Sodium citrate

Sodium citrate may refer to any of the sodium salts of citric acid (though most commonly the third):

The three forms of the salt are collectively known by the E number E331. Sodium citrates are used as acidity regulators in food and drinks, and also as emulsifiers for oils. It allows the cheeses to melt without becoming greasy.

References

Dunkin' Donuts

Dunkin' Donuts is an American global doughnut company and coffeehouse chain based in Canton, Massachusetts, in Greater Boston. It was founded in 1950 by William Rosenberg in Quincy, Massachusetts. Since its founding, the company has grown to become one of the largest coffee and baked goods chains in the world, with more than 11,300 restaurants in 36 countries. The chain's products include doughnuts, bagels, other baked goods, and a wide variety of hot and iced beverages.

The company primarily competes with Starbucks, as over half the company's business is in coffee sales, as well as with Krispy Kreme Doughnuts and Honey Dew Donuts.

Before 1990, Dunkin' Donuts' primary competitor was Mister Donut, but in February of that year Mister Donut was acquired by Dunkin' Donuts' owner Allied-Lyons. After the acquisition of Mister Donut by Allied-Lyons, all Mister Donut stores in North America were offered the chance to change their name to Dunkin' Donuts.

As of 2014, Dunkin' Donuts is owned by Dunkin' Brands Inc., which also owns Baskin-Robbins and previously owned the Togo's chain.

Citric acid

Citric acid is a weak organic tribasic acid. It occurs naturally in citrus fruits. In biochemistry, it is an intermediate in the citric acid cycle, which occurs in the metabolism of all aerobic organisms.

More than a million tons of citric acid are manufactured every year. It is used widely as an acidifier, as a flavoring, and as a chelating agent.

Natural occurrence and industrial production

Citric acid exists in greater than trace amounts in a variety of fruits and vegetables, most notably citrus fruits. Lemons and limes have particularly high concentrations of the acid; it can constitute as much as 8% of the dry weight of these fruits (about 47 g/L in the juices). The concentrations of citric acid in citrus fruits range from 0.005 mol/L for oranges and grapefruits to 0.30 mol/L in lemons and limes. Within species, these values vary depending on the cultivar and the circumstances in which the fruit was grown.

Industrial-scale citric acid production first began in 1890 based on the Italian citrus fruit industry, where the juice was treated with hydrated lime (calcium hydroxide) to precipitate calcium citrate, which was isolated and converted back to the acid using diluted sulfuric acid. In 1893, C. Wehmer discovered Penicillium mold could produce citric acid from sugar. However, microbial production of citric acid did not become industrially important until World War I disrupted Italian citrus exports.

Xanthan gum

Xanthan gum (/ˈzænθən/) is a polysaccharide secreted by the bacterium Xanthomonas campestris, used as a food additive and rheology modifier, commonly used as a food thickening agent (in salad dressings, for example) and a ster (in cosmetic products, for example, to prevent ingredients from separating). It is composed of pentasaccharide repeat units, comprising glucose, mannose, and glucuronic acid in the molar ratio 2:2:1. It is produced by the fermentation of glucose, sucrose, or lactose. After a fermentation period, the polysaccharide is precipitated from a growth medium with isopropyl alcohol, dried, and ground into a fine powder. Later, it is added to a liquid medium to form the gum.

Biosynthesis

Synthesis originates from glucose as substrate for synthesis of the sugar nucleotides precursors UDP-glucose, UDP-glucuronate, and GDP-mannose that are required for building the pentasaccharide repeat unit. This links the synthesis of xanthan to the central carbohydrate metabolism. The repeat units are built up at undecaprenylphosphate lipid carriers that are anchored in the cytoplasmic membrane. Specific glycosyltransferases sequentially transfer the sugar moieties of the nucleotide sugar xanthan precursors to the lipid carriers. Acetyl and pyruvyl residues are added as non-carbohydrate decorations. Mature repeat units are polymerized and exported in a way resembling the Wzy-dependent polysaccharide synthesis mechanism of Enterobacteriaceae. Products of the gum gene cluster drive synthesis, polymerization, and export of the repeat unit.

Sodium

Sodium /ˈsoʊdiəm/ is a chemical element with symbol Na (from Ancient Greek Νάτριο) and atomic number 11. It is a soft, silver-white, highly reactive metal. In the Periodic table it is in column 1 (alkali metals), and shares with the other six elements in that column that it has a single electron in its outer shell, which it readily donates, creating a positively charged atom - a cation. Its only stable isotope is ²³Na. The free metal does not occur in nature, but instead must be prepared from its compounds. Sodium is the sixth most abundant element in the Earth's crust, and exists in numerous minerals such as feldspars, sodalite and rock salt (NaCl). Many salts of sodium are highly water-soluble: sodium ions have been leached by the action of water from the earth's minerals over eons, so that sodium (and chlorine) are the most common dissolved elements by weight in the oceans.

Sodium was first isolated by Humphry Davy in 1807 by the electrolysis of sodium hydroxide. Many sodium compounds are useful, such as sodium hydroxide (lye) for soap-making and sodium chloride for use as a de-icing agent and a nutrient (edible salt).