Bioactive Seaweeds for Food Applications: Natural Ingredients for Healthy Diets

Bioactive Seaweed Substances for Functional Food Applications: Natural Ingredients for Healthy Diets presents various types of bioactive seaweed substances and introduces their applications in functional food products. Presenting summaries of the substances derived from seaweed, this book systematically explores new ingredients and the bioactive substances that are both environmentally friendly and highly beneficial to human health. This evidence-based resource offers an abundance of information on the applications of seaweed as a solution to meet an increasing global demand for sustainable food sources. It is an essential reference for anyone involved in seaweed substance research, seaweed processing, and food and health disciplines.

• Discusses the use of bioactive seaweed substances as a new class of food ingredients
• Outlines the use of seaweed as gelling agents used for food restructuring, coating and encapsulation
• Systematically explores new ingredients and the bioactive substances that are both environmentally friendly and highly beneficial to human health

• Language: English
• Publisher: Academic Press
• Release date: Jan 16, 2018
• ISBN: 9780128133132

Book preview

Bioactive Seaweeds for Food Applications

Natural Ingredients for Healthy Diets

Editor

Yimin Qin

Table of Contents

Cover image

Title page

Copyright

List of Contributors

Editor Description

Preface

Acknowledgments

Part I. Seaweed Bio-Resources and Bioactive Seaweed Substances

1. Seaweed Bioresources

1.1. Marine Biomass

1.2. Marine Algae

1.3. Seaweeds

1.4. Seaweed Cultivation

1.5. Commercial Applications of Seaweed Bioresources

1.6. Summary

2. Bioactive Seaweed Substances

2.1. Introduction

2.2. Carbohydrates

2.3. Lipids

2.4. Pigments

2.5. Secondary Metabolites

3. Production of Seaweed-Derived Food Hydrocolloids

3.1. Introduction

3.2. Market Size and Value

3.3. Alginate Seaweeds and Alginate Production

3.4. Carrageenan Seaweeds and Carrageenan Production

3.5. Agar Seaweeds and Agar Production

3.6. Summary

4. Seaweed-Derived Sulfated Polysaccharides: Scopes and Challenges in Implication in Health Care

4.1. Introduction

4.2. Extraction, Purification, Modification, and Characterization

4.3. Validated Biological Effects

4.4. Regenerative and Nanomedicine Scope

4.5. Insights, Hurdles, and Scopes

4.6. Conclusion

5. Seaweed-Derived Carotenoids

5.1. Introduction

5.2. Sources, Structure, and Classification of Seaweed Carotenoids

5.3. Processing Technology of Seaweed Carotenoids

5.4. Potent Application of Seaweed-Derived Carotenoids in Functional Foods and Animal Feed

5.5. Future Trends

5.6. Conclusions

Part II. Applications of Bioactive Seaweed Substances in Functional Food Products

