Moisture-Mediated Interactions Between Amorphous Maltodextrins and Crystalline Fructose

The effects of coformulating amorphous maltodextrins (MDs) and crystalline fructose, a deliquescent solid, on the moisture sorption, deliquescence point (RH₀ ), and glass transition temperature (T_g ) behaviors were determined. Moisture sorption profiles of binary fructose:MD mixtures and individual ingredients were generated using controlled relative humidity (RH) desiccators and by dynamic vapor sorption techniques. Blends exhibited synergistic moisture uptake at RHs below the RH₀ of fructose, attributed to partial dissolution of fructose in plasticized MD matrices without a significant reduction in the RH₀ of the undissolved fructose. Increasing storage temperature decreased the onset RH for moisture sorption synergy. At all storage RHs, the measured T_g (2nd scan) was significantly reduced in fructose:MD mixtures compared to individual MDs, and was related to both the synergistic moisture uptake in the blends and heat-induced ternary fructose-MD-water interactions in the differential scanning calorimeter. Differences were found between the behavior of fructose:MD blends and previous reports of sucrose:MD and NaCl:MD blends, caused in part by the lower RH₀ of fructose. The enhanced moisture sorption in blends of deliquescent and amorphous ingredients could lead to problematic moisture-induced changes if storage conditions are not controlled.