Sensory and nutritional quality of marama-sorghum composite flours and porridges

Marama bean (Tylosema esculentum (Burch) A. Schreib) is an underutilised, drought- tolerant legume native to the semi-arid areas of Botswana, Namibia and South Africa. The edible seeds of marama beans are good sources of protein and fat, and its flours can potentially enhance the nutritional quality of sorghum porridge, a staple in many African countries. Sorghum has a low protein content and is deficient in lysine. Compositing sorghum with lysine-rich marama flour when preparing porridges would address this problem. Utilisation of marama flour in composite porridge depends on sensory acceptance. In this study nutritional and sensory quality of marama-sorghum composite flours and porridges are investigated. Full fat and defatted flours from unheated and dry heated (150 °C /20 min) marama beans were composited with condensed tannin-free sorghum meal (30:70). Marama flours, sorghum meal, marama-sorghum composite flours and porridges were analysed for proximate composition, amino acid composition, energy value, fatty acid composition, total phenolic content and antioxidant activity. Porridges (10% solids) were subjected to descriptive sensory analysis, consumer acceptance test (n=52), texture analysis, pasting profiles and colour measurements. Sorghum porridge and porridge composite with full fat marama flour from heated beans were more acceptable than other composite porridges. Compositing sorghum meal with marama flour reduced the cooked sorghum aroma/flavour intensities prominent in sorghum porridge. Dry heating marama beans prior to milling resulted in a roasted nutty flavour in the final product. Porridges from heated marama beans were darker in colour than porridges from unheated beans. This could be attributed to flavour and colour development due to Maillard reaction during dry heating. Composite porridges from full fat marama flours were described as buttery/creamy. A bitter taste and aftertaste was perceived in porridges from defatted flours. Presence of fat seems to mask bitterness in porridges. Marama-sorghum composites and Tsabotlhe porridges were less viscous than sorghum porridge. This was confirmed by pasting profiles (low final viscosities) and texture analysis indicating reduced firmness. Starch contributes greatly to the textural properties of sorghum porridge. Marama flour has no starch. Compositing the flour with sorghum reduced starch levels in the composite porridges. This explains the reduction in viscosity and firmness of the porridges. Compositing sorghum meal with marama flours significantly increased protein and fat contents in flours and porridges. The fat content in marama-sorghum flours was in the range of 5.6 to 14.6%. Protein increase ranged from 61% to 96% in marama-sorghum composite porridges compared with sorghum porridge. There was 11-24% energy value increase in marama-sorghum composite porridges compared with sorghum porridge. Porridges composited with full fat flours contributed to higher energy values than those composited with defatted flours. This is because of fat energy contribution. Lysine content in marama flour was significantly higher than sorghum meal. Lysine content was 3 to 4 times higher in marama-sorghum porridges than in sorghum porridge. Unsaturated fatty acids were the most present in both marama-sorghum composite porridges and sorghum porridge. There was an increase in oleic acid as marama flour was composited with sorghum. Marama flours had higher levels of total phenolics than sorghum flour. Marama flour has high levels of tyrosine which could react with the Folin Ciocalteu reagent thus leading to an increase in measurable phenols. Marama flours from dry heated beans had higher total phenolic content and antioxidant activity than flours from unheated beans. Heating may have increased phenolic compound extractability due to release of bound phenolics. There was a positive correlation between the total phenolic content and antioxidant activity (r = 0.80, p < 0.05) in all samples. Findings from this study indicate that marama flour can potentially be used to improve the nutritional quality of sorghum porridges. Furthermore this study shows that use of full fat flour in marama-sorghum composite porridges give more acceptable sensory properties.Dissertation (MScAgric)--University of Pretoria, 2011.Food Scienceunrestricte

The sensory profiles of flatbreads made from sorghum, cassava, and cowpea flour used as wheat flour alternatives

