E.Kayitesi; H.L. de Kock; A. Minnaar; K.G.Duodu
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A poster presented at the 2012 Global Pulse Researchers Meeting, Kigali, Rwanda- “Transforming Grain-Legume Systems to Enhance Nutrition and Livelihoods”. Abstract: Cowpea (Vigna unguiculata L. Walp) is mostly utilised as cooked whole seeds. This is often achieved only after boiling for up to 2 h, resulting in extensive energy consumption. Micronisation, an infrared heat treatment applied to pre-conditioned cowpeas reduces their cooking time. However, micronisation like other heat processing technologies may affect bioactive components such as phenolic compounds, known to have potential health benefits. Cooked samples of three cowpea types namely Blackeye, Bechuana white and Glenda (control and micronised) were analysed for phenolic composition by HPLC/MS, antioxidant activity and protective effect against LDL oxidation. There was a significant reduction in total phenolics and protection against copper induced LDL oxidation after micronisation in all cowpea samples. The radical scavenging activities of micronised Blackeye sample were also significantly lower than the control samples. In contrast, micronisation had no effect on radical scavenging activities of Glenda and Bechuana white cowpeas. Micronisation significantly reduced ferulic acid in all cowpea types, protocatechuic acid in Glenda and Bechuana white types, catechin, and caffeic acid in Blackeye and Bechuana white types. On the other hand, micronisation significantly increased protocatechuic acid in Blackeye and catechin in Glenda. Though micronisation of cowpea results in loss of some phenolic compounds and some health promoting properties, micronised cowpea samples still retain some bioactivity and therefore may offer some potential health benefits.