High‐quality instant sorghum porridge flours for the West African market using continuous processor cooking

The overall goal of this study was to develop high quality, pregelatinised sorghum flours for instant thin and thick porridges, foods that are commonly consumed in the West Africa Sahel. Use of a continuous processor, a high shear/low pressure mixer, with feed sorghum flour moisture content of 30% to 35% and a screw temperature fixed at 168 °C gave instant sorghum flours with stable and creamy thin and thick porridge textures. Water activity of 0.22–0.35 for instant flours was within an acceptable range for dried commercial cereal foods. Molecular weight distributions of starch molecules showed significant fragmentation in instant flours that likely contributed to their smoother and creamy texture, and rheometry showed stronger gels and lower viscosity for the instant thick and thin porridges, respectively. In sensory testing performed in Niger at four locations, instant flour thin and thick porridges scored better than the control prepared locally from the same flour.     

Storage and loss moduli for various stiff porridges

Stiff porridges were prepared from composite flours of maize, sorghum, Bulrush millet and cassava. Cylindrical samples of stiff porridges of 1 cm in diameter and 1 cm long were made and vibrated on a rheolograph at a constant frequency of 3 Hz. The corresponding storage and loss moduli for each composite sample were recorded, and the loss factors were computed. Bulrush millet stiff porridge had the highest storage and loss moduli compared to other porridges. Cassava had the highest loss factor, suggesting that more energy would be spent in chewing the stiff porridge in the mouth. Addition of cassava flour into composite flours resulted in the reduction of both storage and loss moduli in all cases, levelling off at about 30% cassava.     

Physicochemical,nutritional and functional properties of marama bean flour

Marama bean is a protein-rich, underutilised, drought-tolerant legume in sub-Saharan Africa. Its utilisation may be increased through value addition into protein-rich flours. Defatted flour from unheated and dry-heated (150 °C/20 min) whole marama beans (UMF and HMF) were analysed for physicochemical and protein-based functional properties. Heating significantly increased in vitro protein digestibility of marama bean flour. Of functional importance are the high levels of tyrosine present in marama bean flours. Heating significantly reduced protein solubility and emulsifying capacity of marama bean flours whilst water absorption capacity was improved. Foaming capacity was not affected by heating. UMF could be useful in food systems requiring high emulsifying capacity, but would not be suitable for applications requiring high water absorption and foaming capacity. Due to its high protein contents, marama bean flour could be used to increase the protein quality of cereal-based foods to help alleviate protein-energy nutrition in the region.     

Effect of soy flour addition and heat-processing method on nutritional quality and consumer acceptability of cassava complementary porridges

BACKGROUND: The nutritional quality of cassava complementary porridge was improved through extrusion cooking and compositing with either defatted or full fat soy flour (65:35 w/w), and product acceptability by mothers with children of the target population was evaluated. RESULTS: The protein digestibility‐corrected amino acid score (PDCAAS) of extrusion‐ and conventionally cooked composite porridges was within the recommendations for complementary foods. The kinetics of starch digestibility showed that all porridges had a rapid rate of starch digestibility, but the rate was lower when defatted soy flour was added and lowest when full fat soy flour was added. The formation of amylase‐lipid complexes as shown by X‐ray diffraction and differential scanning calorimetry can be attributed to the lower digestibility of extrusion‐cooked porridge with full fat soy flour. If fed thrice per day, extrusion‐cooked porridge with defatted or full fat soy flour would meet the energy, protein and available lysine requirements of a child aged 6–8 months receiving low or average nutrients from breast milk. All porridges were well received by Mozambican mothers who use cassava as a staple food. The mean scores for sensory liking of all porridges were 3 and above on a five‐point hedonic scale. CONCLUSION: Extrusion‐cooked cassava/soy flour porridges have good potential for use as high‐energy/high‐protein complementary foods and have acceptable sensory properties. Copyright © 2012 Society of Chemical Industry     

Ferulic, <Emphasis Type="Italic">p</Emphasis>-coumaric,diferulic and triferulic acids contents of corn tortillas prepared with extruded corn flour and enriched with sorghum (<Emphasis Type="Italic">Sorghum bicolor</Emphasis> (L.) Moench) bran

Two ways of adding sorghum bran to tortillas were evaluated; adding to the corn flour before extrusion or after extrusion. The addition of sorghum bran increased the ferulic (FA), p-coumaric (p-CA), diferulic (di-FA) and triferulic (tri-FA) acids contents in corn flours and tortillas. Extrusion produced an increment of the free forms, and a part of the ferulic acid was degraded as a consequence of the extrusion conditions. Baking produced a reduction of bound and free forms of the phenolic acids in tortillas, however, high retention percentage of the phenolic acids was observed in flours and tortillas (83–90%). The antioxidant activity of flour and tortillas were correlated to the contents of the phenolic acids, especially with bound di-FA and tri-FA combined (r?=?0.92). Adding the sorghum bran before extrusion, produced flours with increased free phenolic acids content, and increased in vitro antioxidant activity.     

