Selena Ahmed

White and green teas (Camellia sinensis var. sinensis): variation in phenolic, methylxanthine, and antioxidant profiles.

Recent investigations have associated white teas with anti-carcinogenic, immune-boosting, and antioxidative properties that may impact human health in a manner comparable to green teas. An in-depth chemical analysis of white tea types was conducted to quantify polyphenols and antioxidant potential of 8 commercially available white teas, and compare them to green tea. Extraction and HPLC protocols were optimized and validated for the quantification of 9 phenolic and 3 methylxanthine compounds to examine inter- and intra-variation in white and green tea types and subtypes. A sampling strategy was devised to assess various subtypes procured from different commercial sources. Variation in antioxidant activity and total phenolic content (TPC) of both tea types was further assessed by the 1-1-diphenyl-2-picrylhydrazyl (DPPH) and Folin-Ciocalteau (F-C) assays, respectively. Total catechin content (TCC) for white teas ranged widely from 14.40 to 369.60 mg/g of dry plant material for water extracts and 47.16 to 163.94 mg/g for methanol extracts. TCC for green teas also ranged more than 10-fold, from 21.38 to 228.20 mg/g of dry plant material for water extracts and 32.23 to 141.24 mg/g for methanol extracts. These findings indicate that statements suggesting a hierarchical order of catechin content among tea types are inconclusive and should be made with attention to a sampling strategy that specifies the tea subtype and its source. Certain white teas have comparable quantities of total catechins to some green teas, but lesser antioxidant capacity, suggesting that white teas have fewer non-catechin antioxidants present. Practical Application: In this investigation white and green teas were extracted in ways that mimic common tea preparation practices, and their chemical profiles were determined using validated analytical chemistry methods. The results suggest certain green and white tea types have comparable levels of catechins with potential health promoting qualities. Specifically, the polyphenolic content of green teas was found to be similar to certain white tea varieties, which makes the latter tea type a potential substitute for people interested in consuming polyphenols for health reasons. Moreover, this study is among the first to demonstrate the effect subtype sampling, source of procurement, cultivation, and processing practices have on the final white tea product, as such analysis has previously been mostly carried out on green teas.

Commercial Teas Highlight Plant DNA Barcode Identification Successes and Obstacles

Appearance does not easily identify the dried plant fragments used to prepare teas to species. Here we test recovery of standard DNA barcodes for land plants from a large array of commercial tea products and analyze their performance in identifying tea constituents using existing databases. Most (90%) of 146 tea products yielded rbcL or matK barcodes using a standard protocol. Matching DNA identifications to listed ingredients was limited by incomplete databases for the two markers, shared or nearly identical barcodes among some species, and lack of standard common names for plant species. About 1/3 of herbal teas generated DNA identifications not found on labels. Broad scale adoption of plant DNA barcoding may require algorithms that place search results in context of standard plant names and character-based keys for distinguishing closely-related species. Demonstrating the importance of accessible plant barcoding, our findings indicate unlisted ingredients are common in herbal teas.

The food environment, its effects on dietary consumption, and potential for measurement within agriculture-nutrition interventions

The food environment in markets constrains and signals consumers what to purchase. It encompasses availability, affordability, convenience, and desirability of various foods. The effect of income on dietary consumption is always modified by the food environment. Many agricultural interventions aim to improve incomes, increase food availability and reduce food prices. Their effects on nutrition could be better understood if food environment measures helped to explain how additional income is likely to be spent, and how food availability and prices change as a result of large-scale interventions. Additionally, measurement of the food environment could elucidate food access gaps and inform the design of nutrition-sensitive interventions. This paper reviews existing measures of the food environment, and then draws from these tools to suggest ways the food environment could be measured in future studies and monitoring.

Effects of Extreme Climate Events on Tea (Camellia sinensis) Functional Quality Validate Indigenous Farmer Knowledge and Sensory Preferences in Tropical China

Climate change is impacting agro-ecosystems, crops, and farmer livelihoods in communities worldwide. While it is well understood that more frequent and intense climate events in many areas are resulting in a decline in crop yields, the impact on crop quality is less acknowledged, yet it is critical for food systems that benefit both farmers and consumers through high-quality products. This study examines tea (Camellia sinensis; Theaceae), the worlds most widely consumed beverage after water, as a study system to measure effects of seasonal precipitation variability on crop functional quality and associated farmer knowledge, preferences, and livelihoods. Sampling was conducted in a major tea producing area of China during an extreme drought through the onset of the East Asian Monsoon in order to capture effects of extreme climate events that are likely to become more frequent with climate change. Compared to the spring drought, tea growth during the monsoon period was up to 50% higher. Concurrently, concentrations of catechin and methylxanthine secondary metabolites, major compounds that determine tea functional quality, were up to 50% lower during the monsoon while total phenolic concentrations and antioxidant activity increased. The inverse relationship between tea growth and concentrations of individual secondary metabolites suggests a dilution effect of precipitation on tea quality. The decrease in concentrations of tea secondary metabolites was accompanied by reduced farmer preference on the basis of sensory characteristics as well as a decline of up to 50% in household income from tea sales. Farmer surveys indicate a high degree of agreement regarding climate patterns and the effects of precipitation on tea yields and quality. Extrapolating findings from this seasonal study to long-term climate scenario projections suggests that farmers and consumers face variable implications with forecasted precipitation scenarios and calls for research on management practices to facilitate climate adaptation for sustainable crop production.

