Stability and rheology of corn oil-in-water emulsions containing maltodextrin Utai Klinkesorn a , Pairat Sophanodora a , Pavinee Chinachoti b , D.J. McClements b, * a Department of Food Technology, Faculty of Agro-Industry, Prince of Songkla University, Hat Yai, Songkhla 90112, Thailand b Department of Food Science, Chenoweth Laboratory, University of Massachusetts, Amherst, MA 01003, USA Received 14 April 2004; accepted 4 May 2004 Abstract The influence of maltodextrin concentration (0–35 wt%) and dextrose equivalent (DE ¼ 10–36) on the stability and rheology of 5 wt% corn oil-in-water emulsions stabilized by Tween 80 was studied. Creaming stability, mean droplet diameter, f-potential, and apparent shear viscosity of emulsions were measured. Rapid creaming was observed when the maltodextrin concentration exceeded a particular value, referred to as the critical flocculation concentration (CFC), which was attributed to depletion flocculation caused by the non-adsorbed maltodextrin. The CFC (wt%) decreased as the DE value of the maltodextrin decreased, i.e., as the molecular weight increased. Above the CFC, emulsions showed a small increase (<15%) in mean droplet diameter (d 43 ) after one week storage, which was attributed to enhanced coalescence of the flocculated droplets. The apparent viscosity of emulsions increased steeply when the maltodextrin concentration exceeded the CFC, and the emulsions exhibited distinct shear thining behavior. The results were interpreted in terms of the impact of maltodextrin on the strength of the colloidal interactions between the emulsion droplets. Addition of maltodextrins to emulsions can be used to create emulsions with different physicochemical and stability properties. Ó 2004 Elsevier Ltd. All rights reserved. Keywords: Maltodextrin; Nonionic surfactant; Oil-in-water emulsion; Critical flocculation concentration; Rheology 1. Introduction Maltodextrins and corn syrup solids are hydrolysis products of starch consisting of a-(1,4) linked D-glucose oligomers and/or polymers (Shahidi & Han, 1993). They may be hydrolyzed by acid, enzyme, or acid/enzyme combinations (Reineccius, 1991; Shahidi & Han, 1993). They differ in average molecular size and are classifiled on the basis of their dextrose equivalent (DE). Dextrose equivalent is a measure of the reducing power of starch- derived polysaccharide/oligosaccharides compared with D-glucose on a dry-weight basis (Wang & Wang, 2000). Normally, maltodextrins are defined as having a DE value <20, whereas corn syrup solids are defined as having a DE value P20 (Reineccius, 1991; Shahidi & Han, 1993). Nevertheless, in this paper the term ‘‘mal- todextrin’’ will be used to include both maltodextrins and corn syrup solids because they have similar prop- erties and applications in food emulsions. Maltodextrins with different DE values have different physicochemical properties, including solubility, freez- ing temperature, viscosity, etc. (Dokic, Jakovljevic, & Dokic-Baucal, 1998; Dokic-Baucal, Dokic, & Jakovlj- evic, 2004). However, maltodextrins with the same DE value may also have different properties depending on the hydrolysis procedure, source of starch (maize, po- tato, rice), and amylose to amylopectin ratio (Dokic- Baucal et al., 2004). Maltodextrins are widely used in food emulsions as stabilizers (Chronakis & Kasapis, 1995; Chronakis, 1997; Dokic-Baucal et al., 2004; Har- das, Danviriyakul, Foley, Nawar, & Chinachoti, 2000; Hogan, McNamee, O’Riordan, & O’Sullivan, 2001). A stabilizer can be defined as single or mixed chemical component that confers long-term stability on emul- sions. Stabilisers may operate by acting as emulsifiers or as texture modifiers (McClements, 1999). Emulsifiers are surface-active ingredients that adsorb to the surface of * Corresponding author. Tel.: +1-413-545-1019; fax: +1-413-545- 1262. E-mail address: mcclements@foodsci.umass.edu (D.J. McCle- ments). 0963-9969/$ - see front matter Ó 2004 Elsevier Ltd. All rights reserved. doi:10.1016/j.foodres.2004.05.001 Food Research International 37 (2004) 851–859 www.elsevier.com/locate/foodres