6. Applications of Bioactive Seaweed Substances in Functional Food Products

6.1. Introduction

6.2. Direct Consumption of Seaweeds as Marine Vegetables

6.3. Bioactive Seaweed Substances for Functional Food Applications

6.4. Summary

7. Seaweed Hydrocolloids as Thickening, Gelling, and Emulsifying Agents in Functional Food Products

7.1. Introduction

7.2. Rheological Properties of Seaweed Hydrocolloid Solutions

7.3. Gelling Properties of Seaweed Hydrocolloids

7.4. Applications of Seaweed Hydrocolloids as Gelling Agents in Functional Foods

7.5. Applications of Propylene Glycol Alginate as an Emulsifying Agent in the Food and Drink Industry

7.6. Summary

8. Seaweed-Derived Hydrocolloids as Food Coating and Encapsulation Agents

8.1. Introduction

8.2. Seaweed Hydrocolloids as Food Coating and Film Agents

8.3. Seaweed-Derived Hydrocolloids as Food Encapsulation Agents

8.4. Conclusions

Part III. Health Benefits of Bioactive Seaweed Substances

9. Health Benefits of Bioactive Seaweed Substances

9.1. Introduction

9.2. A Brief Description of the Bioactive Seaweed Substances

9.3. Health Benefits of Dietary Seaweeds

9.4. Health Benefits of Bioactive Seaweed Substances

9.5. Summary

10. Antioxidant Properties of Seaweed-Derived Substances

10.1. Introduction

10.2. Antioxidants and Their Mechanisms

10.3. Antioxidant Substances From Seaweed

10.4. Phlorotannins

10.5. Antioxidant Strategies, Now and in the Future

10.6. Future Perspective

11. Fucoidan and Its Health Benefits

11.1. Introduction

11.2. Extraction of Fucoidan From Brown Seaweeds

11.3. Chemical and Physical Characteristics of Fucoidan

11.4. Biological and Physiological Functions of Fucoidan

11.5. Health Benefits and Potential Applications of Fucoidan

11.6. Summary

12. Antiobesity, Antidiabetic, Antioxidative, and Antihyperlipidemic Activities of Bioactive Seaweed Substances

12.1. Introduction

12.2. Antiobesity Activity of Bioactive Seaweed Substances

12.3. Antidiabetic Activity of Bioactive Seaweed Substances

12.4. Antioxidative Activity of Bioactive Seaweed Substances

12.5. Antihyperlipidemic Activity of Bioactive Seaweed Substances

12.6. Other Physiological Activities of Bioactive Seaweed Substances

12.7. Summary

13. Absorption of Heavy Metal Ions by Alginate

13.1. Introduction

13.2. Heavy Metal Ion Toxicity

13.3. Remedies for Heavy Metal Ion Contamination

13.4. Absorption of Heavy Metal Ions by Seaweed Biomass

13.5. Removal of Heavy Metal Ions by Alginate

13.6. Removal of Heavy Metal Ions by Alginate as a Food Additive

13.7. Summary

14. Seaweeds and Cancer Prevention

14.1. Introduction

14.2. Effect of Seaweeds on Cancer Prevention

14.3. Effect of Seaweed Extracts on Cancer Prevention

14.4. Effect of Seaweed Polysaccharides on Cancer Prevention

14.5. Effect of Seaweed Polyphenols on Cancer Prevention

14.6. Effect of Seaweed Iodine on Cancer Prevention

14.7. Other Seaweed-Derived Compounds With Antitumor Activities

14.8. Summary

Index

Copyright

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List of Contributors

Zengying Dai,     Qingdao Brightmoon Seaweed Group, Qingdao, China

Suqin Fan,     Qingdao Brightmoon Seaweed Group, Qingdao, China

Chuancai Gao,     Qingdao Brightmoon Seaweed Group, Qingdao, China

Qiaoqiao Gu,     Qingdao Brightmoon Seaweed Group, Qingdao, China

Xiaoxiao Gu,     Qingdao Brightmoon Seaweed Group, Qingdao, China

Ditte B. Hermund,     Technical University of Denmark, Kongens Lyngby, Denmark

Efstathia Ioannou,     National and Kapodistrian University of Athens, Athens, Greece

Jinju Jiang,     Qingdao Brightmoon Seaweed Group, Qingdao, China

Aikaterini Koutsaviti,     National and Kapodistrian University of Athens, Athens, Greece

Haiyan Liu,     Qingdao Brightmoon Seaweed Group, Qingdao, China

Ranran Liu,     Qingdao Brightmoon Seaweed Group, Qingdao, China

Ratih Pangestuti,     Indonesian Institute of Sciences, Jakarta, Republic of Indonesia

Seema Patel,     San Diego State University, San Diego, CA, United States

Yimin Qin,     Qingdao Brightmoon Seaweed Group, Qingdao, China

Guiyan Qu,     Qingdao Brightmoon Seaweed Group, Qingdao, China

Vassilios Roussis,     National and Kapodistrian University of Athens, Athens, Greece

Peili Shen,     Qingdao Brightmoon Seaweed Group, Qingdao, China

Shaojuan Shi,     Qingdao Brightmoon Seaweed Group, Qingdao, China

Evi A. Siahaan,     Indonesian Institute of Sciences, North Lombok, Republic of Indonesia

