Influence of trichloroacetic acid concentration on protein removal and structural preservation of exopolysaccharides obtained from milk fermentations

This study evaluated the effect of two concentrations oftrichloroacetic acid (TCA) on protein removal during theextraction of exopolysaccharides (EPS) produced by milk fermentationusing kefir grains (KGs) or Lactobacillus delbrueckiisubsp. bulgaricus NCFB 2772 (Lc2772). The results showedthat treatment with 10% TCA solution yielded more lyophilizedsolids (LS) in both fermentations compared to 80%TCA. Moreover, the solids obtained with 10% TCA exhibitedhigher sugar concentrations—34.95 ± 0.78 and 23.22 ± 0.25mgeq glucose mL-1 for LS-Lc2772 and LS-KGs, respectively. Incontrast, 80% TCA resulted in up to a 60% reduction in sugarcontent, suggesting potential polysaccharide hydrolysis.Although 80% TCA was more effective at removing proteins,it adversely affected EPS integrity, potentially compromisingtheir functional properties. These findings highlight the needto develop alternative protein removal methods that preservethe structural integrity of EPS.