Speaker
Prof.
Job Ubbink
(California Polytechnic State University)
Description
`Glassy matrices for the encapsulation and stabilization of bioactive compounds often consist of molecularly miscible blends of a carbohydrate of higher molecular weight and a low molecular weight carbohydrate or polyol. Typical examples of such blends are maltodextrin/sucrose and trehalose/glycerol. The optimization of the barrier properties of such matrices depends in a subtle way on the balance between the plasticization and antiplasticization of the high molecular weight carbohydrate by the low molecular weight compound [1]. Here, we report on the phase behavior of encapsulation matrices consisting of blends of a hydrophobically-modified starch and sucrose. By differential scanning calorimetry (DSC), it is shown that the blends exhibit two glass transitions, with the specific heat and the temperatures of the transitions varying in a systematic way with the blend composition [2]. This hints at a limited degree of phase separation of the matrix into two amorphous phases. We present a model to calculate the degree of phase separation of the blends and the composition of the phases from the dependence of the glass transition temperatures of the blends on the sucrose content. The antiplasticization of the starch-rich phase by sucrose is confirmed by the decrease in molecular hole size with increasing sucrose content as determined by positron annihilation lifetime spectroscopy (PALS) [3] and the stiffening of the starch chains solid state NMR by the addition of sucrose to the matrix. We conclude the lecture by discussing the advantages and disadvantages of the two-phase system for its use in encapsulation systems.`
`References`
[1] J. Ubbink, `$\textit{Advanced Drug Delivery Reviews}$` `$\textbf{100}$`, 10-26 (2016).
[2] C. Tedeschi, B. Leuenberger and J. Ubbink, `$\textit{Food Hydrocolloids}$` `$\textbf{58}$`, 75-88 (2016).
[3] D. Hughes, C. Tedeschi, B. Leuenberger, M. Roussenova, A. Coveney, R. Richardson, G. Badolato Bönisch, M.A. Alam and J. Ubbink, `$\textit{Food Hydrocolloids}$` `$\textbf{58}$`, 316-323 (2016).
Primary author
Prof.
Job Ubbink
(California Polytechnic State University)
Co-authors
Prof.
Ashraf Alam
(H. H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol, BS8 1TL, UK)
Dr
Bruno Leuenberger
(DSM Nutritional Products AG, Research Center Formulation & Application, P.O. Box 2676, 4002 Basel, Switzerland)
Dr
Concetta Tedeschi
(DSM Nutritional Products AG, Research Center Formulation & Application, P.O. Box 2676, 4002 Basel, Switzerland)
Dr
David Hughes
(H. H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol, BS8 1TL, UK)
Dr
Fransesca Martini
(Dipartimento di Chimica e Chimica Industriale, Università di Pisa, Italy)
Dr
Gabriela Badolato
(DSM Nutritional Products AG, Research Center Formulation & Application, P.O. Box 2676, 4002 Basel, Switzerland)
Dr
Marco Geppi
(Dipartimento di Chimica e Chimica Industriale, Università di Pisa, Italy)
