An objective classification of commercial thickened foods was studied for Korean elderly people with swallowing difficulty as based on rheological properties. A total of 16 commercial products (grain porridges, vegetable porridges, meat porridges, fish and shellfishes porridges, nut porridges) were measured using a stress-controlled rheometer with stainless steel plate-plate geometry and building material cell. Joint consideration has been made of viscous behavior (flow and thixotropy) and viscoelastic behavior (oscillatory testing). Rheological measurements were fitted to different rheological and empirical mathematical models, and a total of 11 parameters were generated. Based on these parameters and the use of fuzzy clustering and the c-means method, an objective classification of all the products was obtained. 16 commercial products were divided to 3 clusters. Each class has been defined from the parameters of the centroids generated by the classification method used - thus allowing us to know the common rheological characteristics of any of the products belonging to a given class. The results of this classification encourage further to develop of the new products for Korean elderly people.

The present paper proposes an categorization of commercial fluid products. A total of 21 commercial fluid products were analyzed(porridges, universal design foods, foods for special medical purposes) corresponding to 11 different commercial brands. Joint consideration has been made of viscous behavior (flow and thixotropy) and viscoelastic behavior (oscillatory testing). Rheological measurements were fitted to different rheological mathematical models, and a total of 4 parameters were generated. Our results correspond to three different classes. The three defined classes have been named in a way similar those most commonly used in the literature. Each class has been defined from the parameters allows us to know the common rheological characteristics of any of the products belonging to a given class.