The Effect of Adding Sappan Wood (Caesalpinia sappan L.) Powder at Different Percentages on Viscosity and Color of Cow's Milk Yoghurt

Abstract

Natural colorants are increasingly sought as replacements for synthetic dyes in dairy products, and sappan wood (Caesalpinia sappan L.) is a promising source because its brazilin pigment is both intensely coloured and bioactive. This study evaluated the effect of adding sappan wood powder at different levels on the viscosity and instrumental color (L*, a*, b*) of cow's milk yogurt and identified the level giving the most favorable physical characteristics. A completely randomized design with four treatments — P0 (0%), P1 (1%), P2 (1.5%), and P3 (2% of milk weight) — and five replications was used, and data were analyzed by analysis of variance followed by orthogonal-polynomial and least-significant-difference tests. Sappan wood powder had no significant effect on viscosity (P>0.05; overall mean 418.78±62.60 cP) but a highly significant effect on color (P<0.01). Lightness (L*) decreased quadratically with increasing powder level (R² = 89.6%), while redness (a*) and yellowness (b*) increased quadratically (R² = 87.4% and 83.0%, respectively); the overall means were L* = 55.79, a* = 4.76, and b* = 15.62. The color shift is consistent with the pH-dependent behavior of brazilin during acidification, whereas the unchanged viscosity indicates that the protein gel network was not materially altered over the 0–2% range tested. Sappan wood powder can therefore be applied at up to 2% as a natural colorant that markedly enhances the red–yellow appearance of cow's milk yogurt without compromising its consistency.