Impact of the Season on Total Polyphenol and Antioxidant Properties of Tea Cultivars of Industrial Importance in Northeast India.

Tocklai vegetative (TV) cultivars are extensively planted in the tea-growing regions of Northeast India. The present investigation explores the impact of season on the total polyphenol (TP) content and the antioxidant activity of thirty-one TV cultivars (TV1-TV31) and four other commercially popular cultivars, namely, Betjan, Kharijan, S.3A/3, and T.3E/3. The TP content of the cultivars was observed to be highest in the monsoon season, with values ranging from 230.57 to 283.53 mg g-1. In the pre-monsoon season and autumn, the TP content ranged from 197.87 to 256.77 mg g-1 and from 169.97 to 223.50 mg g-1, respectively. Antioxidant activity was measured through DPPH, ABTS, FRAP, and lipid peroxidation inhibition assays. The cultivars showed the highest antioxidant activity in the monsoon in tandem with TP content. A bivariate correlation indicated a highly significant (p ≤ 0.01) positive correlation of antioxidant activity with TP content (R2 = 0.83-0.96).

Assessment of gamma radiation through agro-morphological characters in camellia sinensis L. (O.) kuntze.

PURPOSE: To study the effects of gamma radiation on tea seed germination, morphological changes, and genetic variation by using gamma radiation. MATERIAL AND METHOD: Fresh Tea seed material were irradiated with twenty different doses of gamma radiation such as 0, 2, 4, 6, 8, 10, 15, 20, 25, 30, 40, 50, 60, 70, 80 90, 100, 200, 500 and 1000 Gy from Cobalt 60Co source from Regional Nuclear Agriculture Research Center, Bidhan Chandra Krishi Viswavidyalaya (BCKV), West Bengal, in between 2019 and 2020. RESULT AND CONCLUSION: The growth behavior of tea seedling was recorded under varying levels of gamma radiation and its performance at nursery stages. It was observed seed irradiated with doses from 35 Gy to 100 Gy could germinate but could not survive beyond five (05) months. When treated with higher doses as 200 Gy, 500 Gy and 1000 Gy, no seed germination takes places due to possible damages occur in the DNA structure. Screening of growth characteristics of tea plant generally monitored by the characteristics like plant height, number of leaves, number of primary branches, base diameter, and total leaf area of plants and we found that these characteristics significantly increased with the progress of time and increasing levels of gamma radiation; however, the plant height showed decreasing trend with the increasing levels of gamma radiation, which could be due to the change in chromosomal structure and genetic alteration. After 90 weeks of planting, the plant height, no. of primary branches, the number of leaves, plant base diameter, and total leaf area per plant recorded were 36.42 cm, 1/plant, 7.11/plant, 0.62 c.m, 22.92 cm2/plant respectively under the radiation level 30 Gy, whereas the corresponding figures of the above parameters at the control treatment were 85.32 cm, 1/plant, 18.84/plant, 1.18 c.m and 26.68 cm2/plant, respectively. The total plant height, no. of primary branches, the number of leaves, plant base diameter, and total leaf area per plant were significantly influenced by the rising levels of gamma radiation (up to 100 Gy), finally, after 90 weeks of planting, the maximum no. of branching was observed in the treatment of 8 Gy, 10 Gy and 15 Gy respectively. The study reveals a hitherto open the possibility of using gamma radiation on tea plant for creation of variation in the tea seed planting materials. Further studies on mutation using tea planting materials would give an insight into its mutable gene behavior.

Physiological and biochemical evaluation of high anthocyanin pigmented tea (Camellia sinensis L. O. Kuntze) germplasm for purple tea production.

