What Makes Mustard Yellow?


Mustard is a popular condiment used in various cuisines around the world. One of the distinctive characteristics of mustard is its yellow color. In this article, we will explore the factors that contribute to the yellow color of mustard and delve into the fascinating science behind it.

1. The Chemistry of Mustard Seeds

Mustard seeds, the primary ingredient used to make mustard, contain compounds called glucosinolates. Glucosinolates are natural chemicals found in many plants of the Brassicaceae family, which includes mustard plants.

1.1 Types of Glucosinolates in Mustard Seeds

Mustard seeds contain different types of glucosinolates, such as sinigrin, sinalbin, and gluconasturtiin. These glucosinolates are responsible for the pungent taste and aroma of mustard.

1.1.1 Sinigrin

Sinigrin is the most abundant glucosinolate in yellow mustard seeds (Sinapis alba). When the seeds are crushed or ground, an enzyme called myrosinase is activated, which converts sinigrin into allyl isothiocyanate. Allyl isothiocyanate is the compound responsible for the sharp, spicy flavor of yellow mustard.

1.1.2 Sinalbin and Gluconasturtiin

Sinalbin and gluconasturtiin are the main glucosinolates found in brown or black mustard seeds (Brassica juncea and Brassica nigra). These seeds also contain myrosinase, but instead of producing allyl isothiocyanate, they produce different isothiocyanates with distinct flavors.

2. The Yellow Pigment – Curcumin

While the glucosinolates provide the pungent taste and aroma, the vibrant yellow color of mustard comes from a different compound called curcumin. Curcumin is a natural pigment found in turmeric, which is often added to mustard to enhance its color.

2.1 The Role of Curcumin in Mustard

Curcumin acts as a colorant in mustard, giving it the characteristic yellow hue. It is soluble in oil, making it suitable for creating a homogeneous color in mustard paste or sauce.

2.1.1 Turmeric in Mustard

Turmeric powder, derived from the rhizome of the Curcuma longa plant, is commonly added to mustard recipes to enhance its yellow color. Turmeric contains curcumin, which imparts a bright yellow color to the mustard.

2.1.2 Mustard Varieties without Curcumin

Some mustard varieties, such as Dijon mustard, do not contain curcumin. Instead, they derive their color from the natural pigments present in the mustard seeds themselves.

3. Mustard Processing and Color

During the processing of mustard, various factors can influence its color. Let’s explore some of these factors:

3.1 Grinding and Crushing

When mustard seeds are ground or crushed, the release of myrosinase triggers the breakdown of glucosinolates into isothiocyanates. This enzymatic reaction is essential for the development of the characteristic yellow color in mustard.

3.1.1 Particle Size

The particle size of mustard seeds affects the color of the final product. Finely ground seeds allow better enzymatic activity and promote the release of curcumin from turmeric, leading to a more vibrant yellow color.

3.1.2 Temperature Control

The temperature during the grinding process also plays a role in preserving the color of mustard. High temperatures can degrade curcumin and result in a less intense yellow color.

3.2 Addition of Vinegar or Acid

Many mustard recipes include vinegar or other acidic ingredients. The acidity helps stabilize the yellow color and prevents it from fading over time. It also enhances the flavor profile of the mustard.

4. FAQs about Mustard’s Yellow Color

FAQ 1: Why is mustard yellow and not another color?

Mustard is yellow primarily due to the presence of curcumin, a natural pigment found in turmeric. Curcumin imparts a bright yellow color to mustard.

FAQ 2: Can mustard be made in different colors?

Yes, mustard can be made in different colors by using various ingredients or altering the processing methods. For example, Dijon mustard is typically brown because it does not contain curcumin like yellow mustard does.

FAQ 3: Does the color of mustard affect its taste?

No, the color of mustard does not significantly affect its taste. The flavor primarily comes from the glucosinolates present in the mustard seeds, which remain unchanged regardless of the color.

FAQ 4: Can the color of mustard change over time?

Yes, the color of mustard can change over time due to factors such as exposure to light and heat. Curcumin, the yellow pigment, is sensitive to degradation under certain conditions, leading to a fading of the yellow color.

FAQ 5: Is curcumin used in all mustard varieties?

No, curcumin is not used in all mustard varieties. Some mustard types, like Dijon mustard, derive their color from the natural pigments present in the mustard seeds themselves.

FAQ 6: Can the color of mustard affect its shelf life?

The color of mustard does not directly affect its shelf life. However, the addition of acidic ingredients like vinegar, which is common in mustard recipes, can help preserve the yellow color and extend the shelf life of the product.

FAQ 7: Can mustard without curcumin be yellow?

Yes, mustard without curcumin can still be yellow. The natural pigments present in the mustard seeds themselves can contribute to a yellow color, although it may not be as vibrant as mustard with curcumin.

FAQ 8: Can mustard’s color be artificially enhanced?

While it is possible to enhance mustard’s color artificially using food coloring or other additives, traditional mustard recipes rely on natural ingredients like turmeric or the natural pigments in mustard seeds for color.

FAQ 9: How can I make homemade mustard with a vibrant yellow color?

To achieve a vibrant yellow color in homemade mustard, you can use yellow mustard seeds, grind them finely, and add turmeric powder. The combination of the natural pigments in the mustard seeds and the curcumin in turmeric will result in a vibrant yellow hue.

FAQ 10: Can mustard’s color indicate its quality?

Mustard’s color alone cannot indicate its quality. The taste, aroma, and overall freshness are more reliable indicators of mustard’s quality. However, a vibrant yellow color may suggest the presence of fresh ingredients.


The yellow color of mustard is a result of the combination of glucosinolates, curcumin, and the processing methods used. Mustard seeds contain glucosinolates, which release isothiocyanates responsible for the pungent flavor. Curcumin, a natural pigment found in turmeric, imparts the vibrant yellow color to mustard. The grinding process, temperature control, and addition of vinegar or acid during processing influence the final color of mustard. While the color adds visual appeal, it does not significantly affect the taste or quality of mustard.

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