Phenolic compounds and kernel characteristics of Zimbabwean sorghums

TLDR: In this paper, the chlorox test, vanillin-HCl, the ferric ammonium citrate and butanol-HCL methods were used to identify those with desirable properties and develop suitable processing methods.

Abstract: Sixteen sorghum varieties widely cultivated in Zimbabwe were examined for levels of phenolic compounds and kernel characteristics, to help identify those with desirable properties and develop suitable processing methods. Assays for polyphenols included the chlorox test, the vanillin- HCl, the ferric ammonium citrate and the butanol-HCl methods. Free phenolic acids were analysed using reverse-phase high performance liquid chromatography. Varieties DC-75, Mutode and Chirmaugute had the highest levels of condensed tannins. The polyphenols in Chibonda were mostly unextractable in methanol. No significant levels of polyphenols were found in 13 varieties. Phenolic acid content was related to pericarp colour. Endosperm texture and pericarp thickness were evaluated using video image analysis. Katandanzara and SV1 had relatively corneous endosperms ( 0.060 mm). Endosperm texture was not correlated with phenolic compounds. A positive correlation, however, was observed between pericarp thickness and polyphenol content (r> 0.64). Zimbabwean sorghums lack ideal agronomic and processing physico-chemical characteristics defined in terms of high polyphenols, plus hard endosperm and thin pericarp. Research is required to develop effective methods to process the available polyphenol-rich sorghums. # 1999 Society of Chemical Industry