Effect of Sodium Alginate on the Yogurt Stability and the Mechanisms

Abstract

In this study, the effect of sodium alginate on the yoghurt stability and the related mechanisms were investigated. It was found that low-concentration sodium alginate (≤ 0.2%) reduced whey separation of yogurt, while whey separation was aggravated by high-concentration sodium alginate (≥ 0.3%). Moreover, sodium alginate increased the viscosity and viscoelasticity of yogurt and this effect was positively correlated with its concentration, which confirmed its thickening effect. However, confocal laser scanning microscopy analysis demonstrated that the yogurt gel was damaged after adding ≥ 0.3% sodium alginate. On the other hand, it was found that when the sodium alginate concentration was ≤ 0.2%, casein micelles and sodium alginate were miscible. Thus, adding ≤ 0.2% sodium alginate improved the yogurt stability through the thickening effect. However, when the concentration was ≥ 0.3%, phase separation occurred to the casein micelle/sodium alginate mixtures. Correspondingly, adding ≥ 0.3% sodium alginate decreased the yogurt stability.

Keywords: Yogurt, Sodium alginate, stability, casein micelles, the thickening effect, phase separation