Current Opinion in Colloid & Interface Science xxx (2010) xxx–xxx
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Current Opinion in Colloid & Interface Science
j o u r n a l h o m e p a g e : w w w. e l s e v i e r. c o m / l o c a t e / c o c i s
Rheology of food materials
Peter Fischer ⁎, Erich J. Windhab
Institute of Food, Nutrition and Health, ETHZurich, 8092 Zurich, Switzerland
a r t i c l e
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a b s t r a c t
Food rheology focuses on the ﬂow properties of individual food components, which might already exhibit a complex rheological response function, the ﬂow of a composite food matrix, and the inﬂuence of processing on the food structure and its properties. For processed food the composition and the addition of ingredients toobtain a certain food quality and product performance requires profound rheological understanding of individual ingredients their relation to food processing, and their ﬁnal perception. © 2010 Elsevier Ltd. All rights reserved.
Article history: Received 12 July 2010 Accepted 13 July 2010 Available online xxxx Keywords: Rheology Suspensions Emulsions Foams Microstructure Flow geometriesTribology Squeeze ﬂow Interfacial rheology Soft glasses
1. Introduction Global challenges in food science are the sustainable and safe access to clean water and supply of sufﬁcient energy sources, i.e. food based on fats, proteins, and carbohydrates for high quality human nutrition. In this context food quality is mostly deﬁned by sensorial characteristics and consumer-driven preferences selecting theconvenience level as well as health supporting properties of the chosen food. Depending on the socio-economical and nutritional background of the consumer, individual diets might be different but will be, in particular in the socalled Western Diet, based on food products that are partially or entirely processed. The resulting decomposition and subsequent re-composition of food materials allows usto design food according to nutritional guidelines and to add ingredients for enhancing the nutritional beneﬁts of the ﬁnal product (e.g. fortiﬁcation with micronutrients). The newly tailored or designed food might be stabilized by the same mechanism as the original food components, but removed or added components will need additional stabilizing methods. It is not surprising that along with theemergence of processed foods, food science has devoted signiﬁcant research to the role of individual ingredients, in particular to stabilizing agents. Journals focusing on food hydrocolloids, carbohydrate biopolymers, or food hydrocarbons and on interactions of ingredients with the food matrix were established in the 1980 s, while research on noncomposed food such as starch-based productsnucleated journals
⁎ Corresponding author. E-mail address: peter.ﬁscher@ilw.agrl.ethz.ch (P. Fischer). 1359-0294/$ – see front matter © 2010 Elsevier Ltd. All rights reserved. doi:10.1016/j.cocis.2010.07.003
already in the early 1950 s. Food processing heavily relies on complex ﬂow processes. Therefore, rheological characterization of the individual ingredients as well as the composed food productfound on supermarket shelves is an integral part of food science. Rheological research in food science is therefore closely linked to the development of food products and could address the industrial production of food (stirring, pumping, dosing, dispersing, spraying), home based cooking as well as consumption of food (oral perception, digestion, well-being). Properties of processed food productsare increasingly tailored to meet consumers' requirements and beneﬁts. Tailored product properties are designed along structure–property and process– structure guidelines, considering structure from the molecular to the macroscopic scales and its consequences on processing and perception. Rheology comes into play in the context of structure as one of its most prominent dynamic properties. The...