What is Lactose Definition Structure Formula Hydrolysis and Uses
Disaccharides are sugars that get formed when two simple sugars (monosaccharide) come together. Sucrose, maltose, and lactose are the most common disaccharides out there. You are already familiar with the latter one, that is, lactose. It is the primary element found in the milk of all mammals. In contrast with the majority of saccharides, lactose is not sweet. In simple words, lactose is a sugar that’s in milk. It gets used by the body for energy and numerous other functions. However, most people have difficulty in digesting lactose. In this article, you can learn about lactose intolerance, its symptoms, and the structure of lactose.
What is Lactose?
Lactose is a disaccharide containing two units, glucose and galactose. These units get bonded together by 1-4 glycosidic bonds in a beta orientation. Our bodies use an enzyme called lactase to digest the lactose, so it gets absorbed into the body. But, people not having adequate lactase in their body suffer from lactose intolerance.
Lactose Monohydrate
You can find lactose monohydrate mainly in milk and dairy products. It’s a naturally occurring disaccharide. You should know that lactose crystals have the water of crystallization due to which molecular mass becomes 360.3 g/mol as compared to 342.3 g/mol of anhydrous lactose. It is available in the white, crystalline powder.
Lactose monohydrate is soluble in water and slightly soluble in ethanol. Also, when the disaccharide gets heated to 418K temperature, it results in the loss of one of the molecules of water from lactose anhydrous. Below you can have a look at the structure of lactose monohydrate.
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Formation of Lactose Monohydrate
Lactose monohydrate is the crystalline form of lactose, and it’s the primary carbohydrate in cow’s milk. It gets composed of two simple sugars, galactose and glucose bonded together. It is found in two forms having different chemical structures – alpha and beta-lactose.
Lactose monohydrate gets produced when alpha-lactose from cow’s milk gets exposed to low temperatures until crystals begin to form. Further, the unwanted moisture gets dried off to render a dry, white or pale yellow powder.
It tastes slightly sweet and much similar to the milk. In simple words, lactose monohydrate gets produced by crystallizing lactose, the primary sugar in cow’s milk, into a dry powder.
Uses of Lactose Monohydrate
In food and pharmaceuticals, lactose monohydrate gets known as milk sugar. Since it has long shelf-life, sweet taste, great mix-ability, it has a great range of applications.
Mostly, it gets used as a food additive and filler for drug capsules. A major chunk of its application involves industrial use and not domestic.
Fillers such as lactose monohydrate get added to an active drug in a medication. So, it can render a pill or tablet, which is easy to swallow or consume.
As a matter of fact, 20% of prescription drugs and 65% of OTC drugs like calcium supplements, birth control pills, and acid reflux medications use lactose.
It also gets added in infant formulas, packaged snacks, and frozen meals. Further, processed cookies, cake, pastries, soups, sauces, and other food items contain the lactose too.
The main purpose of using lactose is to add sweetness or serve as a stabilizer so that ingredients don’t mess up.
Animal feeds have lactose monohydrates as it facilitates an affordable way to up the food volume and weight.
Lactose Intolerance
If your body cannot digest lactose, a sugar found in milk and other dairy goods, you have lactose intolerance. The condition occurs when the small intestine doesn’t produce adequate lactase, the enzyme that helps digest the lactose.
So, when your body is not producing enough lactase, the lactose you consume via dairy products doesn’t get digested. Instead, it gets treated or broken down by the bacteria in your colon, which further causes gas. It all can escalate quickly and show unpleasant symptoms.
Symptoms of lactose intolerance: These symptoms rely on the lactase production in your body. The typical symptoms of lactose intolerance include diarrhoea, vomiting, gas, gurgling, bloating, aches or cramps, etc.
FAQs on Lactose Structure Properties and Biological Role
1. What is lactose in chemistry?
Lactose is a disaccharide sugar composed of one glucose unit and one galactose unit with the molecular formula C12H22O11. In carbohydrate chemistry, lactose is known as "milk sugar" because it is naturally found in milk. It is formed by a glycosidic linkage between:
- β-D-galactose
- D-glucose
2. What is the chemical formula of lactose?
The chemical formula of lactose is C12H22O11. This formula indicates:
- 12 carbon (C) atoms
- 22 hydrogen (H) atoms
- 11 oxygen (O) atoms
3. Is lactose a reducing sugar?
Yes, lactose is a reducing sugar because it has a free anomeric carbon that can act as a reducing agent. In lactose, the glucose unit retains a free hemiacetal group, which allows it to:
- Reduce Benedict’s solution
- Reduce Fehling’s solution
4. What type of glycosidic bond is present in lactose?
Lactose contains a β(1→4) glycosidic bond between galactose and glucose. Specifically:
- The bond forms between carbon-1 of β-D-galactose
- And carbon-4 of D-glucose
5. How is lactose formed chemically?
Lactose is formed by a condensation reaction between galactose and glucose, releasing one molecule of water. The simplified reaction is:
- Galactose + Glucose → Lactose + H2O
- A glycosidic bond forms between the two monosaccharides
- A molecule of water is eliminated (dehydration synthesis)
6. How is lactose hydrolyzed?
Lactose is hydrolyzed into glucose and galactose by breaking its β(1→4) glycosidic bond using water. The balanced hydrolysis reaction is:
- C12H22O11(aq) + H2O(l) → C6H12O6(aq) + C6H12O6(aq)
- Enzymatically using lactase
- By acid-catalyzed hydrolysis in laboratory conditions
7. What is the difference between lactose and sucrose?
The main difference between lactose and sucrose is that lactose is a reducing disaccharide, while sucrose is non-reducing. Key differences include:
- Lactose: Glucose + Galactose, β(1→4) bond, reducing sugar
- Sucrose: Glucose + Fructose, α(1→2) bond, non-reducing sugar
8. What functional groups are present in lactose?
Lactose contains multiple hydroxyl (–OH) groups and one hemiacetal group. Its key functional groups include:
- Several alcohol (–OH) groups on both sugar units
- A glycosidic ether linkage (C–O–C)
- A free hemiacetal group on the glucose unit
9. What is the molar mass of lactose?
The molar mass of lactose (C12H22O11) is approximately 342.30 g·mol-1. It is calculated as:
- Carbon: 12 × 12.01 = 144.12 g·mol-1
- Hydrogen: 22 × 1.008 = 22.18 g·mol-1
- Oxygen: 11 × 16.00 = 176.00 g·mol-1
10. Why is lactose important in chemistry and biochemistry?
Lactose is important in chemistry because it is a model disaccharide used to study glycosidic bonds, reducing sugars, and carbohydrate reactions. Its significance includes:
- Demonstrating β(1→4) glycosidic linkage
- Serving as an example of a reducing sugar
- Illustrating enzymatic hydrolysis by lactase
- Applications in food chemistry and pharmaceutical formulations
