You’ve probably been eating it for years and not even realized you had been consuming it. From citrus fruits to most of your favorite sodas, citric acid is widely used in food, but what exactly is it? This article explores citric acid and the various uses behind its inclusion in our diets.
What is citric acid?
Citric acid is an organic acid that belongs to the family of carboxylic acids. It is a white crystalline solid at room temperature, soluble in water, ethanol and ethers. Its acidity is between two and three times that of acetic acid (acidity of vinegar).
Citric acid is found naturally in citrus fruits as well as other plants such as sugar beets, barley and many other species of fungi and bacteria. It is commercially manufactured from glucose using fermentation processes or from petroleum by steam cracking.
Citric acid is used in food and beverages as a flavoring agent and preservative; it also gives a sour taste to these products. It can be used to preserve canned fruit and prevent discoloration. Citric acid is often added to soft drinks such as lemonade, orange juice and root beer because it adds both tartness and effervescence to these beverages. The addition of citric acid also prevents the growth of microorganisms in canned foods such as canned fruits or vegetables that are highly susceptible to spoilage by microorganisms during storage at room temperature.
The pharmaceutical industry uses citric acid in its production process for many drugs including antibiotics such as penicillin or tetracycline because of its antibacterial effects.
Two types in market
The market offers both anhydrous and monohydrate forms of citric acid. When heated above 37 °C, monohydrate can become anhydrous.
Natural sources
Citrus fruits contain a high level of citric acid. Citric acid is found in the following fruits:
- Lemon
- Lime
- Pineapple
- Oranges
- Tomatoes
- Strawberries
- Peaches
- Apples
- Grapefruits
- Blueberries
- Bananas
Concentration
Citric acid is found in lemon juice and lime juice. Concentrates contain around 31 mg/kg and ready-to-consume lemon juice has around 41 mg/kg. Lime juice contains 39 mg/kg and 30 mg/kg. Commercial lemon juice-based drinks, such as lemonade, contain 0.62 to 0.96 mg/kg.
How is citric acid made?
A glucose or sucrose carbohydrate substrate derived from corn is used to produce citrus acid commercially.
It is usually made by feeding substrate into a black mold. In the microbial production of citric acid, Aspergillus niger is the major organism.
FDA-approved manufacturing processes include the following:
- It is derived from plant sources, such as lemon juice or pineapple juice.
- Mycological fermentation using Candida species.
- Fermentation liquor from Aspergillus niger.
Approximately 99% of the world’s citric acid has been produced by Aspergillus niger since 1919, according to a study published in Toxicology Reports in 2018. As a result, the third method above is the most commonly used.
Specification
| Other Names |
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| CAS Number |
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| Chemical formula |
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| Molecular Weight |
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| Melting Point | 156 °C |
| Boiling point | 310 °C |
Structure
Properties
Appearance
It is a white powder or granular substance that tastes strongly acidic.
Pka
Acid dissociation is described by PKa. Because citric acid contains three carboxylic acid functional groups, it has three PKa values, PKa1 = 3.14, PKa2 = 4.77, and PKa3 = 6.39.
PH
PH measures the concentration of H+ ions or H3O+ ions in citric acid solutions. Citric acid concentration and dissociation determine the PH value. Citric acid has a PH value of 2.62 at 10 mM (0.01mol/L) concentration.
What is the procedure for calculating the pH value of citric acid?
Step 1: The dissociation equation should be written.
Citric acid is a tricarboxylic acid, so we should do a systematic calculation involving all three equations.
Step 2: As it is a weak acid, we could only calculate the first dissociation.
- [H3O+] is the Hydronium concentration
- The conjugate base concentration is [C6H7O7−]
- Citric acid concentration is [C6H8O7]
[C6H7O7*] and [H3O+] have the same concentration. In this case, we assume a concentration of X. Therefore, [C6H8O7] has a final concentration of 0.01 – X.
Step 3: This equation can be written as X*X/0.01-X = Ka1=10^-3.14.
Attention: the equation cannot be similar to X*X/0.01 = 10*-3.14 since X cannot be negligible in comparison with 0.01.
Step 4: Make sure it is negligible
As 0.01/10*3.14=10*1.14, it should be factored in.
Step 4: Calculate the equation and we’ll get X=10^-2.62. This gives us the value of 2.62 for PH.
Solubility
In water
Anhydrous: highly soluble in water (592 g/L, 20°C)
Monohydrate: soluble in water
In organic solvents
It is soluble in ethanol and sparingly soluble in ether when anhydrous; it is sparingly soluble in ether when monohydrate.
What are the health benefits of citric acid?
In addition to preventing kidney stones and keeping our skin healthy, citric acid can help our bodies fight oxidation.
- Body antioxidation
- Prevent kidney stones
- Skin Benefits
Body antioxidation
Antioxidants such as citric acid may protect human cells from free radical damage.
