Citric acid is one of the most versatile and widely used organic acids in both industrial and domestic settings. Naturally occurring in citrus fruits like lemons and oranges, citric acid is prized for its tart flavour, chelating properties, and ability to adjust pH levels. In the commercial market, citric acid is available in two primary forms: anhydrous and monohydrate. Understanding the differences between these two forms and their specific uses can help you select the right type for your needs.
What Is Citric Acid?
Citric acid is a weak organic acid with the chemical formula C6H8O7. It is colourless, odourless, and crystalline in form. Known for its sour taste, citric acid plays a vital role in the citric acid cycle (Krebs cycle), an essential part of cellular metabolism.
Commercially, citric acid is produced through fermentation, typically using the mould Aspergillus niger on a sugar-containing substrate. It is then crystallised into different forms, primarily anhydrous citric acid and citric acid monohydrate.
Differences Between Citric Acid Anhydrous and Monohydrate
1. Water Content
-
Citric Acid Monohydrate contains one molecule of water (H2O) per molecule of citric acid.
-
Citric Acid Anhydrous contains no water molecules.
2. Appearance and Texture
-
Monohydrate: Appears as colourless crystals or white crystalline powder.
-
Anhydrous: Appears as a finer white powder, less crystalline in texture.
3. Melting Point
-
Monohydrate: Melts at 100°C due to water content.
-
Anhydrous: Melts at 153°C.
4. Storage and Shelf Life
-
Monohydrate: Slightly more hygroscopic due to water content.
-
Anhydrous: More stable in dry conditions and longer shelf life when kept dry.
5. Applications
While both forms are chemically similar, the presence or absence of water can influence their suitability for different applications.
Common Uses of Citric Acid
Citric acid's versatility makes it valuable across numerous industries:
Food and Beverage Industry
-
Acts as a preservative and flavour enhancer.
-
Example: In soft drinks, 2g of citric acid per litre enhances tartness.
-
Used in jams, jellies, and canned foods to maintain pH balance.
Cleaning Products
-
Excellent at breaking down limescale, especially in hard water areas.
-
Usage: Dissolve 100g of citric acid in 1L of warm water to descale kettles or coffee machines.
Cosmetics and Personal Care
-
Adjusts pH in shampoos, conditioners, and bath bombs.
-
Example: 5g of citric acid per 100g of bath bomb mix helps maintain skin-friendly pH.
Pharmaceuticals
-
Acts as a stabiliser and preservative in medicines.
-
Used in effervescent tablets where it reacts with sodium bicarbonate to produce carbon dioxide.
Industrial Applications
-
Used in metal cleaning and as a chelating agent.
-
Common in textile and leather processing.
Choosing the Right Type of Citric Acid
When to Use Citric Acid Monohydrate
Choose citric acid monohydrate UK online if your application involves water or if you're creating products where the water content can be tolerated or is beneficial (e.g., food and beverage, bath bombs).
When to Use Citric Acid Anhydrous
Select citric acid anhydrous UK online for applications requiring dry ingredients or longer shelf stability. It's ideal for dry mixes and powdered formulations.
Practical Examples
Descaling a Coffee Machine
-
Dissolve 100g of citric acid (anhydrous or monohydrate) in 1 litre of warm water.
-
Pour into the water reservoir.
-
Run a brewing cycle halfway, then let sit for 30 minutes.
-
Complete the cycle and rinse twice with clean water.
Making Bath Bombs
-
Mix 100g baking soda, 50g citric acid monohydrate, 25g cornflour, and essential oils.
-
Add a few drops of water, form into moulds.
Where to Buy Citric Acid in the UK
For reliable quality and fast delivery, visit HD Chemicals – your trusted UK chemical supplier. You can directly purchase:
FAQs About Citric Acid
1. Can citric acid be used for descaling kettles? Yes, both anhydrous and monohydrate forms work well for descaling.
2. Is citric acid safe for food use? Yes, food-grade citric acid is safe and commonly used in beverages, jams, and canned foods.
3. What is the shelf life of citric acid? When stored in a cool, dry place, citric acid anhydrous can last up to five years, while monohydrate lasts about three years.
4. Can I use citric acid in dishwasher cleaning? Yes, it effectively removes limescale and grease.
5. Is citric acid the same as Vitamin C? No, they are different compounds. Vitamin C is ascorbic acid.
6. How much citric acid should I use in homemade cleaners? Typically, 1 tablespoon (about 15g) per 500ml of water works well.
7. Can citric acid damage metal? It can etch or corrode some metals if left for too long. Rinse thoroughly after use.
8. What’s better for bath bombs, anhydrous or monohydrate? Monohydrate is preferred due to its water content aiding the fizzing reaction.
9. Is citric acid biodegradable? Yes, it is environmentally friendly and biodegradable.
10. Can I substitute anhydrous for monohydrate? Yes, but adjust for water content; anhydrous is more concentrated by weight.
For all your citric acid needs, whether industrial, household, or cosmetic, HD Chemicals has you covered with high-quality products and expert support. Visit us today to explore our full range!