Acest tip de ceai este cel mai popular in regiunea Pu'er de

langa Simao, Yunnan, China.

De altfel, de aici ii vine si numele. Ceaiul Pu-erh sau Puer se obtine din

frunzele foarte mari ale unei specii de Camellia Sinensis si se gaseste, in

principal sub doua forme: brut - raw (sheng) si copt sau invechit (shou).

Specific acestui tip de ceai este modul de prezentare, de la mici turtite (tou

cha) sau cuib de pasare, la "caramizi" de cei presat, pana la diverse forme

obtinute prin presarea lui.

Acest ceai se mai imparte in doua categorii importante: pu-erh verde

si pu-erh negru, in functie de procesul de obtinere. Diferenta

intre ceaiul verde si ceaiul pu erh verde este aceea ca, in primul caz, este

oprit procesul de oxidare, pe cand in celalalt, procesul de oxidare este

continuu, chiar daca viteza lui este foarte mica. Acest lucru face ca o

cantitate foarte mare de enzime sa se gaseasca in pu erh-ul verde,

conferidu-i acestuia deosebite calitati terapeutice.

Timpul de infuzare variaza de la cateva secunde pana la cateva minute,

insa, pentru cei care beau pentru prima oara acest ceai este recomandata

o infuzie usoara.

Beneficiile ceaiului Pu-erh

1. Previne bolile cardiovasculare

Consumul pe termen lung de ceai Pu-erh reduce tensiunea ridicata si

nivelul colesterolului, prevenind astfel bolile de inima. Ceaiul de acest tip

facut din frunzele arborilor salbatici batrani are efecte mai puternice,

continand un Qi ridicat (Qi-ul este "energia vietii"). El ajuta la o mai buna

functionare a sistemului circulator.

2. Detoxifica organismul.

Ceaiul Pu-erh elimina rapid toxinele din corp, poate vindeca dizenteria si

calmeaza durerile usoare.

3. Controleaza diabetul.

4. Te ajuta sa slabesti

Pu-Erh este unul dintre cele mai bune ceaiuri in ceea ce priveste reducerea

procentului de grasimi in organism. Este folosit in regimurile de slabire

pentru ca accelereaza metabolismul. Doza zilnica recomandata este de 3

cani, dupa fiecare masa, timp de trei luni. Dupa aceasta perioada, se poate

bea doar o cana pe zi – in scopul mentinerii greutatii dorite.

5. Echilibreaza tranzitul intestinal

Ceaiul Pu-erh faciliteaza digerarea alcoolului, zaharului si a carnii,

actionand direct asupra ficatului, stomacului si intestinelor. El echilibreaza

tranzitul intestinal, elimina dificultatile de digestie si balonarile.

6. Imbunatateste vederea si intarzie procesul de imbatranire

Pu-Erh-ul este un ceai foarte diferit de cele cunoscute în lumea occidentală. Acesta este ceaiul tradiţional al regiunii Yunnan. Frunzele folosite pot proveni fie de pe plantaţii, fie de pe copaci sălbatici din pădurile subtropicale ale regiunii.Numele acestui tip de ceai a fost preluat de la oraşul Pu’er, un important nod comercial din Yunnan aflat pe Drumul Ceaiului unde era vândut ceai de pe cei Şase Munţi Renumiţi ai Yunnan-ului.Pu-Erh-ul se împarte în două mari categorii:

Pu-Erh viu, verde (Sheng) Pu-Erh închis (Shu)

Prelucrarea acestui tip de ceai seamănă în mare parte cu prelucrarea ceaiului verde. Iniţial frunzele sunt lăsate să se usuce puţin, după care sunt rulate manual astfel pornindu-se oxidarea. Acest proces chimic este oprit prin prajirea ceaiului in wok (procedeu numit Sha qing), la fel ca în cazul ceaiului verde, diferenţa fiind că procedeul este repetat de mai puţine ori decât la cel verde. În urma acestor procese ceaiul îşi pierde jumătate din greutate si se numeşte mao cha.

