A Comparative Study of Camellia sinensis var. sinensis and var. assamica

Executive Summary

This report consolidates three independent student research projects undertaken at the Indian School of Tea (IST).

More than fifteen green tea samples representing Darjeeling, Assam, Nilgiri, Kangra, Meghalaya, Sikkim and Manipur were evaluated to determine whether a single brewing standard can be applied across different plant types and terroirs.

Each tea was first brewed using a common SOP (2.5 g leaf, 150 ml water, 80°C, 2.5 minutes) and subsequently re-brewed with adjusted parameters based on sensory observations.

Research Objective

To determine whether green teas from different plant types (Sinensis and Assamica) require different brewing parameters to achieve optimum sensory balance, and to identify the influence of regional origin and processing style on extraction.

Methodology

• Three independent studies consolidated.
• 15+ green tea samples.
• Regions: Darjeeling, Assam, Nilgiri, Kangra, Meghalaya, Sikkim and Manipur.
• Standard SOP applied to every sample before optimisation.
• Sensory evaluation included liquor appearance, aroma, flavour progression, body, finish and balance.

Key Findings

1. A universal brewing SOP is not optimal for all green teas.
2. Sinensis teas consistently produced balanced, aromatic and well-structured cups under the standard SOP.
3. Assamica teas displayed greater variability, often showing over-extraction (astringency) or under-extraction (thin body).
4. Plant type is the strongest determinant of brewing behaviour.
5. Regional origin, harvest season and processing style further influence extraction dynamics.
6. Adaptive brewing significantly improved flavour expression in Assamica teas.

Discussion

The consolidated evidence demonstrates that extraction behaviour is governed primarily by plant genetics and modified by terroir and manufacture.

While Sinensis teas generally tolerated the standard SOP, Assamica teas required careful adjustment of temperature, infusion time and, in some cases, leaf ratio.

The findings support moving away from rigid brewing recipes towards an adaptive, sensory-led brewing framework.

Recommendations

• Maintain the standard SOP for most Sinensis green teas.
• Reduce temperature and/or infusion time for sensitive Assamica teas prone to astringency.
• Increase extraction for robust Assamica teas with thicker leaves where body development is insufficient.
• Evaluate brewing using sensory outcomes rather than fixed parameters.

Conclusion

The study concludes that there is no universally optimal brewing protocol for green tea.

Brewing should be guided first by plant type, then refined according to regional characteristics, harvest and processing style.

These findings provide a foundation for developing an IST Adaptive Brewing Framework for professional tea education and sensory evaluation.

Acknowledgement

Compiled from research projects by Chirag Prakash Arora, Swathy R and Ragini Khatri under the Indian School of Tea (IST).