Engineering Aspects of Food Emulsification and Homogenization

Marilyn Rayner, Petr Dejmek

• Publisher: CRC Press
• Year: 2015
• eBook ISBN: 9781498760157
• Edition: 1
• Topic: Tecnología e ingeniería
• Subtopic: Ciencia de los alimentos

Emulsions are found in a wide variety of food products, pharmaceuticals, paints, and cosmetics, thus emulsification is a truly multidisciplinary phenomenon. Therefore understanding of the process must evolve from the combination of (at least) three different scientific specializations. Engineering Aspects of Food Emulsification and Homogenization d

Section I

Emulsion Fundamentals

Chapter 1

Scales and Forces in Emulsification

Marilyn Rayner

ABSTRACT This chapter introduces the mechanical aspects of the formation and breakup of emulsion droplets. An overview of the most common types of emulsification machines and homogenization devices is provided. Droplet disruption mechanisms are presented considering the forces, length, and timescales involved in the various types of flow regimes encountered in the mechanical production of emulsions by different categories of equipment. Finally, the energy efficiency of emulsification methods is discussed, highlighting some complications with the theory presented, in addition to some general comments on the future in the area.

1.1 Introduction

In order to make an emulsion, four basic ingredients are required: two immiscible phases (often oil and water), energy to create the oil–water interface of the emulsion drops, and surfactants to stabilize this interface to prevent the drops from coalescing immediately upon contact. By varying the amounts and composition of these four basic ingredients, we can control key emulsion properties such as emulsion type (i.e., oil-in-water [O/W] versus water-in-oil [W/O]), droplet volume fraction, ϕ (also known as “dispersed phase faction”), droplet size and size distribution, and the nature of the stabilizing layer surrounding the droplets. These properties determine many of the central organoleptic properties of emulsion-based food products such as shelf life, appearance, rheology, texture, and flavor. How we convert energy from bulk mechanical stresses during emulsification to generate and stabilize the new interfacial area created as a result of the emulsion drops is, of course, central to the study of emulsification technologies and the focus of much of this book. A wide variety of processing equipment and technologies are available for the generation of emulsions, many of which will be thoroughly discussed in Chapters 5 through 11. In line with the aim of this book, we consider emulsification in the context of food emulsions, and thus only the mechanical production of emulsions will be discussed. In the chemical industry, there are other methods to produce emulsions that do not rely on mechanical generation of droplets, such as precipitation of the dispersed phase previously dissolved in the continuous phase and the phase inversion temperature method. These and other nonmechanical methods, however, are outside the scope of this book. This chapter is an overview of the physics and technologies used in the mechanical production of emulsions. For a more comprehensive treatment of the topic, the reader is referred to Walstra’s eminent works in the area (Walstra 1993, 2003, Walstra 2005, Walstra and Smulders 1998) as well as Schubert and Ax (2003), Karbstein and Schubert (1995), and McClements (2005).

The basic physical process of emulsification is illu...

Table of contents

• Series Preface
• Series Editor
• Preface
• Editors
• Contributors
• Synopsis
• Section I - Emulsion Fundamentals
• Section II - High-Energy Processes
• Section III - Low-Energy Processes