Abstract: The effect of the traditional processing method of nine steaming-sun drying cycles on the contents of polysaccharides and irritant components (saponins, calcium oxalate, and n-hexanal) in Polygonatum kingianum Collett & Hemsl. By integrating chemical analysis, microscopic observation, and sensory evaluation, the study explored the pattern of compositional changes and its intrinsic link with the reduction of irritation. The results showed that the polysaccharide content decreased overall with increasing steaming-sun drying cycles, with a 70% reduction after nine steaming-sun drying cycles compared with the raw material. The saponin content showed a unimodal curve of first increasing and then decreasing, reaching its peak (46.78 mg/g) after three cycles. The calcium oxalate content was highly positively correlated with the sensory irritation (r = 0.94). Its acicular morphology gradually became blunted and eroded with increasing processing cycles, and its content continued to decline. With respect to volatile components, the content of n-hexanal sharply decreased after the first cycle (by more than 90%), the contents of aldehydes decreased in general, and the contents of acids and ketones increased. Time-intensity sensory evaluation indicated that the irritation of the raw material reached its peak within 30 seconds, while the sensory irritation of the sample subjected to six steaming-sun drying cycles basically disappeared within 120 seconds. Principal component analysis (PCA) showed that acicular calcium oxalate crystals were the major contributor to the irritation. Through correlation analysis, a comprehensive evaluation index for the removal of the irritation of P. kingianum Collett & Hemsl. was established: R/% =[1 − (0.272 × saponin content + 0.465 × calcium oxalate content + 0.262 × n-hexanal content)] × 100. This index can effectively quantify the removal of irritant components during the processing of P. kingianum Collett & Hemsl and has great practical application value.

Key words: Polygonatum; nine steaming-sun drying cycles; polysaccharides; irritant components; comprehensive assessment index