Tea Granules Research Articles

Process technology for production of soluble tea powder

Instant tea is presently manufactured by spray/freeze drying of the concentrated brew of processed tea leaves/dust and the drawbacks of this method are inferior quality, high cost and energy. A novel technique has been developed for the production of instant/soluble tea powder from the expressed juice of green leaves. After plucking, the leaves are crushed and juice pressed out. The juice is then subjected to fermentation under specified conditions. The fermented juice is steamed, centrifuged and freeze-dried to get instant tea powder. The pressed leaf residue is subjected to fermentation and drying for preparation of tea granules. The instant tea produced is of good liquoring characteristics and various constituents are also in the acceptable range [Theaflavin (TF) to Thearubigin (TR) ratio – 10.71 for instant tea (IT) and 12.12 for tea granules (TG), Caffeine content 40.4 mg/cup of IT and 96 mg per cup of TG]. The tea granules produced is comparable to CTC (crushing, tearing & curling) tea in quality and liquoring characteristics. There is considerable savings in the economy as the juice and residue are converted into value added products in this method.

Optimization of Fermentation Time in Instant Tea Production

Fermentation should be optimum for the production of good quality tea. One of the methods commonly followed today is based on the amount of theaflavin (TF) formed during fermentation. For this, samples (juice for instant tea (IT) and pressed leaf residue for black tea granules (TG» were collected at specific interval of time during fermentation and the optical density values were determined by a spectrophotometer. Optimum period was indicated by the peak of the curve obtained by plotting optical density (00) values of the sample vs. fermentation time. The optimum fermentation time for IT was I h and for TG was 1.5 h. The amount of TF formed, as indicated by the increase in 00 in juice increased with increase in fermentation time up to 60 min and after that it decreased. Similar trend was found for pressed leaf residue also where the 00 increased up to 90 min. The decrease in theaflavin content beyond a certain time may be due to the conversion of theaflavin to the a FU bigins (TR). The result was emphasized by another experiment in which IT and TG were prepared with different fermentation times, and the prepared samples were analyzed for the quality by a sensory evaluation panel

Characterization and quantification of eight water-soluble constituents in tubers of Pinellia ternata and in tea granules from the Chinese multiherb remedy Xiaochaihu-tang

In traditional Chinese medicine, multiple herbs are usually used in combination to generate the joint actions of a multiherb remedy. The recent development of LC-hyphenated techniques enables efficient and rapid profiling of the chemical constituent in extracts from multiherb remedies. Xiaochaihu-tang is a seven-herb remedy that has attracted a great deal of attention for reported ability to treat liver dysfunction. Dried tubers of Pinellia ternata (banxia in Chinese) is one of the ingredients, but its chemical contribution to Xiaochaihu-tang remains poorly understood. In the study presented here, LC-UV-MS, LC-MS-MS, and LC-NMR were used in a complementary manner to determine the nature and content of eight water-soluble constituents of banxia and their presence in various tea granules from Xiaochaihu-tang. Among the eight chemicals identified in banxia, cytidine, adenosine, tryptophan, uridine, and adenine are reported for the first time, while tyrosine, guanosine, and phenylalanine were previously described. These chemicals are also present in all of the samples of Xiaochaihu-tang granules, and the amounts of the chemicals ingested due to a daily dose of the multiherb remedies range from 0.008 to 6.3mg.

Wavelet transform based image texture analysis for size estimation applied to the sorting of tea granules

This paper describes a new texture feature estimation technique for discriminating images of eight different grades of CTC (cutting, tearing, and curling) tea. This new set of feature vectors can discriminate the images of different sized tea granules with more efficiency than the statistical feature vectors do. The technique conjugates the feature information of one group of images along with the information of rest of the groups. This is executed by considering range of different groups of images of the same granule size. Indeed, ranges are estimated using the existing statistical texture features, namely variance, entropy and energy, in difference form. Daubechies’ wavelets transform (WT) based sub-band images are utilized for calculating these statistical features. The techniques, for estimating these ranges and calculating the final feature set, adopt a simplified version of Mahalanobis distance calculation. Later, the data visualization method, principal component analysis (PCA), which is used to visualize the existing classes of textures, has found distinguishable characteristics among the new feature sets. It is further observed that the unsupervised clustering algorithm self organizing map (SOM) can classify the images efficiently into appropriate clusters. Two neural networks, namely multi-layer perceptron (MLP) network and learning vector quantization (LVQ) were used for texture classifications. The classification accuracy, for example 74.67% and 80% in MLP and LVQ, respectively, outperforms the other results obtained by using existing statistical texture features.

Fluoride levels in various black tea commodities: Measurement and safety evaluation

In order to determine the fluoride content of various products of black tea and to make safety evaluations, 37 commodities in the different manufactured forms of tea were assessed by means of ion-selective electrode and spectrophotometric methods. The results showed wide differences in fluoride levels. The fluoride content was found 0.95–1.41 mg/L in black tea sticks, 0.70–2.44 mg/L in black tea granules and 1.15–6.01 mg/L in black tea bags. Of the products tested, the fluoride content was greatest in black tea bags, presumably because black tea bags are made of low cost, and older tea leaves. According to WHO’s recommendation, fluoride exposure threshold for children is 2 mg of daily intake and for adult, 4 mg. Assuming that children’s daily intake of black tea was 800 ml and adult’s 1500 ml, 56% of black tea bags should be considered unsafe for children and 44% should be considered unsafe for adults. At average rates of consumption, 24% of the black tea bags could result in an increasing risk of osteofluorosis and fractures (WHO). In the areas with drinking water fluoridation or other fluoride supplements, excessive fluoride exposure can become even more severe with even lower intake tea made from black tea bags. The potential hazards of fluoride arising from consumption of black tea has not aroused due public attention. Therefore, it is necessary to establish reliable fluoride surveillance in food and beverage commodities and conduct additional epidemiological research on fluoride hazards. In addition, it is urgent that governmental and international agencies adopt safe standards of fluoride content in tea commodities.

Sonoelectroanalysis--an overview.

The coupling of power-ultrasound with well established but under-exploited electrochemical stripping voltammetry has led to the emergence of a powerful new analytical technique--sonoelectroanalysis. Where classical electroanalytical techniques were plagued with electrode-fouling and/or sensitivity limitations, the introduction of ultrasound into the system has given great increases in analytical efficiency and substrate applicability, predominantly through enhanced mass transport and electrode surface activation. This revitalised analytical technology has been applied to a range of modern analytical problems, allowing sensitive determination of a wide number of analytes from a variety of otherwise hostile matrices, including copper in beer and blood, lead in wine, petrol and river bed sediment, vanadium in aqueous media, nitrite in egg and manganese in instant tea granules. This paper gives an overview of these recent advances.