Differences between Alcoholic and Lactic acid Fermentation

Differences between alcoholic fermentation and lactic acid fermentation in simple terms. Both processes are ways for cells to make energy without using oxygen, but they produce different end products and are used by different organisms.

Alcoholic Fermentation

1. What it is:

Alcoholic fermentation is a process in which yeast (a type of fungus) and some bacteria convert sugar into alcohol and carbon dioxide (CO₂). This happens when there isn’t enough oxygen available for regular energy production.

2. How it works:

• First, glucose (a type of sugar) is broken down in a process called glycolysis. This produces a small amount of energy (2 ATP) and pyruvate (a smaller molecule derived from glucose).

• Without oxygen, pyruvate is then converted into ethanol (alcohol) and CO₂.

• During this process, NADH (a molecule that carries electrons) gives up its electrons and turns back into NAD⁺. This step is important because NAD⁺ is needed to keep glycolysis going, allowing the cell to continue making small amounts of energy.

3. Where it happens:

• Alcoholic fermentation is mainly used by yeast and some bacteria. In yeast, this process is critical for producing foods and drinks like bread, beer, and wine.

• In bread-making, the CO₂ gas bubbles make the dough rise, while the alcohol evaporates during baking.

4. End Products:

• The main byproducts are ethanol (alcohol) and CO₂. Ethanol gives alcoholic drinks their effects, and CO₂ helps bread to rise.

Lactic Acid Fermentation

1. What it is:

Lactic acid fermentation is a process where certain bacteria and muscle cells in animals (including humans) convert sugar into lactic acid when there isn’t enough oxygen. This is common in hard-working muscles or in bacteria that help ferment foods.

2. How it works:

• Just like in alcoholic fermentation, glucose is first broken down by glycolysis, producing 2 ATP and pyruvate.

• Since there’s no oxygen, pyruvate doesn’t go to the mitochondria for further breakdown. Instead, it’s converted directly into lactic acid.

• NADH gives up its electrons, turning back into NAD⁺, allowing glycolysis to continue.

3. Where it happens:

• Muscle cells: When you do intense exercise, like sprinting, your muscles might not get enough oxygen. In this case, they switch to lactic acid fermentation to keep producing some energy. This is why muscles sometimes feel sore or burn during hard exercise, as lactic acid builds up.

• Certain bacteria: Some bacteria, like Lactobacillus, use lactic acid fermentation. They’re used to make foods like yogurt, kimchi, and sauerkraut, where lactic acid gives the food a tangy flavor.

4. End Product:

• The main byproduct is lactic acid, which builds up in muscles during exercise and adds a sour taste to fermented foods.

Key Differences Recap:

• End Products: Alcoholic fermentation produces alcohol (ethanol) and CO₂; lactic acid fermentation produces lactic acid.

• Organisms: Alcoholic fermentation is done by yeast and some bacteria; lactic acid fermentation is done by certain bacteria and muscle cells in animals.

• Uses: Alcoholic fermentation is used in making alcoholic drinks and bread; lactic acid fermentation is used in muscle energy during exercise and in making fermented foods.

In summary, both processes allow cells to produce energy without oxygen, but they result in different products and are carried out by different types of cells and organisms, each with unique uses in food and the body.