Analytical Methods for Food and Dairy Powders E-Book

Pierre Schuck

• Herausgeber: John Wiley & Sons
• Kategorie: Fachliteratur
• Sprache: Englisch

Seitenzahl: 270

Veröffentlichungsjahr: 2012

Beschreibung

Food and dairy powders are created by dehydrating perishable produce, such as milk, eggs, fruit and meat, in order to extend their shelf life and stabilise them for storage or transport. These powders are in high demand for use as ingredients and as food products in their own right, and are of great economic importance to the food and dairy industry worldwide. Today, the ability to control food and dairy powder quality is a source of key competitive advantage. By varying the dehydration process design, and by controlling the technological and thermodynamic parameters during dehydration, it is possible for manufacturers to engineer the biochemical, microbiological and physical characteristics of the food powder to meet their specific product requirements.

This book provides an overview of the existing, adapted or new techniques used to analyse safety and quality in modern food and dairy powders. Based on original research by the authors, the book uses 25 commercial dairy and non-dairy powders to illustrate a range of biochemical and physical methods used to evaluate and characterise powdered food products. Written from a practical perspective, each chapter focuses on a particular analytical technique, outlining the purpose, definition and principle of that method. The authors guide the reader through all of the instruments needed, the safety measures required, and the correct procedures to follow to ensure successful analysis. Instructions on accurate measurement and expression of results are included, and each chapter is richly illustrated with original data and worked examples.

Analytical Methods for Food and Dairy Powders is a unique step-by-step handbook, which will be required reading for anyone involved in the development and manufacture of powdered food products. Food and dairy scientists based in industry will find it essential for new product development and improved quality control, while researchers in the laboratory will especially value the new techniques it comprises.

Leseprobe

Contents

Cover

Title Page

Copyright

Foreword

Chapter 1: Dehydration Processes and their Influence on Powder Properties

1.1. Overview of Operations

1.2. Properties of Dehydrated Products

1.3. Bibliography

Chapter 2: Determination of Dry Matter and Total Dry Matter

2.1. Determination of Free Moisture or Dry Matter

2.2. Determination of Total Moisture or Total Dry Matter

2.3. Bibliography

Chapter 3: Determination of Nitrogen Fractions

3.1. Determination of the Total Nitrogen Content (Kjeldahl Method)

3.2. Determination of the Nitrogen Content Soluble at pH 4.60

3.3. Determination of the Non-protein Nitrogen Content

3.4. Determination of Non-denatured Whey Protein Nitrogen in Skimmed Milk Powder

3.5. Protein Nitrogen Conversion Factors Based on Amino Acid Composition in the Case of Milk and Soy

3.6. Bibliography

Chapter 4: Determination of the Rate of Lactose Crystallisation

4.1. Definitions

4.2. Principle

4.3. Expression of Results

4.4. Remarks

4.5. Examples

4.6. Bibliography

Chapter 5: Determination of Total Fat and Free Fat Content

5.1. Determination of Total Fat Content

5.2. Determination of Free Fat Content

5.3. Bibliography

Chapter 6: Determination of the Ash Content

6.1. Definitions

6.2. Principle

6.3. Instruments and Glassware

6.4. Personal Protection

6.5. Procedure

6.6. Expression of Results

6.7. Precision values

6.8. Examples

6.9. Bibliography

Chapter 7: Determination of Particle Size and Friability

7.1. Definition

7.2. Principle

7.3. Methods

7.4. Reagents and Other Products

7.5. Instruments and Glassware

7.6. Personal Protection

7.7. Procedure

7.8. Expression of Results

7.9. Remarks

7.10. Precision Values

7.11. Examples

7.12. Bibliography

Chapter 8: Determination of Flowability and Floodability Indices

8.1. Definition

8.2. Principle

8.3. Reagents and other products

8.4. Instruments and glassware

8.5. Procedure

8.6. Expression of results

8.7. Remarks

8.8. Precision values

8.9. Examples

8.10. Bibliography

Chapter 9: Determination of Density, Interstitial Air Content and Occluded Air Content

