RESUMO
ObjectiveOn the basis of sensory evaluation， the changes of volatile components in gecko before and after processing were compared， and the odor correction effect of different processing methods of gecko was discussed. MethodRaw products， fried yellow products， vinegar processed products， wine processed products， talcum powder scalding products and white wine sprayed products after scalding talcum powder of gecko were prepared， and 10 odor assessors were invited to evaluate the 6 samples in turn by sensory evaluation. Headspace solid-phase microextraction-gas chromatography-mass spectrometry （HS-SPME-GC-MS） and relative odor activity value （ROAV） were used to analyze the key odor components， and multivariate statistical methods were used to analyze the difference of volatile components between raw and processed products of gecko. Taking water-soluble extract and protein contents as internal indicators， sensory evaluation score and content ranking of differential components as external indicators， and assigning a weight of 0.25 to them respectively， the comprehensive scores of raw products and processed products of gecko were calculated to evaluate the odor correction effect of each processing method. ResultThe average sensory evaluation scores of the raw products， fried yellow products， vinegar processed products， wine processed products， talcum powder scalding products and white wine sprayed products after scalding talcum powder of gecko were 1.6， 5.2， 6.2， 6.1， 7.2 and 8.0， respectively. ROAV results showed that key components affecting odor of gecko were 2-ethyl-3，5-dimethylpyrazine， isovaleraldehyde， trimethylamine， 1-octen-3-ol， n-octanal， nonanal， 2-methylnaphthalene， γ-octanolide， 2-heptanone and phenol. Principal component analysis （PCA） significantly distinguished raw products from processed products. Orthogonal partial least squares-discriminant analysis （OPLS-DA） results showed that there were 16， 13， 16， 16， 16 differential components between raw products， fried yellow products， vinegar processed products， wine processed products， talcum powder scalding products and white wine sprayed products after scalding talcum powder of gecko. Among these differential components， there were 4 common components， namely， the contents of different odor components （2-methylnaphthalene and 2-ethyl-p-xylene） decreased， while the contents of different flavor components （2-decanone and 2，3，5-trimethylpyrazine） increased. The comprehensive scoring results showed that the odor correction effect of each processed products was in the order of talcum powder scalding products>wine processed products>vinegar processed products>fried yellow products>white wine sprayed products after scalding talcum powder. ConclusionTalcum powder scalding is a better method to improve the odor of gecko， and it can provide an experimental basis for the processing of gecko to correct the odor.
RESUMO
ObjectiveTo analyze the quality changes of Platycladi Semen before and after the deterioration of moth-eaten and rancidity during storage. MethodFour types samples of Platycladi Semen， including normal， moth-eaten， oxidative rancidity and hydrolytic rancidity， were determined for volatile components， odor， and taste based on headspace solid phase microextraction/gas chromatography-mass spectrometry （HS-SPME/GC-MS） and electronic sensory techniques such as electronic nose and electronic tongue. Volatile components were identified by searching the database and manual comparison， the odor and taste were determined by the response values of the electronic nose and electronic tongue sensors， and the difference between samples before and after deterioration was studied by multivariate statistical analysis. ResultA total of 85 compounds were identified in Platycladi Semen samples. Compared with the normal samples， the number of volatile compounds in samples after hydrolytic rancidity decreased by 5， the number of volatile compounds in samples after moth-eaten and oxidative rancidity increased by 1 and 21， respectively. Aldehydes and acids accounted for majority of types. Among them， the contents of N-hexanoic acid， hexanal and propionic acid in the samples of oxidative rancidity reached 11.49%， 10.21% and 7.52%， which became the key indicators of rancidity. There was significant variance among the odor components corresponding to W1W， W2W and W1S sensors by electronic nose analysis. It was indicated that the value of sourness in deteriorated samples generally increased by mean of electronic tongue analysis. Compared with normal samples， the moth-eaten samples had changed slightly and rancidity samples had changed significantly especially oxidative rancidity samples of volatile components， odor and taste by multivariate statistical analysis. ConclusionIn terms of Platycladi Semen， the oxidative rancidity caused by nature storage for 12 months has the greatest impact on the quality. Therefore， it should be mainly to prevent oxidative rancidity to ensure the quality of Platycladi Semen.
RESUMO
Headspace-solid phase microextraction/gas chromatography-mass spectrometry (HS-SPME/GC-MS) were used to analyze the interaction between the β-lactoglobulin (β-LG) and the botany volatile organic compounds (BVOCs) from pomelo peel to screen out the pharmacodynamic active BVOCs substance group. The selective binding effect between β-LG and BVOCs was analyzed by quantitative recovery of BVOCs, and the binding parameters were calculated. Then, the molecular model of BVOCs binding with β-LG was established by molecular docking and spectroscopic method, and the molecular mechanism of interaction between pharmacodynamic active BVOCs and β-LG was discussed from the perspective of omics. The results showed that dipentene (Dt), linalylacetate (La) and nootkatone (Nt) of BVOCs were selected by HS-SPME/GC-MS by the interaction of β-LG and BVOCs substance group. Parameter calculation showed that β-LG had the strongest affinity with Nt, but the binding force was not strong, and the affinity for La was the weakest. The affinity of β-LG to Dt was weak, but the binding force was the strongest, with a binding rate of 54. 66%, indicating that the selective binding strength of β-LG with the pharmacodynamic active BVOCs depended on the chemical structure of BVOCs molecules. The β-LG preferred to bind to the aldehyde and ketone BVOCs molecules containing carbonyl oxygen structure. The molecular model of β-LG and BVOCs group (Dt, La, Nt) was established to evaluate the binding position of BVOCs group (Dt, La, Nt) on β-LG. The loosening, extension and conformational change of β-LG secondary structure caused by the introduction of BVOCs are the result of van der Waals force, hydro-phobicity and hydrogen bonding. This study provides a new method for screening pharmacodynamic active BVOCs from the perspective of whole substance group of BVOCs, and provides a useful reference for investigating the binding mechanism between pharmacodynamic active BVOCs and functional protein molecules from the perspective of omics.