Addition of small-molecule polysaccharides and polyols improves the porous microstructure and quality of freeze-dried strawberry slices enriched with Lactobacillus plantarum.

Small-molecule polysaccharides and polyols are widely used as protectants in probiotic fruit and vegetable. This study investigated the effects of glucose, trehalose, sorbitol, glycerol, and their combinations on pore microstructure and quality attributes of freeze-dried strawberry slices enriched with Lactobacillus plantarum. Compared with single protectants and controls, compound protectants resulted in higher viable L. plantarum count; a more uniform, stable, and well-developed porous microstructure; lower equilibrium hygroscopicity; improved volatile compound profiles; and brighter color characteristics. In the compound group, hardness and chewiness (from texture profile analysis), penetration hardness, and penetration work were 40.27%, 38.38%, 56.70%, and 39.36% higher, respectively, than those in the control group. Higher porosity rate, larger pore equivalent diameter, pore wall thickness, isolated pore volume, and smaller connected pore equivalent diameter were significantly correlated with improved mechanical properties and sensory scores. These findings support the application of polysaccharide and polyol protectants in freeze-dried probiotic fruit and vegetable.