Zhanyi Sun,     Qingdao Brightmoon Seaweed Group, Qingdao, China

Chunxia Wang,     Qingdao Brightmoon Seaweed Group, Qingdao, China

Jue Wang,     Qingdao Brightmoon Seaweed Group, Qingdao, China

Zongmei Yin,     Qingdao Brightmoon Seaweed Group, Qingdao, China

Demeng Zhang,     Qingdao Brightmoon Seaweed Group, Qingdao, China

Mengxue Zhang,     Qingdao Brightmoon Seaweed Group, Qingdao, China

Pengpeng Zhang,     Qingdao Brightmoon Seaweed Group, Qingdao, China

Wenchao Zhang,     Qingdao Brightmoon Seaweed Group, Qingdao, China

Lili Zhao,     Qingdao Brightmoon Seaweed Group, Qingdao, China

Ting Zhao,     Qingdao Brightmoon Seaweed Group, Qingdao, China

Editor Description

Dr. Yimin Qin obtained his PhD from the University of Leeds between 1986 and 1990. After spending 3  years in Heriot-Watt University working on his postdoctoral project, he became the product development manager in Advanced Medical Solutions Plc in Cheshire, UK, where he led a team of scientists and developed a number of high-performance wound dressings from alginate, chitosan, and other natural polymers. He then went on to study an MBA in the Manchester Business School and, after graduation, took up the position of Fibers Product Manager in SSL International, working on advanced antimicrobial biomaterials. In 2002, Dr. Qin returned to China and taught at Jiaxing College, Zhejiang Province. In 2015, Dr. Qin was appointed as the Director of State Key Laboratory of Bioactive Seaweed Substances at Qingdao Brightmoon Seaweed Group, where his main research interests focused on the extraction, modification, and applications of alginate and other novel bioactive seaweed substances.

Preface

Bioactive seaweed substances are a group of chemical components extracted from seaweed biomass, which can influence the biological processes of living organisms through chemical, physical, biological, and other mechanisms. These substances include biomass components in the extracellular matrix, cell wall, plasma, and other parts of the seaweed cells generated through primary and secondary metabolism, of which the primary metabolites are generated when the seaweed cells process nutrients through biodegradation or biosynthesis, such as amino acids, nucleotides, polysaccharides, lipids, vitamins, etc., whereas secondary metabolites are those chemicals modified from primary metabolites, including genetic materials, medicinal materials, biotoxins, functional materials, and other seaweed-based substances.

There is a long history of the applications of bioactive seaweed substances in functional food products. Seaweed-derived hydrocolloids have long been used as food ingredients. In particular, the unique biophysical properties of alginate and carrageenan are highly valuable in the development of functional food products. As food ingredients, the applications of alginate and carrageenan are based on three main properties, i.e., thickening, gelling, and film forming. In particular, the unique gelling abilities at low temperature alongside good heat stability make alginate ideal for use as thickeners, stabilizers, and restructuring agents. Recently, alginate is increasingly used in a myriad of newer applications, from encapsulating active enzymes and live bacteria to acting as the carrier for protective coating of prepacked, cut, or prepared fruits and vegetables. With novel chemical and biological modifications to alter its structures and properties, there are possibilities of novel applications of specific alginates in the food industry that have high bioactivities at low concentrations. In general, seaweed-derived functional foods can provide health benefits by reducing the risk of chronic diseases and enhancing the ability to manage chronic diseases, thus improving the quality of life. They can also promote growth and development and enhance performance.

Marine nutraceuticals can be derived from the many varieties of seaweeds. For example, fucoidan is a complex fucose-rich sulfated carbohydrate, which can be extracted from brown seaweeds. This biologically active carbohydrate has been shown to inhibit a wide range of cancer cell lines, and studies in mice indicate that anticancer effects are also seen in vivo. As a marine nutraceutical product, fucoidan has been used in many health products and is important for its high bioactive properties, for example, antibacterial, anticoagulant, antiviral, antitumor, etc. Seaweeds and marine microalgae are natural sources for β-carotene, astaxanthin, and eicosapentaenoic acid that have high bioactivities and are an important part of nutraceutical products, playing a significant role in a number of aspects of human health.

