinensis. Limited loss in content of phytic acid was noticed under autoclaving compared to soaking and cooking in both the pulses studied. In vitro protein digestibility (IVPD) of V. aconitifolia and V. sinensis was enhanced to 12.5 and 14.8%, respectively, under autoclaving. Of all the processing methods, autoclaving seemed to be the most efficient for reduction in content of the antinutrients, except phytic acid, and improving IVPD in both the pulses.     

Changes in chemical composition,grain malting,starch and tannin contents and protein digestibility during germination of sorghum cultivars

Malting loss and changes in chemical composition, starch and tannin contents and in vitro protein digestibility (IVPD) were determined during germination of low (0.32%) and high (1.44%) tannin sorghum cultivars. For both cultivars, crude protein, fibre, fat and ash contents were slightly decreased after soaking and germination of the seeds. Malting loss was slightly increased for both cultivars and for all germination periods. Starch degradation was high for both cultivars. Depending on the soaking time about 56–66% and 98–99% tannin were lost during 72 h germination in low and high tannin cultivars, respectively. IVPD was markedly decreased in the low tannin cultivar and markedly increased in the high tannin one with the germination time. Soaking, on the other hand, was found to have a minor effect on IVPD. It is suggested that tannins are responsible for retarding the protein digestibility and starch degradation, especially in the high tannin cultivar.