ABSTRACT
ObjectiveBy exploring the volatile components， polysaccharide composition and changes in the contents of five carbohydrate components of Polygonatum cyrtonema rhizoma before and after processing， and then the effect of yellow rice wine on the odour formation of P. cyrtonema rhizoma was investigated. MethodThe volatile components of P. cyrtonema rhizoma before and after processing were detected by headspace gas chromatography-mass spectrometry（HS-GC-MS）， and sample data were subjected to principal component analysis（PCA） and orthogonal partial least squares-discriminant analysis（OPLS-DA） using SIMCA 14.1， then the differences between these components of P. cyrtonema rhizoma before and after processing were screened according to the principle of variable importance in the projection（VIP） value>1. Crude carbohydrate components in raw and wine-processed P. cyrtonema rhizoma were subjected to oxime and silylation， the carbohydrate components were analyzed by gas chromatography-mass spectrometry（GC-MS/MS）， and the relative contents of various components were calculated by peak area normalization， then quantitative analysis of four carbohydrate components was also carried out. ResultA total of 23 volatile components were identified from the raw products and the wine-processed products， including 15 components in raw products and 20 components in wine-processed products. Among them， 2-methylbutyraldehyde and isovaleraldehyde had a sweet odor and their contents increased after processing， but the contents of hexanal and caproic acid decreased， new components such as 2-acetylfuran and 5-methylfuranal were produced after processing. PCA and OPLS-DA results showed that there were significant differences between raw products and the wine-processed products， a total of 13 differential compounds were screened out， of which 7 showed an upward trend in relative content and 6 showed a downward trend. A total of 7 carbohydrate components， including 5 monosaccharides and 2 disaccharides， were identified in raw products and the wine-processed products. The results of determination showed that the contents of fructose， glucose， mannose and sucrose in P. cyrtonema rhizoma increased after wine-processing， and their increases were 4.54， 1.51， 2.93， 3.66 times， respectively. ConclusionAfter processing， the increase of aromatic flavor of P. cyrtonema rhizoma may be related to the increase of the contents of aldehydes such as 2-methylbutyraldehyde and isovaleraldehyde， while the decrease of raw flavor may be related to the decrease of the contents of volatile components such as hexanal and hexanoic acid， the increase of sweet flavor may be related to the increase of the contents of monosaccharides and oligosaccharides such as fructose and sucrose.
ABSTRACT
ObjectiveBy comparing the difference of volatile components of the decoction pieces before and after being processed by braising method of Jianchangbang and steaming method included in the 2020 edition of Chinese Pharmacopoeia， the influence of processing methods on the flavor formation of Polygoni Multiflori Radix （PMR） was compared. MethodHeadspace-gas chromatography-mass spectrometry （HS-GC-MS） was used to detect the volatile components of 30 batches of PMR samples from 3 origins with 3 processing methods. The GC was performed under programmed temperature （starting temperature of 40 ℃， rising to 150 ℃ at 5 ℃·min-1， and then rising to 195 ℃ at 10 ℃·min-1） with high purity helium as carrier gas and the split ratio of 10∶1. Mass spectrometry conditions were electron impact ion source （EI） and the detection range of m/z 50-650， the peak area normalization method was used to calculate the relative mass fraction of each component. The chromaticity values of different processed products were measured by a precision colorimeter， the relationship between chromaticity values and relative contents of volatile components was investigated by OriginPro 2021， principal component analysis （PCA） and orthogonal partial least squares-discriminant analysis （OPLS-DA） were performed on the sample data by SIMCA14.1. The differential components of different processed products of PMR were screened according to the principle of variable importance in the projection （VIP） value>1.5， and the material basis of different odor formation of PMR and its processed products was explored. ResultA total of 59 volatile components were identified， among which 34 were raw products， 33 were braised products， and 27 were steamed products. PCA and OPLS-DA results showed that there were significant differences between the three， but there was no significant difference between samples from different origins of the same processing method. Color parameters of a*， b*， E*ab had no significant correlation with contents of volatile components， while L* was negatively correlated with contents of 2-methyl-2-butenal， 2-methyltetrahydrofuran-3-one and 2，3-dihydro-3，5-dihydroxy-6-methyl-4（H）-pyran-4-one （P<0.05）. The contents of pungent odor components such as caproic acid， nonanoic acid and synthetic camphor decreased after processing， while the contents of sweet flavor components such as 2-methyl-2-butenal， furfural and 5-hydroxymethylfurfural increased after processing， and the contents of furfural， 5-methyl-2-furanmethanol， 5-hydroxymethylfurfural and other aroma components in the braised products were significantly higher than that in the steamed products. ConclusionHS-GC-MS can quickly identify the volatile substance basis that causes the different odors of PMR and its processed products. The effect of processing methods on the odor is greater than that of origin. There is a significant correlation between the color parameter of L* and contents of volatile components， the "raw" taste of PMR may be related to volatile components such as caproic acid， pelargonic acid and synthetic camphor， the "flavor" after processing may be related to the increase of the contents of 2-methyl-2-butenal， furfural， 5-hydroxymethylfurfural， methyl maltol and furfuryl alcohol.