Correlation Analysis and Modeling of Salivary Flow Rate and Spicy Sensory Intensity Grading

The aim of this study was to investigate the correlation between spiciness and saliva flow rate by measuring the saliva flow rate of subjects after consuming different concentrations of capsaicin solutions, and to establish a rapid method for determining the spiciness of foods. The physiological change caused by the increasing of saliva secretion after eating spicy food was used as the influential indicators of spicy taste intensity. The salivary flow rate was calculated by the salivary secretion of the subjects, and the relationship between the spicy intensity and salivary flow rate was fitted. Based on the fitting model, a new grading system for rapid and accurate calibration of spiciness was constructed, and the model grading results were verified by sensory evaluation method. The results showed that the intensity of spiciness significantly affects salivary flow rate (P<0.05), and the spiciness could be accurately and quickly graded by salivary flow rate. According to the salivary flow rate range, the spiciness was classified into 5 levels according to the salivary flow rate range: Grade 1 slightly spicy Scoville heat units (SHU)10~500 (inclusive): Saliva flow rate (g/min) 0.496~1.395 (inclusive). Grade 2 light spicy SHU500~1000 (inclusive): Saliva flow rate (g/min) 1.395~2.153 (inclusive). Grade 3 medium spicy SHU1000~1500 (inclusive): Saliva flow rate (g/min) 2.153~2.749 (inclusive). Grade 4 heavy spicy SHU1500~3000 (inclusive): Saliva flow rate (g/min) 2.749~3.569 (inclusive). Grade 5 hot (SHU>3000): Saliva flow rate (g/min)>3.569. By collecting the saliva secretion of 5~10 people after eating spicy food, the spiciness of the food tasted by the testers could be rated quickly by combining the quantitative relationship between spicy taste intensity and saliva flow rate. The saliva flow rate spiciness rating result was in the same spicy taste measurement level as the sensory rating result, which could basically reflect the real spiciness feeling of people after eating spicy food.