Increased Market Integration, Value, and Ecological Knowledge of Tea Agroforests in the Akha Highlands of Southwest China

This study assesses the persistence and change of traditional land use patterns and ecological knowledge in response to expanded commercialization of tea (Camellia sinensis var. assamica (L.) Kuntze Theaceae) in an indigenous Akha (Hani) community in the midlevel montane forests of southwest Yunnan, China. Surveys were conducted in 2005 and 2008, over a period corresponding to a regional tea market boom and bust cycle, to compare the valuation smallholders attribute to land use types and to determine the role that value systems play in shaping environmental behavior and knowledge. At the community level, increased market integration of tea agroforests is associated with reconfiguration of land use, intensified management, reorganization of labor structures, and generation of knowledge on tea resources. Akha have tapped into customary resources and forged new social networks with tea industry agents to take advantage of emerging market opportunities. They have resisted state reforms calling for the cultivation of high-intensity plantations and introduced cultivars. Consequently, they have benefited from price premiums through niche market networks for tea sourced from agroforests and proprietary landraces not available to other communities disempowered by market cycles. Subsistence agriculture, home gardening, and foraging persist for food security despite tea wealth. However, as traditional values are reoriented toward market-based ideologies, the community may risk a breakdown of the social institutions that support sustainability.

Comparative homegarden medical ethnobotany of Naxi healers and farmers in Northwestern Yunnan, China

BackgroundHomegardens are ecologically and culturally important systems for cultivating medicinal plants for wellbeing by healers and farmers in Naxi communities of the Sino Himalayan region. The cultivation of medicinal plants in Naxi communities and associated ethnomedical knowledge base for maintaining and utilizing these resources is at risk with expanded commercialization of natural resources, development policies and rapid socio-economic change in China. Research is needed to understand the medicinal plant species maintained in Naxi homegardens, their use and contribution to community wellbeing, and how these practices and knowledge base varies between Naxi healers and farmers in order to develop plans for biodiversity conservation and preservation of ethnomedical practices. The main objective of this study is to document and compare medicinal plant species in Naxi homegardens and associated ethnomedical knowledge between Naxi healers and farmers.MethodsEthnobotanical homegarden surveys were conducted with three Naxi healers and 28 farmer households in two Naxi communities in Lijiang Prefecture in Northwest Yunnan Province of China. Surveys included inventories of medicinal plants in homegardens and semi-structured interviews with homegarden managers to document traditional medicinal uses of inventoried plants. Inventoried plants were classified into 13 ‘usage categories’ of medical condition groupings that impact a system of the body. Finally, plant species richness was calculated for each homegarden and species richness was compared between healers and farmers as well as between study sites using a Least Square Means Tukey HSD function.ResultsEthnobotanical surveys at the study sites found that 13% of households rely exclusively on traditional Naxi medicine, 26% exclusively use Western medicine and 61% use a combination of traditional Naxi and Western medicine. A total of 106 medicinal plants were inventoried in Naxi homegardens representing 50 botanical families. Over 85% of inventoried medicinal plants were herbaceous. The most represented families were Asteraceae (12.8%), Ranunculaceae (8.3%), Apiaceae (8.3%), and Polygonaceae (7.3%). The primary medical functions of inventoried plants were to treat inflammation (73 species), circulatory system disorders (62), nervous system disorders (41), detoxification (39), digestive system disorders (33), muscular-skeletal system disorders (26), genitourinary system disorders (26), skin conditions (23), respiratory systems disorders (22), and cold and flu (20). Local herbal experts maintained greater medicinal plant species richness in their homegardens compared to local farmers as well as had greater knowledge of medicinal functions of plants. Healers maintained medicinal plants primarily for healing while farmer households maintained approximately 90% of the medicinal plants in their homegardens for commercialization and the remaining for household healthcare.ConclusionsThis study highlights the importance of biodiversity and traditional ecological and medical knowledge for human wellbeing and livelihoods in Naxi communities. Conservation efforts and policies are necessary to preserve the ecological and cultural base that maintains medicinal plant use by both healers and farmers in Naxi homegardens of the Sino Himalayan region.

Metabolite profiling of Camellia sinensis by automated sequential, multidimensional gas chromatography/mass spectrometry reveals strong monsoon effects on tea constituents.

