Orthodox Averaged Higher Than CTC in an Assam Caffeine Study
An average cup of black tea carries about 48 milligrams of caffeine, roughly half of what a cup of coffee holds. Here is the lab measure of Assam's leaf, orthodox against CTC, how fast caffeine leaves the leaf, and the decaffeinated black tea CSIR-NEIST in Jorhat has developed.
An average cup of black tea carries about 48 milligrams of caffeine, against roughly 96 in a cup of brewed coffee, by the Mayo Clinic's own reference chart.
What the lab actually measures
In this study caffeine was measured by HPLC on dry leaf. The clearest number for Assam specifically comes from a study that sampled 32 finished black teas from Upper Assam and the North Bank in 2023 and ran them through high performance liquid chromatography under ISO protocol, published in January 2026. The result: caffeine ran from 15.51 to 39.24 milligrams to the gram, dry weight, averaging 30.09 across the full set. Upper Assam samples averaged 28.40 to the gram; North Bank samples ran higher, at 32.91.
The study puts the spread down to cultivation practice, leaf maturity, processing and agroclimate; caffeine is made mainly in young leaves, and its content falls as leaves mature.
The surprise: orthodox averaged higher than CTC
In that same Upper Assam and North Bank study, orthodox samples averaged more caffeine than CTC, the method that crushes, tears, and curls the leaf by machine: in Upper Assam, orthodox samples averaged 29.84 milligrams of caffeine to the gram, ahead of CTC's 25.05. In the North Bank, orthodox averaged 34.58 against CTC's 31.24. Orthodox came out ahead in both regions tested.
How much caffeine sits in the leaf is not the same question as how much caffeine reaches your cup.
How fast caffeine leaves the leaf
A study of low-grown Ceylon CTC tea from Sri Lanka found caffeine coming out fastest in the first two minutes of brewing, and put the optimum brewing time at two to eight minutes.
In that study caffeine left the leaf much faster than the tea's total polyphenols.
A decaffeinated Assam black tea
In September 2025, the CSIR North East Institute of Science and Technology, headquartered in Jorhat, launched India's first indigenously developed decaffeinated black tea. It was unveiled by Union Minister of State for Science and Technology Dr Jitendra Singh at CSIR's 84th Foundation Day event in New Delhi. The process, led by principal scientist Dr Bipul Das of the institute's Chemical Engineering Division, removes 95 percent or more of a black tea's caffeine without affecting its natural qualities, EastMojo reports.
CSIR-NEIST licensed it to two companies: Jalan Investments Pvt Ltd of Dibrugarh, for producing the decaffeinated tea itself, and Gangwal Healthcare Pvt Ltd of Mumbai, which EastMojo says is focusing on extracting caffeine from tea waste for pharmaceutical use. A production plant at the South Jalan Nagar tea estate in Dibrugarh was reported, as of that September 2025 announcement, to be expected in early 2026.
Sources
- Biochemical Quality Profile of Black Tea from Upper Assam and North Bank Region of Assam, India1, an HPLC study of 32 black tea samples collected in 2023 and published in January 2026, the source for the dry-leaf caffeine ranges and the orthodox-versus-CTC comparison by region.
- Extraction Kinetics of phytochemicals and antioxidant activity during black tea (Camellia sinensis L.) brewing2, on how fast caffeine and other compounds leave Sri Lankan CTC leaf once brewing starts.
- Caffeine content for coffee, tea, soda and more3, Mayo Clinic's reference chart, the source for the 48 milligram black tea and 96 milligram coffee baseline.
- India's first decaf black tea launched by CSIR-NEIST Jorhat using local technology4, The Assam Tribune, on the September 2025 launch, the institute, and the officials present.
- Assam to host India's first decaffeinated black tea plant5, EastMojo, on the lead scientist, the caffeine-reduction figure, and the two licensee companies.