Highly viscous dough-forming properties of marama protein

Marama bean is an indigenous southern African oilseed legume with an unusual protein composition. Hence, its rheological properties were studied. Marama protein formed a highly viscous and extensible dough when compared to soya and gluten. With a dough of 38% moisture, marama protein extensibility was very high (304% of its original length), twice that of gluten and soya, and this increased considerably (>3-fold) when the moisture content was increased to 45%. With added peroxidase, the storage modulus (G′) of marama protein dough increased with time, suggesting the formation of new and strong protein networks. Dityrosine crosslinks were detected in the doughs. Marama protein showed a single transition with a denaturation temperature higher than soya glycinin. Marama protein was more hydrophobic and contained more β-sheet structure than did soya. Thus, the highly viscous and extensible rheological behaviour of marama protein is probably related to its high β-sheet conformation, hydrophobic interactions and tyrosine crosslinks.     

Effects of reducing phytate content in sorghum through genetic modification and fermentation on in vitro iron availability in whole grain porridges

Improved iron availability from sorghum porridges will benefit many malnourished communities in rural Africa, where there is a high prevalence of iron deficiency. This research compared the efficacy of reducing sorghum phytate content by genetic modification (GM) and natural lactic acid fermentation on in vitro iron availability in porridges. GM low phytate, non-tannin (38% phytate reduction) and tannin (36% phytate reduction) sorghums and their null controls were processed into thick unfermented and fermented porridges. The inhibitory effect of the tannins seemed to prevent any increase in in vitro iron availability, regardless of the level of phytate reduction. Only the additive effect of GM in combination with fermentation in reducing the phytate content appeared to cause a substantial increase in in vitro iron availability in the GM fermented porridge (30%) made from the non-tannin line, compared to the GM unfermented porridge (8.9%) or the fermented porridge (17.6%) of the control sorghum. This could be of nutritional significance.     

Polyphenol oxidase activity in white tan‐plant‐type sorghums: An important determinant of the relatively dark colour of their porridges

The relatively dark colour of food products from white tan‐plant (food‐grade) sorghums can compromise their acceptability. The relationship between white tan‐plant sorghum polyphenol oxidase activity (PPO) and porridge colour was investigated, primarily using lines grown in the same locality over two seasons. Sorghum was intermediate in PPO between wheat and maize. White tan‐plant sorghum and white maize whole grain flours were similar in colour. However, with white tan‐plant sorghum, the transition from flour to porridge caused a much larger reduction in L* value. Further, the correlation between white tan‐plant sorghum PPO activity and porridge L* values was highly significantly negative (P < 0.001), the relationship accounting for 40–50% of variation. PPO in white tan‐plant‐type sorghums is therefore an important determinant of the relatively dark colour of porridges. Breeding to reduce PPO activity could improve consumer appeal. Cultivar Sima (IS 23520) that had low PPO activity and produced light‐coloured porridge could be useful for breeding.     

Composition of marama bean protein

The protein composition of marama beans, an indigenous African oilseed legume, was determined in comparison with soya beans. Marama bean protein contained a substantial amount of tyrosine compared with soya bean protein. It was slightly richer in proline than was soya. By SDS–PAGE, marama protein contained fewer protein bands than did soya. The patterns of these bands in marama under non-reducing and reducing conditions were similar, suggesting an absence of disulphide bonds. The vicilin (7S) and acidic 11S subunits seemed to be absent in marama. This is most unusual in legume proteins. Only a major basic legumin (11S) (20 kDa), medium (63 kDa) and high (148 kDa) molecular weight protein bands were separated for marama. Most polypeptides in the marama proteome map are basic compared with soya. Only one polypeptide match, comparable to soya, was tentatively identified. Marama protein composition is very different from that of soya.     

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.     

The effect of sorghum type and processing on the antioxidant properties of African sorghum-based foods

This work determined the effect of sorghum type and different processing technologies of traditional African sorghum foods on total phenols, tannin content and antioxidant activity. The products were prepared by fermentation, conventional and extrusion cooking of whole and decorticated ground grain. The tannin sorghum types, had higher ABTS and DPPH antioxidant activities, compared to the types without tannins. Antioxidant activity was significantly correlated with total phenols and tannins (r > 0.95). Decortication, reduced antioxidant activity of both tannin and non-tannin sorghum by 82–83% due to the removal of the pericarp and the testa, which decreased phenols. Processing, generally decreased antioxidant activity, however, conventionally cooked porridges had higher antioxidant activity than the extrusion cooked products. The retention of antioxidant activity, particularly in fermented and unfermented porridges, means that whole tannin sorghum can be processed into foods with potential health benefits.     

