Assam Tea Research Articles

An analysis of the determinants of productivity of Assam tea growers

An analysis of the determinants of productivity of Assam tea growers

Quantitative analysis of bioactive compounds in five black tea sortiments of the romanian market

Five black tea types, Assam, Darjeeling, Earl Grey, English Breakfast and Oolong were tested for their chlorophyll, carotenoid, flavonoid, total phenolic content and essential oil content. English Breakfast had the highest chlorophyll content (834 mg/kg) and Earl Grey, the highest carotenoid content (360 mg/kg). Total phenolic content was the highest in Darjeeling (an average of 40,874 mg/kg ), while flavonoids, specifically, reached the highest concentrations in Oolong (498 mg/kg). Total essential oils were maximum in Assam tea blend (4,600 mg/kg). Tea pH values ranged between 6.13-6.66. Bangladesh J. Bot. 53(3): 555-560, 2024 (September)

Seasonal dynamics of phytometabolites content in Assam tea, Camellia sinensis var. assamica by LC-MS/MS: Implications for quality

The study examines the seasonal variation in phytometabolite content in Camellia sinensis var. assamica, a prevalent tea variety in Northeast India. Focusing on both bud and dormant leaf (banjhi) samples harvested during the monsoon, autumn, and winter seasons, the research aims to assist cultivators in selecting optimal harvesting times for tea production. An LC-MS/MS method was developed and validated for phytometabolite quantification. Epigallocatechin gallate (EGCG) emerged as the most abundant catechin, with concentrations ranging from 78.01±13.31–125.21±5.65 µg/mg in buds during the monsoon and decreasing to 17.86±1.22–51.11±1.21 µg/mg in winter. Banjhi leaves exhibited even higher EGCG levels, from 203.86±21.06–312.58±28.23 µg/mg in the monsoon, dropping to 74.43±15.22–97.52±8.47 µg/mg in autumn. Similarly, epicatechin gallate concentrations in buds ranged from 17.04±2.57–24.78±1.15 µg/mg in the monsoon and decreased to 5.36±0.39–11.16±1.74 µg/mg in winter, while banjhi leaves showed a decline from 63.61±1.60–72.72±1.23 µg/mg in the monsoon, dropping to 12.73±2.07–15.35±1.33 µg/mg in autumn. The study also noted seasonal variations in catechin hydrate, caffeine, gallic acid, theanine, and theaflavin. These findings underscore the importance of harvest timing for maintaining tea quality and optimizing cultivation and processing practices for sustainability amid environmental changes.

Microbial Population and Physicochemical Properties of Miang Fermented in Bamboo Tubes by the Luar Ethnic Group in Lao PDR.

Miang is a traditional fermented food made from Assam tea leaves and consumed as a snack. This study investigated the underground Miang fermentation process practiced by the Luar ethnic group in Laos, specifically examining the nutritional composition and microbial dynamics. Lactic acid bacteria and yeast were dominant in the fermentation process, reaching 8.43 and 8.50 log CFU/g after one week before gradually declining, while the coliform bacterial count was at 5.31 log CFU/g in the initial week but became undetectable in the later stages of fermentation. Next-generation sequencing identified Firmicutes (75.02%) and Proteobacteria (23.51%) as the primary phyla. Bacterial genera included Lactobacillus (73.36%) and Acetobacter (21.06%), with fungi mainly represented by Pichia (85.52%) and Candida (13.45%). Fundamental microbes such as Lactobacillus and Acetobacter were predominantly present, alongside Pichia and Candida, in the fungal communities. Microbial activities played a crucial role in generating essential enzymes for Miang's transformation. The nutritional transformation appears to be complete at 5 weeks of fermentation. The moisture content in the final products was approximately 74% and correlated with a change in nitrogen-free extract (NFE) and crude fiber. The fat content showed a slight increase from 1.3% to 2.52%, but protein content slightly declined from 17.21% to 16.05%, whereas ash content did not change significantly. Key polysaccharide-degrading enzymes, particularly pectinase and β-mannanase, were revealed and peaked at 48.32 and 25.32 U/g Miang, respectively. The total polyphenols increased from 103.54 mg/g dry Miang to 144.19-155.52 mg/g during fermentation. The lowered IC50 value indicated an increase in antioxidant activity. A fermentation period of at least 3 weeks proved to be optimal for enhancing antioxidant properties and bioactive compounds, and mitigating the risk of coliform bacteria.