Looking into the future, bioactive seaweed substances are valuable in a group of industries including pharmaceuticals, nutraceuticals, functional foods, biomedical materials, cosmetics, and fertilizers, in addition to the traditional applications in textiles, chemicals, and environmental protection. Once extracted, separated, and purified, the various types of bioactive seaweed substances can be screened for their bioactivities and utilized in an appropriate application. Modern technologies can allow the separation of these native ingredients into purified chemical compounds. Once structurally characterized and functionally assessed, the highly active compounds can be applied in marine drugs, whereas those with lower activities can be used in herbal medicines, nutraceuticals, biomedical materials, functional foods, and other applications based on the level of their bioactivities.

Because bioactive seaweed substances and functional foods cover a large field with a diversified range of specialist knowledge, it is inevitable that this book will not be able to offer precise explanation in all areas and the author appreciates critical feedback in such cases.

Yimin Qin

April 30, 2017

Acknowledgments

The ever-increasing human population and its standard of living have placed new demand for more and healthier resources for food and its ingredients. With more than 70% of the globe’s surface, ocean-derived biomass and related biomaterials are not only vast in quantity, but they are also structurally diverse with many unique biological activities. Marine species comprise approximately one half of the total global biodiversity and the ocean offers an enormous resource for novel compounds that can be explored for their health and nutritional benefits. Among the many marine organisms thriving in the vast ocean, seaweeds represent a bioresource that is both old and new. Historically, seaweeds have been explored for their bioactivities in many parts of the world dating back to ancient times. In China, where the homology of medicine and food has been recognized for over 2000  years, the health benefits of seaweeds were recognized in ancient medicinal books such as Sheng Nong’s Herbal Classic, Supplementary Records of Famous Physicians, Marine Herbal, Compendium of Materia Medica, etc.

Modern science and technology have uncovered the many bioactive seaweed substances and allowed their separation and purification into high-valued bioproducts, which are now widely used in a wide range of health-related industries. The natural and cultivated seaweeds are a unique source of raw materials for the production of seaweed-based bioproducts. They have large scale varieties, and are green, environmentally friendly, and renewable. In addition, seaweed biomass and the natural products derived from them are hydrophilic, biocompatible, and biodegradable, and contain many substances with high bioactivities, which are important supplement to land-based resources.

To fully explore the many bioactive seaweed substances and develop them into an environmentally friendly and sustainable industrial chain, in particular with a view of promoting their applications in functional food products, we set out to write this book and, after a year of hard work, I am glad that we have been able to compile the many sources of information into this book. As an editor, I am grateful to the following people who have made the successful completion of this book:

Patricia Osborne and Karen Miller at Elsevier who project managed the manuscript preparation processes;

Dr. A. Koutsaviti, Dr. E. Ioannou, Dr. V. Roussis, Dr. S. Patel, Dr. R. Pangestuti, Dr. E. A. Siahaan and Dr. D. B. Hermund who wrote excellent chapters for this book;

I am also indebted to the State Key Laboratory of Bioactive Seaweed Substances at Qingdao Brightmoon Seaweed Group for providing the resources that made this book possible. In particular, I would like to thank Mr. Guofang Zhang, chairman of BMS Group for his support to this project; Mr. Kechang Li, deputy CEO, for providing important data to this book; and Mr. Fahe Wang, Technical Manager, for his assistance during manuscript preparation. I am also grateful to the group of scientists at the State Key Laboratory, Demeng Zhang, Lili Zhao, Jinju Jiang, Peili Shen, Zhanyi Sun, Zongmei Yin, Guiyan Qu, Chunxia Wang, Zengying Dai, Wenchao Zhang, Suqin Fan, Haiyan Liu, Ranran Liu, Ting Zhao, Jue Wang, Pengpeng Zhang, Kuntian Feng, Qiaoqiao Gu, and Shaojuan Shi, for their contribution to this book.

