Exploring a Simple Method of Thaumatin Extraction from Thaumatococcus daniellii

Abstract

Thaumatin is a naturally occurring protein sweetener found in the arils of Thaumatococcus daniellii fruits. In spite of its high market value as a safe flavour enhancer and high-intensity sweetener, challenges associated with the extraction and purification process have limited the economic exploitation of T. daniellii for thaumatin production in the West and Central Africa. This study examined a simple extraction technique that could be adapted locally. The arils of T. daniellii fruits were homogenized (in water), and filtered through a double-folded muslin cloth to obtain a crude protein extract. The extract was precipitated with 80% ammonium sulphate, dialysed and purified by gel filtration (Sephadex G-75). The crude protein extract and proteins from dialysed and gel chromatographic fractions were separately freeze-dried and run through SDS-PAGE. The extract of T. daniellii arils contained sweet-tasting proteins (thaumatin) with average molecular weight of about 22 kDa. The proteins were extremely sweet at 20 – 40oC; the sweetness decreased as temperature increased and became faint at 70oC. Protein recovery from ammonium sulphate precipitation and gel filtration was 76.14% and 63.0%, respectively. The crude extract was light brown whereas the purified protein was cream coloured. The simple process of homogenisation and filtration through muslin cloth can be adapted for extraction and initial processing of thaumatin in West Africa. Enzymatic hydrolysis of the sticky substances (polysaccharides) in the arils can enhance the extraction process.