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Polyphenol Oxidase
Polyphenol oxidase (PPO; also polyphenol oxidase i, chloroplastic), an enzyme involved in fruit browning, is a tetramer that contains four atoms of copper per molecule. PPO may accept monophenols and/or ''o''-diphenols as substrates. The enzyme works by catalyzing the ''o''- hydroxylation of monophenol molecules in which the benzene ring contains a single hydroxyl substituent to ''o''-diphenols (phenol molecules containing two hydroxyl substituents at the 1, 2 positions, with no carbon between). It can also further catalyse the oxidation of ''o''-diphenols to produce ''o''-quinones. PPO catalyses the rapid polymerization of ''o''-quinones to produce black, brown or red pigments (polyphenols) that cause fruit browning. The amino acid tyrosine contains a single phenolic ring that may be oxidised by the action of PPOs to form ''o''-quinone. Hence, PPOs may also be referred to as tyrosinases. Common foods producing the enzyme include mushrooms ('' Agaricus bisporus ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Enzyme
An enzyme () is a protein that acts as a biological catalyst by accelerating chemical reactions. The molecules upon which enzymes may act are called substrate (chemistry), substrates, and the enzyme converts the substrates into different molecules known as product (chemistry), products. Almost all metabolism, metabolic processes in the cell (biology), cell need enzyme catalysis in order to occur at rates fast enough to sustain life. Metabolic pathways depend upon enzymes to catalyze individual steps. The study of enzymes is called ''enzymology'' and the field of pseudoenzyme, pseudoenzyme analysis recognizes that during evolution, some enzymes have lost the ability to carry out biological catalysis, which is often reflected in their amino acid sequences and unusual 'pseudocatalytic' properties. Enzymes are known to catalyze more than 5,000 biochemical reaction types. Other biocatalysts include Ribozyme, catalytic RNA molecules, also called ribozymes. They are sometimes descr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tyrosinase
Tyrosinase is an oxidase that is the rate-limiting enzyme for controlling the production of melanin. The enzyme is mainly involved in two distinct reactions of melanin synthesis otherwise known as the Raper–Mason pathway. Firstly, the hydroxylation of a monophenol and secondly, the conversion of an o-diphenol to the corresponding o-quinone. o-Quinone undergoes several reactions to eventually form melanin. Tyrosinase is a copper-containing enzyme present in plant and animal tissues that catalyzes the production of melanin and other pigments from tyrosine by oxidation. It is found inside melanosomes which are synthesized in the skin melanocytes. In humans, the tyrosinase enzyme is encoded by the ''TYR'' gene. Catalyzed reaction Tyrosinase carries out the oxidation of phenols such as tyrosine and dopamine using dioxygen (O2). In the presence of catechol, benzoquinone is formed (see reaction below). Hydrogens removed from catechol combine with oxygen to form water. The substra ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Smoothie
A smoothie is a beverage made by puréeing ingredients in a blender. A smoothie commonly has a liquid base, such as fruit juice or milk, yogurt or ice cream. Other ingredients may be added, including fruits, vegetables, non-dairy milk, crushed ice, whey powder or nutritional supplements. History of smoothies Health food stores on the west coast of the United States began selling smoothies with the invention of the electric blender. The actual term "smoothie" was being used in recipes and trademarks by the mid-1980s. In the 1960s Steve Kuhnau was inspired by his work as a soda jerk and began experimenting with smoothies. They were an alternative for the lactose intolerant Kuhnau to taste his own concoctions using unique blends of fruit juices, vegetables, protein powder, and vitamins. Kuhnau discovered early success in his smoothie sales and founded Smoothie King. Smoothie King expanded throughout the United States and would pioneer other smoothie businesses. The ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Berry
A berry is a small, pulpy, and often edible fruit. Typically, berries are juicy, rounded, brightly colored, sweet, sour or tart, and do not have a stone or pit although many pips or seeds may be present. Common examples of berries in the culinary sense are strawberries, raspberries, blueberries, blackberries, white currants, blackcurrants, and redcurrants. In Britain, soft fruit is a horticultural term for such fruits. The common usage of the term "berry" is different from the scientific or botanical definition of a berry, which refers to a fleshy fruit produced from the ovary of a single flower where the outer layer of the ovary wall develops into an edible fleshy portion( pericarp). The botanical definition includes many fruits that are not commonly known or referred to as berries, such as grapes, tomatoes, cucumbers, eggplants, bananas, and chili peppers. Fruits commonly considered berries but excluded by the botanical definition include strawberries, raspber ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Flavan-3-ol
Flavan-3-ols (sometimes referred to as flavanols) are a subgroup of flavonoids. They are derivatives of flavans that possess a 2-phenyl-3,4-dihydro-2''H''-chromen-3-ol skeleton. Flavan-3-ols are structurally diverse and include a range of compounds, such as catechin, epicatechin gallate, epigallocatechin, epigallocatechin gallate, proanthocyanidins, theaflavins, thearubigins. They play a part in plant defense and are present in the majority of plants. Chemical structure The single-molecule (monomer) catechin, or isomer epicatechin (see diagram), adds four hydroxyls to flavan-3-ol, making building blocks for concatenated polymers (proanthocyanidins) and higher order polymers (anthocyanidins). Flavan-3-ols possess two chiral carbons, meaning four diastereoisomers occur for each of them. They are distinguished from the yellow, ketone-containing flavonoids such as quercitin and rutin, which are called flavonol, flavonols. Early use of the term bioflavonoid was imprecisely applie ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lactuca Sativa
