Tea Glossary
GLOSSARY Provided by the Specialty Tea Institute, Foundations of Tea
A #
Amino acids – Critical to life, most importantly in their variety of roles in metabolism and as the building blocks of proteins. Amino acids can be linked together in varying sequences to form a vast variety of proteins. Amino acids are also important in other biological molecules, such as forming parts of enzymes.
Anabolic reactions – Reactions that build macromolecules, organs and tissues.
Antioxidant – A molecule capable of slowing or preventing the oxidation of other molecules. Oxidation reactions can produce free radicals, which start chain reactions that damage cells. Antioxidants terminate these chain reactions by removing free radical intermediates, and inhibit other oxidation reactions by being oxidized themselves.
B #
Biosynthesis – The formation of a chemical compound by a living organism.
C #
Carbohydrate – Carbohydrates serve as energy stores, fuels, and signaling molecules, mediating interactions between cells and interactions between cells and other elements in the cellular environment. They also make up a significant portion of the physical structure of plants. As a result, carbohydrates are one of the most abundant organic compounds on Earth. Carbohydrate is synonymous with saccharide (sugar.)
Catabolic reactions – Reactions that break macromolecules into constituent sub-units.
Catalyst – Any chemical compound that lowers the energy requirement for a reaction, thereby increasing the rate of the reaction. Unlike other compounds that participate in the chemical reaction, a catalyst is not consumed by the reaction itself.
Catechins – Polyphenolic plant metabolites. The term catechin is also commonly used to refer to the related family of flavonoids and the subgroup flavan-3-ols (or simply flavanols.)
Cell – The cell is the basic structural and functional unit of all known living organisms. It is the smallest unit of life that is classified as a living thing, and is often called ‘the building block of life.’
Cellulose - An organic compound known as a polysaccharide consisting of a linear chain of several hundred to over ten thousand linked glucose molecules. Cellulose is the structural component of the primary cell wall of green plants. Cellulose is the most common organic compound on Earth. On average, about 33 percent of all plant matter is cellulose.
Cell disruption – A method or process for releasing biological molecules from inside a cell.
Chloroplast – The key organelle for photosynthesis. Along with chlorophyll, it contains enzymes and co-enzymes necessary for the process of photosynthesis.
Cultivar– A cultivar is a cultivated plant that has been selected and given a unique name because of desired characteristics. The naming of a cultivar should conform to the International Code of Nomenclature for Cultivated Plants (the ICNCP, commonly known as the Cultivated Plant Code). For this, it must be distinct from other cultivars and it must be possible to reproduce it reliably, in the manner prescribed for that particular cultivar, either by sexual or asexual means. The word cultivar is generally regarded as a combination of ‘cultivated’ and ‘variety.’ The word cultivar is not interchangeable with the botanical rank of variety or with the legal term ‘plant variety.’ (‘Varietal’ is a wine term that does not apply to tea.)
Cytoplasm– The part of a cell that is enclosed within the plasma membrane. The cytoplasm houses the self-contained organelles. The cytoplasm is the site where most cellular activities occur. The inner, granular mass is called the endoplasm and the outer layer is called the cell cortex or the ectoplasm.
D #
Denaturation– A process in which proteins or enzymes lose their structure by application of some external stress or compound, such as a strong acid or base, or heat. If proteins in a living cell are denatured, this results in disruption of cell activity and possibly cell death. Denatured proteins can exhibit a wide range of characteristics including loss of solubility.
E #
Enzymatic browning (also referred to as enzymatic oxidation)– The result of polyphenols combining with polyphenol oxidase or other enzymes in the presence of oxygen. The resulting chemical processes create brown-hued melanins, resulting in a visibly brown color. The most important factors that determine the rate of enzymatic browning are the concentrations of active polyphenol oxidase and phenolic compounds, as well as pH, temperature and oxygen availability.
Enzymes – Proteins that catalyze biochemical reactions. Enzymes are catalysts in metabolism and catabolism. Most enzyme reaction rates are millions of times faster than those of comparable un-catalyzed reactions. As with all catalysts, enzymes are not consumed by the reactions they catalyze, nor do they alter the equilibrium of these reactions.
Epidermis – A single-layered group of cells that covers plants leaves, flowers, roots and stems. It forms the boundary between the plant and the external world. The epidermis serves several functions: it protects against water loss, regulates gas exchange, secretes metabolic compounds, and (especially in roots) absorbs water and mineral nutrients.
F #
Flush – The newest growth of leaves on a plant.
Free radical – Atoms, molecules, or ions with unpaired electrons on an otherwise open shell configuration. These unpaired electrons are usually highly reactive, so radicals are likely to take part in chemical reactions. Radicals play an important role in combustion, atmospheric chemistry, polymerization, and many other chemical processes, including human physiology.
Fermentation – (in tea processing) Traditionally the term used in the tea industry for the aerobic treatment of tea leaves to break down certain unwanted chemicals and modify others to develop the flavor of the tea, correctly known as oxidation. Dark teas, such as pu’erh, are teas that are actually fermented after processing, and continue to age and/or develop flavor.