Antibacterial Activities of Phenolic Compounds in Miang Extract: Growth Inhibition and Change in Protein Expression of Extensively Drug-Resistant Klebsiella pneumoniae.

The rising incidence of extensively drug-resistant (XDR) Klebsiella pneumoniae, including carbapenem- and colistin-resistant strains, leads to the limitation of available effective antibiotics. Miang, known as chewing tea, is produced from Camellia sinensis var. assamica or Assam tea leaves fermentation. Previous studies revealed that the extract of Miang contains various phenolic and flavonoid compounds with numerous biological activities including antibacterial activity. However, the antibacterial activity of Miang against XDR bacteria especially colistin-resistant strains had not been investigated. In this study, the compositions of phenolic and flavonoid compounds in fresh, steamed, and fermented Assam tea leaves were examined by HPLC, and their antibacterial activities were evaluated by the determination of the MIC and MBC. Pyrogallol was detected only in the extract from Miang and showed the highest activities with an MIC of 0.25 mg/mL and an MBC of 0.25-0.5 mg/mL against methicillin-susceptible Staphylococcus aureus, methicillin-resistant S. aureus, Escherichia coli ATCC 25922, colistin-resistant E. coli, and colistin-resistant K. pneumoniae. The effects on morphology and proteomic changes in K. pneumoniae NH54 treated with Miang extract were characterized by SEM and label-free quantitative shotgun proteomics analysis. The results revealed that Miang extract caused the decrease in bacterial cell wall integrity and cell lysis. The up- and downregulated expression with approximately a 2 to >5-fold change in proteins involved in peptidoglycan synthesis and outer membrane, carbohydrate, and amino acid metabolism were identified. These findings suggested that Miang containing pyrogallol and other secondary metabolites from fermentation has potential as an alternative candidate with an antibacterial agent or natural active pharmaceutical ingredient against XDR bacteria including colistin-resistant bacteria.

Tea Tourism: Navigating the Future of Assam's Agritourism

Assam, a state brimming with diverse tourism opportunities, boasts rich wildlife, cultural heritage, monuments, and abundant natural flora and fauna. Despite its vast potential, Assam has yet to secure a prominent position on the global tourism map. While recent government initiatives aim to rejuvenate the state's tourism, one overlooked sector is Agritourism, a facet of Community-based Tourism that allows visitors to engage directly with the host community. This study specifically delves into the agricultural realm, focusing on Assam's tea sector, a pivotal contributor to the state's economy and employment with over 800 major tea estates. Positioned as a prime candidate for Tea tourism, these estates offer a wealth of attractions, including century-old bungalows, lush green lawns, and expansive tea plantations. The study aims to explore the untapped potential of tea tourism, proposing approaches for development while addressing current challenges and presenting viable solutions. With its roots in community-based tourism and agritourism, tea tourism not only has the capacity to elevate the state's tourism industry but also positively impact the host communities involved.

Recent insights into catechins-rich Assam tea extract for photoaging and senescent ageing

Tea (Camellia spp.) is an important medicinal herb. C. sinensis var. sinensis is the most studied tea variety due to its more preferred flavor than C. sinensis var. assamica (Assam tea), the less economic importance with more bitter variety. A bitter taste highlights its potential as a candidate source for tea catechins, the health beneficial actives applicable for ageing treatment. Nonetheless, indicative data for tea on UV-induced and senescent ageing remain unclarified. Assam tea extract (ATE) was prepared and standardized in terms of TPC, TFC and TTC. EGCG was HPLC quantified as the prime ATE catechin. In vitro antioxidant activity of ATE was exhibited with ABTS, DPPH and FRAP assays. ATE’s cellular antioxidant activity was indicated in HDFs at a stronger degree than ascorbic acid. The photoaging protection of ATE was evidenced in a coculture of HaCaT cells and HDFs. ATE markedly suppressed UV-induced IL-6, IL-8, MMP-1 and MMP-9 expressions. The proficiency of ATE targeting on senescent ageing was demonstrated in an ex vivo human skin model, where IL-6 and MMP-1 expressions were suppressed, whilst hyaluronic acid and collagen syntheses were promoted. ATE was chemically stabled as indicated by the catechin contents and color parameters following 6 months storage under conditions recommended for topical product. ATE enriched in catechins warrants its applicability as a new generation of photoaging protectant agent promising for the prevention and treatment for senescent ageing. The findings indicate the proficiency of ATE for innovative anti-ageing agent.

