Detection and quantification of cashew in commercial tea products using High Resolution Melting (HRM) analysis.

Tea, a popular aromatic infusion and food supplement, prepared from Camellia sinensis (L.) Kuntze leaves, is often subjected to adulteration with various undeclared inorganic and plant-derived materials. Cashew (Anacardium occidentale L.) nut husk is one of the most common plant tea adulterants. To date, there are limited DNA-based technologies for tea authentication and quantitative detection of adulterants. Herein, we used a universal plant DNA barcoding marker coupled with High Resolution Melting (Bar-HRM) analysis to authenticate tea products from cashew ground nut. Additionally, cashew-specific markers coupled with HRM technology were used to detect and quantify adulteration of tea with cashew DNA. This methodology can reliably detect admixtures as low as 1% v/v cashew in commercial tea products. Overall, our results demonstrate that the HRM technology is a strong molecular approach in tea authentication, capable of detecting very low adulterations in DNA admixtures. PRACTICAL APPLICATION: In this study, we established the use of high-resolution DNA-based technologies for the detection of cashew adulteration in tea, even in very low quantities. The technology could be applied to a greater range of plant-based tea adulterants. This work is expected to facilitate the traceability and authenticity of tea products and form the basis for the development of strategies against fraudulent practices.

Differences in Chemical Composition among Commercially Important Cultivars of Genus Camellia.

Leaves from plants of the genus Camellia are used to make beverages and food products; however, there is limited data that compares the chemical composition of the unprocessed leaves of cultivars traditionally used to make these products. Plucked, fresh leaves from 14 commercially important cultivars were analyzed by ultra-performance liquid chromatography-quadrupole time-of-flight tandem mass spectrometry. On the basis of assessment of 61 compounds that are known to be affected by postharvest tea processing methods, significant variation among unprocessed cultivar leaves was observed for compounds in five chemical classes: amino acids, catechins, flavonoids and flavone glycosides, phenolic acids, and alkaloids. These chemical differences were of sufficient magnitude to render two distinct chemically defined clusters of Camellia cultivars that did not reflect the traditional grouping of these cultivars based by species variant, tea type, or production region. Advanced statistical techniques identified candidate biomarkers for each chemical class to guide the development of comprehensive targeted analyses for constituents of biosynthetic pathways in which marked expression plasticity was observed. Targeted analyses of this type have the potential to identify Camellia species/cultivars that will facilitate the formulation of new beverages and designer foods with improved organoleptic characteristic and enhanced prebiotic or nutraceutical activity.

Polycyclic aromatic hydrocarbons in teas using QuEChERS and HPLC-FLD.

Polycyclic aromatic hydrocarbons (PAHs) are food-processing contaminants considered to be carcinogenic and genotoxic. Due to its drying process stage, teas may be contaminated with PAHs. The aim of the study was to validate an analytical method involving QuEChERS and HPLC-FLD for the determination of PAH4 in teas and evaluate the contamination levels in 10 different types of teas from Brazil. Recoveries varied from 54% to 99% and relative standard deviations from 1% to 21%. Limits of detection and quantification were from 0.03 to 0.3 µg/kg and 0.1 to 0.5 µg/kg, respectively. Mate tea presented the highest PAH levels, with PAH4 varying from 194 to 1795 µg/kg; followed by black (1.8-186 µg/kg), white (24-119 µg/kg), and green teas (3.1-92 µg/kg). Teas with lowest PAH4 were strawberry, lemongrass, peppermint, and boldo. Only trace levels of PAHs were detected in tea infusions, so apparently it would not affect PAH intake by Brazilian population.

Immobilized tannase treatment alters polyphenolic composition in teas and their potential anti-obesity and hypoglycemic activities in vitro.

