Swallowing and the Rheological Properties of Soft Drink and Agar Gel

Mastication and swallowing are essential steps in food ingestion and nutrient absorption in humans. Mastication is the process in which food taken from the mouth is crushed and mixed with saliva in the oral cavity to create food boluses that are optimal for swallowing. The use of facial and jaw muscles, in addition to teeth, is necessary for mastication. Foods with gel-like texture are crushed by mastication, and the resulting boluses are transferred from the oral cavity to the pharynx with assistance from tongue pressure and then to the esophagus by suction generated upon elevation of the larynx. Bolus formation by mastication is closely associated with the swallowing process. Meanwhile, liquid foods are transferred from the oral cavity to the pharynx without mastication. However, the swallowing method of a drink changes by the additions included in the drink. It is important to know the relationship between physical property of drink and the linguapalatal swallowing pressure, the relationship between the preprandial food size and the nature of food bolus, and then the relationship between the texture property of the food bolus and the swallowing.