Recent studies of the volatile compounds in tea

Volatile compounds are important components of tea aroma, a key attribute of sensory quality. The present review examines the formation of aromatic volatiles of various kinds of teas and factors influencing the formation of tea volatiles, including tea cultivar, growing environment and agronomic practices, processing method and storage of tea. The determination of tea volatiles and the relationship of active-aroma volatiles with the sensory qualities of tea are also discussed in the present paper.

https://www.mdpi.com/1420-3049/21/3/338/pdf

Recent Advances in Volatiles of Teas

Identification of key odorants responsible for chestnut-like aroma quality of green teas.

Green tea flavour determinants and their changes over manufacturing processes.

This article presents a comprehensive review on the success and limitations of biotechnological approaches aimed at genetic improvement of tea with a purpose to explore possibilities to address challenging areas.
 Tea is a woody perennial tree with a life span of more than 100 years. Conventional breeding of tea is slow and limited primarily to selection which leads to narrowing down of its genetic base. Harnessing the benefits of wild relatives has been negligible due to low cross-compatibility, genetic drag and undesirable alleles for low yield. Additionally, being a recalcitrant species, in vitro propagation of tea is constrained too. Nevertheless, maneuvering with tissue/cell culture techniques, a considerable success has been achieved in the area of micropropagation, somatic embryogenesis as well as genetic transformation. Besides, use of molecular markers, “expressomics” (transcriptomics, proteomics, metabolomics), map-based cloning towards construction of physical maps, generation of expressed sequenced tags (ESTs) have facilitated the identification of QTLs and discovery of genes associated with abiotic or biotic stress tolerance and agronomic traits. Furthermore, the complete genome (or at least gene space) sequence of tea is expected to be accessible in the near future which will strengthen combinational approaches for improvement of tea. This review presents a comprehensive account of the success and limitations of the biotechnological tools and techniques hitherto applied to tea and its wild relatives. Expectedly, this will form a basis for making further advances aimed at genetic improvement of tea in particular and of economically important woody perennials in general.

Biotechnological advances in tea ( Camellia sinensis [L.] O. Kuntze): a review

Darjeeling teas are the highest grown teas in the world and preferred for its flavour, aroma and quality. Apart from the genetic makeup of the plant, earlier reports suggest that insect infestation, particularly jassids and thrips triggers the aroma and flavour formation in Darjeeling tea. The present work encompasses the identification of the genes/transcriptomes responsible for the typical flavour of Darjeeling tea, besides understanding the role of jassids and thrips in particular, in producing the best cup character and quality. The quantitative real time PCR analysis was based on a suppression subtractive hybridisation forward library of B157 (tea clone infested with thrips), providing us transcripts related to aroma and flavour formation. We observed the expression of genes like leucine zipper, ntd, nced, geraniolsynthase, raffinose synthase, trehalose synthase, amylase, farnesyl transferase, catalase, methyl transferase, linalool synthase, peroxidases, elicitor responsive proteins, linamarase, nerolidol linalool synthase 2, 12-oxophytodienoate reductase, glucosidase, MYB transcription factor, and alcohol dehydrogenase, highly regulated due to insect infestation, manufacturing stresses and mechanical injury. The first report on gene expression dynamics in thrips infested Darjeeling tea leaves can be extrapolated with increase in volatiles which is responsible for enhancing the quality of Darjeeling tea, specially the flavour and aroma of the infusion. We hope to model these responses in order to understand the molecular changes that occur during Darjeeling tea flavour formation.

G. Gurusubramaniam

Papers

Understanding Darjeeling tea flavour on a molecular basis