Dielectric and Mechanical Properties Around Glass Transition of Milk Powders

Flavor release from spray-dried amorphous matrix: Effect of lactose content and water plasticization

“…The T α values of powders decreased with increasing water content as a result of water plasticization, which was in agreement with the study of Silalai and Roos (2010). S1 showed significantly higher T α values than other powders after spray drying.…”

“…In addition, since the presence of high molecular weight protein or carbohydrate in the amorphous lactose-based systems could increase diffusion distance (Potes, Kerry, & Roos, 2012;Silalai & Roos, 2010, the ratios of low molecular weight compounds in encapsulation systems could affect the properties of whey protein-based systems. Furthermore, water is a highly efficient plasticizer of carbohydrates and the glass transition temperature of an amorphous carbohydrate matrix decreases strongly with increasing water content (Jouppila, Kansikas, & Roos, 1997;Jouppila & Roos, 1994;Partanen et al, 2008;Velasco, Holgado, Dobarganes, & Márquez-Ruiz, 2009;Zhou & Roos, 2012).…”

Coupling of dielectric and mechanical relaxations with glass transition and stickiness of milk solids

“…The importance of glass transition to amorphous solid characteristics has been well recognized (Levine and Slade, 1986;Roos and Karel, 1990;Roos, 1995;Slade and Levine, 1995), and several studies have contributed to the understanding of dielectric and mechanical relaxation processes around the glass transition of food solids (Champion et al, 2000;Fukao and Miyamoto, 2000;Silalai and Roos, 2010b). Dielectric and dynamic mechanical properties reported for several important carbohydrates have confirmed similarities in changes in dielectric properties and mechanical moduli of amorphous carbohydrates around their glass transition (Kalichevsky et al, 1992;Noel et al, 1992Noel et al, , 1996Noel et al, , 2000.…”

“…DEA was used to measure changes in dielectric properties from the dielectric constant or permittivity (e 0 ), dielectric loss (e 00 ), and their ratio tan d = (e 00 /e 0 ) as a function of temperature. The e 0 describes an alignment of dipoles (permittivity) and the e 00 (dielectric loss) describes an energy that is required to align dipoles (Talja and Roos, 2001;Laaksonen and Roos, 2003;Silalai and Roos, 2010b). Around 1 g aliquots of each powder were prepared and humidified in vacuum desiccators over saturated salt solutions for 5 days as described by Silalai and Roos (2010b).…”

“…The temperature dependence of relaxation times below the glass transition may follow the Arrhenius relationship, but changes above the glass transition become highly temperature-dependent and deviate from Arrhenian behavior which is used to classify materials to fragile and strong glass formers (Angell, 1993) The composition and water content of carbohydrate glass-formers has been found to affect their sub-T g and a-relaxations (Chan et al, 1986;Roos, 1995;Noel et al, 1996Noel et al, , 2000Champion et al, 2000;Le Meste et al, 2002;Psurek et al, 2004;Cummins et al, 2006;Kaminski et al, 2008a,b;Silalai and Roos, 2010b), but there is very little information on the miscibility and effects of composition on the relaxation behavior of mixtures of lowmolecular-weight carbohydrates and polymers. The objective of the present study was to determine effects of composition of milk solids at varying protein contents on their dielectric and mechanical a-relaxations as well as the temperature dependence of relaxation times around and above the glass transition.…”