"This method makes it possible to clearly differentiate between the five types of tea – something that is often not easy to do by eye alone – by using analysis of the leaves' mineral content and then mathematically processing these data", José Marcos Jurado, co-author of the study and a researcher at the US, tells SINC.
The technique makes it possible to distinguish between the five main tea varieties (white, green, black, Oolong and red) using chemometrics, a branch of chemistry that uses mathematics to extract useful information from data obtained in the laboratory.
Firstly, the concentrations of the chemical elements in the leaves were determined using 'inductively-coupled plasma atomic emission spectroscopy', which showed the most abundant elements to be calcium, magnesium, potassium, aluminium, phosphorus and sulphur.
Other essential elements were also identified in the tea, such as copper, manganese, iron and zinc, according to this study, which has been published online in the journal Food Chemistry.
Once the mineral content of the leaves was established, probabilistic neural networks were used to find out which type of tea a sample belonged to. These networks are "mathematical algorithms that mimic the behaviour of the neurons in the human nervous system in order to process the information", the expert explains.
This generates a model that receives an input signal (chemical data) and produces an output one, making it possible to predict the type of tea in the sample with a probability of 97%.
The second most commonly drunk beverage in the world
Tea is the second most commonly drunk beverage in the world after water, and this has been the case since 2700BCE. This infusion is prepared from the plant Camellia sinensis. The five tea varieties result from the different kinds of preparation process that the leaves are subjected to after being harvested.
White tea is a non-fermented tea made up of new buds and leaves that are protected from sunlight as they grow in order to limit chlorophyll production. Green tea is another unfermented tea, but it is made by using older green leaves.
The Oolong and black tea varieties are made by fermenting the leaves, although in the first case these are completely fermented, while black tea undergoes an intermediate controlled fermentation process of between 10% and 70%.
Red, or Pu-erh, tea is a fermented product obtained from another variety of the plant, Camellia sinensis var assamica, which is cultivated in the Chinese region of Yunnan.
The health benefits of the leaves of this plant are well known. Aside from acting as an antioxidant, diuretic and relieving hypertension, it is also an important source of essential elements such as aluminium, copper, zinc, calcium and potassium.
James S. McKenzie, José Marcos Jurado y Fernando de Pablos. "Characterisation of tea leaves according to their total mineral content by means of probabilistic neural networks". Food Chemistry 123 (3): 859�, 2010. Doi: 10.1016/j.foodchem.2010.05.007.
SINC | EurekAlert!
The balancing act: An enzyme that links endocytosis to membrane recycling
07.12.2016 | National Centre for Biological Sciences
Transforming plant cells from generalists to specialists
07.12.2016 | Duke University
In recent years, lasers with ultrashort pulses (USP) down to the femtosecond range have become established on an industrial scale. They could advance some applications with the much-lauded “cold ablation” – if that meant they would then achieve more throughput. A new generation of process engineering that will address this issue in particular will be discussed at the “4th UKP Workshop – Ultrafast Laser Technology” in April 2017.
Even back in the 1990s, scientists were comparing materials processing with nanosecond, picosecond and femtosesecond pulses. The result was surprising:...
Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...
A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.
Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...
In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.
“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...
The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.
The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...
16.11.2016 | Event News
01.11.2016 | Event News
14.10.2016 | Event News
07.12.2016 | Health and Medicine
07.12.2016 | Life Sciences
07.12.2016 | Health and Medicine