Multifaceted approach to the impact of drying techniques on Lycium barbarum polysaccharide yield, quality, and bioactive retention: insights from HPLC monosaccharide quantification.

Lycium barbarum (goji berry, LB) is a nutrient-dense fruit that requires drying for preservation, but this process can degrade its bioactive compounds. This study compares the effects of hot-air drying (HAD), infrared drying (IRD), and pulsed vacuum drying (PVD) on drying kinetics, microstructure, and polysaccharide yield, with HPLC used for monosaccharide quantification and FT-IR for structural analysis. PVD significantly reduced drying time to 11 h, representing a 50.0% reduction compared to HAD (22 h), a 47.6% reduction compared to IRD (21 h), and a 42.1% reduction compared to HAD+ (19 h), while preserving visual quality, resulting in the lowest color difference (ΔE = 28.6) and browning index. Microstructure analysis revealed that PVD yielded a porous structure, whereas HAD led to shrinkage. Blanching improved color stability but resulted in a loss of water-soluble polysaccharides. Among all methods, HAD of unblanched LB achieved the highest LB polysaccharide (LBPs) yield (7.2%), while PVD of blanched LB produced the second-highest yield (6.6%) with better preservation of molecular structure, as confirmed by FT-IR. HPLC analysis identified glucose as the dominant sugar. These results highlight the crucial role of drying techniques in preserving the bioactivity of LBPs, offering valuable insights for optimizing their processing in functional food applications.