G #
Glucose – A monosaccharide (or simple sugar) and a very important carbohydrate in biology. The living cell uses it as a source of energy and metabolic intermediate. Glucose is one of the main products of photosynthesis and starts cellular respiration.
H #
Hectare – 1 hectare = about 2.5 acres
I #
L #
Lipids – A broad group of naturally-occurring molecules which include fats, waxes, sterols, fat-soluble vitamins and others. The main biological functions of lipids include energy storage and as structural components. Although the term lipid is sometimes used as a synonym for fats, fats are a subgroup of lipids called triglycerides. Fatty acids are lipids.
M #
Macromolecule – A very large molecule most often created by some form of polymerization. The term may be applied to the four conventional biopolymers - nucleic acids, proteins, carbohydrates, and lipids.
Maintenance foliage – The established leaf growth of a cultivated plant that provides the metabolic resources for the maintenance of the plant while other parts are harvested.
Melanins – any various black, dark brown, reddish-brown, or yellow pigments found in plant (and animal) structures.
Metabolism – The set of chemical reactions in living organisms to maintain life. These processes allow organisms to grow and reproduce, maintain their structures, and respond to their environments. Metabolism is usually divided into two categories: catabolism and anabolism.
Metabolites – are the intermediates and products of metabolism. The term metabolite is usually restricted to small molecules. A primary metabolite is directly involved in the normal growth, development, and reproduction. A secondary metabolite is not directly involved in those processes, but usually has important ecological function. Examples include antibiotics and pigments.
Mouthfeel - A product's physical and chemical interaction in the mouth. It is evaluated from initial perception on the palate, to first bite, through mastication to swallowing and aftertaste.
N #
O #
Organelle – In cell biology, an organelle is a specialized major sub-cellular structure within a cell that has a specific function. It is usually separately enclosed within its own membrane.
Oxidation – (in chemistry) The loss of electrons or an increase in oxidation state by a molecule, atom or ion.
Oxidation – (in tea processing) The hydrolysis and oxidation of leaf constituents by enzymes.
P #
Pectin – A complex set of polysaccharides that are present in most primary cell walls and particularly abundant in the non-woody parts of terrestrial plants. Pectin is present throughout primary cell walls as well as between plant cells where it helps to bind cells together. The amount, structure and chemical composition of the pectin differs between plants, within a plant over time and in different parts of a plant.
Phloem – The living tissue that carries organic nutrients to all parts of the plant where needed. The phloem is concerned mainly with the transport of soluble organic material made during photosynthesis.
Photosynthesis – The chemical process in green plants where light energy is captured by chlorophyll in the chloroplasts of the leaves and used to convert water, carbon dioxide, and minerals into oxygen and energy-rich organic compounds (simple and complex sugars) that are the basis of both plant and animal life.
Polyphenol oxidase (PPO) – A class of enzymes widely distributed in nature. Polyphenol oxidase is thought to play an important role in the resistance of plants to microbial and viral infections and to adverse climatic conditions.
Polyphenol – Chemical substances found in plants characterized by the presence of more than one phenol unit or building block per molecule (poly = many + phenol.) Polyphenols are generally divided into hydrolyzable tannins (gallic acid esters of glucose and other sugars) and phenylpropanoids, such as lignins, flavonoids, and condensed tannins.
Primary metabolites – The organic compounds directly involved in normal growth, development, and reproduction.
Proteins – Complex organic macromolecules made of amino acids that contain carbon, hydrogen, oxygen, nitrogen, and usually sulfur. Proteins are fundamental components of all living cells and participate in virtually every process within cells. Many proteins are enzymes that catalyze biochemical reactions and are vital to metabolism.
Q #
S #
Secondary metabolites – The organic compounds not directly involved in the normal growth, development, or reproduction of organisms. Unlike primary metabolites, absence of secondary metabolites does not result in immediate death.
Substrate – The material or substance on which an enzyme acts.
T #
Taxonomy – The practice and science of classification.
Turgor pressure – The force exerted outward on the leaf’s cell walls by the water contained in the cell. This force gives the plant rigidity, and may help to keep it erect. Excessive turgor pressure may also result in the bursting of a cell.
U #
V #
Variety – In botanical nomenclature variety is a taxonomic rank below that of species. As such, it gets a name in three parts, i.e. Camellia sinensis sinensis. A variety will have an appearance distinct from other varieties, but will hybridize freely with those other varieties (if brought into contact.) Usually varieties will be geographically separate from each other. (‘Varietal’ is a wine term that does not apply to tea.)
Vacuole – A cellular sub-structure. It is defined by the vacuolar membrane called the tonoplast which separates the vacuolar contents from the cell's cytoplasm. Most mature plant cells have one large central vacuole that typically occupies at least one third of the cell's volume. Vacuoles store food which has been absorbed by the organism, and assist in the digestive and waste management processes for the cell. Another main role of the central vacuole is to maintain turgor pressure against the cell wall.
W #
X #
Xylem – Transport tissue whose major function is to move water, with hormones, mineral elements and other nutrients dissolved in it, throughout the plant.
Y #
Z #
