Effects of Sugar Osmosis on Quality and Microstructure of Vacuum Freeze-dried Pear Slices

SONG Yang; ZHANG Kangzhuang; HU Dandan; LIU Zhenzhen; WANG Xiaoxuan; TANG Xuanming

doi:10.15933/j.cnki.1004-3268.2026.04.017

Abstract：To explore the microscopic mechanism of different small-molecule sugars in texture formation and their effects on the quality of vacuum-freeze-dried pear slices,pear slices were pretreated with glucose,fructose,and sucrose as penetrants,and then the samples were prepared by vacuum freeze-drying.The physicochemical properties,texture characteristics,microstructure and cell wall chemical constitution of pear slices were systematically analyzed by conventional physical and chemical detection combined with Fourier transform infrared spectroscopy and X-ray diffraction,with blank group as control(CK).The results showed that compared with the CK group,small molecule sugar treatments significantly increased the brightness index of the samples,with the largest increase observed in the sucrose group(11.30％).The total sugar content of the samples increased obviously,and the total sugar content significantly increased by 133.50％after glucose treatment.The total phenol content and total antioxidant capacity significantly decreased by 68.77％—70.35％and 51.12％—51.40％,respectively.Compared with the CK group,sugar osmotic treatment significantly increased the glass transition temperature of the samples,with an increase of 60.05％in the sucrose group.The moisture absorption rate obviously decreased,and the moisture absorption rate of the sucrose group decreased most significantly,with a decrease of 26.22％.After sugar osmosis,the structure of the samples was more compact,the pore wall was thickened,and the hardness was significantly improved.Sucrose treatment also improved the uniformity of the pore structure,increasing the brittleness of the samples by 70.32％.The results of Fourier transform infrared spectroscopy showed that the hydrophilic groups of small molecular sugars could form hydrogen bonds with the components containing O-H in the cell wall of pear slices.The results of X-ray diffraction showed that the sugar molecules did not change the original crystal form of the samples,but combined with the amorphous polysaccharide of the cell wall through hydrogen bond competition to form a more stable system.In conclusion,different small-molecule sugars exhibit different effects on the physicochemical properties of freeze-dried pear slices.Sucrose can effectively improve the commercial quality of vacuum freeze-dried pear slices,especially in terms of texture characteristics.