Guwahati: With fluctuations in temperature, rainfall, and sunlight patterns impacting tea throughout the year, the question arises: when is the best time to harvest to get the best quality and prices?
Tea, derived from Camellia sinensis var. assamica leaves, is renowned for its diverse flavours and potential health benefits. Its rich taste and aroma stem from a complex blend of compounds, including polyphenols, amino acids, alkaloids, and volatile substances. These constituents enhance tea’s sensory experience, physiological effects, and therapeutic properties.
A pioneering study conducted by researchers from the National Institute of Pharmaceutical Education and Research (NIPER) in Guwahati has uncovered significant seasonal variations in the chemical composition of Assam tea leaves. Two people from the tea industry have contributed to the study too.
The research, published in the Journal of Food Composition and Analysis, highlights the crucial role of environmental factors in determining tea quality, offering valuable insights for cultivators aiming to optimize their harvests. The raw materials were collected from the Koliabur tea estate in Assam.
The influence of seasonal variations on the composition of tea leaves has long been acknowledged. “Fluctuations in temperature, rainfall, and sunlight patterns throughout the year impact the metabolic processes and accumulation of compounds within plants, leading to variations in the chemical makeup of tea leaves across different seasons. These changes ultimately affect the final tea product’s quality, flavour, and nutritional content. Despite its significance, there has been limited research into the seasonal variations of tea compounds as a whole,” the study says.
“The optimal time to harvest tea is during the monsoon season. This period is identified as having the highest concentrations of key phyto metabolites, such as EGCG (Epigallocatechin gallate) and ECG (Epicatechin gallate), which are crucial for tea quality. The monsoon season shows peak concentrations of these compounds, which significantly decline during autumn and winter. Therefore, harvesting tea during the monsoon season ensures the highest quality due to the elevated levels of beneficial phyto metabolites,” the study says.
This information is crucial for producing high-quality tea extracts, as these compounds are responsible for many of the health benefits and sensory qualities of tea extracts.
Roshan M Borkar, Assistant Professor in the Department of Pharmaceutical Analysis at NIPER-Guwahati and the corresponding author of the study, says the main reasons for attempting this study were to (a) understand the impact of climate changes and how seasonal variations affect the quality of tea, specifically in the Camellia sinensis var. assamica, and (b) investigate how specific plucking standards during periods of leaf dormancy are essential for maintaining the desired quality and yield of tea.
“Our main findings indicate that climate changes and seasonal variations significantly influence the chemical composition, in particular epigallocatechin gallate, and overall, the quality of tea leaves. By adopting appropriate plucking standards, especially during dormancy periods, tea producers can optimize the quality and yield of their tea despite the challenges posed by climatic fluctuations,” Borkar says.
Similarly, the highest concentration of caffeine, a prominent bioactive compound in tea known for its stimulant effects, was observed in the monsoon harvest. During the composition profiling of tea samples, it emerged as the second most abundant compound.
The highest concentration of theanine, an amino acid found in buds, was observed in the monsoon season, indicating a more than 5-fold decrease in concentration during the winter season.
The study is highly relevant for individuals and businesses involved in the production and use of tea extracts for several reasons. The study highlights the seasonal variations in the concentrations of key phytometabolites like EGCG and ECG in tea leaves. This information is crucial for producing high-quality tea extracts, as these compounds are responsible for many of the health benefits and sensory qualities of tea extracts.
“Knowing that the monsoon season yields the highest concentrations of beneficial compounds can help extract producers time their purchases of raw tea leaves to ensure they are using the most potent and high-quality material for extraction,” experts say.
With insights into the composition and seasonal variability of tea phytometabolites, businesses can develop new tea extract-based products that highlight these health benefits. This can include supplements, beverages, skincare products, and more.
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