Din mao cha sunt presate turtele de Pu-Erh viu. Presarea ceaiului in diferite forme avea din timpuri străvechi roluri practice. Astfel ceaiul era mult mai uşor de transportat de caravanele ce străbăteau Drumul Ceaiului, totodată păstrându-se si prospeţimea ceaiului datorită contactului mai redus cu aerul.În mod tradiţional ceaiul este presat între două pietre cu ajutorul greutăţii unui om care se urca pe ele. Totuşi în ziua de azi această practică este foarte rar întalnită, presarea fiind făcută de maşini care folosesc si aburi in proces, astfel ceaiul păstrându-şi mai bine forma.

În dinastia Tang toate ceaiurile (în afară de cel alb) care erau destinate nobilimii chineze erau presate.Odată cu trecerea anilor ceaiul presat suferă un proces de fermentare ulterioară numită Houfajiao. Prin acest proces Pu-Erh-ul viu devine mai bun şi mai valoros. La fel ca unele vinuri de înaltă calitate, şi acest tip de ceai, cu cât este mai vechi, cu atât este mai scump. Există turte de ceai care au fost vândute la un preţ mai ridicat decât valoarea greutăţii lor în aur.

Chiar şi în ziua de azi în China tinerii care se căsătoresc primesc din partea naşilor o turta de Pu-Erh. Forma de cerc a turtei reprezinta integritatea familie, iar ceaiul este simbolul longevităţii.

Pu-erh tea is made via a natural fermentation process. In this study, Pu-erh tea was used as a raw material for nanomaterials preparation and as an antibacterial agent. Antibacterial activities on Escherichia coli of Pu-erh tea, Pu-erh tea powder (PTP) of different sizes, and Pu-erh tea residual powder were firstly determined, respectively. With polyvinyl alcohol as the carrier, through an electrospinning technique, different kinds of nanofibrous membranes were obtained from the extract of Pu-erh tea and nano-PTP (NPTP), and their antibacterial properties and mechanism against E. coli were evaluated. The results showed better antibacterial activity with smaller PTP particles, the nano-sized particles had the best effects, and the MIC of NPTP was 13.5 mg/mL. When NPTP was in nanofibrous membranes, the antibacterial activity decreased slightly, but increased with modification by ZnO. Pu-erh tea in nanofibrous membranes damaged the E. colicell membranes and caused leakage of K+ and enzymes. What is more is that damage of the cell walls led to the leakage of fluorescent proteins from enhanced green fluorescence protein-expressing E. coli. These results indicate that the Pu-erh tea nanofibrous membranes had good antibacterial activities against E. coli, which may provide a promising application of novel antibacterial materials.

Multivariate Analysis Based on GC-MS Fingerprint and Volatile Composition for the Quality Evaluation of Pu-Erh Green Tea

Based on the fully automatic headspace solid-phase microextraction (HS-SPME)/gas chromatography-mass spectrometry (GC-MS) and multivariate statistical methods, a novel model of identifying and evaluating the quality of Yunnan Pu-erh green tea was constructed for the first time in this work. Twelve Pu-erh green teas from 12 typical production sites of Pu-erh district in Yunnan Province and 6 regular green teas from Zhejiang, Sichuan, Anhui, Henan, Hubei, and Jiangsu provinces of China were used to construct the model. Data from 18 green tea samples by GC-MS were processed with fingerprint technology and chemometric methods. The GC-MS fingerprints from 12 Pu-erh green teas whose correlation coefficients

and congruence coefficients were over 0.850 and demonstrated Pu-erh green tea samples from different production sites in Yunnan were consistent to some extent in spite of slightly different chemical indexes. A total of 77 volatile compounds were identified in 18 green teas, mainly including linalool, linalool oxides, phytol, caffeine, geraniol, and dihydroactinidiolide, and their chemical compositions were slightly similar. Cluster analysis (CA) and principal component analysis (PCA) demonstrated that 12 Pu-erh green teas could be clearly distinguished from other six regular green teas according to their chemical characteristics. Our results thus indicate that the chromatographic fingerprint combined with multivariate statistical techniques is useful for the identity and consistency evaluation of Pu-erh green teas. Such an approach is believed to be equally applicable to other green teas.