Editor

August 30, 2017

Part I

Seaweed Bio-Resources and Bioactive Seaweed Substances

Outline

1. Seaweed Bioresources

2. Bioactive Seaweed Substances

3. Production of Seaweed-Derived Food Hydrocolloids

4. Seaweed-Derived Sulfated Polysaccharides: Scopes and Challenges in Implication in Health Care

5. Seaweed-Derived Carotenoids

1

Seaweed Bioresources

Yimin Qin     Qingdao BrightMoon Seaweed Group, Qingdao, China

Abstract

Marine biomass represents a vast amount of structurally diverse natural resources, of which, seaweeds are among the most commercially important bioresources from the ocean. They are widely used for food in direct human consumption and also as raw materials for the extraction of bioactive ingredients for the global food, cosmetics, and pharmaceutical industries; fertilizers; and animal feed additives. Seaweeds can be collected from the wild but are now increasingly cultivated. Brown and red seaweeds are used to produce marine hydrocolloids such as alginate, carrageenan, and agar, which are used as thickening and gelling agents. Other varieties of seaweeds are also increasingly used to extract bioactive seaweed substances that can be applied in a wide range of industries.

Keywords

Bioactive seaweed substances; Marine algae; Natural resources; Seaweed cultivation; Seaweeds

Chapter Outline

1.1 Marine Biomass

1.2 Marine Algae

1.3 Seaweeds

1.3.1 Brown Seaweeds

1.3.2 Red Seaweeds

1.3.2.1 Carrageenan-Bearing Red Seaweeds

1.3.2.2 Agar-Bearing Red Seaweeds

1.4 Seaweed Cultivation

1.5 Commercial Applications of Seaweed Bioresources

1.5.1 Marine Functional Foods

1.5.2 Marine Nutraceuticals

1.5.3 Marine Drugs and Health Products

1.5.4 Marine Cosmetics

1.5.5 Marine Biomedical Materials

1.5.6 Marine Fertilizers

1.6 Summary

References

Further Reading

1.1. Marine Biomass

Biomass is the mass of living biological organisms in a given area or ecosystem at a given time. Among the many varieties of microorganisms, plants, and animals that form the overall quantity of biomass on earth, marine biomass represents a relatively underexplored resource, which is attracting much attention in recent years partly because of the over exploration of land-based resources. The ever increasing human population and its standard of living have dramatically increased the global demand for living space, food, energy, and other natural resources from the earth. As oceans cover more than 70% of our planet’s surface, attention has been directed toward the utilization of ocean-based resources, with the emergence of the so-called blue economy aimed at the comprehensive development of ocean-based resources and products (Charette and Smith, 2010; Gage and Tyler, 1991; Steele, 1985; Pietra, 2002).

Marine biomass, both natural and cultivated, is not only vast in quantities, but also structurally diverse with many unique biological activities. With marine species comprising approximately one half of the total global biodiversity, the world’s oceans offer an enormous resource for novel substances that are important for human health. Right now, more than 20,000 new substances have been isolated from marine organisms, with a wide range of applications from pharmaceutical products to functional foods (Hu et al., 2012). Different kinds of substances have been procured from marine biomass because marine environment gives the many organisms thriving in the vast ocean unique genetic structures and life habitats, opening the door to the development of many more novel bioactive substances that can be utilized in food, beverage, pharmaceutical, cosmetics, textiles, leather, electronic, medicine, biotechnology, and many other industries (Thakur and Thakur, 2006; Kim, 2015).

1.2. Marine Algae

Algae are quantitatively the largest biomass in the ocean (Nedumaran and Arulbalachandran, 2015; Chapman, 2013). The term algae refers to a large and diverse assemblage of organisms that contain chlorophyll and carry out oxygenic photosynthesis. Biologically, algae represent a segment of the ocean’s food chain, which proceeds from phytoplankton to zooplankton, predatory zooplankton, filter feeders, predatory fish, and beyond. Among these different varieties of marine organisms, cyanobacteria are the smallest known photosynthetic organisms, with Prochlorococcus at just 0.5–0.8  μm in diameter. However, Prochlorococcus is probably the most plentiful species on earth with a single milliliter of surface seawater containing 100,000  cells or more.

