Pullulan

Processing, Properties, and Applications

Shakeel Ahmed, Aisverya Soundararajan, Shakeel Ahmed, Aisverya Soundararajan

• Publisher: Jenny Stanford Publishing
• Year: 2020
• eBook ISBN: 9781000093100
• Topic: Physical Sciences
• Subtopic: Biology

Pullulan is a polysaccharide produced by the fungus Aureobasidium pullulans and possesses some distinct properties such as excellent transparent film–forming ability, moisture absorptivity, water solubility, non-toxicity, and adhesivity. These properties allow pullulan to find potential applications in various industries such as pharmaceuticals, cosmetics, food, and health care.

This book presents the chemistry and properties of pullulan, along with the method of its production at the laboratory level. It discusses the structural engineering, processing methods, and versatile applications of pullulan, as well as highlights the challenges that still have to be overcome for its large-scale production. This unique book comprehensively summarizes many of the recent research findings on pullulan, contributed by leading experts in this research domain. It is a useful reference book for scientists, academicians, researchers, chemists, technologists, graduate and postgraduate students, and general readers who are interested in pullulan.

Chapter 1

Polysaccharides: An Overview

S. Vijayanand,^a Ashwini Ravi,^a Aisverya Soundararajan,^b Annu,^c P. N. Sudha,^b and J. Hemapriya^d

^aBioresource Technology Lab, Department of Biotechnology, Thiruvalluvar University, Serkkadu, Vellore 632115, Tamil Nadu, India

^bBiomaterial Research Lab, Department of Chemistry DKM College for Women (Autonomous), Vellore 632001, Tamil Nadu, India

^cDepartment of Chemistry, Jamia Millia Islamia, New Delhi 110025, India

^dPG & Research Department of Microbiology, DKM College for Women (Autonomous), Vellore 632001, Tamil Nadu, India

[email protected]

Polysaccharides, commonly known as “Cinderella of biopolymers,” are molecules composed of monosaccharide residues, which are joined together by O-glycosidic linkages. Naturally, polysaccharides are produced by various biological entities such as plants, microbes, seaweeds, and animals. Polysaccharides were often found to have linear structure, and it may also contain various degrees of branching. Despite their structure, they also vary in various components such as monosaccharide composition, linkage type, pattern of linkage, chain type, degree of polymerization, etc. based on the source of production. This variable structure of polysaccharides is responsible for their physiochemical and biological characteristics, which in turn is responsible for their diversified applications. They are used in various industries such as pharmaceutical industry, food industry, and other non-food industries. With further advancements in technologies, polysaccharides have been structurally modified and studied for their various functions. In addition to these, the formation of nanocomposite with these polymers has been studied extensively for various applications from biosensors to drug delivery They also find their importance in environmental applications by taking up several xenobiotics. Therefore, in this chapter, various polysaccharides from nature have been discussed in detail along with their applications.

1.1 Introduction

Polysaccharides are carbohydrate molecules made up of monosaccharide units bonded together by glycosidic linkages with a molecular weight of hundreds to thousands of Daltons [112, 149]. Depending on the number of monosaccharide units, they have been classified as linear or branched polysaccharides. They also have several functional groups such as hydroxyl group, carboxylic acid group, and amino group [103]. The naturally existing polysaccharides exhibit distinct features in terms of molecular weight, monosaccharide composition, glycosidic linkage types and patterns, configuration, charging properties, chain shapes, degree of polymerization, degree of branching, etc. These diversified structural properties of polysaccharides determine their functional properties such as solubility, flow behavior, gelling potential, surface and interfacial properties [54, 70].

Polysaccharides are the integral component of plant biomass, and 90% of the total polysaccharide produced on earth is constituted by vegetables. Apart from vegetables, they are produced by bacteria, fungi, algae, and animals [39, 99]. Different types of polysaccharides include starch, glycogen, cellulose, pectin, chitin, hemicellulose, lignin, etc [35]. Since ancient times, polysaccharides have been used in several industrial applications such as pharmaceuticals, food and nutrition, and other non-food industries. In the food industry, it has been used as emulsifiers, stabilizer, thickening agent, and as packaging materials [90, 104]. In addition to these, they play a vital role in the pharmaceutical industry due to their several advantageous characteristics such as biocompatibility, biodegradability, and ability of chemical modification [151]. They have been widely applied as binders, drug-release modifiers, thickeners, stabilizers, disintegrants, suspending agents, gelling agents, and as biodhesives [53]. Because of these wide ranges of applications, the market of polysaccharides market is continuously increasing. Therefore, it is essential to know the different types of polysaccharides produced by the biological entities. This chapter deals with the different types of natural polysaccharides and their applications in various fields.

1.2 Types of Polysaccharides

The various types of natural polysaccharides produced from different organisms are discussed as follows:

1.2.1 Plant Polysaccharides

Polysaccharides are the main constituents of vegetable biomass, and around 90% of cellulose has been obtained from plants. The various types of plant-based polysaccharides are discussed as follows:

1.2.1.1 Cellulose

Cellulose is the most abundant polysaccharide produced from plants. It was first discovered by the French chemist Anselme Payen when studying different types of wood. He found a substance that is not starch but can be broken into basic units of glucose. He named this compound “cellulose” [32, 132, 192]. In 1870, cellulose was commercially produced as a thermoplastic polymer by the Hyatt Celluloid Manufacturing Company [83]. The structure of cellulose is given in Fig. 1.1.

Payen found that cellulose is made up of 44–45% carbon, 6–6.5% hydrogen, and the remaining was oxygen. Based on this data, the molecular formula of cellulose was designated as C₆H₁₀O₅ [133]. Later in 1920, Haworth depicted the chain-like structure of cellulose and Staudinger produced the final structure of cellulose [60, 61, 166]. Since then it has been understood that cellulose is made up of repeating units of D-anhydroglucopyranose units (AGU) linked by β-1,4-glycosidic linkages with two ends. One end has C4−OH, which is alcohol borne and is called the non-reducing end, whereas the other terminating end has C1−OH made up of aldehyde group, called the reducing end [15, 84]. Some cellulose molecules were also found to have additional carbonyl and carboxyl gro...

Table of contents

• Cover
• Half Title
• Title Page
• Copyright Page
• Table of Contents
• Preface
• 1. Polysaccharides: An Overview
• 2. Pullulan: Recent Progress and Technological Prospects
• 3. Synthesis of Pullulan
• 4. Factors Affecting Pullulan Production
• 5. Pullulan: Properties and Applications
• 6. Functional Characteristics of Pullulan: Its Physicochemical and Physiological Properties
• 7. Pullulan-Degrading Enzymes and Their Biochemical Features
• 8. Microbial Pullulan: Properties, Bioprocess Engineering, and Applications
• 9. Transformation of an Aureobasidium Pullulan Synthetase Gene into Saccharomyces cerevisiae
• 10. Role of Pullulans in Cosmetics
• 11. Biomedical Applications of Pullulan
• Index