Impact of saliva secretion on bolus properties and swallowing during mastication of Stewed Pork with Brown Sauce

Twelve subjects chewed the fat layer and the lean layer of Stewed Pork with Brown Sauce, the boluses were collected at different stages of the mastication process, including the swallowing point. Chewing parameters and saliva added for each subject and food type during mastication were assessed, and the changes of bolus moisture content in different positions of Stewed Pork with Brown Sauce was analyzed contemporarily.Results showed that the chewing cycles for each subject and each food type increased significantly ( p < 0.05) , whereas the chewing frequency was stabilized respectively ( p > 0.05) .The saliva added for each subject and food style increased significant ( p < 0.05) , while the saliva flow decreased significantly ( p < 0.05) and tend to be stable. Moisture content of wet and dry basis in the boluses during oral processing increased significantly depending on the subject and food types studied ( p < 0.05) . At the same stage of mastication, the saliva added and the saliva flow for each subject chewing the fat layer of Stewed Pork with Brown Sauce were significantly lower compared to the lean layer ( p < 0.05) .Moisture content of wet and dry basis in the fat layer boluses tended to be lower significantly compared to the lean layer ( p < 0.05) . As a result of the difference of individual chewing behavior and saliva secretion, the difference on bolus moisture content on the point of swallowing between food types was significant ( p < 0.05) , while it was similar ( around 25% ~30% for the fat layer and 60% ~65% for the lean layer) .It was likely to be an important symbol on triggering a swallowing for the moisture content of food.