Finding promising purple tea germplasm that would target new tea products for diversification and value addition boost the tea industry's economic growth. Accordingly, 10 tea germplasm viz. TRA St. 817, TRA St. 293, TRA St. 400, TRA 177/3, TRA 376/2, TRA 376/3, TRA 427/7, TRA P7, TRA P8, and TV1 were evaluated in terms of gas exchange parameters, multiplication performance, and biochemical markers such as chlorophyll, carotenoids, and anthocyanin content, which are related to the purple tea quality. The investigated gas exchange and biochemical parameters revealed significant differences. Germplasm TRA St.817 was physiologically more efficient (24.7 µmol m-2 s-1), followed by TRA St. 293, exhibiting the highest net photosynthesis, water use efficiency (19.02 µmol mmol-1), carboxylation efficiency (0.73), chlorophyll fluorescence or photochemical efficiency of PSII (0.754) and mesophyll efficiency (ci/gs ratio: 2.54). Net photosynthesis was positively correlated with water use efficiency, carboxylation efficiency, mesophyll efficiency, and photochemical efficiency of PSII (r = 0.965**, 0.937**, 0.857**, 0.867**; P = 0.05), respectively, but negatively correlated with the transpiration ratio (r = -0.878**; P = 0.05) based on Pearson correlation analysis. The total anthocyanin content (4764.19 µg.g-1 fresh leaf weight) and carotenoid content (3.825 mg.g-1 fresh leaf weight) were highest in the TRA St.817 germplasm, followed by germplasm TRA St. 293 (2926.18 µg.g-1 FW). In contrast, total chlorophyll content was significantly low (1.779 mg.g-1 fresh weight), which is very suitable for manufacturing purple tea. The highest carotenoid concentration in TRA St. 817 was 3.825 mg.g-1 FW, followed by TRA P8 (3.475 mg.g-1 FW), favoring the formation of more volatile flavor constituents. The promising germplasm, TRA St 817, has a multiplication success rate of 91.4% through cleft grafting. The outcome reveals that TRA St.817 is a promising germplasm that can be used to make speciality teas, i.e., purple tea.

Quality assessment of fresh tea leaves by estimating total polyphenols using near infrared spectroscopy.

This paper reports on the development of an integrated leaf quality inspecting system using near infrared reflectance (NIR) spectroscopy for quick and in situ estimation of total polyphenol (TP) content of fresh tea leaves, which is the most important quality indicator of tea. The integrated system consists of a heating system to dry the fresh tea leaves to the level of 3-4% moisture, a grinding and sieving system fitted with a 250 micron mesh sieve to make fine powder from the dried leaf. Samples thus prepared are transferred to the NIR beam and TP is measured instantaneously. The wavelength region, the number of partial least squares (PLS) component and the choice of preprocessing methods are optimized simultaneously by leave-one-sample out cross-validation during the model calibration. In order to measure polyphenol percentage in situ, the regression model is developed using PLS regression algorithm on NIR spectra of fifty-five samples. The efficacy of the model developed is evaluated by the root mean square error of cross-validation, root mean square error of prediction and correlation coefficient (R2) which are obtained as 0.1722, 0.5162 and 0.95, respectively.

Micronutrients (B, Co, Cu, Fe, Mn, Mo, and Zn) content in made tea (Camellia sinensis L.) and tea infusion with health prospect: A critical review.

Tea (Camellia sinensis L.) is a perennial acidophilic crop, and known to be a nonalcoholic stimulating beverage that is most widely consumed after water. The aim of this review paper is to provide a detailed documentation of selected micronutrient contents, viz. boron (B), cobalt (Co), copper (Cu), iron (Fe), manganese (Mn), molybdenum (Mo), and zinc (Zn) in made tea and tea infusion. Available data from the literature were used to calculate human health aspect associated with the consumption of tea infusion. A wide range of micronutrients reported in both made tea and tea infusion could be the major sources of micronutrients for human. The content of B, Co, Cu, Fe, Mn, Mo, and Zn in made tea are ranged from 3.04 to 58.44 µg g-1, below detectable limit (BDL) to 122.4 µg g-1, BDL to 602 µg g-1, 0.275 to 13,040 µg g-1, 0.004 to 15,866 µg g-1, 0.04 to 570.80 µg g-1 and 0.01 to 1120 µg g-1, respectively. Only 3.2 µg L-1 to 7.25 mg L-1, 0.01 µg L-1 to 7 mg L-1, 3.80 µg L-1 to 6.13 mg L-1, 135.59 µg L-1 -11.05 mg L-1, 0.05 µg L-1 to 1980.34 mg L-1, 0.012 to 3.78 µg L-1, and 1.12 µg L-1 to 2.32 µg L-1 of B, Co, Cu, Fe, Mn, Mo, and Zn, respectively, are found in tea infusion which are lower than the prescribed limit of micronutrients in drinking water by World Health Organization. Furthermore, micronutrient contents in tea infusion depend on infusion procedure as well as on the instrument used for analysis. The proportion of micronutrients found in different tea types are 1.0-88.9% for B, 10-60% for Co, 2.0-97.8% for Cu, 67.8-89.9% for Fe, 71.0-87.4% for Mn, 13.3-34% for Mo, and 34.9-83% for Zn. From the results, it can also be concluded that consumption of three cups of tea infusion per day does not have any adverse effect on human health with respect to the referred micronutrients rather got beneficial effects to human.