Sorghum, cowpea, and cassava are underutilised gluten-free sources of flour that have the potential to be used in bread products in sub-Saharan Africa. Excessive wheat imports affect the economies of countries in sub-Saharan Africa, driving the search for wheat flour alternatives. To extend the use of sorghum, cowpea, and cassava flours toward bread production, it is vital that the sensory properties of these flours are better understood. A trained sensory panel evaluated and described the sensory properties of flatbread models prepared from red non-tannin sorghum, fractions (whole and dehulled) of two cowpea varieties, cassava starch, and designated flour composites. The composites were prepared using cassava starch and sorghum flour at 0%, 35%, and 70%, respectively, with 30% cowpea flour. The addition of sorghum intensified sorghum aroma in flatbread, while cowpea flours contributed a beany flavour. Flatbreads from cassava-cowpea composites had a chewier and rubberier mouthfeel, an intense fermented aroma and flavour, and a sour aftertaste compared to single flours, but were most similar to the wheat flatbread, with a residual beany flavour. Information from this study can guide food product developers toward developing new bread products from sorghum, cassava, and cowpea composite flours, thereby moving Africa towards a more sustainable food system. Further research on the effects of the sensory characteristics on consumer liking of the flatbreads is needed

Functional properties and in vitro starch digestibility of infrared-treated (micronized) green banana flour

BACKGROUND : The consumption of green banana flour (GBF) products has been linked to reduced glycemic index (GI) and low risk of type 2 diabetes and obesity. The purpose of this study was to investigate the effect of micronization (high-intensity infrared heating method) on the molecular, microstructure and in vitro starch digestibility of five GBF cultivars grown in South Africa. The GBF was micronized at three surface temperatures (90, 120 and 150 °C for 30 min) and the in vitro starch digestibility was determined with Megazyme kits. RESULTS : Micronization at the highest temperature (150 °C) increased the swelling power by 6.00% in all five GBF cultivars when compared to control (unmicronized GBF). Micronization slightly reduced the resistant starch (RS) of the GBF cultivars by up to 8.63%. The FHIA-01 cultivar showed the highest RS (86.50%), whereas Grande Naine – 150 °C cultivar had the lowest RS (76.00%). Both micronized and control GBF exhibited similar X-ray diffraction patterns with all cultivars and at all micronization temperatures. Similarly, the functional properties of the GBF were not altered by micronization when observed with Fourier transform infrared spectroscopy. Scanning electron microscopy showed changes in the surface morphology of starch granules after micronization and these were dependent on temperature. CONCLUSION : Overall, micronization at 120 °C showed the best improvement in functional properties of GBF and this makes it suitable for potential application for the manufacture of instant breakfast products, baked goods and pasta. In addition, the micronized GBF cultivars retained high RS, suggesting potential health benefits for people with diabetes and obesity.The University of Johannesburg's postgraduate funding, the National Research Foundation South Africa and Centre of Excellence – Smart Food Project.https://onlinelibrary.wiley.com/journal/10970010am2024Consumer ScienceSDG-02:Zero HungerSDG-03:Good heatlh and well-bein

Physicochemical characteristics, microstructure and health promoting properties of green banana flour

This study aimed to investigate the proximate composition, mineral content, functional properties, molecular structure, in vitro starch digestibility, total phenolic content (TPC), total flavonoid content (TFC) and antioxidant activity (DPPH, FRAP) of green banana flour (GBF) cultivars grown in South Africa. With proximate composition, Finger Rose and Pisang Awak had the highest protein (4.33 g/100 g) and fat (0.85 g/100 g) content, respectively. The highest ash content (3.50 g/100 g) occurred with both Grand Naine and FHIA-01 cultivars. Potassium and copper were the most abundant and least minerals, respectively. Pisang Awak cultivar had the highest water absorption capacity (67.11%), while Du Roi had the highest swelling power (0.83 g/g) at 90 C. Scanning electron microscopy (SEM) images revealed that starch granules from all GBF cultivars were irregular in shape and they had dense surfaces with debris. All the GBF cultivars had similar diffraction patterns with prominent peaks from 15 –24 diffraction angles. The resistant starch (RS) and amylose content of the FHIA-01 cultivar indicates that the GBF has the potential to lower risks of type 2 diabetes and obesity. The highest TPC, TFC and antioxidant activity occurred with the Grande Naine cultivar. Based on their functional characteristics, the Grand Naine and FHIA-01 GBF cultivars could potentially be used as raw materials for bakery products as well as for the fortification of snacks.The National Research Foundation South Africa, Centre of Excellence–Smart Food Project and the University of Johannesburg’s postgraduate funding.https://www.mdpi.com/journal/foodsam2022Food ScienceConsumer Scienc

