| Sichuan tallow hotpot has attracted wide attention because of its unique flavor.As an indispensable raw material of Sichuan tallow hotpot,chili pepper has made outstanding contributions to the formation of the overall flavor.China is one of the largest chili producers in the world.Due to the rich varieties and different flavors of chili plants,there are significant differences in their impact on the flavor of tallow.At present,the research on its flavor still mainly remains in the level of volatile substances and aroma profile,while the research on its characteristic aroma properties,key aroma compounds,especially their types,sources and formation mechanism,is relatively scarce.In addition,the regulation of chili pepper on tallow flavor during processing needs to be further studied.Therefore,based on molecular sensory science,combined with instrument analysis,sensory evaluation and other modern flavor chemistry methods,this paper systematically analyzed and compared the flavor characteristics of Sichuan tallow hotpot made from different cultivars of chili pepper,analyzes the composition of key flavor substances and their formation mechanism,explores the regulation of frying process on key flavor substances,and realizes the maximization of chili pepper on tallow flavor.The main contents are as follows:Firstly,the total capsaicinoid(including ccapsaicin and dihydrocapsaicin)contents and flavor characteristics of Sichuan tallow hotpot prepared from 20 representative chili peppers in China were systematically analyzed by high performance liquid chromatography(HPLC),gas chromatography-mass spectrometry(GC-MS),headspace solid phase microextraction(HS-SPME),quantitative description sensory evaluation(QDA)and principal component analysis(PCA).The results showed that the capsaicinoids content(0.02 mg/g-1.54 mg/g)and pungency(311.93 SHU-23690.97 SHU)of tallow hotpot prepared by different varieties of chili pepper were significantly different(p<0.05).Six odor attributes were obtained by quantitative description of sensory evaluation,and the sensory scores of 20 kinds of tallow hotpot were significantly different(p<0.05).The overall flavor of the XYD tallow hotpot was the best,reaching 42.2 points.A total of 73 volatile compounds were identified,including 18 aldehydes,7 alkenes,11 alcohols,13 esters,8 ketones,7 acids,6 nitrogen-containing compounds and 3 other compounds.Pearson correlation analysis showed that there was a certain correlation between volatile compounds and sensory analysis.Principal component analysis showed that 20 kinds of tallow hotpot were divided into 4 groups.Secondly,in view of the unknown key aroma compounds of Sichuan tallow hotpot,the key aroma compounds of four representative tallow hotpots were analyzed by molecular sensory science methods,including gas chromatography-mass spectrometer-olfactometer(GC-O-MS)combined with HS-SPME,aroma extract dilution analysis(AEDA)and recombination experiment.The results showed that 15 flavor active compounds were identified from 4 kinds of tallow hotpot,including 7 aldehydes,2 ketones,2 alkenes,2 acids,1 alcohol and 1 nitrogenous compound.Among them,XYD tallow hotpot has detected 13 kinds,TYJ has detected 11 kinds,HJ has detected 12 kinds,and SSL has detected 7 kinds.The highest dilution factor is 32,including(E)-2-nonenal,(E)-2-decennial,(E,E)-2,4-decadienal,β-ionone,furanone,caryophyllene,anisole,linalool,and acetic acid.The key aroma compounds were obtained by OAV calculation,including nonanal,(E)-2-octenal,(E)-2-nonenal,(E)-2-decenal,(E)-2-undecenenal,(E,E)-2,4-decadienal,5-methylfuranal,β-ionone,furaneol,caryophyllene,anethole,linalool,and acetic acid.The reconstitution experiment showed that the aroma profile of the reconstituted sample was well consistent with that of the original sample,which verified the above key aroma compounds and proved the successful identification and quantitation of the key aroma compounds.Finally,aiming at the problem that the frying process has great influence on the flavor and the mechanism is still unclear,the effects and changes of frying temperature and time on the flavor and key aroma compounds of the XYD tallow hotpot were studied by using the single factor variable method.GC-MS and sensory evaluation were also performed.The results showed that the frying temperature and time had a significant effect on the content of key aroma compounds in the tallow hotpot(p<0.05).The concentrations of nonanal,(E)-2-octenal,(E)-2-nonenal,(E)-2-decenal,furaneol,caryophyllene,anethole,and linalool showed a trend of rising first and then falling with the increase of frying temperature and time.While the concentrations of(E,E)-2,4-decadienal,(E)-2-undecenenal,β-ionone and acetic acid showed a arising trend.According to the sensory evaluation,the content of key aroma compounds in the XYD tallow hotpot was higher and the overall flavor was the best when frying at 160℃ for 16 minutes.In summary,this study has confirmed the differences of the flavor and volatile substances of the tallow hotpot made from different cultivars of chili pepper.It was identified the key aroma compounds,including nonanal,(E)-2-octenal,(E)-2-nonenal,(E)-2-decenal,(E)-2-undecenenal,(E,E)-2,4-decadienal,5-methylfuranal,β-ionone,furaneol,caryophyllene,anethole,linalool,and acetic acid.It was revealed the regulation of cooking temperature and time on the key flavor in the tallow hotpot processing.This article provides a basis for the production and analysis of flavor-oriented hotpot products. |
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