Study On Grade Classification And Quality Standard Improvement Of Yam Pieces

As one of the representative plants for both medicine and food published by the Ministry of Health,yam has good market prospects due to its medicinal properties of"Ping Bu San Jiao".Yam is rich in a variety of chemical components such as protein,polysaccharides and allantoin.Nowadays,its market demand is increasing,but the quality of yam decoction pieces currently on the market is uneven.The quality of the decoction pieces will directly affect the clinical efficacy of traditional Chinese medicine.The research on the classification of yam decoction pieces will help ensure the high quality and good price of decoction pieces in the market.The inspection of the optimal harvest period can better regulate the yam’s harvesting link and provide guarantee for the improvement of the overall quality standard.This study combines traditional evaluation with modern physical and chemical evaluation,The traits and microstructure of yam decoction pieces were systematically studied by trait identification and optical microscopy.Thin-layer chromatography was used to identify thin-layer yam pieces from different sources.The moisture,ash,water-soluble extractives,and SO₂residues of yam pieces were measured according to the methods prescribed in the 2015 edition of the Chinese Pharmacopoeia.A method for determination of allantoin in yam and a characteristic map of yam pieces were established by high performance liquid chromatography.SPSS was used to analyze the correlation of the indicators,and the main classification indicators were selected for clustering,and the quality of the pieces was initially graded.Comprehensively examine and analyze the dynamic changes of the allantoin content in the yam and the change law of the drying rate of the medicinal parts to regulate the optimal harvest time of yam.The texture of yam pieces is crunchy,easy to break,and rich in powder.The cut surfaces are white or Yellowish white,with slight gas,light taste,slightly acid,and thickness ranging from 3 to 5mm;all contain ducts,starch granules,calcium oxalate needles and fibers structures;thin-layer chromatography bands are basically the same;the moisture range is between 8.23¹4.08%,which is lower than the pharmacopoeia limit and meets the standard;the total ash range is between 1.04².93%,and the acid-insoluble ash range is Between 0.06⁰.30%,the total ash content of samples S32 and S49 exceeded the Pharmacopoeia limit and did not meet the standard;the content of water-soluble extractives ranged from 5.19 to 11.57%,all of which met the Pharmacopoeia standard;the allantoin content range was 0.141⁰.869%;SO₂ residues still exist in a large proportion of yam pieces;in the establishment of HPLC fingerprint characteristics of yam pieces,5 common peaks were identified,and the overall similarity of 49 batches was above0.8,and the similarity evaluation was good;After analysis,the allantoin content was selected as the main grading index,and the average cluster-to-group clustering method is used to perform a systematic clustering analysis on all the sampled pieces.Based on the clustering results,49batches of yam pieces were divided into three grades（samples 7、10、35and 40 were classified as first grade,samples 1、3、13、19、23、33and 42 were classified as second grade and the rest all decoction pieces were classified as third grade）;the overall trend of the allantoin of the yam’s chemical component and the overall trend of the drying rate of the medicinal materials are basically the same,and it is finally confirmed that the best harvest time of yam is from late October to early November.