Tea is one of the most pleasant and popular beverages, and China is one of the largest tea producers, exporters, and consumers in the world, contributing 35.4 % to the total global production (Serpen et al. 2012). In China, tea can be classified into six different types based on different processing methods employed, such as white tea, green tea, oolong tea, black tea, yellow tea, and dark tea (Zhao et al. 2011a). In these different types of tea, green tea is a kind of non-fermented tea and represents 20 % of world consumption particularly in Asian countries like China, Korea, and Japan (Lambert and Elias2010). Taxonomically, there are mainly two different varieties of tea, Camellia sinensis var. sinensis and var. assamica. In China, the Camellia sinensis var.sinensis of tea plants grow slowly and have smaller leaves; they are mainly distributed in six provinces: Zhejiang, Sichuan, Anhui, Henan, Hubei, and Jiangsu, and are generally used for producing regular green tea. On the other hand, the Camellia sinensis var. assamica of tea plants are faster growing and have larger leaves, and they are mainly distributed in Pu-erh district of Yunnan Province, which are the best raw materials in manufacturing Pu-erh green tea (Hu et al. 2009; Zhao et al. 2011b).Pu-erh green tea is an agricultural product of geographical indication, and production regions are protected by the People’s Government of Yunnan Province. Based on this rule, only those products processed in the specific areas could be called Pu-erh green tea. Part of the Pu-erh green tea is further used to produce Pu-erh ripe tea (a kind of microbial post-fermentation tea), and its quality mostly depends on the choice of raw

materials and processing methods of Pu-erh green tea. Nowadays, Pu-erh green tea has gained high popularity with potential biological and medicinal benefits, such as anticancer, hypolipidemic, antioxidant, and eliminates effectively oxygen free radical, etc. (Du et al. 2012; Kuo et al. 2004).Because the processing methods of green tea is almost the same, namely, withering, pan firing, rolling, and drying, so these green teas from different production areas or plant varieties may have same appearance, aroma, or flavor characteristics, which make them quite difficult to differentiate. In recent years, the prices of Pu-erh green tea have shot skyward, and due to high added value of Pu-erh green teas, the authenticity identification of Pu-erh green tea is very important. False use of geographical origins not only damages the interests of consumers, but also harms the profits of tea producers (Huo et al.2014). To date, the identification and quality evaluation data on Pu-erh green tea are extremely deficient to support its drinking and consumption worldwide. Now, the China government has realized the importance of authenticity identification of Pu-erh green tea and is searching for new methods to solve this problem. So far, the quality of tea is still evaluated by traditional sensory evaluation method (Jumtee et al. 2011). However, this approach is a complicated work and long experiences, and time is required for completing it (Pongsuwan et al. 2006). Therefore, evaluating tea quality by employing a high reproducible instrumental would be popular and advantageous. Fingerprint technique has recently been widely used as an important approach for the quality evaluation and control of traditional Chinese medicine (TCM; Yi et al. 2009). It emphasizes a systematic “fingerprint” characterization of analytic target that contains a large number of information possible and relates to the classification of samples based on integral chemical background rather than characterizing a limited number of individual components (Pongsuwan et al. 2008). However, fingerprint technologies contain only limited information. In some situations, the limited fingerprint information may not be enough to reflect the comprehensive quality characteristics of some extremely complex samples, such as tea and TCM, so some fine distinctions between very similar chromatograms might be missed (Peng et al. 2011). Therefore, some multivariate statistical methods, such as principal component analysis (PCA) and cluster analysis (CA) have been proposed as proper tools to solve chromatographic problems and extract maximum useful information from the chromatographic fingerprints and thus improve the accuracy of results (Hakimzadeh et al. 2014; Ma et al. 2013; Song et al. 2012; Wu et al. 2013).

