Colloidal characteristics and dispersion stability of ascorbate-zinc-isoleucinate triple chelated complex in fermented dairy matrix

Abstract

Zn deficiency is a major global health problem affecting over 2 billion people worldwide, so it is important to approach the issue of its highly effective delivery to the body. In this study, a zinc ascorbate isoleucinate (ZAI) triple chelate complex was synthesized and characterized for the first time. The optimal synthesis parameters for ZAI were determined to be: pH = 3–8, t = 25–65 °C, τ = 5–20 min. It was observed that fortifying milk with ZAI is effective at concentrations of ≤ 0.005 mol/L. Notably, at 0.005 mol/L ZAI, cfu value (1.55 ×106 in 1 mL) was higher than that of the control sample (0.8 ×106 in 1 mL), indicating a growth stimulation effect on lactic acid bacteria. During fermentation, there was a significant decrease in pH value (from 6.74 to 4.37), an increase in titratable acidity (from 22.52 to 110.41 °T) and viscosity (from 3.3 to 625.8 mPa•s). However, the experimental fermented dairy product with ZAI received the highest sensory score, whereas the fortified milk before fermentation scored the lowest score.