Thickness suitability of prebiotic dairy desserts: Relationship with rheological properties P.L. Arcia a,b , E. Costell a , A. Tárrega a, ⁎ a Physical and Sensory Properties Laboratory, Instituto de Agroquímica y Tecnología de Alimentos, CSIC. P.O. Box 73, 46100 Burjassot (Valencia), Spain b Laboratorio Tecnológico del Uruguay, Av. Italia 6201, C.P. 11500, Montevideo, Uruguay abstract article info Article history: Received 18 May 2010 Accepted 16 September 2010 Available online xxxx Keywords: Inulin Rheology Adequacy of thickness JAR In food product development it is important to know to what extent changes in formulation modifies the product, affecting its sensory properties and acceptability. Addition of polysaccharides like inulin can affect product structure in particular, modifying both rheological behaviour and perceived texture. The aim of this work was to assess to what extent rheological properties can explain the acceptability of thickness perceived by consumers in starch-based desserts. Low-fat dairy desserts were prepared varying the concentration of sucrose, flavor aroma and the fat replacer with prebiotic properties (inulin) but with fixed amounts of skimmed milk and starch. The rheological behavior was characterized and the level of sample thickness suitability was evaluated by a total of 100 consumers using a 5-point JAR scale (1 = too weak, 3 = just about right; 5 = too strong). Results indicated that flow and viscoelastic parameters varied among samples depending on inulin and sucrose concentration. According to sensory results, thickness suitability varied greatly between samples. The relationships between instrumental and sensory results are studied and discussed. © 2010 Elsevier Ltd. All rights reserved. 1. Introduction Functional product development provides an opportunity to contribute to the improvement of food quality and consumer health and well-being (Hasler, 1998; Milner, 1999). A common approach employed in the food industry to develop these kinds of added-value foods involves the addition of a healthy component. It is important to know to what extent this new component modifies the product, affecting its sensory properties. In the case of macromolecules such as polysaccharides or proteins, changes in composition can affect product structure in particular, modifying both rheological behaviour and perceived texture (Dickinson, 2007; Purwanti, van der Goot, Boom, & Vereijken, 2010). For liquid and semisolid products, thickness is the textural attribute that most influences consumer response, though smoothness and creaminess are also influential (de Wijk, van Gemert, Terpstra, & Wilkinson, 2003; González-Tomás & Costell, 2006). In semisolid products with complex rheological behaviour (thixotropy, pseudoplas- ticity and viscoelasticity), studies aimed at identifying the physical stimuli responsible for thickness perception have proposed different indexes (Van Vliet, 2002). The initial resistance to flow (yield stress value), storage modulus at 1 Hz (Tárrega & Costell, 2007) and the complex viscosity at 50 rad s −1 (Hill, Mitchell, & Sherman, 1995; Richardson, Morris, Ross-Murphy, Taylor, & Dea, 1989) have shown significant correlations with thickness intensity. However one must recognize that acceptability may not always be directly related with sensory attribute intensity but rather with its adequacy (Costell, Tárrega, & Bayarri, 2010). Traditionally, perceptible differences in food attributes are evaluated using sensory descriptive analysis by trained judges while hedonic aspects are evaluated separately by consumers. JAR scale is an alternative method that combines both intensity attribute and hedonics assessed by consumers (Gacula, Rutenbeck, Pollack, Resurreccion, & Moskowitz, 2007). This technique provides information on how consumers feel about the product attribute and then determines both the adequate attribute level for this product and how much a sample deviates from this ideal point. Inulin is a very interesting functional ingredient that is increasingly being used to formulate new fibre-enriched products or with prebiotic benefits (Roberfroid, 2007). Chemically it is a polymer of fructose units that can have different chain lengths. Long-chain inulin can modify texture because it crystallises in presence of water forming a particle network structure (Chiavaro, Vittadini, & Corradini, 2007; Hébette et al., 1998). Consequently it is being used in low-fat products to improve creaminess and consistency, mimicking those of full-fat products (González-Tomás, Bayarri, Coll-Marqués & Costell, 2009; Paseephol, Small & Sherkat, 2008; Soukoulis, Lebesi, & Tzia, 2009; Tárrega & Costell, 2006). Nutritional studies have recommended the combination of inulin with different chain lengths in order to maximise its fermentative and prebiotic effects (Biedrzycka & Bielecka, 2004; Coudray, Tressol, Gueux, & Rayssiguier, 2003). From a technological viewpoint the use of mixed- chain inulin, instead of only long-chain inulin, may decrease its thickening ability. Tárrega, Rocafull, and Costell (2010) showed that Food Research International xxx (2010) xxx–xxx ⁎ Corresponding author. Tel.: + 34 96 3900022; fax: + 34 96 3636301. E-mail address: atarrega@iata.csic.es (A. Tárrega). FRIN-03304; No of Pages 8 0963-9969/$ – see front matter © 2010 Elsevier Ltd. All rights reserved. doi:10.1016/j.foodres.2010.09.013 Contents lists available at ScienceDirect Food Research International journal homepage: www.elsevier.com/locate/foodres Please cite this article as: Arcia, P.L., et al., Thickness suitability of prebiotic dairy desserts: Relationship with rheological properties, Food Research International (2010), doi:10.1016/j.foodres.2010.09.013