Calcium chloride (CaCl2)

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Calcium chloride (CaCl2) is a white crystalline substance and is commonly used in the food and agricultural industries. It is a substance that can absorb moisture and is well soluble in water. When dissolved in water, hydrochloric acid and anode calcium will form. It is often used in the forms of CaCl2.2H2O, CaCl2.4H2O and CaCl2.6H2O.

Calcium chloride is a substance classified as GRAS (Generally Recognized As Safe) and used to fill in some foods. Also, it is generally accepted by experts that it is safe for consumption, which is widely used in many applications, such as a preservative and firming agent in vegetable and fruit industries, both fresh fruits and primary processing, as well as used to improve the taste of meats.

The use of calcium chloride in food products under suitable conditions needs not be approved by the Food and Drug Administration (FDA) of the USA. Calcium chloride (CaCl2) is a water-soluble substance and decomposes to provide calcium and chlorine. The use of this substance may result in bitterness and off-flavours due to the presence of free chlorine residuals in the skin or tissue of products.

Calcium chloride is naturally found in many forms, such as calcium chloride anhydrous (CaCl2), calcium chloride monoanhydrate (CaCl2.H2O), calcium chloride dihydrate (CaCl2.2H2O), calcium chloride tetrahydrate (CaCl2.4H2O), and calcium chloride hexahydrate (CaCl2.6H2O), which have different temperature stabilizations as follows (Shepelev et al, 1950)(2):
· CaCl2.H2O at 175-238 °C
· CaCl2.2H2O at 39-175 °C
· CaCl2.4H2O at 14-45 °C
· CaCl2.6H2O at (-55) – (+30.1) °C

Calcium chloride

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Physical and chemical properties
Trade name : Calcium chloride
Chemical name : Calcium chloride
Molecular formula : CaCl2
Molecular weight : 111.0 g/mole
Appearance : White
Physical state : Solid
Odor : Odorless
Melting point : 772 °C
Boiling point : 1670 °C
Flammability : Non-flammable
Flash point : Non-flammable
Density : 1.54 g/cc at 20 °C
Solubility : Completely soluble in water
Enthalpy of fusion : 2.23 kcal/mol
Latent heat of vaporization : 36.7kcal/mol at 1,482 °C
Heat of combustion : 151.9 cal/g
CAS No.: 10043-52-4

Production of calcium chloride
1. Calcium chloride is produced from calcium.
2. Calcium chloride is produced from ammonium soda by reacting in the solution of ammonia, carbon dioxide and sodium chloride and then becoming sodium bicarbonate and ammonium chloride solution. The following process is an extraction of sodium bicarbonate and then ammonium chloride that will react with lime and become calcium chloride solution. Final stage includes concentration and precipitation.

Calcium chloride sold in the market is mainly derived from the preparation of soda ash (Na2CO3) or ammonium soda. Usually, calcium chloride products obtained are in the form of monoanhydrate (CaCl2.H2O) and calcium chloride hexahydrate (CaCl2.6H2O). Pure calcium chloride can well absorb moisture so it is often used to absorb the moisture from the air and the water from the solvents in the industry.

Reaction in water

CaCl2 + H2O = CaO + 2HCl

Use and applications
· Calcium chloride is used in the construction of concrete for hardening the accelerators and increasing the compressive strength of concrete.
· Calcium chloride solution is used for reducing the fruit splitting and extending the shelf life of agricultural products, such as fruits and vegetables. The process is by spraying the solution in both pre-harvest and post-harvest products or by directly dipping the products in the solution.
· In some industries, calcium chloride is used for desiccating the water and absorbing of the solvents.
· In fruit canning industry, calcium chloride is used for creating the crispness in fruits.
· In meat industry, calcium chloride is used for meat tenderness of meat products, such as beef and chicken.
· In some industries, calcium chloride is used as microbial inhibitor in foods.
· In some industries, calcium chloride is commonly used as a flavoring agent and used for extracting the protein from meat, such as in sausage production and marinated beef production.
· Calcium chloride is used as a thickening agent in dairy products, such as sweetened condensed milk, unsweetened condensed milk, skim milk and cream powder.
· Calcium chloride is used as a firming agent for stability in products, such as canned grapefruits, canned peas through unused sodium carbonate and sodium citrate, canned peas, canned strawberries, jams, mixed fruit jellies, pickled cucumbers, and pickled vegetables and fruits.

Calcium chloride1

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Use of calcium chloride in vegetables and fruits
Calcium has a molecular weight of 40.08 grams and is an alkaline mental that is naturally found in plants and animals. Calcium that can be absorbed by plants is in the form of the covalent calcium ion (Ca2 +) and an element that is difficult to move. Therefore, when Ca2 + is in the in the plant’s tissues, it will rarely move to other parts. The functions of calcium can be summarized as follows:

  1. It is a component of the cell walls in the form of calcium pectate, which is produced by calcium ions connecting to pectic acid in the middle lamella of the cell wall As a result, Ca2 and bridge occur that provides the plant’s tissues with a strong structure.
  2. It is involved with the metabolism process, production of nucleus and mitochondria, and cell division and expansion.
  3. It provides the cell membrane with a complete structure and function to control the permeability of certain substances in the cells and the calcium salt of lecithin. It is a component of lipid,which is associated with the structure of cell membrane.
  4. It plays a role towards certain enzymes and is a component in α-amylase. In addition, it motivates the activation of phosphatase, phospholipase, arginine kinase and other enzymes.
  5. It affects the nodulation and nitrogen fixation process of the rhizobium fungi in the leguminous plants.
  6. It reduces the toxicity of oxalic acid by condensing itself as a calcium oxalate crystal in the vacuole.

