Developing Natural Pigments from Microalgae

 Seagriculture EU 2024
Natural food colorants from microalgae

Natural food colorants from microalgae. Photo Credit: Wageningen University and Research

by Dr. Vetrivel Anguselvi

P​igments are substances used for imparting color to various materials. The word is derived from the Latin “pigmentum” and “pingere” meaning a coloring substance.

In ancient times, pigments were mainly derived from plant based substances discovered by our ancestors. There was enormous evidence associated with plant-based pigments from vedas — religious texts originating in ancient India and written in Sanskrit — that constitute the oldest scriptures of Hinduism. In Indian mythology the plant-based pigments played a significant role symbolizing different aspects of life.

The pigments industry, worldwide, is growing quickly due to huge demand for coloring agents, especially in the food, cosmetics, and textile industries. Globally the market size of dyes and pigments was estimated at a valuation of 38.2 billion USD in 2022 and is anticipated to expand at a 5.3% compound annual growth rate from 2023 to 2030.

Algae-based pigments, such as chlorophyll (green), anthocyanin (red, purple, blue), xanthophyll (yellow), and beta-carotene (orange), are commonly used as natural food colorants. They provide an alternative to synthetic dyes and are often used in products like candies, beverages, and baked goods. Algae-based pigments such as red, green, orange, brown and yellow are sources of natural dyes, providing a sustainable and eco-friendly option for textile coloring, for example.

Algae based pigments are used in cosmetics to provide natural colors for products like lipsticks, eye shadows, and blushes. Algae-based pigments are used in pharmaceuticals to color pills and capsules naturally. Artists and craftspeople use algae-based pigments as natural alternatives to synthetic paints and dyes.

In more recent times, many natural pigments and dyes were replaced by synthetic dyes in order to meet the growing demand.

However, chemical based dyes have drawbacks. They can enter into the food chain and pollute groundwater, causing skin irritation, allergies, and even cancer. They remain persistent in the environment resisting natural degradation, leading to long term environmental impact with disruption to ecosystems. Also, the manufacturing of these chemical pigments and dyes are energy consuming and generate high amounts of hazardous waste and greenhouse gases.

Algae-based organic dyes and pigments have huge advantages over synthetic dyes and pigments. They are environmentally friendly with enhanced biodegradability, producing a lower carbon footprint. Since algae-based pigments are extracted from renewable resources they promote sustainable agriculture. They are non-toxic and non-allergenic as compared to synthetic pigments or dyes.

The most common algal pigments are:

(a) Chlorophylls (Fig 1&2).
The primary source of this photosynthetic green pigment is Chlorella spp. It can be used as a food coloring agent. The chlorophyll has anti-mutagenic properties and lowers the risk of cancer by stimulating the production of carcinogen-detoxifying enzymes.

Fig (1&2)

Fig (1&2) Chemical structure of Chlorophyll a and b

(b) β-Carotene
The halophilic green algae Dunaliella salina is utilized in the β-carotene (Fig 3) synthesis process. The primary application for this pigment is as a yellow-orange food coloring. Because D. salina is high in Vitamin A, it is frequently used as a nutraceutical additive in addition to being used as
a colorant.

Fig (3)

Fig (3) Chemical structure of β-Carotene

(c) Fucoxanthin
This pigment is used to color food products brown. It comes from Phaeophytes. There is ample evidence to support its fat-reducing ability. Fucoxanthin (Fig 4) can be further exploited for its colorant applications in the textiles and cosmetics industries.

Fig (4)

Fig (4) Chemical structure of Fucoxanthin

(d) Peridinin
The pigment peridinin (Fig 5) is an Apocarotenoid that absorbs light and is linked to chlorophyll. Although it is present in many other species, the dinoflagellate Amphidinium carterae is the most well-known algal source of this pigment (Hofmann et al., 1996).

Fig (5)

Fig (5) Chemical structure of Peridinin

(e) Phycoerythrin
Red algae (Rhodophyta) is the source of the red pigment phycoerythrin Fig (6). Porphyridium cruentum is the species most frequently used in the production of phycoerythrin. It is cultivated in synthetic seawater supplemented with potassium nitrate, and 21°C is the ideal growth temperature for Porphyridium.

Fig (6)

Fig (6) Chemical structure of Phycoerythrin

(f) Phycocyanin
Blue green algae, or Cyanophyta, are the source of the blue pigment known as phycocyanins (Fig 7). Spirulina platensis is the most well-known source of this pigment among algae. It needs a salinity of 30 g/L and an alkaline pH range of 7.2 to 9.0. Spirulina grows at 27°C in the wild.

Fig (7)

Fig (7) Chemical structure of Phycocyanin

Research for the food, textiles, and cosmetics industries

The research group from Renewable Energy and Biotechnology Department, CSIR-Central Institute of Mining and Fuel Research (CSIR-CIMFR), Digwadih, Dhanbad, India is working on research and production of algae-based dyes and pigments for their usage in the food, textiles, and cosmetics industries.

The freshwater algae such as Spirulina and Chlorella were isolated from the Dhanbad, identified and cultured using Zarrouk media. The selected algae were used for carbon dioxide capture for energy industries. The carbon captured algal biomass (CCAB) was further processed for the production of pigments such as yellow, red, and green. The extracted pigments were water soluble, non-toxic, non-allergic, renewable and biodegradeable.

Algae-based pigment production requires less investment and its growth rate is higher when compared to land crops. Algae-based pigments are cost effective and environment friendly.

The widespread use of pigments across diverse industries, emphasizes their significance in adding color, functionality, and aesthetic appeal to a wide range of products. More species of algae can be explored for the extraction of natural pigments for the benefit of mankind. The expanding opportunity for microalgal-based pigments cannot be understated.
 

Potential microalgae for pigments

Division
Common name
Botanical name
Pigment colour
Major pigment
Applications
Chlorophyta
Green algae
Chlorella sp.
Green
Chlorophyll b
Cosmetics
Charophyta
Water silk or pond silk –green algae
Spirogyra
Green
Chlorophyll b
Cosmetics
Charophyta
Water Net
Hydrodictyan
Green
Chlorophyll
Cosmetics
Euglenophyta
Plant-animal Euglenoids
Euglena gracilis
Green
Chlorophyll b, Chlorophyll c1 + c2
Food industry
Cyanophyta
Spirulina  Blue green algae
Arthrospira  platensis
Blue green
Phycoerythrin, Phycocyanin
Cosmetics
Phaeophyta
Bladder Wrack Brown algae
Fucus vesiculosus
Brown
Fucoxanthin
Cosmetics
Chrysophyta
Green halophilic algae
Dunaliella salina
Yellow Orange and Red Orange
Chlorophyll c1 + c2, Fucoxanthin, Zeaxanthin, echinenone, β-carotene
Cosmetics Food industry
Chrysophyta
Green halophilic algae
Dunaliella sp.
Yellow
Lutein
Cosmetics
Rhodophyta
Red algae
Porphyridium cruentum, Porphyridium purpureum
Red
Phycoerythrin, Phycocyanin
Cosmetics, Food industry
Chlorophyta
Unicellular algae
Haematococcus sp.
Red
Astaxanthin
Cosmetics, Food industry
Chrysophyta
Jewells of the sea or Living opals
Diatoms
Yellow, Orange
Β Carotene, Xanthophyll
Cosmetics, Food industry

 
Vetrivel Anguselvi, Renewable Energy and Biotechnology CSIR Central Institute of Mining & Fuel Research
vaselvi@yahoo.com

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