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Bioactive phenolics in sorghum-cowpea composite porridge and their potential to alleviate radical-induced oxidative stress
Thesis (PhD (Food Science))--University of Pretoria, 2014.
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| Format: | Thesis |
| Language: | English |
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2026
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| _version_ | 1867613543352762368 |
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| access_status_str | Open Access |
| author2 | Duodu, Kwaku Gyebi |
| author_browse | Duodu, Kwaku Gyebi |
| author_facet | Duodu, Kwaku Gyebi |
| collection | Thesis |
| description | Thesis (PhD (Food Science))--University of Pretoria, 2014. |
| format | Thesis |
| id | oai:repository.up.ac.za:2263/110065 |
| institution | University of Pretoria (South Africa) |
| language | English |
| last_indexed | 2026-06-10T12:37:49.221Z |
| license_str | Not specified — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from UPSpace — University of Pretoria Institutional Repository |
| publishDate | 2026 |
| publishDateRange | 2026 |
| publishDateSort | 2026 |
| record_format | dspace |
| source_str | UPSpace — University of Pretoria Institutional Repository |
| spelling | oai:repository.up.ac.za:2263/110065 Bioactive phenolics in sorghum-cowpea composite porridge and their potential to alleviate radical-induced oxidative stress Duodu, Kwaku Gyebi franklinapeabah@yahoo.com Minnaar, Amanda Bester, Megan J. Apea-Bah, Franklin Brian Sorghum-cowpea porridge phenolic compounds in vitro digestion maiza-soybean porridge antioxidant properties. Thesis (PhD (Food Science))--University of Pretoria, 2014. Oxidative stress resulting from an imbalance between reactive oxygen and nitrogen species and the natural antioxidants in the body is believed to play a central role in many chronic diseases such as cardiovascular disease and cancer. Sorghum and cowpea are grain cereal and legume, both of which are indigenous to Africa and provide dietary energy and protein to millions of people in developing countries. They also contain phenolic antioxidant compounds which can potentially contribute to alleviating oxidative stress. In this research, the effects of compositing sorghum with cowpea and porridge preparation, on the phenolic composition and radical scavenging properties of sorghum-cowpea composite flour was studied. Also, the effect of simulated in vitro gastrointestinal digestion on the phenolic composition and antioxidant properties of the resulting sorghum-cowpea composite porridge was studied. A maize-soybean composite porridge was used as reference sample. Total phenolic content (Folin-Ciocalteu method), total flavonoid content (NaNO2-AlCl3 method) and radical scavenging properties (2,2'-diphenyl-1-picrylhydrazyl, trolox equivalent antioxidant vi capacity, nitric oxide and oxygen radical absorbance capacity assays) of the flours, porridges and digests were determined. Liquid chromatography-mass spectrometry was used for determining phenolic composition. Protective effects of the porridges and digests against 2,2'-azobis(2- methylpropionamidine) dihydrochloride (AAPH)-induced human erythrocyte haemolysis, oxidative DNA damage and Cu2+ -catalysed human low density lipoprotein (LDL) oxidation were determined. The cereal (sorghum and maize) flours, legume (cowpea and soybean) flours, their composites and porridges contained mainly phenolic acids and flavonoids. Flavonoid classes identified in sorghum included flavones, flavanones, flavan-3-ol and flavanonol. White maize generally lacked flavonoids but was rich in phenolic acids, especially bound ferulic acid. Flavonoid classes identified in cowpea included flavan-3-ols, flavonols and flavanonol, while soybean contained mostly isoflavones. The composite flours had higher total phenolic content and radical scavenging capacities than the corresponding cereal flours alone due to the legume phenolic compounds, especially the flavonoids, complementing those of the cereal phenolic compounds. Porridge preparation reduced the extractability of the phenolic compounds and radical scavenging capacities of the cereal and cereal-legume composite flours probably due to thermally-induced phenolic oxidation and phenolic-protein binding. The simulated in vitro gastrointestinal digests of the cereal and cereal-legume composite porridges had higher total phenolic content, total flavonoid content and radical scavenging capacities than the corresponding undigested porridges, probably due to protein digestion and consequent release of phenolic compounds bound to proteins. All the cereal and cereal-legume composite undigested porridges and porridge simulated gastric digests protected erythrocytes from haemolysis and inhibited LDL oxidation. However, the porridge simulated gastric digests demonstrated better protection than the corresponding undigested porridges. The porridge simulated duodenal digests contained hydroperoxides and therefore caused haemolysis and LDL oxidation. The simulated gastric digest of sorghum-cowpea composite porridge inhibited LDL oxidation better than that of the maize-soybean composite porridge. This is probably due to the higher vii antioxidant properties of the flavonoids (flavones, flavanones, flavan-3-ols) in the simulated gastric digest of sorghum-cowpea composite porridge compared to mainly isoflavones in the simulated gastric digest of maize-soybean composite porridge. All the porridges and simulated gastrointestinal digests protected DNA from AAPH-induced oxidative damage. However, the simulated gastrointestinal digest of sorghum-cowpea composite porridge showed the best protection against oxidative DNA damage. The observed radical scavenging properties of the cereal-legume composite porridges and their simulated digests and their ability to protect erythrocytes, LDL and DNA from oxidative damage, demonstrates their potential to contribute to alleviating radical-induced oxidative stress. However, sorghum-cowpea composite porridge simulated digests showed better protection against LDL oxidation and oxidative DNA damage than maize-soybean composite porridge simulated digests. It is concluded from this research study that a red non-tannin sorghum-high polyphenol cowpea composite porridge is a functional food that shows better promise than a white maize-cream coloured soybean composite porridge for contributing to alleviating oxidative stress-related chronic diseases such as cardiovascular disease and cancer. Food Science PhD (Food Science) 2026-05-15T17:26:13Z 2026-05-15T17:26:13Z 15/03/31 2014 Thesis http://hdl.handle.net/2263/110065 en application/pdf |
| spellingShingle | Sorghum-cowpea porridge phenolic compounds in vitro digestion maiza-soybean porridge antioxidant properties. Bioactive phenolics in sorghum-cowpea composite porridge and their potential to alleviate radical-induced oxidative stress |
| title | Bioactive phenolics in sorghum-cowpea composite porridge and their potential to alleviate radical-induced oxidative stress |
| title_full | Bioactive phenolics in sorghum-cowpea composite porridge and their potential to alleviate radical-induced oxidative stress |
| title_fullStr | Bioactive phenolics in sorghum-cowpea composite porridge and their potential to alleviate radical-induced oxidative stress |
| title_full_unstemmed | Bioactive phenolics in sorghum-cowpea composite porridge and their potential to alleviate radical-induced oxidative stress |
| title_short | Bioactive phenolics in sorghum-cowpea composite porridge and their potential to alleviate radical-induced oxidative stress |
| title_sort | bioactive phenolics in sorghum cowpea composite porridge and their potential to alleviate radical induced oxidative stress |
| topic | Sorghum-cowpea porridge phenolic compounds in vitro digestion maiza-soybean porridge antioxidant properties. |
| url | http://hdl.handle.net/2263/110065 |