Physical-Chemical Properties of Foods

New Tools for Prediction

Aïchatou Musavu Ndob, Malik Melas, André Lebert

• Publisher: ISTE Press - Elsevier
• Year: 2015
• Print ISBN: 9781785480072
• eBook ISBN: 9780081008065
• Topic: Technology & Engineering
• Subtopic: Food Science
• Index: Technology & Engineering

The physical and chemical properties of food products have central roles in biotechnology and the pharmaceutical and food industries. Understanding these properties is essential for engineers and scientists to tackle the numerous issues in food processing, including preservation, storage, distribution and consumption.This book discusses models to predict some of the physical-chemical properties (pH, aw and ionic strength) for biological media containing various solutes. In recent years, food production has involved less processing and fewer additives or preservatives. If health benefits for consumers are obvious, it is not only necessary to adapt current processing and preservation processes but also to verify that appropriate technological and health properties are preserved.The authors present established models, but also introduce new tools for prediction with modeling methods that are part of a more general approach to understand the behavior of fluid mixtures and design new products or processes through numerical simulation.- Describes the construction of a tool to allow you to predict the physical-chemical properties of foods and bacterial broths- Shows you how to apply this tool with complex medias to predict water activity and pH levels and how to integrate this tool with a process simulator- Full with theoretical equations and examples to help you apply the content to your data

1

The Main Physical-chemical Properties

Abstract

Simulation processes and their optimization require knowledge of the physical-chemical properties of the pure substances and the mixtures being implemented. This constitutes the field of study of applied thermodynamics that allows, from the molecular representation of pure substances and mixtures, the prediction of the physical-chemical properties while ensuring consistency with experimental data.

Keywords

Brain-heart infusion (BHI) culture medium

Chemical potential

Gelatin sorption curves

Partial molar quantity

Quick thermodynamics primer

Redox potential (Eh)

Semi-empirical modeling

Sorption isotherms

State quantities

a_w designer

Simulation processes and their optimization require knowledge of the physical-chemical properties of the pure substances and the mixtures being implemented [TOU 14]. This constitutes the field of study of applied thermodynamics that allows, from the molecular representation of pure substances and mixtures, the prediction of the physical-chemical properties while ensuring consistency with experimental data.

1.1 Physical-chemical properties and qualities of biological products

The purpose of this section is not to make a comprehensive survey of all the knowledge of the relationships between the physical-chemical properties and the qualities of food products, but merely to show by means of examples the need to measure and predict these properties.

Physical-chemical properties of biological media (pH, a_w and E_h) are crucial for the preservation of food products, for their nutritional qualities to be maintained and for the development of their organoleptic properties. Physical-chemical properties are related to the composition of the food (salt concentration, water, organic acid amounts, etc.): any modification in food composition or in the process causes a change of the physical-chemical properties, and therefore of the final product.

Water activity is a property of equilibrium, it is constantly used to evaluate the diffusion of water during processing. The relationship between the amount adsorbed (equivalent to the water content) of various gases such as oxygen, nitrogen and water vapor depending on their activity coefficient (equivalent to water activity) was put forward by Brunauer, Emmett and Teller at the end of the 1930s, then gradually extended to water and biological products. This connection is often represented in the form of sorption isotherms [RAH 09]. This explains why the concept of water activity is used by both researchers and technologists. Therefore, it is necessary to understand several additional aspects such as the methods of measurement of water activity and sorption curves, the models of representation and prediction of water activity and the curves of sorption as well a...

Table of contents

• Cover image
• Title page
• Table of Contents
• Copyright
• Introduction
• 1: The Main Physical-chemical Properties
• 2: A Thermodynamic Approach for Predicting Physical-chemical Properties
• 3: Applications to Biological Media
• 4: Usage in Process Simulators
• Conclusion: The Extensions of the Thermodynamic Approach
• Appendix 1: The UNIFAC Model
• Appendix 2: Debye–Hückel Expression for Long-Range Interactions
• Appendix 3: Solvation Equations
• Appendix 4: List of Functional Groups
• Appendix 5: Parameters of Interaction Between Functional Groups
• Bibliography
• Index