Purification and characterization of crude fructooligosaccharides extracted from red onion (Allium cepa var. viviparum) by yeast treatment

BackgroundYeast treatment has been used for purification of fructooligosaccharides (FOSs). However, the main drawback of this approach is that yeast can only partially remove sucrose from crude FOSs. The main objective of this research was to screen yeast strains for the capability of selectively consuming unwanted sugars, namely fructose, glucose, and sucrose, in crude FOSs extracted from red onion (Allium cepa var. viviparum) with minimal effect on FOS content.ResultsAmong 43 yeast species isolated from Miang, ethnic fermented tea leaves, and Assam tea flowers, Candida orthopsilosis FLA44.2 and Priceomyces melissophilus FLA44.8 exhibited the greatest potential to specifically consume these unwanted sugars. In a shake flask, direct cultivation of C. orthopsilosis FLA44.2 was achieved in the original crude FOSs containing an initial FOSs concentration of 88.3 ± 1.2 g/L and 52.9 ± 1.2 g/L of the total contents of fructose, glucose, and sucrose. This was successful with 93.7% purity and 97.8% recovery after 24 h of cultivation. On the other hand, P. melissophilus FLA48 was limited by initial carbohydrate concentration of crude FOSs in terms of growth and sugar utilization. However, it could directly purify two-fold diluted crude FOSs to 95.2% purity with 92.2% recovery after 72 h of cultivation. Purification of crude FOSs in 1-L fermenter gave similar results to the samples purified in a shake flask. Extracellular β-fructosidase was assumed to play a key role in the effective removal of sucrose. Both Candida orthopsilosis FLA44.2 and P. melissophilus FLA44.8 showed γ-hemolytic activity, while their culture broth had no cytotoxic effect on viability of small intestinal epithelial cells, preliminarily indicating their safety for food processing. The culture broth obtained from yeast treatment was passed through an activated charcoal column for decolorization and deodorization. After being freeze dried, the final purified FOSs appeared as a white granular powder similar to refined sugar and was odorless since the main sulfur-containing volatile compounds, including dimethyl disulfide and dipropyl trisulfide, were almost completely removed.ConclusionThe present purification process is considered simple and straight forward, and provides new and beneficial insight into utilization of alternative yeast species for purification of FOSs.

Effect of Ultrasound-Assisted Extraction and Drying Methods on Bioactive Compounds, Phenolic Composition, and Antioxidant Activity of Assam Tea Cultivar (Camellia sinensis var. assamica) Cultivated in Thailand.

Tea is a rich source of phytochemicals; their composition in tea extracts varies depending on the cultivar, climate, production region, and processing and handling processes. The method of extraction plays a crucial role in determining the biological effects of the bioactive compounds in tea leaves. However, reports on the catechin profiles and antioxidant activities of the extracts obtained from leaves at different stages of maturity are limited. Here, we aimed to evaluate the effect of ultrasound-assisted extraction (UAE) and different drying methods, freeze drying (FD) and spray drying (SD), on the composition of bioactive compounds, phenolic composition, and antioxidant activity of extracts obtained from different part of leaves, top (TT), middle (ML), and mature (MT), of Assam tea cultivar (Camellia sinensis var. assamica) cultivated in Thailand (Thai Assam tea). High-performance liquid chromatography analysis showed that the extracts obtained by UAE with FD from TT leaves (UAEFD-TT) had the highest catechins (341.38 ± 0.11 mg/g extract) and caffeine (93.20 ± 0.36 mg CF/g extract) contents compared with those extracted from ML and MT using the same method as well those obtained by SD. The total phenolic and total flavonoid contents were the highest in UAEFD-TT extracts (456.78 ± 4.31 mg GAE/g extract and 333.98 ± 0.83 mg QE/g extract, respectively). In addition, UAEFD-TT exhibited the highest antioxidant activity; the IC50 values obtained by 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) assays were 1.31 ± 0.02 and 7.51 ± 0.03 μg/mL, respectively. In the ferric-reducing antioxidant power (FRAP) assay, the UAEFD-TT extract demonstrated the highest antioxidant activity (324.54 ± 3.33 μM FeSO4/mg extract). These results suggest that extraction from TT using UAE followed by FD produced the highest amount of antioxidant compounds in Thai Assam tea extracts.

