伞枝犁头霉纯菌与强化发酵普洱茶研究

Pure Culture and Enhanced Fermentation of Pu-erh Tea through Inoculation with Absidia corymbifera

为提高普洱茶的品质,将伞枝犁头霉(Absidia corymbifera)A1接种于灭菌和未灭菌的晒青茶中,分别进行纯菌发酵与强化发酵(enhanced fermentation,EF)。结果表明,经纯菌发酵后茶叶中茶多酚和5种儿茶素含量显著降低(P<0.05),茶褐素和茶红素含量显著增加(P<0.05)。与自然发酵(normal fermentation,NF)相比,EF中茶褐素和可溶性糖含量显著升高(P<0.05),而儿茶素、儿茶素没食子酸酯、表儿茶素、没食子儿茶素没食子酸酯、表没食子儿茶素没食子酸酯、表儿茶素没食子酸酯和表没食子儿茶素含量显著降低(P<0.05);感官审评时EF茶汤的甜味和厚重感分数增加,苦味、涩味和酸味分数降低;色差仪测定发现EF茶汤的a*、b*值增加,L*值降低。真菌内转录间隔区(internal transcribed spacer,ITS)和细菌16S核蛋白体RNA(16S ribosomal RNA,16S rRNA)扩增子测序发现,伞枝犁头霉A1没有成为EF的优势真菌,但改变了EF微生物群落结构,表现在EF中Brunneoclavispora bambusae、食腺嘌呤芽生葡萄孢酵母、微小根毛霉、葡萄球菌、假单胞菌和芽孢杆菌的相对丰度较NF高,而黑曲霉、马克斯克鲁维酵母、大肠埃希-志贺菌和克雷白氏菌的相对丰度较低。因此,接种伞枝犁头霉A1发酵,可通过与其它微生物的协同作用改变茶叶中的特征成分,从而提高普洱茶的感官品质。

To improve the quality of Pu-erh tea,Absidia corymbifera A1 was inoculated in sterilized and unsterilized sun-dried tea leaves to develop pure culture fermentation and enhanced fermentation(EF)of Pu-erh tea.The results showed that the contents of tea polyphenol and five catechins decreased(P<0.05),while the contents of theabrownin and thearubigins in tea increased(P<0.05)in tea after pure culture fermentation.Compared with the conditions in normal fermentation(NF),the levels of theabrownin and soluble sugars in EF were higher(P<0.05),whereas those of(+)-catechin,(-)-catechin gallate,(-)-epicatechin,(-)-gallocatechin gallate,(-)-epigallocatechin-3-gallate,(-)-epicatechin-3-gallate and(-)-epigallocatechin were lower(P<0.05).In sensory evaluation,the scores of sweet and thickness elevated,while those of bitterness,astringency and acidity reduced in EF tea infusion.The values of a*and b*were higher and the value of L*was lower in EF tea infusion,which were detected by the chromameter.The fungus internal transcribed spacer(ITS)and bacterium 16S ribosomal RNA(16S rRNA)amplicon sequencing found that although A.amstelodami A1 failed to become the dominant fungus in EF,the microbial communities in EF were changed.To be specific,the relative abundances of Brun-neoclavispora bambusae,Blastobotrys adeninivorans,Rhi zomucor pusillus,Staphylococcus,Pseudomonas and Bacillus were higher and the relative abundances of Aspergillus niger,Kluyveromyces marxianus,Escherichia-Shigella and Klebsiella in EF were lower than those in NF.Therefore,EF by inoculating A.amstelodami A1 changed the characteristic components of tea through the synergistic effect with other microorganisms,thus im-proving the sensory quality of Pu-erh tea.