The aim of this work was to assess the effect of immobilized-tannase treatment on black, green, white and mate tea components and on their bioactivities relevant to obesity. Tannase treatment caused predictable changes in polyphenol composition with substantial reduction in galloylated catechins in green, white and black tea. Mate tea, which is rich in chlorogenic acids, was much less affected by tannase treatment although some degradation of caffeoyl quinic acid derivatives was noted. The original tea samples were effective in inhibiting digestive enzymes in vitro. They inhibited amylase activity, some with IC50 values ∼70 µg mL(-1), but were much less effective against α-glucosidase. They also inhibited lipase activity in vitro and caused dose-dependent reductions in lipid accumulation in cultured adipocytes. The bio-transformed tea samples generally matched the effectiveness of the original samples but in some cases they were markedly improved. In particular, tannase treatment reduced the IC50 value for amylase inhibition for green tea and white tea by 15- and 6-fold respectively. In addition, the bio-transformed samples were more effective than the original samples in preventing lipid accumulation in adipocytes. These in vitro studies indicate that bio-transformed tea polyphenols could assist in the management of obesity through improvement in energy uptake and lipid metabolism and also indicate that biotechnological modification of natural food molecules can improve the benefits of a common beverage such as tea.

Age and gender differences in the influence of extrinsic product information on acceptability for RTD green tea beverages.

BACKGROUND: The introduction of ready-to-drink (RTD) green tea beverage has allowed diverse consumers to consume green teas and related products. Green tea that has been traditionally consumed for its delicate flavor characteristics is also widely consumed for its recognition as a healthy product. Because it is reported that age difference exists in consideration of health-related information, the objective of the study was to investigate how sensory and non-sensory factors, in particular health-related information, price and packaging, would affect the flavor acceptability of green tea beverages, depending on consumers' age and gender. RESULTS: Regardless of the product information, old consumers preferred products that provided an indication of health beneficial effect. On the other hand, young consumers tended to be influenced by extrinsic product information such as packaging, brand/manufacturer and/or price, though these consumers were not so much influenced by health beneficial information as were the old consumers. CONCLUSION: The findings of the study implied that the influence of non-sensory information such as health beneficial information in flavor liking differed depending mostly on consumers' age, and little on gender, for RTD green tea beverages.

Effects of climate change on the economic output of the Longjing-43 tea tree, 1972-2013.

Based on phenological and economic output models established and meteorological data from 1972 to 2013, changes in the phenology, frost risk, and economic output of the Longjing-43 tea tree in the Yuezhou Longjing tea production area of China were evaluated. As the local climate has changed, the beginning dates of tea bud and leaf plucking of this cultivar in all five counties studied has advanced significantly by -1.28 to -0.88 days/decade, with no significant change in the risk of frost. The main tea-producing stages in the tea production cycle include the plucking periods for superfine, grade 1, and grade 2 buds and leaves. Among the five bud and leaf grades, the economic output of the plucking periods for superfine and grade 1 decreased significantly, that for grade 2 showed no significant change, and those for grades 3 and 4 increased significantly. The economic output of large-area tea plantations employing an average of 45 workers per hectare and producing superfine to grade 2 buds and leaves were significantly reduced by 6,745-8,829 yuan/decade/ha, depending on the county. Those tea farmers who planted tea trees on their own small land holdings and produced superfine to grade 4 tea buds and leaves themselves experienced no significant decline in economic output.

A comparison of the flavor of green teas from around the world.

BACKGROUND: Green teas can be grouped based on their flavor profiles. The country of origin appears to have a strong influence on the flavor of green tea probably because similar processing methods are widely used within each particular country and flavor is dependent, in part, on processing. The aim of this article is to determine what flavor differences exist among a wide range of green teas (n = 138) produced in various countries. RESULTS: In this study we found that roast-processed teas were mostly responsible for brown-related flavors and steam-processed teas were responsible for green-related flavors. The prices of the green teas did not differentiate the flavors of the samples. Often highly priced green teas were grouped with low-priced green teas from the same manufacturer or country of origin according to their flavor attributes. CONCLUSIONS: Differences in the tea plant varieties or cultivars likely affects flavors in green tea. However, those were not known for many samples in this research and more study will be needed to determine the effects of specific differences in varieties or cultivars.

Heavy metal content of black teas consumed in Iran.

