Thai basil and holy basil are related to each other and both are fixtures in Thai and other Southeast Asian cuisines. They are popular because each of them has certain distinctive qualities. To get the best from these two basil varieties, you will need to understand those distinctive qualities. We will examine what makes each of these herbs unique in this edition of SPICEography Showdown.
How do Thai basil and holy basil differ?
Thai basil is a different plant from holy basil. The Latin name for Thai basil is Ocimum basilicum; the Latin name for holy basil is Ocimum tenuiflorum. It is important to note this fact since some resources claim that they are the same plant. It is easier to make that mistake than you might think since holy basil is sometimes referred to as Thai holy basil.
The differences lie in several areas with the key area being flavor. Thai basil is known primarily for being sweet. It has a strong licorice and anise note that allows it to stand out in Thai curries and soups. The anise note is so strong and so sweet that you can eat Thai basil raw.
Holy basil brings another flavor profile to the table in that it is intensely spicy, so much so that it is sometimes referred to as hot basil. When consumed raw, holy basil has a slight numbing effect on the tongue that is similar to the effect of Szechuan pepper. The flavor is more like a combination of black pepper and clove than like the sweeter notes of Thai basil. It tends to get even spicier as it is cooked.
These two herbs also differ in how they look. Thai basil has distinctive purple stems and leaves. There are two varieties of holy basil: a white one and a red one. The leaves of both are hairy and more delicate than the leaves of Thai basil.
Can you use Thai basil in place of holy basil and vice versa?
Thai basil will work in place of holy basil as long as you remember how sweet it is. Thai basil will give you a strong aromatic note but none of the spiciness that comes from holy basil.
If you are trying to replicate a Thai dish that you have had in the West, the flavor that you want is probably Thai basil even if the dish is traditionally made with holy basil. The reason is that it is difficult to find holy basil outside of Asia, so most restaurants use the more readily available Thai basil in its place. You can use holy basil in place of Thai basil as well. You will have to adjust how much of it you use to compensate for its peppery flavor and you can sweeten it by adding a little sweet basil, which is also called Mediterranean basil.
When should you use Thai basil and when should you use holy basil?
Use Thai basil for a Western version of classic Thai dishes like drunken noodles and in both green and red curries. You should also use it in Taiwanese sanbeiji. It is the traditional accompaniment some Vietnamese dishes where the leaves are served as a table condiment. Use holy basil if you want a more authentic version of drunken noodles and red and green curries. Holy basil is the herb of choice for pad gaprao, the Thai pork stir-fried dish.