Preface

Lactose is a disaccharide with unique characteristics. For instance, the beta-glycosidic bond that joins galactose and glucose. This sugar also has a lower caloric value and a lower glycemic index than other mono and disaccharides. Furthermore, lactose sweetness is less than that of sucrose, and the crystals of lactose have excellent plasticity and compressibility properties. Consequently, lactose and lactose derivatives are widely used in the food and pharmaceutical industries. This book reviews some aspects of lactose properties and synthesis (Section 1) as well as the recent advances in the recovery of lactose and lactose derivatives from cheese whey (Section 2).

In the first section, two chapters describe lactose synthesis, its biological role in mammals, and its key physicochemical properties. The exclusive source of lactose is mammals' milk since this sugar is synthesized in the mammary glands by the Golgi apparatus of alveolar epithelial cells. Unlike other disaccharides, a beta-glycosidic bond joins the galactose and glucose in a lactose molecule. Accordingly, lactose metabolism requires a unique enzyme (lactase) able to hydrolyze the beta-glycosidic bond. Newborn and young mammals produce enough lactase enzyme to completely metabolize lactose; nevertheless, adult mammals metabolize lactose deficiently, leading to maldigestion problems upon consumption of milk or food products containing lactose. The food and pharmaceutical industries are aware of the lactose intolerance problems among the population. Hence, these industries are looking for lactose substitutes or derivatives that could be used in food and drug production.

In the second section, the first chapter provides information on recovering lactose from cheese whey through membrane technology. The following chapters are devoted to production of lactose derivatives, including lactitol, organic acids (acetic, ascorbic, butyric, citric, propionic, succinic, and lactic acid), lactulose, sialyl lactose, galacto-oligosaccharides, and lactosucrose. Cheese whey is a byproduct of the cheesemaking industry that contains chiefly water, lactose, proteins, and a minor proportion of minerals and fat. The conventional method of recovering lactose from cheese whey is crystallization, but membranes have recently gained attention in the dairy industry. Alternatively, the lactose in cheese whey can be transformed into organic acids by fermentation. Microorganisms like lactic acid bacteria are used to produce galacto-oligosaccharides or other polysaccharides. Lactose derivatives like lactitol are used in bakery, confectionery, chocolate, desserts, and chewing gum. This sugar alcohol is not found in nature, and it has a low caloric value (2.0 kcal g-1) since the lactase enzyme can barely hydrolyze lactitol. All these lactose derivatives open new perspectives in the use of lactose in the food and pharmaceutical industries.

I want to thank all the authors who contributed with their hard work and knowledge of lactose and lactose derivatives. This book would not have been possible without your excellent work. I also would like to thank IntechOpen Author Service Manager Ms. Sandra Maljavac for her support during the publication of this book.

> **Néstor Gutiérrez-Méndez** Chemistry Faculty, Autonomous University of Chihuahua, Chihuahua, Mexico

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Section 1

Lactose Properties

and Synthesis

Section 1
