Effects of fructooligosaccharides on quality attributes of freeze-dried cheese: Insights into water status, microstructure, texture and rheology.

Freeze-dried cheese is high-value-added, yet its porous structure and hygroscopicity limit quality and storage stability. This study evaluated the effects of fructooligosaccharides (FOS) on freeze-dried cheese properties. FOS reduced water activity (from 0.13 to 0.08 at 10%FOS) and hygroscopicity, enhancing storage stability. Low-field nuclear magnetic resonance (LF-NMR) and Fourier-transform infrared spectroscopy (FTIR) confirmed enhanced hydrogen bonding after FOS addition, with free water converted to bound water. Scanning electron microscopy (SEM) and micro-computed tomography (μCT) confirmed this redistribution optimized pore morphology and reduced large pores (>150 μm), yielding a dense homogeneous network. These structural improvements increased hardness but reduced brittleness, with 10%FOS delivering the best texture balance. Rheological tests further showed that network strength rose with FOS dosage; tan δ stayed below 0.3 over 25-80 °C. Collectively, FOS supplementation improved the overall quality of freeze-dried cheese, with 10%FOS identified as the optimal level offering superior comprehensive performance and great application potential.