背景:咖啡的水果芳香花束最近引起了人们的兴趣,以区分高价值的市场产品作为特色咖啡。尽管绿色和烘焙咖啡豆中存在的挥发性化合物已被广泛描述,还没有研究将品种分子差异与更丰富的特定物质联系起来,并支持特种咖啡的香气特异性。
结果:这项研究比较了四种阿拉比卡基因型,包括一种,艺妓特别,建议制作特色咖啡。咖啡饮料的正式感官评估强调了咖啡基因型在香气感知中的重要性,并且艺妓Especial制作的咖啡因具有良好的果味而脱颖而出,和花卉,香气和更平衡的酸度。绿色和烤豆挥发性化合物的比较SPME-GC-MS分析表明,GeishaEspecial的挥发性化合物的不同之处在于,柠檬烯和3-甲基丁酸的含量较高,与咖啡杯的香气感相符。对这四个品种的成熟豆转录组的基因本体论差异的搜索表明,由于异戊烯基-焦磷酸生物合成基因和萜烯合酶的基因表达更高,它们在与萜烯生物合成相关的代谢过程上有所不同。在所研究的四个品种的豆类中,只有一种萜烯合酶(CaTPS10样)的表达模式与浆果成熟的最后阶段的柠檬烯损失和柠檬烯含量平行。其在烟草叶片中的功能表达证实了其作为柠檬烯合酶的功能。
结论:综合来看,这些数据表明,咖啡品种的基因型特异性可能会影响成熟浆果的化学型和最终的咖啡香气单一性。对于特色咖啡品种艺妓Especial,增加萜烯生物合成基因的表达,包括CaTPS10样,柠檬烯合酶,导致青豆中柠檬烯的丰度增加,烤豆和独特的柑橘咖啡饮料。
BACKGROUND: The fruity aromatic bouquet of coffee has attracted recent interest to differentiate high value market produce as specialty coffee. Although the volatile compounds present in green and roasted coffee beans have been extensively described, no study has yet linked varietal molecular differences to the greater abundance of specific substances and support the aroma specificity of specialty coffees.
RESULTS: This study compared four Arabica genotypes including one, Geisha Especial, suggested to generate specialty coffee. Formal sensory evaluations of coffee beverages stressed the importance of coffee genotype in aroma perception and that Geisha Especial-made coffee stood out by having fine fruity, and floral, aromas and a more balanced acidity. Comparative SPME-GC-MS analyses of green and roasted bean volatile compounds indicated that those of Geisha Especial differed by having greater amounts of limonene and 3-methylbutanoic acid in agreement with the coffee cup aroma perception. A search for gene ontology differences of ripening beans transcriptomes of the four varieties revealed that they differed by metabolic processes linked to terpene biosynthesis due to the greater gene expression of prenyl-pyrophosphate biosynthetic genes and terpene synthases. Only one terpene synthase (CaTPS10-like) had an expression pattern that paralleled limonene loss during the final stage of berry ripening and limonene content in the studied four varieties beans. Its functional expression in tobacco leaves confirmed its functioning as a limonene synthase.
CONCLUSIONS: Taken together, these data indicate that coffee variety genotypic specificities may influence ripe berry chemotype and final coffee aroma unicity. For the specialty coffee variety Geisha Especial, greater expression of terpene biosynthetic genes including CaTPS10-like, a limonene synthase, resulted in the greater abundance of limonene in green beans, roasted beans and a unique citrus note of the coffee drink.