Plant Pigments Overview

Plant Pigments

• Plant pigments are natural substances found in plant cells and tissues that give plants their color.
• These pigments are crucial for photosynthesis, growth, and development.
• Key plant pigments include chlorophylls, carotenoids, flavonoids (anthocyanins), and betalains.

Chlorophylls

• Chlorophylls are responsible for the green color of many plants, especially leaves and leafy vegetables.
• Chlorophyll a and chlorophyll b are the two main types used as food colorants.

Carotenoids

• Carotenoids are widely distributed pigments that produce red, orange, and yellow colors in plants.
• Carotene is the primary carotenoid pigment responsible for the color of butter, cheese, carrots, and cereal grains.
• Carrots, yams, sweet potatoes, papaya, pumpkins, cantaloupe, mangos, tomatoes, bell peppers, and oranges contain carotenoids.

Flavonoids (Anthocyanins)

• Anthocyanins are major polyphenol pigments that determine the colors of flowers and fruits.
• These pigments can range from orange, pink, red, to blue or purple.
• They are increasingly used as food colors instead of synthetic dyes in products like confectionery and soft drinks.
• Examples of foods rich in anthocyanins include elderberries, black grape skins, purple corn, and red cabbage.

Betalains

• Betalains are pigments responsible for the deep red color found in vegetables like beets and fruits like red dragon fruit.
• Sources include beetroot, prickly pear, and pitaya.

Effect of Heat, Acid, Alkali, Air on Plant Pigments

• Chlorophyll: Heat and acid can negatively affect chlorophyll, leading to a dirty brown color. To prevent browning, use slightly alkaline cooking water (e.g., with sodium bicarbonate).
• Carotenoids: Generally stable in their natural environment. More soluble in fats than water, so color doesn't fade easily with heat. Less intense under acidic conditions and sunlight.
• Anthocyanins: Water-soluble, heating doesn't change them significantly. Color shifts from red in acidic conditions to blue or purple under alkali. Red cabbage leaves can turn blue/purple when cooked, and blueberries can change color in preparation methods.
• Betalains: Degraded by light and air. Most stable between pH 4 and 6. Below pH 4, more violet; above pH 9, more blue.

Browning Reaction

• Enzymes within fruits and vegetables, such as phenolase, play a role in ripening.
• Cutting fruits/vegetables releases these enzymes, triggering an oxidation reaction.
• This oxidation process forms melanin, causing the brown discoloration.
• This enzymatic browning can be prevented by preventing oxidation through methods like denaturing the enzymes via heat or altering the pH.

Preventing Browning and Maintaining Nutrient Content

• Methods like careful cooking and storage help maintain a fruit or vegetable's nutrient value, color, and texture.
• Using heat, acids, or blanching prevents enzymatic browning.
• The oxidation process impacts some nutrients, especially Vitamin C, if the fruit or vegetable is exposed to air for extended periods.

Food Preservation Methods

• Steaming: Steaming helps to mitigate water loss, preserving vitamins, color, and texture.
• Roasting: Dry cooking methods such as roasting and grilling avoid significant nutrient, flavor, and color loss when the vegetables are coated with oil to speed up cooking times.
• Blanching: Deactivates enzymes, essential for preparing high-quality frozen vegetables. Also destroys microorganisms on surface.
• Freezing: A quick and convenient preservation method at home; blanching helps maintain good quality and maximum nutritional value.
• Gelatin: It is formed from partial hydrolysis of collagen, serves as a component of microcapsules for flavors, and in soft capsules in the pharmaceutical industry. Used extensively in the food industry as a component for candy, marshmallow, and dessert preparations.

Bureau of Standards (BSJ)

• The BSJ is Jamaica's regulatory body for food standardization.
• They have standards to promote standardization in relation to commodities, processes, and practices in Jamaica.
• There are regulations for food processors when processing food in Jamaica.
• The BSJ has specific standards for fruit and vegetable products.

Explore the fascinating world of plant pigments that give color to plants, playing a vital role in photosynthesis and growth. Learn about the key types such as chlorophylls, carotenoids, and flavonoids, and their significance in plant biology. This quiz delves into the characteristics and functions of these pigments.