Lettuce (''Lactuca sativa'') is an annual plant of the family Asteraceae mostly grown as a leaf vegetable. The leaves are most often used raw in green salads, although lettuce is also seen in other kinds of food, such as sandwiches, wraps and soups; it can also be grilled. Its stem and seeds are sometimes used; celtuce (asparagus lettuce) is one variety grown for its stems, which are eaten either raw or cooked. In addition to its main use as a leafy green, it has also gathered religious and medicinal significance over centuries of human consumption. Europe and North America originally dominated the market for lettuce, but by the late 20th century the consumption of lettuce had spread throughout the world. , world production of lettuce (and chicory) was 27 million tonnes, 53percent of which came from China. Lettuce was originally farmed by the ancient Egyptians, who transformed it from a plant whose seeds were used to obtain oil into an important food crop raised for its succu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lettuce
Lettuce (''Lactuca sativa'') is an annual plant of the family Asteraceae mostly grown as a leaf vegetable. The leaves are most often used raw in Green salad, green salads, although lettuce is also seen in other kinds of food, such as sandwiches, wraps and soups; it can also be grilled. Its stem and seeds are sometimes used; celtuce (asparagus lettuce) is one variety grown for its stems, which are eaten either raw or cooked. In addition to its main use as a leafy green, it has also gathered religious and medicinal significance over centuries of human consumption. Europe and North America originally dominated the market for lettuce, but by the late 20th century the consumption of lettuce had spread throughout the world. , world production of lettuce (and chicory) was 27 million tonnes, 53percent of which came from China. Lettuce was originally farmed by the ancient Egyptians, who transformed it from a plant whose seeds were used to obtain oil into an important food crop raised fo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Musa (genus)
''Musa'' is one of three Genus, genera in the family Musaceae. The genus includes 83 species of flowering plants producing edible bananas and Cooking banana, plantains, and fiber (abacá), used to make paper and cloth. Though they grow as high as trees, banana and plantain plants are not woody and their apparent "Plant stem, stem" is made up of the bases of the huge leaf Petiole (botany), stalks. Thus, they are technically gigantic herbaceous plants. Description Banana plants are among the largest extant herbaceous plants, some reaching up to in height or in the case of ''Musa ingens''. The large herb is composed of a modified underground stem (rhizome), a false trunk or pseudostem formed by the basal parts of tightly rolled leaves, a network of roots, and a large flower spike. A single leaf is divided into a leaf sheath, a contracted part called a Petiole (botany), petiole, and a terminal leaf blade. The false trunk is an aggregation of leaf sheaths; only when the plant is r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Banana
A banana is an elongated, edible fruit – botanically a berry – produced by several kinds of large treelike herbaceous flowering plants in the genus '' Musa''. In some countries, cooking bananas are called plantains, distinguishing them from dessert bananas. The fruit is variable in size, color and firmness, but is usually elongated and curved, with soft flesh rich in starch covered with a peel, which may have a variety of colors when ripe. It grows upward in clusters near the top of the plant. Almost all modern edible seedless ( parthenocarp) cultivated bananas come from two wild species – '' Musa acuminata'' and ''Musa balbisiana'', or hybrids of them. ''Musa'' species are native to tropical Indomalaya and Australia; they were probably domesticated in New Guinea. They are grown in 135 countries, primarily for their fruit, and to a lesser extent to make banana paper and textiles, while some are grown as ornamental plants. The world's largest producers of bananas ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Persea Americana
The avocado, alligator pear or avocado pear (''Persea americana'') is an evergreen tree in the laurel family (Lauraceae). It is native to Americas, the Americas and was first domesticated in Mesoamerica more than 5,000 years ago. It was prized for its large and unusually Avocado oil, oily fruit. The tree likely originated in the highlands bridging south-central Mexico and Guatemala. Avocado trees have a native growth range from Mexico to Costa Rica. Its fruit, sometimes also referred to as an alligator pear or avocado pear, is botanically a large Berry (botany), berry containing a single large seed. Sequencing of its genome showed that the evolution of avocados was shaped by polyploidy events and that commercial varieties have a Hybrid (biology), hybrid origin. Avocado trees are partly Self-pollination, self-pollinating, and are often Plant propagation, propagated through grafting to maintain consistent fruit output. Avocados are presently cultivated in the tropical and Medi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Malus Domestica
An apple is a round, edible fruit produced by an apple tree (''Malus'' spp.). Fruit trees of the orchard or domestic apple (''Malus domestica''), the most widely grown in the genus, are agriculture, cultivated worldwide. The tree originated in Central Asia, where its wild ancestor, ''Malus sieversii'', is still found. Apples have been grown for thousands of years in Eurasia before they were introduced to North America by European colonization of the Americas, European colonists. Apples have cultural significance in many mythological, mythologies (including Norse mythology, Norse and Greek mythology, Greek) and religions (such as Christianity in Europe). Apples grown from seeds tend to be very different from those of their parents, and the resultant fruit frequently lacks desired characteristics. For commercial purposes, including botanical evaluation, apple cultivars are propagated by clonal grafting onto rootstocks. Apple trees grown without rootstocks tend to be larger and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
