Ascorbic acid is a sugar acid (monosaccharide with carboxyl acid) with antioxidant properties. It appears to be as a white to light-yellow crystal or powder and it is water soluble. Vitamin C is a form of ascorbic acid and it is an essential nutrient for humans.
Vitamin C (ascorbic acid) is a six-carbon lactone that is synthesized from glucose in the liver of most mammalian species, but not by humans, non-human primates and guinea pigs. These species do not have the enzyme gulonolactone oxidase, which is essential for synthesis of the ascorbic acid immediate precursor 2-keto-l-gulonolactone. The DNA encoding for gulonolactone oxidase has undergone substantial mutation, resulting in the absence of a functional enzyme [1, 2]. Consequently, when humans do not ingest vitamin C in their diets, a deficiency state occurs with a wide spectrum of clinical manifestations. Clinical expression of vitamin C deficiency, scurvy, is a lethal condition unless appropriately treated. Thus, humans must ingest vitamin C to survive. Vitamin C is an electron donor and therefore a reducing agent. All known physiological and biochemical actions of vitamin C are due to its action as an electron donor. Ascorbic acid donates two electrons from a double bond between the second and third carbons of the 6-carbon molecule. Vitamin C is called an antioxidant because, by donating its electrons, it prevents other compounds from being oxidized. However, by the very nature of this reaction, vitamin C itself is oxidized in the process.
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What's Vitamin C for?
Protects against the harmful effects of free radicals (an antioxidant)
Assists in the formation of collagen, which is important for the health of blood vessels and gums, development of bones and teeth, and wound healing
Helps resist infection, preventing and treating the common cold
Has been found to decrease risk of cancer, heart disease, cataracts, and other diseases
Â Large concentrations of vitamin C can be found in fruits such as oranges, grapefruits, tangerines, lemons, limes, papaya, strawberries and cantaloupe. Vitamin C and bioflavonoid - the water-soluble substances that help to protect your capillaries - are found in the white linings of these and other plants. Many vegetables also pack in vitamin C including tomatoes, broccoli, green and red bell peppers, raw lettuce and other leafy greens.
The chemical formula and molecular structure of the compound are shown below:
FoodÂ preservationÂ is the science of extending theÂ shelf lifeÂ ofÂ foodÂ while maintaining as much as possible of its nutritional quality and avoiding the growth of unwanted micro organisms.Â FoodÂ preservationÂ has been practiced in a variety of ways for hundreds of years. It refers to any one of a number of techniques used to prevent food from spoiling. All foods begin to spoil as soon as they are harvested or slaughtered. Some spoiling is caused by such microorganisms as bacteria and mold. Other spoilages results from chemical changes within the food itself due to natural processes such as enzyme action or oxidation.
There are a number of different ways of preserving foods. Some involve storage methods, some involve packaging, and some involve treating theÂ foodÂ in particular ways prior to or during storage, either cooking it in whole or part or combining it with other foods or substances.
Common methods of applying these processes includeÂ drying,Â spray drying,Â freeze drying,Â freezing, vacuum-packing,Â canning, preserving in syrup, sugar crystallisation,Â food irradiation, and addingÂ preservativesÂ or inertÂ gasesÂ such as carbon dioxide. Other methods that not only help to preserve food, but also add flavour, includeÂ pickling,Â salting,Â smoking, preserving inÂ syrupÂ orÂ alcohol,Â sugarÂ crystallisation andÂ curing.
What are antioxidants?
Any food prepared with fats or oils-from meat piece to salad cream-is likely to contain antioxidants. Antioxidants reduce the chance of oils, fats and fat-soluble vitamins from combining with oxygen and changing colour or going rancid.
"AnÂ antioxidantÂ is a molecule capable of slowing or preventing the oxidation of other molecules. Oxidation is a chemical reaction that transfers electrons from a substance to an oxidizing agent"
The prefix "anti" means against, in opposition to. In order to understandÂ antioxidants, it helps to learn what exactly these agents oppose and correct. Within the human body, millions of processes are occurring at all times. These processes requireÂ oxygen. Unfortunately, that same life giving oxygen can create harmful side effects, or oxidant substances, which cause cell damage and lead to chronic disease.
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Oxidation reactions can produce free radicals, which start chain reactions that damage cells.Â Antioxidants terminate these chain reactions by removing free radical intermediates, and inhibit other oxidation reactions by being oxidized themselves. As a result, antioxidants are often reducing agents such as thiols, ascorbic acid or polyphenols. In addition to these uses of natural antioxidants in medicine, these compounds have many industrial uses, such as preservatives in food and cosmetics and preventing the degradation of rubber and gasoline.
Measurement of antioxidants is not a straightforward process, as this is a diverse group of compounds with different reactivity to different reactive oxygen species. In food science, the oxygen radical absorbance capacity (ORAC) has become the current industry standard for assessing antioxidantÂ strength of whole foods, juices and food additives. Other measurement tests include the Folin-Ciocalteu reagent, and the Trolox equivalentÂ antioxidantÂ capacity assay.
Antioxidants are found in varying amounts in foods such as vegetables, fruits, grain cereals, eggs, meat, legumes and nuts. Some antioxidants such as lycopene and ascorbic acid can be destroyed by long-term storage or prolonged cooking. OtherÂ antioxidantÂ compounds are more stable, such as the polyphenolic antioxidants in foods such as whole-wheat cereals and tea. The effects of cooking and food processing are complex, as these processes can also increase the bioavailability of antioxidants, such as some carotenoids in vegetables. In general, processed foods contain fewer antioxidants than fresh and uncooked foods, since the preparation processes may expose the food to oxygen.
One way of reducing food spoilage is by lowering the pH.
The pH is a measure of the acidity of something and below are examples of things showing a wide range of pH:
ACIDICÂ Stomach gastric juice
Vinegar, Peaches, Coke
NEUTRALÂ Distilled water, Human saliva
Egg white, Sea water
Most microorganisms grow best at a pH of around 7 and can't grow in an acidic environment. Adding an acid like vinegar or vitamin C (citric acid) will increase the acidity and limit bacterial and fungal growth. In buttermilk, yogurt and many cheeses, the bacteria that get started first lower the pH and produce something that tastes different than milk but is still tasty to some people. In sauerkraut, a finely shreddedÂ cabbageÂ that has been fermentedÂ by variousÂ lactic acid bacteria, salt prevents most bacteria from growing. Those that can survive produce large amounts of lactic acid that lowers the pH and prevents other bacteria from growing.
To find out if Vitamin C (ascorbic acid) has an effect in preventing food from souring, I carried out an experiment where I added different mgs of vitamin C to wine and measured their pH everyday (with about 24 hours interval) over a period of 5 days.
A little about wine
Wine is an alcoholic beverage because it contains ethanol, commonly known as alcohol.
It is typically made of fermented grape juice and it is produced by fermenting crushed grapes using various types of yeast.