Foam and fluid properties of purified saponins and non-purified water extracts from Camellia oleifera cake (by-product).

The physicochemical and foam properties of non-purified water extracts (WE) and purified tea saponins (TS) from Camellia oleifera cake (byproduct) were compared. WE showed different fluid properties at equal saponin concentrations (1.0 wt%) compared to TS. Particularly, it exhibited limited micelle size (average 434.1 nm), effective viscosity (0.15 Pa·s), and surface tension (43.9 mN/m) independently of pH. Moreover, the foam properties of WE were comparable to TS and better than sodium caseinate, especially foam stability. WE foam was more stable than TS foam under pH (3-7) and heating (40-80 °C). In the presence of NaCl, sucrose, and ethanol (5-20 wt%), WE and TS were effective and had similar foam behavior. Low concentrations of sucrose (<10 wt%)/ethanol (<20 wt%) significantly increased the foam capacity, while ethanol over 30 wt% was unfavorable. WE/TS foam contributes significantly to the desired physicochemical and sensory attributes (taste, texture, and appearance) of foods.