| Traditional Chinese medicine has a history of thousands of years of application in my country and is an important part of traditional Chinese medicine.The quality of traditional Chinese medicines is the premise to ensure the safety and effectiveness of clinical application of traditional Chinese medicines,while factors such as base source,origin,processing and storage of traditional Chinese medicines increase the difficulty of evaluating the quality of traditional Chinese medicines.The early quality evaluation methods of traditional Chinese medicine were mainly based on sensory evaluation through the identification of traits(appearance shape,color,smell,etc.);With the development of modern technology,the chemical composition of traditional Chinese medicine was analyzed with the help of modern instrument analysis techniques and chemical pattern recognition methods were used to construct chemical evaluation model of traditional Chinese medicine quality,which is helpful to ensure the safety and effectiveness of clinical use of traditional Chinese medicine.Armeniacae Semen Amarum,(bitter almonds)are dry mature seeds of Rosaceae plants Prunus armeniaca L.var.ansu Maxim.,Siberian apricot Prunus sibirica L.,Northeast apricot Prunus mandshurica(Maxim.)Koehne or apricot Prunus armeniaca L.It has the effect of lowering gas,relieving cough and asthma,and laxative.In this study,the chemical quality of bitter almond was systematically studied from four perspectives: appearance,preparation,odor and storage,with the aim of providing a scientific basis for quality control of bitter almonds.The main research contents are as follows.1.Based on HPLC fingerprint and chemical pattern recognition,the relationship between appearance traits and internal quality of bitter almond was established.The HPLC fingerprint of bitter almond was established and the similarity was evaluated.Based on chromatographic data,unsupervised hierarchical cluster analysis(HCA)and principal component analysis(PCA)models were established for exploratory classification of 31 batches of bitter almonds.In the two models,the samples were automatically clustered into two categories,that is,Class 1 samples were larger than Class 2 samples.Based on the above exploratory classification results,a supervised partial least squares discriminant analysis model(PLS-DA)was established,and the corresponding chemical markers(amygdalin,prunasin and variable 1)were obtained;Taking the chemical markers as variables,the PLS-DA model was reconstructed to further verify the rationality of the chemical markers;Finally,by measuring the content of amygdalin and the appearance trait indices(single kernel weight,length,width,and thickness and kernel shape index)of the two classes of samples,the relationship between the appearance traits and the internal chemical quality of bitter almond was successfully established,that is,bitter almonds that were heavier and larger with long oval shape had better quality.2.Based on HPLC fingerprint and chemical pattern recognition method,this experiment comprehensively compared and analyzed bitter almond and its five processed products(scalded bitter almond,fried bitter almond,honey fried bitter almond,bran fried bitter almond and bitter almond cream).The HPLC fingerprints of bitter almond and its processed products were established and evaluated for similarity,and the bitter almond and its processed products were preliminarily classified.Using cluster heatmap analysis and PCA model,the exploratory cluster analysis of bitter almond and its processed products was carried out.Based on the classification results,the PLS-DA model was established,and the corresponding chemical markers(prunasin,5-hydroxymethylfurfural,amygdalin,variable 2,variable 6 and variable 3)were obtained;By comparing the content,degradation rate and enzyme activity of amygdalin in different processed products,it was found that different processing methods can reduce the content of amygdalin in different degrees(except bitter almond cream),reduce the enzyme activity and reduce the degradation of amygdalin,achieve the purpose of "killing enzymes and protecting glycosides",and explore the material basis of amygdalin processing from the perspective of chemical composition.3.Based on the ultrafast gas-phase electronic nose combined with chemical pattern recognition method,the odors of bitter almond and its five kinds of processed products(scalded bitter almond,fried bitter almond,honey fried bitter almond,bran fried bitter almond and bitter almond cream)were distinguished and identified.The PCA model was used to conduct exploratory cluster analysis on bitter almond and its processed products.Based on the classification results,a soft independent modeling of class analogy(SIMCA)model and a discriminant factor analysis(DFA)model were established.The SIMCA model can distinguish between raw and processed products.The DFA model can distinguish the smell of bitter almonds and different processed products;a total of 37 odor components of bitter almonds were identified through the Aro Chem Base database,and the changes in the relative content of volatile components in different processed products were analyzed visually by using an intuitive heat map;The relative odor activity value(ROAV)obtained the changes of key flavor components before and after processing,which made the odor information objective and standardized,and explored the material basis of bitter almond processing from the perspective of odor components.4.In this experiment,long-term and accelerated experiments were established to explore the changes of physical and chemical indexes(acid value,peroxide value,amygdalin and related fatty acids)of bitter almond and four processed products(scalded bitter almond,fried bitter almond,honey fried bitter almond,and bran fried bitter almond)during storage.Taking the above physical and chemical indexes as variables,the PCA and PLS-DA models of bitter almond and processed products are established,which can distinguish raw products from other processed products.The results of long-term experiment and accelerated experiment showed that the acid value and peroxide value of raw and processed products gradually increased,the content of amygdalin and fatty acid gradually decreased,and the change of each index in processed products was lower than that of raw products.After 28 days of acceleration,the content of amygdalin in raw products did not meet the requirements,and oil deterioration had occurred.The research shows that bitter almond should be stored in low temperature and dry environment,and should not be stored for a long time.Processing can improve its antioxidant capacity,slow down the degree of oil deterioration,and prolong its storage time.In this thesis,HPLC,FGC E-Nose and other analytical techniques combined with chemical pattern recognition methods were used to carry out relevant research from the four aspects of appearance,processing,odor and storage of bitter almond,establish unsupervised and supervised recognition models,and obtain the corresponding chemical markers,so as to provide new research ideas and methods for the quality control and evaluation of bitter almond. |
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