Studies of some functional properties of thaumatin, a protein sweetener

Thaumatin, an intensely sweet protein from the fruit of Thaumatococcus danielli Benth., was isolated, purified on Sephadex G50, and some of its functional properties studied. The functional properties studied included protein solubility, emulsifying activity, emulsion stability, foaming capacity and stability and the effect of pH on the sweetness and temperature stability of thaumatin. The effect of thaumatin on food color stability was also investigated. Gel filtration on Sephadex G50 yielded four fractions of which three possessed thaumatin activity. The purified, freeze-dried sample was fluffy, light cream- colored powder. Thaumatin was soluble over a wide range of pH (2≤ pH ≤ 10). The protein maintained sweetness at high temperature over both acidic and basic pH, while it lost sweetness beyond pH 9. Thaumatin resulted in high whippability (140%) and foam stability. The protein also had relatively good emulsion properties, and heating had little effect on its emulsion stability. All these are suitable properties required of any novel protein for use in food formulations.