Protective role of wood hemicelluloses: Enhancing yeast probiotics survival in spray drying and storage

Wood hemicelluloses, specifically galactoglucomannans (GGM) and glucuronoxylans (GX) are investigated for their efficacy in spray-dried microencapsulation of Saccharomyces cerevisiae subsp. boulardii (SB). Due to differences between bacterial and yeast probiotics, the protective capability of GGM and GX for SB warrants investigation. This study demonstrated that GGM and GX effectively protected SB during spray drying at feed concentrations of 15 and 20% and inlet air temperatures of 105 and 140°C, ensuring survival rates over 90%, comparable to gum Arabic, with all achieving over 10⁸ cfu/g in the microcapsules. However, GGM and GX were unable to sustain SB viability when the microcapsules were stored at 33 and 75% RH (25 °C), beyond 21 and 7 days, respectively. When stored at 4 °C, GX demonstrated a greater ability to protect SB than GGM, with log-cycle reductions of 3 and 6, respectively, after two months. Microstructure analyses showed almost all SB were entrapped by wall materials, with many microcapsules having a wall thickness of 1−2 µm. Overall, GX is effective for stable yeast probiotic powders, enabling the development of new probiotic enhanced formulations with prolonged viability and stability.