Influence of the glass transition temperature on the maltodextrin agglomeration process

Author(s)

Cristina Yoshie Takeiti

• Document type: Doctoral Thesis
• Press: Campinas, SP.
• Institution: Universidade Estadual de Campinas (UNICAMP). Faculdade de Engenharia de Alimentos
• Defense date: 2007-02-28

Examining board members

Fernanda Paula Collares Queiroz; Carmen Cecilia Tadini; Maria Aparecida Silva; Virginia Aparecida da Silva Moris; Kil Jin Park; Carlos Raimundo Ferreira Grosso

• Advisor: Theo Guenter Kieckbusch; Fernanda Paula Collares Queiroz

Abstract

Maltodextrins are water soluble oligossacharides produced by starch hydrolysis. Their functional characteristics depend on their molecular mass distributions which can be taylormade for specific applications through the control of the process conditions during hydrolysis. Maltodextrin are widely used as ingredient in instant food powder mixes and the knowledge of their reconstitution attributes would assist the development of new formulations. Commercial maltodextrins produced by three different Brazilian manufacturers with dextrose-equivalent (DE) degrees ranging from 5 to 20 were evaluated with respect to morphology, moisture content, molecular mass distribution, average particle diameter, bulk and true densities, void fraction, wetting and dissolution times, crystallinity degree, equilibrium isotherms and glass transition temperature (Tg). The maltodextrin powder showed distinct morphological features, which influenced their water reconstitution abilities. The products with moderate instant properties were submitted to a steam jet agglomeration process in a pilot plant instantiser in order to improve their technological qualities. The operational conditions were optimized by surface response methodology. The general trend indicated that the agglomerates morphology as well as their instant properties are influenced by the glass transition temperature. The DE10 maltodextrin agglomerates showed the best process yield and superior instant properties. The agglomerates of maltodextrin with the highest DE, which has the lowest Tg , showed the lowest yield and poor reconstitution properties. A complementary study, conducted in an Plexiglassÿ fluidized bed equipment using maltodextrin solutions as ligand, evaluated the formation of vitreous bridges between inert particles. The moisture content/temperature relations obtained supported the assumption that the agglomeration process is influenced by the molecular mass of the samples and, consequently, by their Tgs. These parameters should be considered in the design and /or operational conditions of agglomerators (AU)