Mustard (අබ)

Mustard has been flavouring food for thousands of years, and it remains one of the world's most versatile spices. In Sri Lanka, mustard — known as අබ (aba) — is an essential ingredient in everything from fiery curries to pickled vegetables, and the seeds, powder, and oil each play distinct roles in the kitchen. Whether you are stocking a pantry at home or exploring Sri Lankan cuisine for the first time, understanding the different types of mustard will help you use it with more confidence.

What types of mustard seeds are there?

There are more than 40 botanical varieties of mustard, but three dominate culinary use worldwide: black, brown, and white (also called yellow). Each comes from a different plant and carries its own flavour intensity and typical application.

• Black mustard seeds (Brassica nigra) — the smallest and most pungent of the three, native to North Africa and parts of Europe and Asia. They have a sharp, nutty heat that develops quickly in hot oil.
• Brown mustard seeds (Brassica juncea) — also known as Indian, Chinese, or Oriental mustard. Slightly larger than black seeds, with a deep, spicy flavour. They range in colour from dark brown to dark yellow depending on the variety.
• White mustard seeds (Sinapis alba) — the mildest of the three, producing the pale tan seeds used to make conventional yellow mustard condiments. They are larger than the other two types and are also commonly used in pickling.

All three varieties are used in Sri Lankan cooking, though black and brown mustard seeds appear most frequently in traditional recipes.

How is mustard used in Sri Lankan cooking?

In Sri Lankan cuisine, mustard seeds are typically tempered whole in hot coconut oil or ghee at the start of a dish — a technique called theldala. The seeds are added to the oil and left to sputter and pop, releasing a nutty, mildly bitter aroma that forms the base of curries, dhal preparations, and vegetable dishes. This method is especially common in the south of the island, where coconut oil is the standard cooking fat.

Mustard also appears in Sri Lankan pickles and achcharu (spiced relishes), where whole or lightly crushed seeds contribute both flavour and a mild preservative quality. Ground mustard powder is used in marinades for fish and meat, and in some regional recipes for egg or potato curry it acts as a key thickening and flavouring agent.

Mustard oil, pressed from brown mustard seeds, has a pungent, slightly bitter edge that mellows when heated. It is used in some northern and eastern Sri Lankan households for cooking and in traditional Ayurvedic preparations for massage and hair care.

What is the difference between mustard seeds, mustard powder, and mustard oil?

Each form of mustard serves a different purpose, and knowing when to reach for each one makes a meaningful difference to the finished dish.

Ground mustard powder is essentially dried, finely milled mustard seeds. When mixed with cold water and left for a few minutes, the milling activates enzymes that produce a sharp, sinus-clearing heat. Adding hot water or an acid such as vinegar stops this reaction and results in a milder flavour.

What are the health properties associated with mustard?

Mustard seeds contain glucosinolates and isothiocyanates — the compounds responsible for their characteristic heat — which have been studied for their antioxidant and anti-inflammatory properties. They are also a source of selenium, magnesium, and omega-3 fatty acids in small amounts. In Ayurvedic medicine, mustard oil has long been used externally to stimulate circulation, relieve muscle stiffness, and condition the scalp. These traditional uses are reflected in products such as Siddhalepa's mustard oil formulations, which combine the oil with other Ayurvedic herbs.

It is worth noting that raw mustard oil contains erucic acid, and its use as a cooking oil is restricted or not recommended in some countries. Sri Lankan and South Asian culinary traditions typically heat the oil before use, which reduces some of these compounds, but if you have specific dietary concerns it is worth consulting a health professional.

How should mustard seeds and powder be stored?

Whole mustard seeds keep their potency well when stored in an airtight container away from direct light and moisture. Kept this way, they typically stay fresh for up to a year. Ground mustard powder loses its heat more quickly once opened — ideally use it within six months and store it in a cool, dark cupboard. Mustard oil should be stored in a dark glass or opaque container to prevent oxidation; once opened, keep it refrigerated if you do not use it regularly.

What is the difference between black and brown mustard seeds?

Black mustard seeds (Brassica nigra) are smaller, harder to harvest mechanically, and more pungent than brown seeds. Because of the harvesting difficulty, black mustard has been largely replaced by brown mustard in commercial production, even in many Indian and Sri Lankan spice markets. What is sold as "black mustard" in some Sri Lankan grocery stores may in practice be a dark-brown variety. True black mustard seeds are noticeably smaller and release a sharper aroma when toasted. Brown mustard seeds are more commonly used in European Dijon-style mustards and in the production of mustard oil across South and East Asia.

How do mustard seed varieties compare in heat level?

Black mustard seeds are generally the most pungent, followed closely by brown, with white mustard seeds being the mildest. The heat in mustard comes from volatile isothiocyanate compounds that are released when the seeds are crushed or broken and come into contact with water. Whole toasted seeds have a gentler, nuttier flavour because the heat-releasing reaction is largely prevented until the seed coat is broken.