Modernity And Education: A Contextual Appraisal With Emphasis On Assam's Tea Tribes

Modernity And Education: A Contextual Appraisal With Emphasis On Assam's Tea Tribes

From Tea Leaves to Skincare: New Perspectives on Anti-Aging Research with Assam Tea Extract

From Tea Leaves to Skincare: New Perspectives on Anti-Aging Research with Assam Tea Extract

Beyond the Colonial Lens: An Investigation into the Chequered History of Assam Tea

This article presents a fresh perspective on tea cultivation in Assam, negating the widely held belief that the British Empire’s introduction to Assam tea symbolised societal advancement and economic growth. This article argues that the primary intention of the British was pure economic that catapulted the destruction of the thick forested areas, marginalised the native population and abolished their kingdoms. Despite this, colonial Assamese elites and mainstream industrialists have glorified the British tea venture. In this attempt of reviewing the history of Assam tea from an alternative point of view, efforts have also been made to analyse how the East India Company’s desire to maintain its monopoly in the Chinese tea trade, the Calcutta Botanical Garden’s desire to uphold the supremacy of the Chinese tea plant, and the military personnel’s quest for new sources of tea played their roles in it.

Ethical Recursivity: Reconciling Ethics and Action in a Publicly Engaged Anthropology

Abstract While anthropologists have been cautious to avoid essentialism, the notion “informant” in anthropology’s promotion of scholar-informant solidarity has been surprisingly undifferentiated. Based on my experience of interlocutors’ heterogeneity during my fieldwork on Assam tea plantations, I illustrate the ambiguity, porosity and mutability of the category of the “informant.” I argue that the general imperative to support informants occludes that there are multiple interlocutors with different, at times conflicting, claims. Therefore, a (conscious or unconscious) decision about whom among the multiple interlocutors to support in the field of study seems inevitable. Inspired by the epistemological concept of recursivity, drawn from the recent framework of a recursive anthropology, I suggest ethical recursivity as one possible answer to the question on what ethical grounds anthropologists could base their decision about whom among the multiple (marginalized) interlocutors they show solidarity to, in order to reconcile ethical premises and actions within a publicly engaged anthropology.

Optimization of the enzymatic extraction of catechins from Assam tea leaves

Optimization of the enzymatic extraction of catechins from Assam tea leaves

Genetic analyses of ancient tea trees provide insights into the breeding history and dissemination of Chinese Assam tea (Camellia sinensis var. assamica)

Chinese Assam tea (Camellia sinensis var. assamica) is an important tea crop with a long history of cultivation in Yunnan, China. Despite its potential value as a genetic resource, its genetic diversity and domestication/breeding history remain unclear. To address this issue, we genotyped 469 ancient tea plant trees representing 26 C. sinensis var. assamica populations, plus two of its wild relatives (six and three populations of C. taliensis and C. crassicolumna, respectively) using 16 nuclear microsatellite loci. Results showed that Chinese Assam tea has a relatively high, but comparatively lower gene diversity (HS = 0.638) than the wild relative C. crassicolumna (HS = 0.658). Clustering in STRUCTURE indicated that Chinese Assam tea and its two wild relatives formed distinct genetic groups, with considerable interspecific introgression. The Chinese Assam tea accessions clustered into three gene pools, corresponding well with their geographic distribution. However, NewHybrids analysis indicated that 68.48% of ancient Chinese Assam tea plants from Xishuangbanna were genetic intermediates between the Puer and Lincang gene pools. In addition, 10% of the ancient Chinese Assam tea individuals were found to be hybrids between Chinese Assam tea and C. taliensis. Our results suggest that Chinese Assam tea was domesticated separately in three gene pools (Puer, Lincang and Xishuangbanna) in the Mekong River valley and that the hybrids were subsequently selected during the domestication process. Although the domestication history of Chinese Assam tea in southwestern Yunnan remains complex, our results will help to identify valuable genetic resources that may be useful in future tea breeding programs.