Prevent kidney stones
Because citric acid inhibits the formation of new stones, citric acid is beneficial for people with kidney stones. Calcium citrate and potassium citrate are also effective at preventing stone formation.
Skin Benefits
What are the application of citric acid?
Due to its multifunctional properties, citric acid is used in a variety of applications, including food and beverages, pharmaceuticals, cosmetics, water treatment, and household detergents.
Food
Along with malic acid and tartaric acid, it is the most common organic acid added to food. Food grade citric acid can be used as an acidulant, preservative, antioxidant, and chelating agent.
Acidulant
Acidic (sour) flavors are commonly added to foods and soft drinks to enhance flavor and to adjust pH.
Preservative
In an acidic environment, bacteria cannot grow, so it is used to preserve food due to its acidic pH.
Antioxidant
In foods, it can slow down or prevent oxidation when present at low concentrations.
Chelating agent
Food quality and stability can be improved by forming chelate complexes with polyvalent metal ions.
Nutrition supplement
Calcium citrate and ferric citrate, its derivatives, are used to supplement foods with calcium and iron.
Cosmetics
- Face serums are skin care products
- Shampoo is one of the hair products
- Using mouthwash
Pharmaceutical
In the pharmaceutical industry, citric acid can chelate metal ions, buffer pH, and impart flavor. It can also be used as an external anticoagulant by reducing the concentration of calcium ions in blood through binding to calcium ions that form a soluble complex. These complexes are difficult to dissolve.
Industry uses
Water softener
Due to its ability to chelate metals, citric acid is used as a water conditioner in industrial and drinking water. EDTA is also a chelating agent capable of binding metal ions, such as calcium and magnesium, in water and removing them from pipes, household appliances, etc.
Household cleaner
In household cleaning products, citric acid can act as a multifunctional cleaner for dishwashers and windows, as well as dish soaps, laundry detergents, rust removers, etc.
Is citric acid safe to eat?
Citric acid is a fairly safe food additive. However, it may cause some irritation of the skin and eyes, so it should be kept away from these areas. It may also cause some abdominal pain when taken in large doses.
Citric acid is an organic acid found in citrus fruits such as lemons and limes that is used for flavoring foods and beverages. It can also be extracted from other sources such as rice bran oil or corn syrup. A citric acid supplement has been suggested to help with weight loss, but more research is needed to determine its effectiveness in this regard.
The Food and Drug Administration (FDA) has approved citric acid as a food additive, meaning that it’s considered safe under normal conditions of use. This includes use as a flavoring agent in many types of foods. Citric acid also acts as an antioxidant by protecting certain vitamins from destruction by oxygen radicals (free radicals).
FDA
Citric acid is generally considered safe (GRAS) and can be used in food without any limitations other than current safe manufacturing practices. In food, it can be used as an antimicrobial agent, antioxidant, flavoring agent, pH control agent, and sequestrant.
EFSA
As food additives, citric acid anhydrous and monohydrate (E330) are regulated by Commission Regulation (EU) No 231/2012 as “additives other than colours and sweeteners.”
Uses
A maximum level of E330 is “quantum satis”, which means there is no specific limit on its use. It may be found in the following foods:
- Mozzarella, whey cheese
- Fats and oils
- A frozen fruit or vegetable, a canned fruit or vegetable, or a bottled fruit or vegetable
- Jam, jellies and marmalades
- Cocoa and chocolate products
- Pasta, minced meat, and unprocessed fish
- Table-top sweeteners in liquid/powder/tablets form
- Formulas for infants, processed cereal-based foods, and baby foods
- Juices, beer, and malt beverages
UK Food Standards Agency
This item is categorized as “Others”
Food Standards Australia New Zealand
In Australia and New Zealand, it is an approved ingredient with code number 330.
JECFA
Functionality class: Food Additives, flavouring agent, acid, antioxidant synergist, sequestrant.
Permissible daily intake: ADI “not limited” set since 1973 for it and its salts.
What is the side effects of citric acid?
Many consumers wonder if citric acid is harmful to their health and what the dangers are. Although it is generally considered safe, some people may be allergic to it.
Allergy & Intolerance
People who are sensitive to citric acid may experience the following allergy symptoms:
- Hives
- Difficulty breathing
- Your face, lips, tongue, or throat may swell.
Other Possible Side Effects
Foods, beverages, or vitamins containing citric acid may cause the following side effects in some people, according to a 2018 report:
- Respiratory symptoms
- Joint pain
- Irritable bowel symptoms
- Muscular pain and enervation
Tooth erosion
Eating acid-containing foods may cause tooth erosion, a chronic loss of dental osseous tissues, enamel, and dentine. A 2015 study found that acidic beverages, such as apple juice or orange juice containing citric acid, have five times the erosive effect of Coca-Cola light.