Spatial variability of theaflavins and thearubigins fractions and their impact on black tea quality.

The spatial distribution of theaflavin and thearubigin fractions and their impact on black tea quality were investigated using multivariate and geostatistics techniques. Black tea samples were collected from tea gardens of six geographical regions of Assam and West Bengal, India. Total theaflavin (TF) and its four fractions of upper Assam, south bank and North Bank teas were higher than the other regions. Simple theaflavin showed highest significant correlation with tasters' quality. Low molecular weight thearubigins of south bank and North Bank were significantly higher than other regions. Total thearubigin (TR) and its fractions revealed significant positive correlation with tasters' organoleptic valuations. Tea tasters' parameters were significantly and positively correlated with each other. The semivariogram for quality parameters were best represented by gaussian models. The nugget/sill ratio indicated a strong/moderate spatial dependence of the studied parameters. Spatial variation of tea quality parameters may be used for quality assessment in the tea growing areas of India.

Polyphenolic compounds and antioxidant activity of CTC black tea of North-East India.

Sixty black tea samples from different agro climatic zones of northeast India were assessed for biochemical constituents that determine quality and also influence organoleptic perception. The antioxidant activities such as α,α-diphenyl-ß-picrylhydrazyl (DPPH) free radical scavenging, lipid peroxidation inhibition, nitrite scavenging and super oxide scavenging, of the collected samples were analysed. Out of the four antioxidant activities, the super oxide scavenging activity was lowest and nitrite scavenging activity was highest. Theaflavin was significantly and positively correlated with nitrite scavenging and lipid peroxidation inhibition activities. Thearubigins showed a significant positive correlation only with nitrite scavenging activity. Correlations between relative antioxidant capacity index (RACI) and TF, TR and tasters' quality were positive and significant. Tea tasters' parameters were significantly and positively correlated with each other. Principal component analysis showed that Upper Assam, North Bank and South Bank produced better quality tea than other regions with respect to TF, TR, RACI and tasters' quality.

Biochemical evaluation of triploid progenies of diploid × tetraploid breeding populations of Camellia for genotypes rich in catechin and caffeine.

To verify the quality of triploid varieties of Camellia tea species at the secondary metabolite level, we tested caffeine and catechin profiles of 97 F(1) segregating progenies in two breeding populations with a common tetraploid parent and diploid parents of two geographic and varietal origins. Catechin and caffeine levels of the triploid progenies were quantified and compared against their diploid parent. Some of the progenies showed better performance than their diploid parent. Most of the progenies of the diploid C. sinensis × tetraploid cross showed heterosis for caffeine and EGCG. Progenies of the C. assamica subsp. lasiocalyx × tetraploid cross showed heterosis for +C, EC, EGC, and TC. The genomic contributions of the diploid parent seem to be the main factor in the variation between the two populations. Our studies showed quantitative enhancement of some of the quality-related parameters in tea, providing a platform to refocus on this classical breeding approach for developing quality cultivars in tea.

Diversity of catechin in northeast Indian tea cultivars.

Tea (Camellia sinensis L.) leaf contains a large amount of catechins (a group of very active flavonoids) which contribute to major quality attributes of black tea. Based on morphological characters tea plants were classified as Assam, China, and Cambod varieties. The present study is an attempt for biochemical fingerprinting of the tea varieties based on catechin composition in green leaf of cultivars grown in Northeast India. Assam variety cultivars contained the highest level of catechins followed by Cambod and China. The average catechin contents were 231 ± 7 mg g(-1), 202 ± 5 mg g(-1), and 157 ± 4 mg g(-1) of dry weight of green leaf for Assam, Cambod, and China cultivars, respectively. Among the individual catechins the variations in epigallocatechin gallate (EGCG) and epigallocatechin (EGC) were the most prominent among the varieties. High EGC content was found to be a characteristic of Assam variety which was further corroborated through multivariate analysis.