Isoelectric focusing

Varietal identification of Thai hot chilli using seed protein analysis by ultrathin layer isoelectric focusing technique

Fern Akrawong, Sermsiri Chanpreme, Rainer Knoblauch, Manfred Demharter and Thammasak Thongket


This research aimed to determine the protein extraction solvent and pH of gel acrylamide that are suitable for conducting varietal verification of Thai hot chilli by ultrathin layer isoelectric focusing. Four extraction solvents, EX 3 (urea + ethylene glycol), phosphate buffer, water and HEPES, and two gel pH ranges, 3-10 and 5-8/2-11, forming eight treatment combinations were compared. Ten chilli cultivars, Capsicum annuum ‘Hua reur yon’, ‘Mun’, ‘Gaw’, ‘Pama’ and ‘Yod son lek’ and C. frutescens ‘Mong’, ‘She deuy kai’, ‘Pop puang’, ‘Som ka rieang’ and ‘Kee noo suan’, were tested. Protein extraction with EX 3 in combination with gel pH 3-10 gave the best varietal verification of chilli varieties in this study. In pairwise comparisons of the 10 chilli varieties, this treatment combination was able to verify all the 45 pairs with 100% efficacy.

Keywords: Capsicum annuum, Capsicum frutescens, extraction solvent, gel pH, Thai hot-chilli

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