Calcium chloride is a firming agent that stabilizes the tissues of vegetables and fruits. When dissolved in water, this compound breaks down and releases the calcium radicals. Also, when reacting with the pectic compounds, it becomes petate salts, which strengthen the structure of plant cells. The use of calcium chloride in fruits and vegetables must not exceed 800 ppm, depending on the type of products and not exceed 250 ppm for compotes.

The use of calcium chloride in vegetables and fruits can help maintain their crispness by strengthening and making the tissues of vegetables and fruits resistant to the digestion of enzymes secreted from the tissues damaged due to the trim. In addition, it can reduces the browning reaction on the surface of trimmed vegetables and fruits, such as soaking them in a solution of calcium chloride at concentrations of 1% and 5% can reduce browning the surface of melons since calcium chloride solution can denature the enzymes that are in turn unable to catch the substrates, which will prevent the browning on the surface of the products. The proper time to soak is 1-5 minutes.

Use of calcium chloride in meats
Calcium chloride is used as a substance to improve the tenderness of meat products with the following mechanism:
After the death of animals, sarcoplasmic reticulum and mitochondria decay with the enzymes that digest required proteins with the stimulation of Ca2 +, also known as CDP (Ca2 + dependent protase). These enzymes are divided into two types depending on the need of Ca2 + in the stimulation, i.e. calpain-I wants a low amount of Ca2+ (about 10 micrograms) and calpain-II requires a high amount of Ca2+ (about 250 micrograms), in order them to work at their full capacity. Calpain can be found at the cytosol and the position where there is the most degradation is Z-line. In addition to the concentration of Ca2+, what affects the function of calpain also depends on the pH level and temperature of the meats.

As calpain-II is an enzyme that needs a high concentration of Ca2 + for its activation, its reaction is slower than calpain-I, so it can work well 24 hours after the animals die. Ca2 + induces the function of both calpain-I and calpain-II to break down the collagen network by reducing the ratio of heat-stable collagen with a effect on perimysial collagen, but the length of sarcomere will increase because the crossbridge of actin and myosin is reduced.

Decomposition process occurs as follows:
1. Initiation calpain in a state of innert is stimulated by a higher concentration level of Ca2+ because the cells are powered down and therefore no longer shrink. As a result, Ca2+ is more collected in sarcoplasm. Together, the deterioration of sarcoplasmic reticulum and mitochondria as a source of calcium in muscle cells will release Ca2+ more, which at a sufficient level can activate the function of calpain. This stage is the beginning point to make the tenderness of meats.
2. Calpain activated by Ca2 + is inhibited by an inhibitor, calpastatin. This inhibition can occur well in the early stages where the pH value is still high and when the pH value drops, this inhibition will be reduced accordingly.
3. Even at a pH value below 5.7, the inhibition of calpastatin si still low and calpain-I will lose its ability to react up to 60% after the animals are dead for about 24 hours. However, at a pH value of 5.7, calpain-II will react fully so the meats can be tender continuously.
4. Inactivation of calpastation occurs by a thoil-group proteolytic enzyme, calpain, which can destroy calpastatin,
5. Tenderization is created by the degradation of proteins in animal tissues because of the reaction of calpain activated by Ca2+. In this case, there is a disintegration of proteins at Z-line because the protein fibers called Protonin are destroyed.

Therefore, the use of calcium chloride is a method for increasing the tenderness of meats by increasing the volume of Ca2 + from an exogenous source to stimulate calpain to degrade the collagen network until the meats are softer and more flexible.

Terms of calcium chloride in foods
According to the standards of calcium chloride for food industries, calcium chloride compounds used in foods must contain calcium chloride not less than 99% and no more than 107% and other contaminants as follows (Food Chemical Codex, 1981)(1):
·  Lead no more than 10 mg/kg.
· Fluoride no more than 40 mg/kg.
· Magnesium and salts no more than 4%.
· Heavy metals no more than 20 mg/kg.
· Arsenicno more than 3 mg/kg.

Toxicity of calcium chloride
· It can corrode metals to create rusts.If it is used in the concrete construction, the concrete is usually shrunken and has a reduced sulfate resistance.
· It’s solution is acidic (hydrochloric acid) that causes an irritation on both skin and eye contacts. Contacting with a highly concentrated solution can cause a severe irritation and kill the tissues at that area.
· The use of calcium chloride in all kinds of vegetable, fruit and food products may create the residuals of chlorine that may cause toxicity. In addition,the effects of residual chlorine often make foods with unappetizing odor and bitter taste.

Precautions of use

  1. During use, a mask, chemical goggles, cloths, boots and other chemical protective equipment must be worn at all times.
  2. When dissolved in water, it’s hould not be inhaled because the chlorine vapors will be easily exposed.
  3. Contacting with all kinds of metals should be avoided due to the corrosion.

References
1. Food and Nutrition Board Division of Biological Science, 1981. Food Chemical Codex. National Academy Press, Washington D.C., U.S.A. 735 p.
2. Shepelev, A.I., M.N. Lyashenko and I.G. Druzhinin, 1950. Crystallooptical constants of CaCl2, Inc, Westport, Connecticut, USA. 323 p.