Shifting Narratives of Soil in Scientific Discourses of Colonial Assam Tea Plantations

With the establishment of tea plantations in Assam in the first half of the nineteenth century, colonial tea planters and scientists began to examine ways to profitably produce tea for a growing global market. Apart from the visible landscape alterations through mass deforestation, tea monocultures also surreptitiously effected considerable transformation on its immediate physical environment, particularly on the soil. This paper highlights how the question of soil came under the purview of the colonial tea scientists when over the years, consequently and inevitably, these plantations showed a decline in the quality and quantity of tea produced. As a result, the initial conviction in the fertility of Assam’s soil within the tea discourse began to be replaced with discussions that revealed how plantation cultivation of tea itself was at the root of these problems in the late nineteenth and early twentieth centuries.

“It would taste better with sugar”—Navigating deprivation and confidence in everyday life on a tea plantation in Assam

SummaryThis story focuses on an ordinary working day on a tea plantation in Assam from the perspective of Jiya—a tea plucker on Dolani Tea Estate. It illustrates how Jiya navigates fundamental deprivations in her everyday life structured by the company's relentless siren without losing track of the scope for confident action. The photos, the plantation, the protagonist, and the incidents described in the story are based on real places, persons, and observations I encountered during thirteen months of fieldwork on Assam tea plantations between 2014 and 2017. However, the compilation of multiple observations into one day is a work of fiction. All names of persons and places in the story are pseudonyms. Quotations in the text are my own translations from Hindi into English.

Prevalence and Determinants Of Intergenerational Métiers Mobility of the Labourers of Assam Tea Gardens

The study aims to explore the intergenerational métiers mobility pattern of Assam tea garden labourers. Simultaneously, the current study unfolds the various factors responsible for this phenomenon. This predominantly empirical study utilises the Transition matrices and Multinomial Logistic Regression on 251 household-level primary data to explore the objectives. The empirical results disclose that horizontal motility is more prominent than vertical motility among the tea garden labourers of Assam. Various social-economic-demographic factors, like years of education, annual household expenditures, sex, and the number of dependents influence the vertical motility among the labourers of Assam tea gardens. The study also offer suitable policy prescriptions.

Quorum sensing activities and genomic insights of plant growth-promoting rhizobacteria isolated from Assam tea.

Secretion of quorum sensing (QS) molecules is important for the effective colonization of host plants by plant growth-promoting rhizobacteria. The current study aims at the isolation and characterization of tea rhizo bacteria, which produce the QS molecules, acyl homoserine lactone (AHLs), along with multiple plant growth-promoting (PGP) activities. Thirty-one isolates were isolated from the tea rhizosphere, and screening for PGP activities resulted in the selection of isolates RTE1 and RTE4 with multiple PGP traits, inhibiting the growth of tea fungal pathogens. Both isolates also showed production of AHL molecules when screened using two biosensor strains, Chromobacterium violaceum CV026 and Escherichia coli MT 102(jb132). The isolates identified as Burkholderia cepacia RTE1 and Pseudomonas aeruginosa RTE4 based on genome-based analysis like phylogeny, dDDH, and fastANI calculation. Detailed characterization of AHLs produced by the isolates using reverse-phase TLC, fluorometry, and LC-MS indicated that the isolate RTE1 produced a short chain, C8, and a long chain C12 AHL, while RTE4 produced short-chain AHLs C4 and C6. Confocal microscopy revealed the formation of thick biofilm by RTE1 and RTE4 (18 and 23μm, respectively). Additionally, we found several genes involved in QS, and PGP, inducing systemic resistance (ISR) activities such as lasI/R, qscR, pqq, pvd, aldH, acdS, phz, Sod, rml, and Pch, and biosynthetic gene clusters like N-acyl homoserine lactone synthase, terpenes, pyochelin, and pyocyanin. Based on the functional traits like PGP, biofilm formation and production of AHL molecules, and genetic potential of the isolates B. cepacia RTE1 and P. aeruginosa RTE4 appear promising candidates to improve the health and growth of tea plantations.

Sensorium

Sensorium