Yeast derived metabolites and their impact on nutritional and bioactive properties of African fermented maize product

DATA AVAILABILITY : The research data is from literature sources.Fermented foods are an integral part of the diet for many communities in Africa. The fermentation of maize is characterized by an improved nutrient content/bioavailability and the presence of bioactive compounds which are largely attributed to the activity of the microbial population mainly lactic acid bacteria (LAB) and yeasts. The role of LAB in maize and other cereal fermentations has been extensively studied. However, limited literature is available on the role of yeasts in maize fermentations and resultant nutritional and health promoting properties. This review explores the contribution of yeasts to the nutritional and health properties of fermented maize and other cereal products. Additionally, the proliferation and growth characteristics of dominant yeasts and their derived metabolites are discussed. It is particularly important to comprehend the processes and type of yeasts involved in maize fermentation as an essential step in maize product development. This will facilitate the development of yeast-based starter culture, improve maize fermentation process and provide better understanding of associated nutrition and bioactive properties.The National Research Foundation of South Africa.https://www.elsevier.com/locate/fbiohj2024Consumer ScienceFood ScienceSDG-02:Zero Hunge

Food Metabolomics: A New Frontier in Food Analysis and its Application to Understanding Fermented Foods

The emergence of food metabolomics, otherwise known as foodomics, has opened new frontiers and possibilities for scientists to characterize and simultaneously determine and obtain the comprehensive profile of the food metabolome. Qualitative and quantitative determinations of this metabolome offer insights into the underlying processes involved and details about the content of the food analytes. This had seemed technically challenging and impossible over time, but can now be done due to the advent of sophisticated analytical equipment and chemometric tools. The application of this technique offers enormous opportunities to obtain detailed information that can be correlated to various properties, functionalities and potentials in fermented foods. This chapter thus evaluated and documented studies presented in the literature on the food metabolomics study of fermented foods, with a view of appraising its prospects, applications and subsequent utilization in the study of fermented foods

Selenium nanoparticles–enhanced potato starch film for active food packaging application

This work developed an active selenium nanoparticles-based potato starch film. The incorporation of selenium nanoparticles (SeNPs) improved the microstructure, physical and biological properties of the nanocomposite film. Scanning electron microscopy (SEM) showed a slight increase in surface roughness and heterogeneity of nanocomposite film. Addition of SeNPs resulted in an improvement in film thickness and density from 0.02 ± 0.01 to 0.04 ± 0.00 mm and 1.01 ± 0.12 to 1.31 ± 0.03 g cm−3, respectively, while water content, film solubility, swelling degree as well as water vapour transmission rate decreased. Integration of SeNPs into potato starch film caused a significant change (P < 0.05) of colour to red (a*) and yellow (b*). The tensile strength also improved with addition of SeNPs from 3.42 to 9.86 MPa. The presence of SeNPs in the potato starch film enhanced its antioxidant and antimicrobial activity. The overall migration and specific migration were within acceptable levels as stipulated in the EU regulations. The findings of this study present an alternative biodegradable biopolymer material that can be used as active food packaging material in replacement of nonbiodegradable synthetic polymer material.Centre for Nanomaterials Science Research; DST-NRF Centre of Excellence - Smart Foods; Thuthuka National Research Foundation; University of Johannesburg; Water Research Commission.https://onlinelibrary.wiley.com/journal/13652621hj2023Consumer ScienceFood Scienc

Genome in silico and in vitro analysis of the probiotic properties of a bacterial endophyte, Bacillus paranthracis strain MHSD3

