Moisture‐Mediated Interactions Between Amorphous Maltodextrins and Crystalline Fructose

Abstract

The effects of coformulating amorphous maltodextrins (MDs) and crystalline fructose, a deliquescent solid, on the moisture sorption, deliquescence point (RH ), and glass transition temperature (T ) 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 RH of fructose, attributed to partial dissolution of fructose in plasticized MD matrices without a significant reduction in the RH of the undissolved fructose. Increasing storage temperature decreased the onset RH for moisture sorption synergy. At all storage RHs, the measured T (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 RH 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.

Shelf-Life Stability of Ready-to-Use Green Rooibos Iced Tea Powder—Assessment of Physical, Chemical, and Sensory Properties

“…The effect of microencapsulation and the addition of crystalline ingredients become more complicated to understand as also indicated by Ortiz and colleagues [ 16 , 33 ]. Generally, higher physical and chemical instability have been reported for blends of deliquescent crystalline and amorphous ingredients compared to individual amorphous components [ 34 ]. Ortiz and colleagues [ 16 , 33 ] found that the addition of citric acid to amorphous green tea powders resulted in a decrease in physical and chemical stability.…”

Relative humidity–temperature transition boundaries for anhydrous β‐caffeine and caffeine hydrate crystalline forms

“…However, caffeine hydrate could form if β‐caffeine is exposed to approximately 100% RH for several hours to days (Pirttimäki & Laine, 1994) or to liquid water during processing. The incorporation of caffeine hydrate into a packaged final product would result in a delayed release of water if the a w /RH in the product was below the caffeine hydrate → β‐caffeine boundary condition, and this release of water in a closed system could lead to undesirable water–solid interactions (e.g., deliquescence and glass transition lowering) that could cause clumping and degradation of labile compounds (Khankari & Grant, 1995; Mauer & Taylor, 2010; Thorat et al., 2017).…”

Optimizing the Quality of Food Powder Products: The Challenges of Moisture-Mediated Phase Transformations

“…The interactions of water vapor with blends of amorphous solids and deliquescent crystals (not hydrate formers within the experimental space) were also found to vary based on formulation in a series of studies that used the deliquescent crystals sucrose, sodium chloride, and fructose and a series of amorphous maltodextrins with different molecular weights (Ghorab et al 2014a,b;Thorat et al 2017). In deliquescent crystalline-amorphous ingredient blends, there are two main options for moisture-mediated effects: (a) Significant water absorption into the amorphous matrix occurs first (because amorphous solids are often more hygroscopic at lower RHs) or (b) deliquescence of the crystalline compound occurs before significant plasticization of the amorphous compound.…”

“…The saturated solution forming on a crystal surface as it deliquesces has the potential to plasticize the amorphous matrix. Many blends of crystalline and amorphous ingredients have been found to sorb more water as RH increases than that predicted by an additive model, which resulted in lower T g s than were found for the single amorphous ingredient in the same environment (Ghorab et al 2014a,b;Thorat et al 2017). In sealed (packaged) systems, as shown in Figure 5, exposing a blend of crystalline and amorphous ingredients to increased temperatures resulted in increasing the a w of the amorphous compound to the extent that the a w crossed above the RH 0 of the crystalline ingredient and caused deliquescence of the crystal in the matrix (and complicated identification of the T g during thermal analysis) (Thorat et al 2017).…”

“…Many blends of crystalline and amorphous ingredients have been found to sorb more water as RH increases than that predicted by an additive model, which resulted in lower T g s than were found for the single amorphous ingredient in the same environment (Ghorab et al 2014a,b;Thorat et al 2017). In sealed (packaged) systems, as shown in Figure 5, exposing a blend of crystalline and amorphous ingredients to increased temperatures resulted in increasing the a w of the amorphous compound to the extent that the a w crossed above the RH 0 of the crystalline ingredient and caused deliquescence of the crystal in the matrix (and complicated identification of the T g during thermal analysis) (Thorat et al 2017). In reclosable packages, the cycles of opening and closing expose products to RH fluctuations, which has led to stability issues in products that contain a variety of both crystalline and amorphous ingredients, such as caking of bouillon mass much earlier than what could be predicted from the individual ingredient behaviors.…”