OBJECT Essays - Food And Drink, Chemistry, Fruit Juice, Biochemistry

OBJECT Essays - Food And Drink, Chemistry, Fruit Juice, Biochemistry OBJECT Inhibition of Polyphenol Oxidase activity in Apple by using some natural and synthetic anti browning agents . REQUIREMENTS Acidic fruit juices (pineapple, orange, lime, lemon ) 1% Salt solution 1% HCL solution 1% NAOH solution Tap water Apple slice s THEORY E nzymatic browning is one of the most important reactions that occur in fruits and vegetables, usually resulting in negative effects on color, taste, flavor, and nutritional value. The reaction is a consequence of phenolic compounds' oxidation by polyphenol oxidase (PPO), which triggers the generation of dark pigments. This is particularly relevant for apples, which are rich in polyphenols and highly su sceptible to enzymatic browning. In plant cells, phenolic compounds are located in the vacuoles, whereas polyphenol oxidase ( PPO) is located in plastids. Damaged areas in cells allow the contact between PPO and phenolic compounds, triggering the reaction known as enzymatic browning. Examples of beneficial enzymatic browning: Developing color and flavor in Coffee, Cocoa beans, and tea. Developing color and flavor in dried fruit such as figs and raisins. Examples of non-beneficial enzymatic browning: A non-desirable enzymatic browning reaction is involved in the formation of brown spots on the peel of bananas ,avocados,apples and potatoes Polyphenols - main components in enzymatic browning Polyphenols , also called phenolic compounds, are group of chemical substances present in plants (fruits, vegetables) which play an important role during enzymatic browning, because they are substrates for the browning-enzymes. Phenolic compoun ds are responsible for the colo r of many plants, such as apples, they are part of the taste and flavo r of beverages (apple juice, tea), and are important anti-oxidants in plants. Polyphenols are normally complex organic substances, which contain more than one phenol group (carbolic acid): Polyphenol oxidase (PPO ) Polyphenoloxidases are a class of enzymes that were first discovered in mushrooms and are widely distributed in nature. They appear to reside in the plastids and chloroplasts of plants, although freely existing in the cytoplasm of senesci ng or ripening plants. Polypheno loxidase is thought to play an important role in the resistance of plants to microbial and viral infections and to adverse climatic conditions. Polyphenoloxidase also occurs in animals and is thought to increase disease resistance in insects and crustaceans. In the presence of oxygen from air, the enzyme catalyzes the first steps in thebiochemicalconversion of phenolics to produce quinones, which undergo further polymerization to yield dark, insoluble polymers referred to as melanins . These melanin form barriers and have antimicrobial properties which prevent the spread of infection or bruis ing in plant tissues. Example of a general reaction of polyphenols by Polyphenol Oxidases that catalyzes enzymatic browning. The production of Quinones undergoes more reactions which eventually form brown pigments on the surface of fruits and vegetable. PREVENTION OF ENZYMATIC BROWNING The control of the enzymatic browning is of great importance to the horticulture industry, because this reaction occurs in many fruits and vegetables, often negatively affecting the attributes of color, taste, flavor, and nutritional value. It is estimated that more than 50% of fruit market losses ar e a result of enzymatic browning . Researchers are especially interested in studying the control (inhibition) of browning by different methods that can be employed to maximize this inhibition and ultimately pr olong the shelf l ife of commodity.Several methods can be applied to avoid enzymatic browning, based on inactivating the enzyme (heat) or by removing essential components (m ost often oxygen) from the product Blanching is a short heat treatment to destroy or inactivate enzymes before freezing of prod ucts (mainly vegetables). The enzyme activity is pH dependent. Lowering of the pH to 4.0 by the addition of citric,ascorbicor otheracidsinhibits the enzyme activity. Addition of chemical inhibitors like acidulants ,chelating agents, reducing agents may also directly react with enzyme and substrate or change the product composition . METHOD Cut one apple into small thin slices in such way that its pulp portion is exposed to our reagent . Separately place an apple slice in petri dishes and labeled them . With natural anti browning agent, in four samples out of all, squeeze some suitable amount of fresh fruit juices on apple slice. With the synthetic browning agent, firstly prepare solutions

Countries That Lie on the Earths Equator

Countries That Lie on the Earths Equator Although the equator stretches  24,901 miles  (40,075 kilometers) around the world, it travels  through the territory of just 13 countries- and yet the landmasses of two of these countries do not touch the Earths  equator. Did You Know? The equator is an imaginary line that circles the Earth, splitting it into northern and southern hemispheres. Any location that lies along the equator is equidistant from the North and South Poles. The 13 Countries That Lie on the Equator Of the 13 countries that lie on the equator, seven are in Africa- the most of any continent- while South America is home to three of the nations (Ecuador, Colombia, and Brazil). The remaining three (Maldives, Kiribati, and Indonesia) are island nations in the Indian and Pacific oceans.   The countries of Sao Tome and Principe, Gabon, Republic of the Congo, the Democratic Republic of the Congo, Uganda, Kenya, Somalia, Maldives, Indonesia, Kiribati, Ecuador, Colombia, and Brazil all lie along the equator. The landmasses of Maldives and Kiribati, however, do not touch the equator itself. Instead, the equator passes through water controlled by these two island countries. Latitude and Longitude The equator is one of five lines of latitude that help provide relative locations on an atlas. The other four include  the Arctic Circle, the Antarctic  Circle, the Tropic of Cancer, and the Tropic of Capricorn.  Because the Earth bulges at the center, the equator is significantly longer than any of the other lines of latitude. Along with the lines of longitude which run from pole to pole, they make it possible for cartographers and navigators to locate any spot on the globe. The plane of the equator passes through the sun at the March and September equinoxes. The sun appears to travel directly north to south over the equator at these times. Because of this, people living along the equator experience the quickest sunrises and sunsets as the sun travels perpendicular to the equator most of the year, with the length of days being almost entirely the same throughout- daylight lasting 14 minutes longer than nighttime. Climate and Temperatures Most countries that lie along the equator experience much warmer temperatures year-round than other areas of the world that share the same elevation. Thats because of the equators near-constant exposure to the same levels of sun exposure regardless of the time of year. As a result, the countries that lie along the equators include almost half of the worlds rainforest; they are concentrated in the African nations of Congo, Brazil, and Indonesia. Even so, the equator offers a surprisingly diverse climate due to the geographical features of countries that lie along it. There is little fluctuation in temperature throughout the year, though there may be dramatic differences in rainfall and humidity, which are determined by wind currents. In fact, the terms summer, fall, winter, and spring dont really apply to regions along the equator. Instead, people who live in the especially humid tropic regions refer to only two seasons: wet and dry. Equator Extremes Its reasonable and largely accurate to assume that the weather is uniformly warm or hot around the equator. But of course, weather and climate relate not only to latitude but also to geography. Some countries that lie on the equator are flat and warm but others, like Ecuador, include high mountains where the weather is extremely cold. In fact, you will find snow and ice year-round on  Cayambe, a volcano in Ecuador that reaches to 5,790 meters (nearly 19,000 feet). It is the only place on the equator where snow lies on the ground year-round.