Fatty acid composition,oxidative stability,antioxidant and antiproliferative properties of selected cold-pressed grape seed oils and flours

Cold-pressed chardonnay, muscadine, ruby red, and concord grape seed oils and their defatted flours were studied for their fatty acid composition, oxidative stability and antioxidant and antiproliferative activities. The phenolic profiles of the seed flours were also measured. The most abundant fatty acid in the oils was linoleic acid, ranging from 66.0 g/100 g of total fatty acids in ruby red seed oil to 75.3 g/100 g of total fatty acids in concord seed oil. The oils were also high in oleic acid and low in saturated fat. Ruby red grape seed oil recorded the highest oxidative stability index of 40 h under the accelerated conditions. Total phenolic content (TPC) was up to 100 times lower in the oils than in the flours. Lutein, zeaxanthin, cryptoxanthin, β-carotene, and α-tocopherol levels were also measured. DPPH radical-scavenging capacity ranged from 0.07 to 2.22 mmol trolox equivalents (TE)/g of oil and 11.8 to 15.0 mmol TE/g of flour. Oxidative stability of menhaden fish oil containing extracts of the seed flours was extended by up to 137%. HPLC analysis was conducted to determine the levels of free soluble, soluble conjugated and insoluble bound phenolics in the seed flours. The phenolic compounds analyzed included catechin, epicatechin, epicatechin gallate, quercetin, gallic acid, and procyanidins B1 and B2. Antiproliferative activity was tested against HT-29 colon cancer cells. All of the seed flours and muscadine seed oil registered significant (P < 0.05) inhibition of cancer cell growth. The results from this study demonstrate the potential of developing value-added uses for these seed oils and flours as dietary sources of natural antioxidants and antiproliferative agents for optimal health.     

液态发酵对西农9940苦荞主要成分及其抗氧化活性的强化作用

利用液态发酵技术富集苦荞渣中的营养物质,测定分析西农9940苦荞粉及其经液态发酵后所得苦荞渣的蛋白质、粗脂肪、矿物质、粗纤维、灰分、总黄酮、总酚含量以及氨基酸和脂肪酸组成,并以总还原能力、1,1-二苯基-2-三硝基苯肼(1,1-dipheny1-2-picryl-hydrazyl,DPPH)自由基和2,2'-联氮-双-(3-乙基苯并噻唑啉-6-磺酸)二铵盐自由基(2,2'-azinobis-(3-ethylbenzthiazoline-6-sulphonate)radical,ABTS+·)清除能力为指标对抗氧化活性进行综合评价。结果表明苦荞渣的蛋白质、粗脂肪、灰分、粗纤维、矿物质含量均显著提高,且液态发酵过程不改变苦荞粉的氨基酸及脂肪酸组成。苦荞渣的总酚含量为1 343.22 mg/100 g,显著高于苦荞粉559.76 mg/100 g,总黄酮含量为2 186.06 mg/100 g,显著低于苦荞粉2 464.10 mg/100 g,芦丁和槲皮素含量的测定也进一步证明发酵后苦荞渣的总黄酮含量显著降低,但其总还原能力、DPPH自由基和ABTS+·清除能力显著高于苦荞粉,说明经过发酵后苦荞渣的抗氧化能力更强。     

Use of γ-irradiation to alleviate the poor protein digestibility of sorghum porridge

One limitation to the use of sorghum as a food is that its proteins become more indigestible on wet-cooking, primarily through the formation of disulphide-linked enzymatically resistant protein polymers. Irradiation can modify bonds involved in protein secondary structure. The effects of irradiation (10 and 50 kGy) of dry and wet sorghum and maize flours on the digestibility and solubility of their proteins, when further cooked into porridge, were investigated. Irradiation of sorghum flour, followed by cooking, alleviated the adverse effect of cooking on sorghum protein digestibility. Maize porridge digestibility was unaffected by irradiation of dry flour but decreased with wet-irradiation. Increase in digestibility was not accompanied by an increase in protein solubility, suggesting that it was probably related to modification of protein structure, allowing better access to proteolytic enzymes. Maillard reactions and protein aggregation, at high doses, negatively affected digestibility. Polyphenols influenced the effects of irradiation.     