Tea (Camellia sinensis) is the most widely consumed beverage in several parts of the world. Tea consumption is a major component of the traditional Iranian diet; however, limited data are available indicating heavy metals content of this beverage. This study aimed to assess concentrations of heavy metals, including copper, lead, cadmium, chromium and mercury as well as minerals like zinc and iron in black tea samples. Atomic absorption spectrometry was used to determine the elements of interest in 20 brands of black tea that are widely consumed among Iranians. The mean concentrations were 28.8 for Zn, 135.2 for Fe, 15.9 for Cu and 8.2 for Cr (mg kg⁻¹) and 134.5 for Cd, 209.5 for Pb and 40 for Hg (µg kg⁻¹). It is concluded that tea consumption can be a possible source of some heavy metal intake for the Iranian population.

Aflatoxins in black tea in Iran.

Aflatoxins (AFs) are highly toxic, and carcinogenic secondary fungal metabolites and have been detected in various food commodities. In this regard, 40 black tea samples including domestic and imported black tea were analysed for aflatoxin contamination by high-performance liquid chromatography using a post-column derivatisation procedure (Kobra cell) with fluorescence detection. Samples were randomly collected in 2010 from Tehran markets. The results revealed that 30 among 40 samples were contaminated with aflatoxins (27.5% of the total). Mean AFB1 content was 10.0 ng/g and mean of aflatoxin total was 12.07 ng/g for the 11 contaminated samples.

Lead, cadmium, arsenic, mercury and copper levels in Chinese Yunnan Pu'er tea.

The Yunnan region of China produces a distinctive variety of Pu'er tea, which is consequently labeled as a Chinese geographic indication product. In this study, the safety of Chinese Yunnan Pu'er tea with regard to heavy metal content was evaluated in 30 different brands of Pu'er tea, including 150 commercial samples. Metal levels in the Pu'er tea samples followed the order: copper (12-22 µg/g) > lead (0.26-3.2 µg/g) > arsenic (0.035-0.24 µg/g) > cadmium (0.0059-0.085 µg/g) > mercury (<0.010 µg/g). Mercury was not detected in 17 of the brands of Pu'er tea. Metal-to-metal correlation studies showed that there were no significant correlation between metal pairs. Based on current safety standards, the low levels of metals detected in these Pu'er tea samples mean they are safe for human consumption.

Effect of cigarette taxes on the consumption of cigarettes, alcohol, tea and coffee in Taiwan.

OBJECTIVES: To analyse whether a health tax of 10 New Taiwan Dollars (NT$) (US$0.3) imposed on cigarettes in 2009 will help to reduce cigarette consumption, and whether or not the cigarette tax will affect consumption of alcohol, coffee and tea. STUDY DESIGN: Time series data for consumption and retail prices of tobacco, alcohol, tea and coffee were collected and analysed for the period 1973-2007. METHODS: To establish the Central Bureau of Statistics demand function to estimate the overall demand price elasticities of cigarettes, alcohol, tea and coffee, a seemingly unrelated regression analysis was used. The independent variables were annual consumption of cigarettes, alcohol, tea and coffee. The dependent variables were prices of and expenditures on cigarettes, alcohol, tea and coffee. RESULTS: The estimated own-price elasticities for cigarettes and alcohol are close to -0.726. The own-price elasticities for tea and coffee are less than those for cigarettes and alcohol. Hence, it is predicted that the NT$10 health tax on cigarettes will reduce cigarette consumption by a significant 13.19%. Analysis of cross-price elasticity reveals that alcohol is complementary to cigarettes. CONCLUSIONS: Taxation is an effective smoking control policy tool that not only helps to reduce consumption of cigarettes, but also reduces consumption of alcoholic beverages.

AFLP-based genetic diversity assessment of commercially important tea germplasm in India.

India has a large repository of important tea accessions and, therefore, plays a major role in improving production and quality of tea across the world. Using seven AFLP primer combinations, we analyzed 123 commercially important tea accessions representing major populations in India. The overall genetic similarity recorded was 51%. No significant differences were recorded in average genetic similarity among tea populations cultivated in various geographic regions (northwest 0.60, northeast and south both 0.59). UPGMA cluster analysis grouped the tea accessions according to geographic locations, with a bias toward China or Assam/Cambod types. Cluster analysis results were congruent with principal component analysis. Further, analysis of molecular variance detected a high level of genetic variation (85%) within and limited genetic variation (15%) among the populations, suggesting their origin from a similar genetic pool.