Abstract / Summary
Abstract Goat colostrum is a nutrient-dense dairy matrix with potential for value-added fermented products, although its rapidly changing composition during early lactation may influence fermentation performance and storage stability. This study investigated the combined effects of postpartum milking day and lactic acid bacteria (LAB) strain on the acidification kinetics, colloidal properties, macronutrient stability, microbial viability, molecular organisation, rheology, and microstructure of fermented Local Gorontalo goat colostrum. Colostrum collected on postpartum Days 1–3 was pasteurised and fermented separately with Lactobacillus delbrueckii subsp. bulgaricus , Lactobacillus acidophilus , or Lactococcus lactis subsp. cremoris , followed by refrigerated storage at 4°C for 28 days. All strains reduced pH from approximately 6.3–6.4 to 4.6–5.0, with nonlinear mixed-effects modelling demonstrating strain-dependent acidification kinetics and the lowest predicted limiting pH for L. lactis subsp. cremoris . During storage, zeta-potential values decreased by approximately 15%, whereas particle size increased by 8–20%, indicating progressive colloidal reorganisation. Protein decreased only modestly and fat remained comparatively stable. LAB populations remained above approximately 7.8 log CFU/mL at Day 28. FTIR spectra indicated molecular rearrangement without major loss of characteristic functional groups, while rheological analysis revealed decreasing viscoelastic moduli and complex viscosity with increasing loss factor. Collectively, postpartum stage and starter strain were key determinants of fermentation behaviour and refrigerated structural stability, supporting the potential utilisation of Local Gorontalo goat colostrum for fermented dairy product development.