Comparing Carboxymethyl Cellulose and Starch as Thickeners in Oil/Water Emulsions. Implications on Rheological and Struc
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ORIGINAL ARTICLE
Comparing Carboxymethyl Cellulose and Starch as Thickeners in Oil/Water Emulsions. Implications on Rheological and Structural Properties Carla Arancibia & Sara Bayarri & Elvira Costell
Received: 15 January 2013 / Accepted: 21 February 2013 / Published online: 7 March 2013 # Springer Science+Business Media New York 2013
Abstract The study reported here aims to obtain information on how thickener type and concentration, and oil content influence rheology, particle size, particle charge and microstructure in o/w model emulsions. Emulsions were prepared at two oil concentrations (5 and 30 % wt/wt), each with three CMC concentrations (0.2, 0.3, and 0.4 % wt/wt), or three starch concentrations (2, 3, and 4 % wt/wt). For each oil concentration, a sample without any added thickener was prepared as reference. Both CMC and swollen starch granules showed a dominating effect on emulsion flow behavior, although the presence and concentration of fat droplets also played an important role. Viscoelasticity of CMC-based emulsions mainly depended of oil concentration whilst in starchbased emulsions the most influential ingredient was starch. A similar situation was detected in terms of particle size distribution; CMC effect was dependent on oil content and starch effect was mainly related to the volume occupied by swollen granules. Differences in microstructure and particle size distribution between CMC and starch emulsions were related to their rheological behavior. Apart from enabling the acquisition of food emulsions with different composition but with similar rheological behavior by adding different hydrocolloids, here we consider thickener effect on other properties in order to obtain food emulsions with adequate characteristics. Keywords Food emulsion . Carboxymethyl cellulose . Starch . Rheology . Particle characteristics . Microstructure
C. Arancibia : S. Bayarri : E. Costell (*) Instituto de Agroquímica y Tecnología de Alimentos (CSIC), Avenida Agustín Escardino 7, 46980 Paterna, Valencia, Spain e-mail: [email protected]
Introduction Basically, food emulsions are the result of a homogenization process applied to two immiscible liquids, usually oil and water, to obtain a biphasic system with the fat droplets dispersed in an aqueous phase (oil-in-water emulsions) or with water droplets dispersed in an oil phase (water-in-oil emulsions). Stability and physicochemical and sensory properties of emulsion-based food products are strongly influenced by concentration and characteristics of the droplets that they contain [1–4] and also by the effects of other food ingredients and the interactions among them [5–8]. Due to the practical interest in obtaining food emulsions that remain stable during a determined time period, the identification and description of different instability mechanisms and different ways to assess and control emulsions have been the objective of numerous studies during recent years [9–11]. Selecting the process conditions [12, 13] and the type and concentration of emulsifier and/or stabi
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