Calcium hydroxide, also known as lime or slaked lime, is an inorganic compound formed by a chemical reaction from a single or two calcium, two oxygen, and two hydrogen element. Its chemical formula is Ca(OH)2 or Ca2(OH)2. This white powder, aqueous liquids, or colorless crystal is obtained by reacting the calcium oxide with water in a closed system. In the market, calcium hydroxide has other names, such as pickling lime, caustic lime, and etc. When it is saturated in a water solution, we usually call it lime water.
Let’s talk about the chemical properties of calcium hydroxide first. This chemical compound with a formula of Ca(OH)2 is relatively insoluble in water. However, at ambient temperature, it can dissolves quite good in pure water, creating a new solution with a pH around 12.4. At high pH value, its solubility decrease drastically. On the other hand, it is soluble in glycerol and acids.
In its aqueous form, calcium hydroxide is called lime water that reacts well with acid. It can attack metals such as aluminum while protecting other metals from corrosion. A carbonation, a process in which a lime water turns milky, will happen if there is a carbon dioxide in the solution. Its density in its solid form is around 2.211 g/cm3, with a hexagonal structure and -22.0 x 10-6 cm3/mol magnetic susceptibility.
Because it is relatively safe, calcium hydroxide has been used in a wide range of applications. One of the main uses of carbon hydroxide is in the food industry. After you read this article, you will know how and where carbon hydroxide is used especially in the food industry.
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Here are the Calcium Hydroxide uses in food industry:
1. Sugarcane and sugar beets production
Sugar is one of the chemical compounds that are used as food ingredients. It has many types, such as glucose, fructose, sucrose, lactose, and etc. We can make sugar from extracting it through some process applied in the sugar factory. In the process of the sugar extraction, calcium hydroxide is used. We will talk about it in the next part.
So, in the sugar factory, there is usually two kind of plants that are used as the source of sugar. Sugar beet, and sugar cane. Sugar beet is a plant which has a high concentration of sucrose in its root. It belongs to the Altissimo cultivar group of the Beta vulgaris. Sugar beet is highly produced in Russia, Germany, Turkey, and others. In 2009, 20% of world sugar production comes from sugar beet.
Sugarcane is the next plant that is used in the sugar production. Sugarcane is a several species of different grasses, that belong to the genus Saccharum and belong to the Poaceae family. It is native to South Asia and Melanesia. In the sugar factory, sugarcane is the source of sucrose, that will be extracted and produced massively to meet the demand of sugar around the world.
In the sugar factory, there is a process called sugar refining. It is the process of purifying the raw sugar after being extracted from the plant. In this process, calcium hydroxide, combined with phosphoric acid, is added to the sugar solution after it was mixed with a heavy syrup. The combination of calcium hydroxide and phosphoric acid will result in the precipitation of calcium phosphate, which in turn, entrap some impurities and then float to the top of the solution where they can be removed from the surface.
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2. Processed water for alcoholic beverages and soft drinks
Soft drinks or alcoholic beverages contain a carbonated water as one of its main ingredients. Carbonated water is not a regular water that we drink every day. It is a processed water, meaning that a carbonated water is produced by dissolving carbon dioxide in the water. Some of the carbonated water contains additives such as sodium bicarbonate, sodium chloride or others.
In order to process a water, some chemical might be used to enhance it speeds and the amount carbon dioxide dissolved in the water. Calcium hydroxide is one of the chemical compounds that factory uses to make carbonated water. That’s one of the Calcium Hydroxide uses in food industry.
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3. Pickle cucumbers and other foods
A calcium hydroxide is called a food-grade lime or pickling lime not without a reason. It is called because calcium hydroxide has the ability to preserves the firmness of a cucumber or other foods. It is proven to be effective, and that’s why calcium hydroxide is still used as a pickling lime.
In general, in order to keep a cucumber or other foods fresh, we need to preserve it in some preservatives. By exposing cucumbers in a calcium hydroxide, we will improve the firmness of pickles by strengthening the pectin inside the vegetables, such as cucumbers for at least a day. After that, because calcium hydroxide is an alkaline, we need to get rid of it from our vegetables. We can do it by rinsing the food thoroughly before we start the pickling process.
