Rheological and swallowing properties of agar gel dispersed in paste

We investigated the rheological and swallowing properties of agar gel dispersed in xanthan gum, guar gum, starch paste and water for use in food products for the elderly. Texture measurement and dynamic elasticity were selected as indicators of rheological properties and subjective sensory evaluation was carried out using a 5-level rating method. The flow rate of a bolus in the pharynx was determined using ultrasonography after chewing for 5 and 30 times. The hardness of the agar gel dispersed in xanthan gum paste was the lowest of the samples tested and cohesiveness was the highest. Its rheological and swallowing properties and maximum flow rate were not affected by the mixing ratio in the paste or the amount of chewing. For agar gel dispersed in guar gum paste, the hardness and storage modulus (G') decreased with increasing amount of chewing, whereas the maximum flow rate increased. The hardness and G' of the agar get dispersed in starch paste decreased with increased chewing, but the maximum flow rate increased. On the other hand, the maximum flow rate and the hardness of the agar gel dispersed in water were the highest among all samples, even after chewing. According to subjective measurement, the hardness of all samples significantly decreased as the mixing ratio in the paste increased. The ease of swallowing the xanthan gum and guar gum mixtures was not influenced by the mixing ratio, and was similar for both. These results indicate that rheological and swallowing properties of the agar gel dispersed in xanthan gum paste were the least influenced by chewing and by the mixing ratio among the four kinds paste of paste.