( SINC - FECYT - Spanish Foundation for Science and Technology )
A team of chemists from the University of Seville (US) has managed to distinguish between different kinds of tea leaves on the basis of their mineral content and by using artificial neural networks. This technique makes it possible to differentiate between the five main varieties of tea – white, green black, Oolong and red tea.
"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. ...
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%. ...
via Tea leaves identified using neural networks.
Why not just ask a botanist? Oh, because all the varieties come from the same plant.
There are at least six varieties of tea: white, yellow, green, oolong, black, and pu-erh of which the most commonly found on the market are white, green, oolong, and black. All teas are made from the same species of plant, though different varieties may be used, and the leaves are processed differently, and, in the case of fine white tea, grown differently. - wiki
Green tea is tea made solely with the leaves of Camellia sinensis that have undergone minimal oxidation during processing. - wiki
White tea (白茶) is a tea made with buds, and, in some cases, young leaves which are sun dried or dried by steaming. Like green tea, white tea is not oxidized. - wiki
Yellow tea ... usually implies a special tea processed similarly to green tea, but with a slower drying phase, where the damp tea leaves are allowed to sit and yellow. - wiki
Oolong ... is a traditional Chinese tea (Camellia sinensis) somewhere between green and black in oxidation. It ranges from 10% to 70% oxidation. - wiki
Black tea is a variety of tea that is more oxidized than the oolong, green, and white varieties... Black tea is generally stronger in flavor and contains more caffeine than the less oxidized teas. - wiki
What is oxidation, you ask? The wize geek has a nice answer:
Oxidation is defined as the interaction between oxygen molecules and all the different substances they may contact, from metal to living tissue. Technically, however, with the discovery of electrons, oxidation came to be more precisely defined as the loss of at least one electron when two or more substances interact. Those substances may or may not include oxygen. (Incidentally, the opposite of oxidation is reduction — the addition of at least one electron when substances come into contact with each other.) Sometimes oxidation is not such a bad thing, as in the formation of super-durable anodized aluminum. Other times, oxidation can be destructive, such as the rusting of an automobile or the spoiling of fresh fruit.
We often used the words oxidation and rust interchangeably, but not all materials which interact with oxygen molecules actually disintegrate into rust. In the case of iron, the oxygen creates a slow burning process, which results in the brittle brown substance we call rust. When oxidation occurs in copper, on the other hand, the result is a greenish coating called copper oxide. The metal itself is not weakened by oxidation, but the surface develops a patina after years of exposure to air and water. - wizegeek