Does citric acid cause cancer?
No, on the contrary, a study published in Cell Journal in 2016 found that citric acid prevents esophageal cancer 109 cell growth by inhibiting cell proliferation and inducing apoptosis. According to Nature, citrate can also suppress tumor growth.
Is it safe for pregnant?
It is generally safe, but you should consult your doctor before taking it.
How to get citric acid?
Citric acid is an organic compound that is naturally present in fruits and vegetables. It is also commercially prepared by fermentation of carbohydrates, such as sugar or molasses. Citric acid can be used as an acidulant to give a sour taste to foods and beverages.
Citric acid can be obtained from natural sources such as:
- Fruits and vegetables: Citrus fruits and apples contain high amounts of citric acid.
- Molasses: Molasses is another source of citric acid, but it is not as pure as the former two sources.
How much citric acid as preservative?
The amount of citric acid used as a preservative depends on the type of product and the pH. Generally, it is added at a level of 0.1% to 0.5%.
In general, the more acidic the product, the lower the amount of citric acid needed. For example, if you have an acidic product with a pH below 3, you can use 0.1% citric acid (one part citric acid to one million parts product). If your product is less acidic but still below 4, you would use 0.2% citric acid (one part to 500,000 parts).
The higher the pH of your product is above 4 but below 5 (such as a cleaning solution), then you would use 0.3% citric acid (one part to 333,333 parts).
For products above 5 (such as lotions), use 0.4% or even 0.5%.
How citric acid prevent browning?
Citric acid is the main ingredient in lemon juice and is used as a food additive to inhibit browning. It also prevents the growth of mold on produce, which is why it’s often added to canned fruits.
Lemons and limes, among other citrus fruits, contain the most citric acid of all fruits and vegetables. Citrus fruits also contain natural antioxidants that help prevent browning by slowing down the oxidation process that causes browning.
In addition to preventing browning, citric acid has several other health benefits:
Promotes bone health: Citric acid helps promote bone health by increasing calcium absorption, which strengthens bones and teeth. Citric acid also helps fight osteoporosis by preventing calcium loss through urine.
Boosts immune system: Citric acid contains antioxidants that help kill harmful bacteria and viruses, which boosts your immune system so you’re better able to fight off infections and disease.
What does citric acid cycle do?
The citric acid cycle is a set of enzymatic reactions that take place in the cells of the mitochondria. It is also called the tricarboxylic acid (TCA) cycle, or the Krebs cycle, named after Hans Adolf Krebs. The energy released during these reactions powers the creation of ATP, which can be used to fuel other cellular processes.
The citric acid cycle is a key part of cellular respiration and occurs in both prokaryotes and eukaryotes.
The citric acid cycle occurs in two phases:
Phase 1: Oxidative decarboxylation phase – This phase involves breaking down pyruvate into acetyl CoA (acetyl-coenzyme A). This reaction releases carbon dioxide as a waste product.
Phase 2: Reductive carboxylation phase – In this phase, acetyl CoA enters the citric acid cycle and gets reduced by NAD+ to produce citrate, which then gets oxidized again so that it can rejoin with oxaloacetate to start another round of reactions.
What is citric acid good for skin?
Citric acid is a natural acid found in citrus fruits. It is also used as a preservative in many cosmetic products.
Citric acid is effective in treating oily skin and acne breakouts. It also helps to lighten dark spots on the face, neck and chest, giving you a fairer complexion.
Citric acid is known to have anti-inflammatory properties that help reduce redness and swelling caused by pimples and other skin issues. The humectant properties of citric acid help retain moisture on your skin’s surface, which prevents dryness and flaking of the skin.
Additionally, citric acid has antibacterial properties that prevent bacteria from thriving on your skin’s surface causing inflammation or infection.
What does citric acid and baking soda make?
Citric acid and baking soda are two common ingredients in the home. Both are used for their chemical properties to make cleaning products and as food additives. Adding these two ingredients together creates an explosive reaction that can be used to create fizzy science experiments.
Citric Acid
Citric acid is an organic compound found in citrus fruits such as lemons and limes. It is also produced commercially from sugar cane. Citric acid has a sour taste and it is used as a preservative in foods like lemonade or fruit juices. In the laboratory, it can be used to test for proteins by changing the pH of the solution around them.
Baking Soda
Baking soda is sodium bicarbonate that has many uses in cooking and baking because it reacts with acids to produce carbon dioxide gas, which makes baked goods rise when they are cooked in an oven (called leavening). Baking soda also has antacid properties that can neutralize stomach acidity when added to water before consuming acidic foods like oranges or tomatoes that cause heartburn or indigestion when eaten on an empty stomach.
Where to buy citric acid?