Seasonal variation in tea (Camellia sinensis (L.) Kuntze; Theaceae) chemistry was investigated using automated sequential, multidimensional gas chromatography/mass spectrometry (GC-GC/MS). Metabolite libraries were produced for teas harvested from the Bulang Mountains in Yunnan, China before and after the onset of the East Asian Monsoon. A total of 201 spring and 196 monsoon metabolites were identified, with 169 common and 59 seasonally unique compounds. An additional 163 metabolites were detected but their identity could not be confirmed. Spectral deconvolution of GC/MS data was used to measure the relative concentrations in the teas. Within each family individual metabolite concentrations increased, decreased and stayed the same. The major constituents in both teas were linalool (28%), geraniol (13%), α-terpineol (10%), hotrienol (4%) and nerol (3%). This work provides the foundation to monitor seasonal variations of tea chemistry.

Effects of Water Availability and Pest Pressures on Tea (Camellia sinensis) Growth and Functional Quality

Extreme shifts in water availability linked to global climate change are impacting crops worldwide. This study examines effects of water availability and pest pressures on the growth and functional quality of tea, the worlds most consumed beverage after water. Results show that higher water availability and pest pressures significantly increased the growth of new leaves while their effect on tea quality varied with individual secondary metabolites. Findings point to the fascinating dynamics of climate change effects on tea plants with offsetting interactions between rainfall and pest pressures and the need for future climate studies to examine interactive environmental effects.

Ethnobotanical survey of cooling herbal drinks from southern China

BackgroundLiáng chá (“cooling tea”, “herbal tea” or “cool tisane” in Chinese) are herbal drinks widely produced in southern China and consumed by billions of people worldwide to prevent and treat internal heat as well as a range of associated health conditions. Globalization and renewed interest in botanical remedies has attracted growing attention in cooling herbal drinks by industry, scientists and consumers. However, there is a knowledge gap on the plant species used and commercialized for cooling herbal drinks in southern China and their associated ethnobotanical use, habitat and conservation status. This is the first study to document plant species used and commercialized as liáng chá in southern China’s Lingnan region and associated ethnomedical function, preparation methods, habitat and conservation status.MethodsThree hundred market surveys were conducted between 2010-2012 in the largest herbal drink producing region of China to record plants used for liáng chá and to document knowledge on their medicinal function, habitat and conservation status. Product samples and voucher specimens were collected for taxonomic identification.ResultsAll informants harvest and cultivate plants for preparing herbal drinks for their medicinal, cultural and economic values. A total of 222 ethnotaxa corresponded to 238 botanical taxa (species, varieties or subspecies) belonging to 86 families and 209 genera were recorded as liáng chá to treat health conditions in the study area. Recorded remedies consisted of one or several plant species to treat conditions classified into 27 major health conditions with clearing internal heat being the most common medicinal function. The habitat types of plants documented for use as liáng chá include 112 wild harvested species, 51 species that are either wild harvested or cultivated, 57 cultivated species, and 2 naturalized species. According to China’s Red List and CITES on conservation status, one of these species is endangered, one species is critically endangered, eight species are vulnerable, one is listed in CITES II, three are listed in Regional Red Data Book and the remaining 224 species are in the least concerned conservation category.ConclusionsThe liáng chá industry of southern China reflects the plant species richness and cultural diversity of the region. Future research on safety and efficacy of herbal drinks as well as ecological and cultural conservation efforts are needed for the sustainable growth of China’s botanical industry.

Ethnobotany of dye plants in Dong communities of China.

BackgroundDyes derived from plants have an extensive history of use for coloring food and clothing in Dong communities and other indigenous areas in the uplands of China. In addition to use as coloring agents, Dong communities have historically utilized dye plants for their value for enhancing the nutritive, medicinal and preservative properties of foods. However, the persistence of plant-derived dyes and associated cultural practices and traditional knowledge is threatened with rapid socio-economic change in China. Research is needed to document the ethnobotany of dye plants in indigenous communities towards their conservation and potential commercialization as a sustainable means of supporting local development initiatives.MethodsSemi-structured surveys on plants used for coloring agents and associated traditional knowledge were conducted in fifteen Dong villages of Tongdao County in Hunan Province of South Central China during 2011–2012. Transect walks were carried out with key informants identified from semi-structured surveys to collect samples and voucher specimens for each documented plant species for taxonomic identification.ResultsDong households at the study sites utilize the flowers, bark, stems, tubers and roots of 13 plant species from 9 families as dyes to color their customary clothing and food. Out of the documented plants, a total of 7 are used for coloring food, 3 for coloring clothing and 3 for both food and clothing. Documented plants consist of 3 species that yield black pigments, 3 for brownish red/russet pigments, 3 for red pigments, 2 for dark blue pigments and 2 for yellow pigments. In addition to dyes, the plants have multiple uses including medicinal, ornamental, sacrificial, edible, and for timber.ConclusionsThe use of dyes derived from plants persists at the study sites for their important role in expressing Dong cultural identity through customary clothing and food. Further research is needed to evaluate the safety of dye plants, their efficacy in enhancing food items and their commercial potential. Conservation policies and management plans are called for to preserve these ethnobotanical resources in a sustainable manner that supports local livelihoods while maintaining cultural practices.