Although most marine algae are microscopic in size and are thus considered to be microorganisms, several forms are macroscopic in morphology and are commonly known as seaweeds. One common characteristic is that all types of algae contain chlorophyll a and the colonial forms of algae occur as aggregates of cells, with each of these cells sharing common functions and properties, including the storage products they utilize as well as the structural properties of their cell walls. The presence of phytopigments other than chlorophyll a is a characteristic of a particular algal division. The nature of the reserve polymer synthesized as a result of photosynthesis is also a key variable used in algal classification. Accordingly, their divisions include Cyanophyta, Prochlorophyta, Phaeophyta, Chlorophyta, Charophyta, Euglenophyta, Chrysophyta, Pyrrophyta, Cryptophyta, and Rhodophyta (Sahoo, 2016). When comparing Phaeophyta (brown algae) to other common algal divisions such as the Rhodophyta (red algae), important differences are seen in the storage products they utilize as well as in their cell wall chemistry. In the Phaeophyta (brown algae), laminaran is the main storage product, whereas the Rhodophyta (red algae) is distinguished by the floridean starch it produces and stores.

1.3. Seaweeds

Fig. 1.1 shows an overview of marine algae, which can be divided broadly into macroalgae and microalgae according to their physical sizes. Marine macroalgae are commonly known as seaweeds, which commonly include brown, red, and green seaweeds based mainly on their characteristic pigmentation. Botanists refer to these three groups as Phaeophyceae, Rhodophyceae, and Chlorophyceae, respectively. Brown seaweeds are usually large and range from the giant kelp that is often 20  m long to thick, leather-like seaweeds from 2 to 4  m long, to smaller species 30–60  cm long. Red seaweeds are usually smaller, generally ranging from a few centimeters to about a meter in length. Red seaweeds are not always red. They are sometimes purple, even brownish red, but they are still classified by botanists as Rhodophyceae because of other characteristics. Green seaweeds are also small, with a similar size range to the red seaweeds. Naturally growing seaweeds are often referred to as wild seaweeds, in contrast to seaweeds that are cultivated or farmed.

Seaweeds are raw materials for a wide variety of products that have an estimated total annual value of US$  5.5–6  billion (Porse and Rudolph, 2017), among which, food products for human consumption contribute about US$  5  billion. Substances that are extracted from seaweeds, mainly food hydrocolloids, account for a large part of the remaining billion dollars, while smaller, miscellaneous uses, such as fertilizers and animal feed additives, make up the rest. The world seaweed processing industry uses 7.5–8  million tonnes of wet seaweed annually, which are harvested either from naturally growing seaweeds or from cultivated crops, with the latter being expanded rapidly as demand has outstripped the supply available from natural resources. World wild, commercial harvesting of seaweeds occurs in about 35 countries, spreading between the Northern and Southern Hemispheres, in waters ranging from cold, through temperate, to tropical.

Figure 1.1  An overview of marine algae.

1.3.1. Brown Seaweeds

Brown seaweeds are used for the extraction of alginate, which represents a broad group of biomaterials based on the alkali or alkaline earth salts of alginic acid, with the sodium salt being the most widely used. Alginate, sometimes shortened to algin, is present in the cell walls of brown seaweeds, with those growing in more turbulent conditions usually having a higher alginate content than those in calmer waters. Because alginate was first discovered by E.C.C. Stanford in 1881, its commercial extraction initially took place mostly in Europe, the United States, and Japan. Since the 1980s, major change in the alginate industry took place with the emergence of producers in China, initially in the production of low-cost, low-quality alginate for the local industrial markets from locally cultivated Saccharina japonica. By the 1990s, Chinese producers were competing in Western industrial markets for alginates extracted from S. japonica that is abundant due to the successful introduction of cultivation technologies. However, those early products from China had a low guluronic to mannuronic acid (G/M) ratio, which yields weakly gelling alginates, and their performance is acceptable only for industrial products such as textile printing and paper coating. In recent years, alginate producers in China began importing Chilean and Peruvian medium G seaweeds such as Lessonia nigrescens, which can yield alginates suitable for the food ingredient market in the United States and EU. Chinese producers now account for the majority of alginate products in the global market.