Citric acid is a weak organic acid that can be found in citrus fruits. It is also added to foods as a preservative and flavoring agent. Citric acid can be used for many different things, including cleaning solutions, detergents, and cosmetics.
Citric acid is available at most grocery stores, but if you want to buy it in bulk or as crystals it may be more difficult to find. Here are some places where you can find citric acid:
- Online – You can buy citric acid online directly from Amazon or from other online retailers like eBay and Etsy. The prices will vary based on the size of the container you are buying, but they are not very expensive overall.
- Natural food stores – Natural food stores often carry bulk quantities of citric acid in their bulk foods section. You can ask an employee if they have any available, or look through their products online before going into the store so that you know what brands carry what products at what price points.
- Grocery stores – Some grocery stores carry small amounts of citric acid in their baking sections or near other spices, but few have large quantities of bulk products available for purchase like natural food stores.
Frequently Asked Questions
Is it polar?
Yes, It is polar and soluble in polar substances, such as water.
Is it ionic or covalent?
There are no ionic bonds in this covalent compound.
Is it an amino acid?
The answer is no, citric acid is neither an amino acid nor does it contain amino acids.
Is it a sugar?
No, but Aspergillus niger can ferment sugar substrate to produce it.
Is it natural?
As it occurs naturally in citrus fruits, like lemons and limes, and is produced commercially by fermentation process instead of extraction, it can be considered natural.
Is it organic?
If it is made from organic raw materials, it can be organic.
Is it vegan?
In addition to being vegan, the raw material glucose and/or sucrose carbohydrate used and the manufacturing process do not contain animal products. The ingredient can be added to vegetarian foods as a vegan food ingredient.
Is it halal?
There is no doubt that it is halal as it is permitted under Islamic Law and fulfills Halal’s requirements. And we can find some manufacturers certified with MUI Halal.
Is it kosher?
Yes, it is kosher pareve. The E330 can be certified as kosher or passover if it meets all the kashruth requirements.
Is it gluten free?
The food is usually gluten-free and can be eaten by celiacs. Ingredients containing this ingredient are commonly found on both gluten-free and gluten-containing food labels. In addition to being produced from corn, it complies with the FDA’s definition of glutenless, which means it does not include wheat, rye, barley, or their crossbreeds.
What are the substitutes?
There are some food applications that can benefit from the use of other organic acids, such as malic acid, tartaric acid, and fumaric acid.
Citric acid Vs sodium citrate?
The sodium salt of citric acid is sodium citrate. Citric acid reacts with sodium hydroxide or baking soda to produce it.
It refers to the last of three forms of sodium citrate, monosodium citrate, disodium citrate, and trisodium citrate.
The following is a comparison and difference:
- Acidity: Citric acid is a weak organic acid, while sodium citrate is a weak alkaline.
- Taste: Citric acid is mainly used to enhance flavor with a sour taste, whereas sodium citrate has a less obvious sour taste. The sour taste occurs when it is hydrolyzed into citric acid.
- Uses: There is not much difference between the two applications. In food, both can be used as preservatives, pH buffers, and chelating agents.
Does coffee have citric acid?
The answer is yes, coffee contains caffeine.
What is the difference between citric acid and vitamin C?
They’re both organic acids. Vitamin C is also known as ascorbic acid. Although citric acid and ascorbic acid are both naturally occurring in citrus fruits, they are totally different substances.
Uses: In food, ascorbic acid is primarily used as a nutritional supplement, antioxidant, and color stabilizer. Citric is an acidulant used as PH control, preservative, antioxidant and chelating agent.
Manufacturing: In both cases, fermentation is used, but the processes and microbes are different.
What is encapsulated citric acid?
There is a specific application for it. Citric acid with a coating on the outside that prevents the acid from releasing prematurely.
What are the differences between citric acid, malic acid, tartaric acid, acetic acid, and phosphoric acid?
All of them are acidulants found in food and drinks. The following are brief comparisons between them:
Sources: All fruits contain these acids, except for phosphoric acid, which is an inorganic acid.
Types: As food additives, malic acid and tartaric acid both have L and DL types.
Manufacturing process:
- Glucose fermentation produces citric acid, L-malic acid.
- As a byproduct of winemaking, enzyme process, or fermentation method, L-tartaric acid can be obtained.
- As a result of chemical synthesis, DL-malic acid, acetic acid, and phosphoric acid are produced.
- As a result of the enzyme, DL-tartaric acid is produced.
Form: Powders and granules of the first three acidulants are available, while liquids of the remaining two are available.
Conclusion
Citric acid is considered as a food additive that usually used as an acidity regulator. It is highly effective in neutralizing bitterness and adding a desirable sourness to food products. Citric acid can also be used in different fields like medicine, cosmetics and so on. Supplements containing citric acid are not regulated by the FDA, so some of their ingredients or dosages may not be safe and reliable.
