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توضیحات :
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مشخصات این مقاله :
عنوان مقاله :
Influence of some bulk sweeteners on rheological properties of chocolate
ترجمه فارسی عنوان :
تاثیر برخی از شیرین کننده های رژیمی بر خواص رئولوژیکی شکلات
سال انتشار : 2006
متعلق به مجله یا ژورنال : سبک وزنی (LWT)
فرمت: PDF
تعداد صفحات: 6
شماره پروژه: 5004
کلمات کلیدی :
Chocolate, Rheology, Viscosity, Bulk sweeteners, Particle size
شکلات. رئولوژی، چسبندگى، شیرین کننده های رژیمی، اندازه ذرات
چکیده :
Abstract
Chocolates with reduced calories have become popular among consumers and manufacturers. One way of manufacturing chocolate with reduced calories is to replace sucrose with some alternatives. Effects of different bulk sweeteners (maltitol, isomalt, and xylitol) with different particle size intervals (PSI) (106–53, 53–38 and 38–20 mm) on rheological properties of molten chocolate were investigated. The best model that fit the rheological data was Herschel–Bulkley model. Maltitol resulted in similar rheological properties of chocolate compared to sucrose and thus can be a good alternative. Isomalt resulted in higher plastic viscosity while maltitol resulted in higher yield stress than others. As the particle size increased the plastic viscosity and the yield stress increased. The differences in rheological properties of chocolate with different bulk sweeteners were caused by differences in solid volume fraction and particle size distribution (PSD). A substitute with large particle size should be chosen to replace sucrose for improving rheological properties of chocolate, but the particle size should be small enough to obtain good sensory properties.
مقدمه این مقاله :
Introduction
Molten chocolate is a dense suspension consisting of nonfat particles (sucrose, cocoa, milk) dispersed in cocoa butter as a continuous phase (Chevalley, 1975). Determination of rheological properties of chocolate is important in manufacturing process for obtaining high-quality products with well-defined texture (Servais, Ranc, & Roberts, 2004). Factors such as fat content, particle size distribution (PSD), moisture ontent, emulsifiers,conching time, and temperature affect rheological properties and the production cost (Tscheuschner & Wu¨ nsche, 1979). Flow of molten chocolate is non-Newtonian with an apparent yield stress, and can be described by a number of mathematical models including Bingham, Herschel–Bulkley, and Casson models (Chevalley, 1999; Servais et al., 2004). The International Office of Cocoa, Chocolate and Sugar Confectionery (IOCCC), National Confectioners Association (NCA) and Confectioners Manufacturing Association (CMA) accepted rheological measurement of chocolate in a shear rate range of 5–60 s1 using rotational viscometers with concentric cylinders (bob and cup), and Casson equation for calculation of rheological parameters (Bouzas & Brown, 1995).
Increasing solid concentration results in higher viscosity as shown by Servais, Jones, and Roberts (2002). High solid content, interactions of the suspended particles and their interfacial properties affect rheological properties of chocolate (Bouzas & Brown, 1995). Viscosity of suspensions can be greatly modified by changing PSD while maintaining the same solid content (Chevalley, 1975). Smaller particle sizes in chocolate are known to improve sensory properties (Ziegler, Mongia, & Hollender, 2001) but plastic viscosity and yield stress increase due to increased surface area of particles in contact with cocoa butter (Mongia & Ziegler, 2000). The optimum average sugar particle size in chocolate is 30–33 mm with a maximum of 50 mm in the US and 20–23 mm with a maximum of 35–40 mm in Europe (Jeffery, 1993). Optimum particle size is restricted by sensory attributes. It has been reported that chocolate was acceptable if the proportion of particles above 22 mm were less than 20% (Chevalley, 1975). Chocolate with particle size above 35 mm becomes gritty or coarse in the mouth resulting in lower acceptability (Servais et al., 2002).
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