Rheology - Articles and news items
Issue 4 2014 • 2 September 2014 • Leonard M. C. Sagis and Elke Scholten, Physics and Physical Chemistry of Food, Wageningen University
The rheological properties of food products are very important in the production, preparation, and consumption of food. Rheological measurements are therefore a highly useful tool in the design of novel food concepts. Here we discuss the use of rheological techniques to develop and characterise pasta and noodle products, with high vegetable particle content (up to 30 per cent broccoli particles, based on dry matter). This product is aimed at young children, to increase their vegetable intake, and to contribute to a healthier diet that could prevent obesity problems at a later age. Rheological techniques such as viscometry, oscillatory shear rheometry, and extension tests were used to maximise the volume fraction of incorporated broccoli particles, while maintaining favourable sensory attributes. The result of this study was a product with a vegetable content far exceeding most pasta and noodle products currently on the market.
Issue 3 2014 • 23 June 2014 • Helen Joyner (Melito), School of Food Science, University of Idaho
Rheology is a powerful tool that can help link food physicochemical properties, structure, and sensory texture to form a cohesive, fundamental understanding of structural and physicochemical contributions to food texture. Yield stresses, fluid flow profiles, and fracture properties of firm solids are relatively easily determined with standard rheometry. However, there are still aspects of food texture that cannot be measured via standard rheological testing. Food texture in the later stages of mastication, when the food is being prepared for swallowing, shows poor correlation to mechanical measurements…
Issue 5 2013 • 4 November 2013 • Wolfgang Danzl, Head of Laboratory of Chocolate Technology, Fraunhofer IVV and Dr Gottfried Ziegleder, University of Applied Science
Chocolate can be described as a suspension consisting of non-fat particles (sugar, cocoa solids and milk powder particles) dispersed in cocoa butter and a portion of milk fat as a continuous phase. Its unique pleasant taste is produced by a complex interaction of odour-active volatile compounds, which are supplementary to the fine bitterness of cocoa and the sweetness of sugar. The characteristically pleasant mouth-feel is produced by the melting behaviour of cocoa butter, its flavour release and the rheological properties of the melting mass.
Issue 4 2013 • 28 August 2013 • Isabella Van Damme, Material Science Program Manager R&D, Mars Chocolate
Chocolate is adored by people around the world for its unique flavour and smooth, luxurious texture. It provides an indulgent pleasure with the added benefit that cocoa flavanols promote a range of health benefits. Is it possible to improve the nutritional profile of chocolate while still maintaining the quality aspects the consumer expects of good quality chocolate? The challenge to achieve this lies in being able to control the rheological properties of the new chocolate formulations.
Chocolate rheology describes and quantifies the flow and deformation properties of liquid chocolate. Viscosity, which is a measure of the resistance to flow, is the main rheological parameter used to describe chocolate and is an important quality control parameter. Although chocolate is eaten in the solid state, chocolate melts in the mouth as the body temperature is similar to the melting point of the fat in chocolate. It is the molten chocolate that covers the oral cavity and produces the smooth, luxurious mouth sensation and enables the release of flavours. The rheological properties of the liquid chocolate therefore play a role in the eating experience of chocolate, although several other aspects also impact on the complex processes that contribute to the eating experience1. The design of new products must take into account that any major changes to the chocolate viscosity will impact the chocolate perception. It is, however, in the manufacturing process that rheological properties play a critical role to enable the production of high quality products. The chocolate must be sufficiently fluid to be pumped and adopt the required form of the product achieved through a range of enrobing, moulding or spraying techniques. On the other hand, the chocolate must be retained on the product and maintain its required shape and decorations without showing defects.
Whitepaper: The importance of expanded rheology information and emulsifier functionality in chocolate production
Whitepapers • 31 July 2013 • By Jørgen Holdgaard, Confectionery Application Manager, Confectionery and Bakery Group, Palsgaard A/S.
Keeping rheology simple and accessible can cause problems in the daily production of chocolate due to lack of information.
Issue 2 2011 • 13 May 2011 • Bettina Wolf, Division of Food Sciences, School of Biosciences, University of Nottingham
Chocolate is a multiphase confectionary product which is consumed as a treat or in-between meals to overcome hunger. The popularity of chocolate is almost certainly due to its unique eating characteristics. It melts in the mouth, imparting a sensation of cooling. The surfaces of the oral cavity are coated by the melted chocolate and flavour is released. The intensity of each of the associated sensory attributes depends largely on the characteristics of the chocolate determined by type and concentration of the ingredients and the manufacturing process. The rheological properties of chocolate in its molten state (short referred to as chocolate in the following) are important to the eating quality and processing of chocolate.
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