Lemme see here. We got an insect-damaged crop that would normally spell doom for harvest profit, leaves that are either sucked dry (withered/yellowed) or munched on, and fables of plant antibodies, sudden sweetness and delicate orchid-like aroma, and thus immense desirability.
So I suckered and bought some.
It does has an interesting sweetness and orchid-like flavor.
But wait! The area surrounding these tea estates abound in orchids (itself a lucrative crop). Contrary to popular belief, orchids are pollinated by very specific insects (usually bees). They do not flagrantly spread their pollen on the wind.
So scratch the BS about pollen-sweetening. Wouldn't be surprised if one of the 'secret-steps' for processing involves drying the leaves for a short period with orchid blooms.
Maybe you get elicited chemistry from tea leaves when they are attacked by leaf sucking insects, but given that it's a very BIG PROBLEM for tea growers, you would like this chemical propensity would be rather widespread.
So it has to be related to the cultivar resistance to insect predation. This paper uses a very clever method to determine the type of leaf damage associated with natural resistance of various tea cultivars to insect attack.
Probing behavior of the tea green leafhopper on different tea plant cultivars. 2007. Acta Ecologica Sinica 27(10):3973-3982.
The probing behaviors of the tea green leafhopper, Empoasca vitis (Gothe), on 9 tea cultivars were studied using video-text Direct Current-Electrical Penetration Graph, i.e., DC-EPG. The following 7 types of waveforms produced by the leafhopper stylet probing were determined: A, stylet pathway formation; S, salivation when stylets pierce into and stay in phloems; C, active ingestion before stylets reach phloems; E and F, passive ingestion in phloems; R, the insect resting with its stylet inserted into the leaf tissue and NP without probing. The 9 tested tea cultivars were categorized into 3 groups by the cluster analysis according to the number of probes per insect, waveform durations, or duration per probe of various waveforms on different tea cultivars. Waveforms S, E and F correlated to the main feeding activity of the leafhopper and may provide valuable information on predicting the resis-tance level of the tea plants to the leafhopper. The resistance level of the 9 tea cultivars to the leafhopper was ranked based on the durations of waveforms S, E and F, as well as the duration per probe including various waveforms. The ranking order of the resis-tance was: Longjingchangye > Hangdan > Zhenghedabaicha > Qianmei 601 > Hongyafoshuo > Zhongcha 102 > Zhongcha 302 > Longjing 43 > Anjibaicha, which corresponded to the resistance level determined by the population density (infestation) of the leaf-hopper on the 9 tea cultivars in the tea fields. Our study suggests that this simple and convenient DC-EPG technique might have great potential as a reliable tool to predict the resistance of tea cultivars to the tea leafhopper.
Maybe it's a more general trend in certain cultivars, maybe also a function of soil chemistry of specific locals, that they produce a sweeter tea than ordinary expected, as a result of natural resistance to leaf hopper infestation.
Insect attack induces production of natural compounds that afford a fruity sweetness when processed. Perhaps this quality is intensified by processing steps as well. So we got gene induction going on.
Maybe natural resistance is induced by cultivation conditions as well as genetics. You use less pesticides to control these critters, and allow a bit of attack, to which the plant defense responds and keeps leaf damage to a minimum.
I think that means that leaf damage and insect bits in the processed leaves isn't so big an issue. I went looking for more information, because I found OB to be delightful - really quite flavorful and fragrant. I wanted to know if leaf processing intensified this plant defense flavor quality.
I found a very informative article that sheds light on the interesting chemistry here:
Chemical Profiling and Gene Expression Profiling during the Manufacturing Process of Taiwan Oolong Tea "Oriental Beauty". Biosci Biotechnol Biochem. 2007 71 (6):1476-86.
(Institute for Chemical Research, Kyoto University is a top-notch Japanese research university).
Abstract. Oriental Beauty, which is made from tea leaves infested by the tea green leafhopper (Jacobiasca formosana) in Taiwan, has a unique aroma like ripe fruits and honey. To determine what occurs in the tea leaves during the oolong tea manufacturing process, the gene expression profiles and the chemical profiles were investigated.
Tea samples were prepared from Camellia sinensis var. sinensis cv. Chin-shin Dah-pang while the tea leaves were attacked by the insect. The main volatile compounds, such as linalool-oxides, benzyl alcohol, 2-phenylethanol, and 2,6-dimethylocta-3,7-diene-2,6-diol, increased during manufacture.
The gene expression profiles during manufacture were analyzed by differential screening between fresh leaves and tea leaves of the first turn over. Many up-regulated transcripts were found to encode various proteins homologous to stress response proteins. Accordingly, the endogenous contents of abscisic acid and raffinose increased during manufacture. Thus the traditional manufacturing method is a unique process that utilizes plant defense responses to elevate the production of volatile compounds and other metabolites.
Raffinose is a sugar. Linalool belongs to a group of compounds important to the flavoring and fragrance industries. Plant stress hormone that may affect leaf appearance and deform growth:
http://en.wikipedia.org/wiki/Abscisic_acid
Better living through chemistry!
