Book excerpt: There is considerable diversity in polymers extracted from natural sources and much work has been done to classify them according to their physical and chemical properties. In the second part of this book set, readers will find general information about the physicochemical properties of several naturally occurring polysaccharides followed by a section dedicated to their application in different fields of research and medicine. Key topics in this part include: • chitosan (properties modifications and applications) • microbial biopolymers • biopolymers present in Brazilian seeds • protein-plastic foams • biopolymer microencapsulation in the food industry • biomedical gels • collagen biomaterials • biopolymer electrospinning This reference is intended for students of applied chemistry and biochemistry who require information about the properties and applications of polysaccharides (such as chitosan) and other protein-based biopolymers.