USDA, the department of agriculture in the United States even has the complete guide on how to use and clean out a cucumbers or vegetables using a calcium hydroxide. It is said that we need to soak the cucumbers or vegetables in fresh water for one hour and then repeat it again for at least two times. By then, we will have pure vegetables that don’t contain calcium hydroxide anymore.
But, keep in mind that you need to purchase or look for ‘food-grade lime’, and not the burnt lime or agricultural lime. We have to do it because as you might guess, they are different and have different functions.
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4. Chinese century eggs
Calcium Hydroxide uses in food for Chinese century egg, also called pidan in the Chinese language, is a preserved egg made by preserving egg in clay, ash, rice hulls, quicklime, and salt for several weeks or months, depending on the method used to process it and how long it is going to be preserved. People in China use duck, chicken, or quail eggs as the main source of eggs for the century eggs. Chinese century egg has other names that reflect it longer ‘expiry date’, such as a hundred-year egg, thousand-year egg, millennium egg, or pine patterned egg.
After this process, there will be some changes to the egg. The white part will become a translucent jelly with a salty flavor that has a dark brown color while the yolk becomes creamy with a dark green to gray color. It might have the urine-like odor because as the results of the chemical reaction that produced ammonia and other amines. However, simply soaking raw eggs in horse urine would never be able to achieve the same results as the traditional/modern way of processing century eggs.
A calcium hydroxide, together with sodium carbonate and table salt can be added to a solution to soak the raw eggs for at least 10 days or more to preserve the eggs.
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5. Production of corn tortillas
What’s Calcium Hydroxide uses in food industry? Do you like corn tortillas? Have you ever eat it? If you like it, then maybe you are eating it every day as your source of nutrition. However, some of us don’t know that in the process of making corn tortilla, there is a a nixtamilazation process.
Nixtamilazation is a process to prepare corn, or other grain, in which we soak and cook corn or grain in an alkaline solution. After the soaking and cooking process is finished, the corn or other grain is then washed and then the hull of the grain or corn is removed. Historically, this process is originated from Mexico, known to remove up to 97% to 100% aflatoxins from a corn contaminated by mycotoxin.
Corn tortillas factory use calcium hydroxide as one of the alkaline solutions to soak and the raw corn. After that, they will wash the corn until it is clean and clear so that we can eat it safely. Even though calcium hydroxide is relatively safe, eating or drinking the alkaline solution of calcium hydroxide is still quite bad for us.
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6. Fruit drinks fortification
In the production of fruit drinks or infant milk, factories use calcium hydroxide to fortify the calcium included in the product. In short, fruit drinks factories need to increase the amount of nutrition inside their product so that people wanted to buy for it. Calcium is one of the chemical compounds, and also nutrition that is important for our body as long as it does not exceed the homeostasis.
Adding raw calcium cost a lot, so factories used a process called calcium fortification. It aims to increase the amount of calcium inside a drink. We achieve that by adding calcium-based solution to the original solution of their chemical product. A chemical solution such as calcium citrate malate, calcium lactate, hydroxyapatite or tricalcium phosphate is one of the chemical compounds factories use to achieve that. The other chemical compound used there, is our lovely calcium hydroxide.
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7. Baking soda substitute to make papadum
Papadum is a crisp, thin, disc-shaped food originally comes and made in the Indian subcontinent. Indian people make it from peeled black gram flour, also called urad flour, and then they cook it with dry heat. Papadum has many other names, such as papar, papad, pampad, happala, appalam (from Tamil Nadu), or other. Its main ingredient is black gram, chickpeas, rice flour, and lentils.
Restaurants usually serve papadums as an accompaniment to a meal in many countries, such as Nepal, Sri Lanka, and Bangladesh. Sometimes, they also serve it with toppings such as chopped carrots, churned, or other dips.
Papadum has a lot of variation. Some of the papadum uses baking soda in the cooking process. Sometimes, a papadum chef uses calcium hydroxide as the substitute of baking soda.
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So, that’s what calcium hydroxide uses in foods. In other fields, people also uses calcium hydroxide for a lot of purposes. Don’t worry if you consume calcium hydroxide unintentionally because it won’t be toxic for you.
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