Gas chromatography-mass spectrometry (GC-MS) is often employed to investigate changes in tea volatiles because of its reproducibility, broad dynamic range, and high accuracy; meanwhile, GC-MS workstation system can be used for convenient qualitative and quantitative analysis of volatile compounds based on the standard mass spectral library and retention index (Liu et al. 2014; Yang et al. 2014; Yang et al. 2013a). As a sample preparation technique, headspace solid phase microextraction (HS-SPME) has been widely used for extracting aroma compounds in various foods because it takes less time and greater selectivity and is always used with GC-MS (Arisseto et al. 2013; Ye et al. 2012). CA and PCA as promising and useful methods also have been widely adopted to analyze aroma components of different foods and medicines, such as tallow (Song et al. 2013), vinegar (Cirlini et al. 2011), and Acorusspecies (Lee et al. 2013). Up to now, there are only some publications that discussed that quality control of Chinese Longjing green tea (Song et al. 2012; Wang et al. 2014) and oolong tea (Wang et al. 2011) involves fingerprint analysis of non-volatile compounds using high-performance liquid chromatography (HPLC) while there are no publications that discussed about fingerprint of green tea associated with volatile components by GC-MS. Therefore, it is very necessary to develop a comprehensive strategy to deal with chromatographic fingerprints of green tea by combination of GC-MS and multivariate chemometric methods.In previous study (Lv et al. 2014a), HS-SPME/GC-MS combined with chemometric methods has been used to distinguish Pu-erh ripe tea from Fuzhuan dark tea. Although a good distinction model has been established, previous study only involved the chemometric methods, so the obtained results are correspondingly short of some comparability with fingerprint analysis technology. In the current work, fully automatic HS-SPME coupled with GC-MS was used to construct characteristic fingerprint of Pu-erh green tea for the first time; CA and PCA technology coupled with GC-MS fingerprint data were used to further evaluate the similarity and differences between the samples. The objective of the present study was to establish characteristic fingerprint of Pu-erh green tea and provide a reliable and efficient methodology for quality control of green tea.

Materials and Methods

Materials

Twelve Pu-erh green teas were collected from 12 typical Pu-erh tea production sites in Pu-erh district of Yunnan Province and numbered as 1–12. In addition, regular green teas from six different provinces numbered as 13–18 were collected from Zhejiang, Sichuan, Henan, Anhui, Hubei and Jiangsu provinces, respectively, and used as controls compared with Pu-erh green teas. All 18 green teas were processed in 2013 and kept in aluminum foil bag and stored in a dry and cool place. Table 1 lists the name, regions, and harvest time of all 18 green teas.