Phenolic acid composition of sprouted wheats by ultra-performance liquid chromatography (UPLC) and their antioxidant activities

The phenolic acid profiles of flours from two Canadian wheat classes, Canadian Western Red Spring (CWRS) and Canadian Western Amber Durum (CWAD), were investigated using two different extraction mediums and analysed on an ultra-performance liquid chromatography (UPLC) system at different degrees of sprout damage. A sound (non-sprouted) control sample as well as two different sprouted sub-samples, derived from different germination protocols of the control, were prepared for both the CWAD and CWRS. Free phenolic acids were extracted from the ground whole wheat meal using three repetitive 80% ethanol extractions. Bound phenolic compounds were subsequently released from the residue by alkaline hydrolysis followed by triplicate extraction with diethyl ether:ethyl acetate (1:1, v/v). Twelve phenolic acid standards were clearly resolved and quantified using a short 5 min elution gradient. Seven phenolic acids (4-hydroxybenzoic, vanillic, caffeic, syringic, p-coumaric, ferulic and sinapic) were detected in the CWRS and CWAD alcoholic and alkaline extracts. Syringic acid was the main compound in the free phenolic alcoholic extracts of the wheat meal representing 77.0% and 75.3% of the total amount of detected free phenolic compounds for CWRS and CWAD, respectively. However, the major released phenolic compound detected in the alkaline hydrolysed extracts was ferulic acid accounting for 72.3% and 71.0% for CWRS and CWAD respectively total bound phenolics. During germination, syringic acid levels rose as the length of germination time increased, resulting in the increase in total phenolic compound and antioxidant activity of the sprouted wheat flours. There was an increase in total phenolic compounds and the antioxidant activity of the alcoholic extracts from the CWRS and CWAD wheat flours as the germination time was extended. As a result, the sprouted wheats exhibits better nutritional properties than un-germinated wheat and could be used to improve the nutrition value in food products.     

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.     

Functional,digestibility, and antioxidant properties of brown and polished rice flour from traditional and new‐improved varieties grown in Sri Lanka

Sri Lankan traditional and improved rice varieties were processed into brown and polished rice flours. Samples were analyzed for AM, protein, lipid, total phenolic content, and antioxidant activity. Gelatinization and retrogradation properties were observed in the Rapid Visco Analyzer (RVA) and DSC. The AM content of the samples was high to intermediate (20 to 26%) except for one which was low (17%). Brown rice flour (BRF) samples had lower swelling power, lower RVA viscoamylograph profile, lower gel hardness, lower gelatinization enthalpy but higher gelatinization peak temperature and lower melting enthalpies of its retrograded AP relative to its corresponding polished rice flour (PRF) samples. The BRF showed a lower decrease in peak viscosity in the RVA viscoamylograph as compared to its PRF when treated with α‐amylase indicating inhibition potential. The traditional rice varieties had 68 to 86% higher total phenolic content (TPC) and 86 to 90% antioxidant activity in the BRF samples as compared to the improved varieties. A study on the antioxidant profile of the brown rice of the traditional rice varieties is being undertaken to explore their value as functional foods.     

Development of a Protein-rich Composite Sorghum-Cowpea Instant Porridge by Extrusion Cooking Process

To develop an instant high protein porridge, various ratios of sorghum and cowpeas were extruded at 130 and 165 °C and a water content of 200 g/kg using a twin-screw extruder. An increased proportion of cowpeas resulted in an increase in protein content, nitrogen solubility index (NSI), yellow colour, water absorption (WAI) and solubility (WSI) indexes and in a decrease in total starch (TS), enzyme-susceptible starch (ESS), expansion ratio (ER), and porridge firmness. The higher extrusion temperature gave lower NSI, TS and WAI. ESS, ER and WSI increased with severity of heat treatment. The composite of 50% sorghum and 50% cowpeas extruded at 130 °C was the most similar to a commercial instant maize-soya composite porridge in terms of composition and functional properties. A serving of 100 g would contribute 28% of the recommended dietary allowance (RDA) for protein. This represents a 110% increase in the protein RDA compared to sorghum only.     

Effect of irradiation,with and without cooking of maize and kidney bean flours,on porridge viscosity and in vitro starch digestibility

African traditional weaning foods are usually prepared from starchy flours at a total solids content of 50–100 g l^?1, giving a viscosity of 1000–3000 cP which is consumable by infants. These porridges have very low energy and nutrient densities. Processing to reduce the porridge viscosity and improve the energy and nutrient density may help in solving this problem. Maize, kidney bean and their 70:30 composite flours were irradiated at 0–10 kGy at room temperature. Irradiation greatly reduced the viscosity of porridges, probably by starch depolymerisation. Irradiation improved the starch digestibility of raw bean flours, possibly either by inhibiting α‐amylase inhibitors or by weakening the thick cell walls that enclose the starch granules, thus improving accessibility to enzymes. However, in raw maize, cooked maize and cooked bean flours there was maximum starch digestibility at a dose of 2.5 kGy, followed by small but significant decreases in starch digestibility at higher doses, more so in maize than in bean flours. The decrease in digestibility could be due to the formation of inhibitors of amylolytic enzymes (Maillard reactions products) or to the formation of resistant starch. Irradiation doses required to increase the total solids content of traditional maize‐ and/or bean‐based weaning porridges to at least 200 g l^?1 do not compromise starch digestibility significantly. © 2001 Society of Chemical Industry