Ice Cream and Science

Everyone loves to eat ice cream. Its smooth texture, sweet taste and rich flavor makes it a perfect dessert.

Did you know that chemistry plays a great deal in making the ice cream perfect ?

Know the science of making ice cream to make the perfect one

Why ice cream floats in an ice cream soda ?

Ice cream has a lot of ice crystals that float, a lot of fat which floats and a lot of air which for sure floats. Those ingredients all together make ice cream a great floater!

If you refreeze melted ice cream, why is it never as good as it was before?

The liquid ice cream fills up the air pockets, when the ice cream melts. But when it refreezes, there are fewer air pockets and as a result ice cream is less airy and fluffy. The other reason is that when the ice cream melts, the original tiny ice crystals melts off. Refreezing the ice cream makes larger ice crystals which makes the ice cream too crunchy.

Why ice cream tastes overly sweet at room temperature ?

Cold tends to numb the taste buds, because of which they become less sensitive. So more sugar needs to be added to produce the desired effect at the low temperatures in which ice cream is usually served. Hence when you taste ice cream at room temperature it will taste overly sweet.

Why we get head ache while eating ice cream?

It is a kind of short-term headache typically linked to the rapid consumption of ice-cream, ice pops, or very cold drinks. It is also known as Brain freeze. Sensation of brain freeze is caused by a dramatic and sudden increase in blood flow through the brain’s anterior cerebral artery. As soon as the artery comes to normal, the brain-freeze pain sensation goes off.

Know the science of making ice cream to make the perfect one

How to make perfect ice cream

The name ice of ice cream comes from ‘Ice crystals’. The size of the ice crystals determines how fine, or grainy, the ice cream should become. It’s the ice crystal which gives ice cream its solid shape. Ice crystals range in size from about 1 to over 150 μm in diameter, with an average size of about 25 μm.  Small ice crystals, around 10 to 20 µm in size, give ice cream its smooth and creamy texture, whereas larger ice crystals, greater than 50 μm, impart a grainy texture.

Next ingredient is fat, which gives ice cream it’s creaminess. Fat adds richness, stabilizes the base mix, improves density and the smoothness of texture and generally increases  flavor. The creamiest ice creams have about 16% fat and the least creamy have about 10% fat.

Good quality ice creams contain more fat and less infused air, making for a denser, richer ice cream. whereas cheaper industrial ice creams, tend to go for less fat, with more stabilizers and emulsifiers and sometimes more than 100 % infused air, making for a more fluffy end-product.

Ice cream need to be sweet and sweetness comes from sugar or sucrose, sometimes even honey. Sugar not only imparts sweetness but also contributes to the firmness of ice cream. Since we eat ice cream cold, which make our sense buds numb, ice cream makers add more sugar to it to give the desired sweetness.

In ice cream, liquid particles of fat—called fat globules—are spread throughout a mixture of water, sugar, and ice, along with air bubbles

Next is the cheapest, but most important ingredient- Air. Air cells are largely responsible for the general consistency of ice cream, and greatly affect texture and volume. Air makes up anywhere from 30% to 50% of the total volume of ice cream. The amount of air added to ice cream is known as overrun. If the volume of ice cream is doubled by adding air, then the overrun is 100%, which is the maximum allowable amount of air that can be added to commercial ice cream. Since air is free and increase the volume, non-premium commercial ice creams many a times have an overrun sometimes even exceeding 100 %.  We could clearly see the difference when we compare the net weight of one liter packs of less costly brand of ice cream like Amul or Kwality Walls against costly ones like Baskin Robbins.  We can also easily find the difference by keeping them out. Ice cream with more air will melt faster .

To the ice cream base we need to add non-fat milk solids, such as proteins and mineral salts, and  essence of  vanilla, strawberry, mango and sometimes some colors to make it more attractive. Flavor and other added solids also contribute to the body, texture and smoothness of ice cream. Emulsifiers and stabilizers are added to give ice cream uniformity and stability. In commercial ice cream production, the emulsifiers are often various extractions from oils. Starch, Guar gum, Gelatin and Agar Agar are some examples of stabilizers used.

Once we have all the ingredients, next step involves mixing them all together at sub zero temperature so that it takes a solid shape. This is because once we add solutes to liquid, it will no longer freeze at zero degree, but at a lower temperature. A freezing point depression of 1.86 °C occurs for every mole of solute added to 1 kilogram (kg) of water. Freezing point depression is a colligative property, meaning that the effect is observed regardless of the specific identity of the solute. Home based ice cream makers mainly add salt to lower the freezing temperature of ice. Now it’s possible to make even instant ice cream with the help of liquid nitrogen (-196°C).