| Yunnan white tea has received a lot of attention in the market in recent years.Yunnan white tea is usually processed using Yunnan big leaf kind of tea species,and due to the richness of its fresh leaves,its processed white tea presents unique flavour and efficacy,but little research has been reported on its processing cultivars and processes.In this study,Yunnan big leaf kind of tea and C.sinensis cv.Fuding-dabaicha were selected for processing white tea,and their sensory quality,biochemical and volatile components were analysed.The results of this study provide theoretical guidance to enrich the selection of Yunnan white tea cultivars and promote the development of Yunnan white tea industry.In this paper,11 cultivars of Yunnan white tea were selected for processing into white tea by indoor withering and drying,using gas chromatography-mass spectrometry(GC-MS),biochemical composition and volatile components.The sensory evaluation,composition of volatile substances and their relative contents,biochemical composition of the 11 tea cultivars were analyzed by using gas chromatography-mass spectrometry(GC-MS),biochemical composition determination,sensory evaluation,orthogonal partial least squares-discriminant analysis(OPLS-DA)and other multivariate statistical methods.The main conclusions are as follows:1.sensory evaluation of white tea processed by 11 tea cultivars,C.sinensis var.assamica cv.Yunchaxiang 1 scored the highest and C.sinensis var.assamica cv.Yunkang10 scored the lowest.the overall appearance of the 11 tea cultivars showed buds and leaves with branches,emerald green and showing hairs;the soup colour was mainly light yellow,with C.sinensis var.assamica cv.Zijuan showing light indigo yellow and C.sinensis cv.Fuding-dabaicha showing honey yellow;the leaf base showed yellow-green overall.The aroma of C.sinensis var.assamica cv.Qingshui 3 is rich and persistent,with sweet and mellow taste and watery fragrance;the aroma of C.sinensis var.assamica cv.Fengqing 9 is pure and floral with honey aroma,with fresh sweet and bitter taste;the aroma of C.sinensis var.assamica cv.Yunchaxiang 1 is persistent and floral with honey aroma and fruit aroma,with fresh sweet and sweet taste;the aroma of C.sinensis var.assamica cv.Yunkang 10 is pure and floral,with fresh sweet and bitter taste;the aroma of C.sinensis var.assamica cv.Yuncha-chunyun is rich and persistent,with floral and fruit aroma,rich and persistent,with fresh sweet and astringent taste;the aroma of C.sinensis var.assamica cv.Zijuan is rich and pungent with floral aroma,with sweet and slightly bitter taste.The taste is mellow,sweet and slightly bitter;C.sinensis var.assamica cv.Jinggu-dabaicha aroma is floral with hairs,taste is sweet,fresh and sweet;C.sinensis var.assamica cv.Foxiang 3 has a strong aroma of fruit and flowers,taste is sweet and fresh and sweet;C.sinensis var.assamica cv.Foxiang 3-3 has a strong aroma of soymilk and fruit,taste is sweet and fresh.C.sinensis var.assamica cv.Foxiang 1-5 has a strong aroma of soymilk and flowers,taste is sweet and fresh and sweet;C.sinensis cv.Fuding-dabaicha has aroma of ripe fruit and flowers,taste is sweet and mellow.2.There are differences in the biochemical composition of the white tea processed by the 11 tea cultivars.The amino acid content of Fuding Dabai was significantly higher than other tea cultivars(p<0.05);the caffeine content of C.sinensis var.assamica cv.Fengqing 9and C.sinensis cv.Fuding-dabaicha was significantly higher than other tea cultivars;the polyphenol content of C.sinensis var.assamica cv.Yunkang 10 and C.sinensis var.assamica cv.Fengqing 9 was significantly higher than other teas;the soluble sugar content of C.sinensis var.assamica cv.Foxiang 1-5 was significantly higher than other tea cultivars;C.sinensis var.assamica cv.Jinggu-dabaicha had the highest flavonoid glycoside content,which was not significantly different from C.sinensis var.assamica cv.Qingshui 3 and C.sinensis var.assamica cv.Foxiang 3 but significantly different from other tea cultivars.3.The volatile components identified from different tea cultivars were screened according to a matching degree of ≥80,and a total of 101 compounds were identified,with the aroma components mainly being alcohols,esters,ketones and olefins.A total of 7compounds were common to 11 tea cultivars: linalool,dipentene,3-carene,trans-2-hexenal,β-zirconone,methyl salicylate and methyl palmitate.C.sinensis var.assamica cv.Jinggu-dabaicha had the highest relative content of volatile components and C.sinensis var.assamica cv.Zijuan had the lowest relative content.The 31 major volatile components were screened by orthogonal partial least squares discriminant analysis(OPLS-DA).Further analysis using Heat map showed that C.sinensis cv.Fuding-dabaicha differed significantly from Yunnan big leaf tea cultivars.4.The soup colour of C.sinensis cv.Fuding-dabaicha showed a honey yellow colour and the aroma had a special ripe fruit aroma,while the amino acid content of C.sinensis cv.Fuding-dabaicha was significantly higher than the rest of Yunnan big leaf white tea(p<0.05).Among the volatile components,C.sinensis cv.Fuding-dabaicha had the highest proportion of heterocyclic compounds,which was significantly different from the other Yunnan big leaf cultivars.Meanwhile,cis-3-nonen-1-ol,γ-mucoxene,B-phellandrene,2-methylbutyraldehyde,6,10,14-trimethyl-2-pentadecanone,2,2-dimethyl-1-methylenebicyc lo[7.7.2]heptane,(1R)-2,2-bis-methyl-3-methylenebicyclo[2.2.1]heptane,anthraquinone,cypress brain and bicuculline were only identified in C.sinensis cv.Fuding-dabaicha.5.The results of the sensory evaluation of C.sinensis var.assamica cv.Yunchaxiang 1,C.sinensis var.assamica cv.Jinggu-dabaicha and C.sinensis var.assamica cv.Foxiang 3were high,with the appearance of buds and leaves in succession,the aroma being mainly floral,fruity,millets and honey,the taste being fresh,sweet and mellow,the soup colour being mainly light yellow and the leaf base yellow-green.The three biochemical components are richer and have a better coordination,and therefore have better quality,indicating that the three tea cultivars have good white tea suitability. |