Fig. 1.2 illustrates the main types of brown seaweeds used for alginate production. These seaweeds usually grow in cold waters in both the Northern and Southern Hemispheres. They thrive best in water temperatures up to about 20°C. Originally, harvests of wild seaweeds were the only source for alginate production, but since the mid-20th century demand has gradually outstripped the supply from natural resources and methods for cultivation have been developed. Fig. 1.3 shows the harvest of wild brown seaweeds in 2014.

Biologically, the division Phaeophyta or brown algae comprises a large assemblage of plants that are classified in about 265 genera with more than 1500 species. They derive their characteristic brown color from the large amounts of the carotenoid fucoxanthin contained in their chloroplasts and the presence of various phaeophycean tannins. Brown algae flourish in temperate to subpolar regions where they exhibit the greatest diversity in species and morphological expression. The commercially important species of brown algae are large in size and their main genus include Laminaria, Macrocystis, Ascophyllum, Lessonia, Durvillaea, Ecklonia, Saccharina, etc.

Fig. 1.4 shows the distribution of wild brown seaweeds around the world. Globally, Norway and Chile are the two countries where wild seaweeds are most abundant due to their long coastal lines and suitable environmental conditions. It is estimated that the total quantity of wild seaweed stock in the Norwegian seacoast is around 50–60  million tons, with 7  million tons washed to the shoreline annually.

Regarding the individual species, Ascophyllum seaweeds are mainly harvested in Ireland, Norway, France, and the United Kingdom, whereas Durvillaea is harvested in Australia and Chile. Ecklonia grows in South Africa, and Laminaria digitata is mainly from France and Iceland. Laminaria hyperborea is mainly from Norway, the United Kingdom, Ireland, and France. Lessonia is principally from Chile. Macrocystis pyrifera is from the United States, Mexico, and Chile.

Figure 1.2  Main types of brown seaweeds used for alginate production.

Figure 1.3  Harvest of wild brown seaweeds in 2014.

Figure 1.4  Distribution of wild brown seaweeds around the world. (A) Laminaria hyperborea ; (B) Ascophyllum nodosum ; (C) Macrocystis pyrifera ; (D) Lessonia nigrescens ; (E) Laminaria digitata ; (F) Saccharina japonica ; (G) Ecklonia maxima .

Ascophyllum is found in cold waters of the Northern Hemisphere. It grows in the eulittoral zone, forming distinct bands of dark brown, branched plants 1–4  m long. It prefers somewhat sheltered areas and disappears where there is strong wave action. Durvillaea is found only in the Southern Hemisphere and grows best in rough water, near the top of the sublittoral zone, on rocky shores or offshore reefs. Plants are smaller where summer water temperatures rise to 19°C, but grow best where the temperature does not rise above 15°C.

There are three main species of Laminaria seaweeds, i.e., L. digitata, L. hyperborea, and Laminaria saccharina. All three grow in cold temperate water between 10 and 15°C, and are harvested in the Northern Hemisphere. L. digitata grows in the upper sublittoral zone in rocky, wave-exposed localities, and it is well adapted to this because of its flexible stipe and divided blades. In France, L. digitata is the main raw material for the alginate industry. L. saccharina often grows in close association with L. digitata, and is sometimes harvested at the same time. In Norway, L. digitata grows in masses at the lower end of the eulittoral zone and was previously an important source for the Norwegian alginate industry. In France, it is in the upper sublittoral zone and is harvested around the coast of Brittany and adjacent islands. Iceland is also a source of L. digitata for the alginate industry in Scotland. L. hyperborea grows on rocky bottoms of the midsublittoral zone, in depths of 2–10  m, but in clear water it can be 15–25  m, the limiting factor being sufficient light for growth. It has a strong stipe and the plant stands upright in the water and forms laminarian forests. They can survive for up to 15  years, in contrast to the Laminaria in the upper sublittoral, which have a life of about 3  years. L. hyperborea is also found on the west coast of Ireland, the Outer Hebrides, and the Orkney Islands in Scotland. There are also large quantities of these seaweeds growing around the coast of Brittany in France.