Table 1

The details of the 18 green tea samples in the experiment

No. Name Regions Harvest time

1Pu-erh green tea

Huashan Township, Pu-erh district, Yunnan Province

Apr. 2013

2Pu-erh green tea

He Ping Township, Pu-erh district, Yunnan Province

May. 2013

3 Pu-erh green tea

Taizhong Township, Pu-erh district, Yunnan

Jun. 2013

No. Name Regions Harvest time

Province

4Pu-erh green tea

Wenlong Township, Pu-erh district, Yunnan Province

Jun. 2013

5Pu-erh green tea

Fudong Township, Pu-erh district, Yunnan Province

May. 2013

6Pu-erh green tea

Dajie Township, Pu-erh district, Yunnan Province

Apr. 2013

7Pu-erh green tea

Longjie Township, Pu-erh district, Yunnan Province

Apr. 2013

8 Pu-erh green tea

Tuantian Township, Pu-erh district, Yunnan

May. 2013

No. Name Regions Harvest time

Province

9Pu-erh green tea

Nuozhadu Township, Pu-erh district, Yunnan Province

Jun. 2013

10Pu-erh green tea

Nuofu Township, Pu-erh district, Yunnan Province

Jun. 2013

11Pu-erh green tea

Dashan Township, Pu-erh district, Yunnan Province

May. 2013

12Pu-erh green tea

Wuliang Township, Pu-erh district, Yunnan Province

Apr. 2013

13Longjing green tea

Hangzhou district, Zhejiang Province

May. 2013

No. Name Regions Harvest time

14Zhuyeqing green tea

Leshan district, Sichuan Province

Jun. 2013

15Liuanguapian green tea

Liuan district, Anhui Province

May. 2013

16Xinyangmaojian green tea

Xinyang district, Henan Province

Apr. 2013

17 Enshi green tea

Enshi district, Hubei Province

Apr. 2013

18Biluochun green tea

Suzhou district, Jiangsu Province

Jun. 2013

Sample Preparation

In previous study (Lv et al. 2014a), the HS-SPME parameters of Pu-erh ripe tea have been validated and optimized; therefore, the same method and parameters were adopted in this study for extracting volatile components of Pu-erh green tea. Using the same method would be advantageous for tracing the change of aroma compounds during the production process of Pu-erh ripe tea and provide a comprehensive comparison of the aroma components between Pu-erh green tea and ripe

tea, so as to realize the quality control of Pu-erh tea. A detailed explanation of the HS-SPME parameters follows below.

A total of 2.0-g ground tea sample was placed in a 20-mL sealed headspace vial with 5-mL boiling water, and the temperature of headspace vial was kept at 80 °C with an electric hot plate. Then, a 65-μm polydimethylsiloxane/divinylbenzene (PDMS/DVB) coating fiber (Supelco, Inc., Bellefonte, PA) was exposed to the sample headspace, placed for 60 min. All of the volatile compounds absorbed on the SPME fiber were desorbed at GC-MS injector at 250 °C for 3.5 min and then immediately analyzed by GC-MS. After adsorption, SPME coating fiber was transferred to GC injection port at 250 °C for 30 min.

Cluster Analysis

Unsupervised data analysis methods will only use the information contained in the p × m data matrix X of fingerprints, in order to evaluate the cluster tendency of the different samples, mainly including CA and PCA. These methods are applied as visualization techniques to validate the structure of the data. CA can be used to reveal the natural groups that exist in a data set based on the information provided by the measured variables. The similarity or diversity between different samples (objects) is usually represented in dendrogram for ease of explanation. The objects in the same group are similar to each other whereas different with another group (Chen et al. 2008). The relative contents of 77 aroma components in 18 samples were the elements of this new data matrix, and the data matrix with dimensions of 18 samples × 77 variables (volatile compounds) was constructed to perform CA. As can be seen from Fig. 4, CA shows a clear discrimination among 18 green teas. Cluster I was formed by the 12 samples collected from Pu-erh district in Yunnan Province; cluster II consisted of the samples 13–18 collected from six different provinces. Samples from different sites of the same production area were still clustered, which indicated that the internal quality of these samples was very similar to each other.

Repeatability and Stability Test

The repeatability of the method was determined by performing six replicate HS-SPME/GC-MS analyses on the Pu-erh green tea sample (no. 1) as list in Table 1, under the same extraction conditions. The results showed that similarities of all samples were more than 0.991, and the relative standard deviation (RSD) values of relative retention times and relative peak areas of volatile constituents were lower than 0.23 and 5.65 %, respectively, indicating that the developed method has a satisfactory repeatability. With the same extraction conditions and methods, the stability was determined at 0, 1, 2, 4, 8, 12, and 24 h by using the same sample (no.1), respectively. The results showed that similarities of all samples were more than 0.989. The RSD values of relative retention times and relative peak areas of volatile constituents were less than 0.39 and 4.28 %, respectively. The result suggested that it was feasible to analyze tea samples within 24 h. These results indicated that the developed method was reliable and applicable in the analysis of GC-MS fingerprint of Pu-erh green tea.