Spore-forming Bacillus species are gaining interest in human health recently, due to their ability to withstand the harsh environment of the gastrointestinal tract. The present study explores probiotic features of Bacillus paranthracis strain MHSD3 through genomic analysis and in vitro probiotic assays. The draft genome of strain MHSD3 contained genes associated with tolerance to gastrointestinal stress and adhesion. Cluster genes responsible for the synthesis of antimicrobial non-ribosomal peptide synthetases, bacteriocins, and linear azole-containing peptides were identified. Additionally, strain MHSD3 was able to survive in an acidic environment, had the tolerance to bile salt, and exhibited the capability to tolerate gastric juices. Moreover, the isolate was found to possess strong cell surface traits such as high auto-aggregation and hydrophobicity indices of 79 and 54%, respectively. Gas chromatography–mass spectrometry analysis showed that the strain produced secondary metabolites such as amino acids, phenolic compounds, and organic acid, known to exert health-promoting properties, including the improvement of gastrointestinal tract health.The National Research Foundation of South Africa and the CSIR-DST scholarship.http://www.frontiersin.org/Geneticsam2022Consumer ScienceFood Scienc

The sensory profiles of flatbreads made from sorghum, cassava, and cowpea flour used as wheat flour alternatives

Sorghum, cowpea, and cassava are underutilised gluten-free sources of flour that have the potential to be used in bread products in sub-Saharan Africa. Excessive wheat imports affect the economies of countries in sub-Saharan Africa, driving the search for wheat flour alternatives. To extend the use of sorghum, cowpea, and cassava flours toward bread production, it is vital that the sensory properties of these flours are better understood. A trained sensory panel evaluated and described the sensory properties of flatbread models prepared from red non-tannin sorghum, fractions (whole and dehulled) of two cowpea varieties, cassava starch, and designated flour composites. The composites were prepared using cassava starch and sorghum flour at 0%, 35%, and 70%, respectively, with 30% cowpea flour. The addition of sorghum intensified sorghum aroma in flatbread, while cowpea flours contributed a beany flavour. Flatbreads from cassava-cowpea composites had a chewier and rubberier mouthfeel, an intense fermented aroma and flavour, and a sour aftertaste compared to single flours, but were most similar to the wheat flatbread, with a residual beany flavour. Information from this study can guide food product developers toward developing new bread products from sorghum, cassava, and cowpea composite flours, thereby moving Africa towards a more sustainable food system. Further research on the effects of the sensory characteristics on consumer liking of the flatbreads is needed.Supplementary Materials: Table S1: Sensory descriptors and food reference guide used by the trained descriptive sensory panel; Table S2: Training schedule for descriptive sensory evaluation of the flatbread samples; Table S3: Sensory attributes of cowpea flatbread from different varieties and milling fractions; Table S4: Effect of different composite ratios of cassava starch and sorghum flours on the sensory attributes of flatbreads; Table S5: First six factor scores of principal component analysis of 33 attributes of flatbreads from composites flours and control wheat flour, Video S1; Video demonstration on flatbread preparation.The National Research Foundation (NRF) and the European Union.https://www.mdpi.com/journal/foodsam2022Consumer ScienceFood Scienc

Nutritional quality and antioxidant activity of marama–sorghum composite flours and porridges

Marama bean, an underutilised legume in southern Africa, is a good source of protein, fat and phenolic compounds, the latter known to have potential health benefits. Marama flours, sorghum meal, marama– sorghum composite flours and porridges were analysed for proximate composition, amino acid composition, energy value, fatty acid composition, total phenolic content and antioxidant activity. Compositing sorghum meal (70%) with marama flours (30%) significantly increased the protein and fat contents in flours and porridges. Energy values of marama–sorghum composite porridges were 11– 24% higher than sorghum porridge. Lysine content was 3–4 times higher in marama–sorghum porridges than in sorghum porridge. There was an increase in oleic acid as sorghum meal was composited with marama flour. There was a positive correlation between the total phenolic content and antioxidant activity in all samples. Use of marama flour in sorghum composite flours and porridges improved the nutritional quality and antioxidant activity.This research was sponsored by the EU MARAMA II PROJECT.http://www.elsevier.com/locate/foodchemnf201