There are two main Lessonia species for alginate extraction. L. nigrescens grows in thick belts in the rocky lower eulittoral zone, where its massive holdfast allows it to survive the rough waters in which it thrives. Lessonia trabeculata grows in the sublittoral between 1 and 20  m in depth. It also has a very thick holdfast and stands up underwater, rather like L. hyperborea. Lessonia species are found in both Northern and Southern Hemispheres, but they are only collected in northern Chile where they grow on offshore shoals and are torn off in rough weather.

M. pyrifera, sometimes called the giant kelp, grows best in calm, deep waters in temperatures of 15°C or less. It is sensitive to water temperature and does not withstand a rise above 20°C. It grows on rocky bottoms where its holdfast can become established, and can be found as large underwater forests, with plants rising to and growing along the surface, at times up to 20  m in length. M. pyrifera is harvested from offshore beds that stretch from Monterey in California, United States, to Bahia Asuncion in Baja California Sur, Mexico. Smaller quantities are also collected in northern Chile. Macrocystis angustifolia has been cultivated on an experimental scale in South Africa with a view to eventually growing it for alginate production or abalone feed.

Ecklonia species are found in both Northern and Southern Hemispheres, but are currently only collected in South Africa. Some of them are exported, and some used internally to produce fertilizer. Experimental cultivation of Ecklonia in South Africa has been successful, with growth of young plants on rafts.

Unlike other species of brown seaweeds, which thrive in cold water, Sargassum species are found worldwide in warm temperate and tropical water temperature regions. They are found both in the eulittoral and upper sublittoral zones. They exhibit a wide variety in shape and form. The alginate content is usually low compared with the previously listed genera, and the quality of the alginate is poor. For alginate extraction, they are regarded as the raw material of last resort. Sargassum is collected on the south coast of Java, Indonesia, and the Philippines.

Although wild brown seaweeds can be found in large quantities in many parts of the world, the alginate industry relies heavily on cultivated seaweeds rather than natural sources. In this sense, S. japonica (formerly known as Laminaria japonica) represents the largest cultivated species of all types of seaweeds, both for direct food consumption and the extraction of low M type alginate. S. japonica is widely eaten in Japan and China, and to a lesser extent in the Republic of Korea. This type of brown seaweed was native to Japan and the Republic of Korea and was introduced accidentally to China in 1927 at the northern city of Dalian, probably by shipping. Prior to that, China had imported its needs from the naturally growing resources in Japan and the Republic of Korea. In the 1950s, China developed a way of cultivating S. japonica on long ropes suspended in the ocean, and this became a widespread source of income for large numbers of coastal families. By 1981, they were producing 1,200,000 wet tonnes seaweed annually. In the late 1980s, production fell as some farmers switched to the more lucrative but risky farming of shrimp. By the mid-1990s, production had started to rise and the reported harvest in 1999 was 4,500,000 wet tonnes. Although much of these cultivated seaweeds are used for direct food consumption, they also provide a strong foundation for the thriving alginate industry in China.

1.3.2. Red Seaweeds

1.3.2.1. Carrageenan-Bearing Red Seaweeds

Red seaweeds are used for the production of carrageenan and agar. When carrageenan was first discovered in Ireland, it was first found in the red seaweed Chondrus crispus, commonly known as Irish Moss, which can be collected from natural resources in Ireland, Portugal, Spain, France, and the east coast provinces of Canada. As the carrageenan industry expanded, the demand for raw material began to strain the supply from natural resources, and in the early 1970s, Chondrus was being supplemented by species of Iridaea from Chile and Gigartina from Spain. Fig. 1.5 offers a schematic illustration of C. crispus.

The cultivation of species of Eucheuma in the Philippines during the 1970s provided the carrageenan industry with a much enhanced supply of raw material. A further advantage of this cultivated material was that one species contained almost exclusively a particular type of carrageenan,