9.1. Definition

9.2. Principle

9.3. Methods

9.4. Equipment and Glassware

9.5. Safety

9.6. Procedure

9.7. Expression of Results

9.8. Remarks

9.9. Precision Values

9.10. Examples

9.11. Bibliography

Chapter 10: Determination of Colour and Appearance

10.1. Determination of Colour

10.2. Determination of the Presence of Scorched Particles

10.3. Bibliography

Chapter 11: Determination of the Sorption Isotherm, Water Activity and Hygroscopicity of Powders

11.1. Determination of Water Activity

11.2. Determination of the Sorption Isotherm

11.3. Determination of Hygroscopicity

11.4. Bibliography

Chapter 12: Determination of Glass Transition Temperature Range

12.1. Definition

12.2. Principle

12.3. Methods

12.4. Instruments and Glassware

12.5. Personal Protection

12.6. Procedure

12.7. Expression of Results

12.8. Remarks

12.9. Precision Values

12.10. Examples

12.11. Bibliography

Chapter 13: Determination of Rehydration Ability

13.1. Determination of Wettability

13.2. Determination of Dispersibility

13.3. Determination of Solubility

13.4. Bibliography

Chapter 14: Summary and General Conclusion

Index

A colour plate section falls between pages 156 and 157

This edition first published 2012 © 2012 by John Wiley & Sons, Ltd.

(Except for French language rights, which are copyright of the authors.)

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Library of Congress Cataloging-in-Publication Data

Schuck, Pierre

Analytical methods for food and dairy powders / Pierre Schuck, Anne Dolivet, and Romain Jeantet.

p. cm.

Includes bibliographical references and index.

ISBN 978-0-470-65598-6 (hardcover: alk. paper)

1. Food–Analysis. 2. Food–Composition. 3. Dairy products–Drying. I. Dolivet, Anne. II. Jeantet, Romain. III. Title.

TX541.S34 2012

664′.07–dc23

2011037449

A catalogue record for this book is available from the British Library.

Foreword

The main purpose of drying dairy and food products is to stabilise them in order to facilitate storage and extend shelf life. Since the 1970s, the most common dehydration technique for liquid food has been spray drying. This technique was developed based on industrial know-how through empirical reasoning given the lack of scientific and technical papers on the subject, and, in particular, the impact of spray drying and the physicochemical and microbiological properties of the concentrate on the quality of the powder. Today, the diversity and complexity of the concentrates make it necessary to develop a more rigorous approach taking into account physicochemical and thermodynamic factors. This approach is based on a better understanding of the biochemical properties of the concentrate before drying, water transfers during drying, powder properties and the factors that influence them.

Food powders are generally characterised by their dry matter content. However, other characteristics need to be taken into account such as, for example, biochemical properties (protein, carbohydrate, lipid and mineral composition), as well as microbiological and physical properties (e.g. density, interstitial and occluded air, particle size, solubility, dispersibility, wettability, flowability, floodability, hygroscopicity, etc.), all of which will be discussed in this book. These characteristics depend on the manufacturing process (premixing, co-drying, dry-mixing, etc.), technological and thermodynamic parameters during the different stages of dehydration (drying chamber design, type of spray drying, fines recycling and thermodynamic properties of the air: temperature, relative humidity and velocity) and the characteristics of the concentrate before spraying (composition, physicochemistry and rheology, water availability, etc.). All these properties determine:

the preservation/storage conditions of powders, in relation to their sensitivity to different types of alteration (non-enzymatic browning or Maillard reactions, oxidation, microbial growth, etc.)the use properties of powders (flowability, solubility, rehydration, etc.)and, more generally, powder quality, from a functional, nutritional and sensory perspective.

Today, the quality control of powders based on these elements is a key competitive advantage. However, this involves controlling all the influencing factors, whether they are related to the composition of the products or the technologies used. The main barriers to understanding the impact of composition and process parameters on spray-dried products were methodology and analytical protocol. The physicochemical analyses described in the literature mainly result from methods applied to basic dairy powders, often yielding poor or inadequate results for the characterisation of new functionalities or complex non-dairy powders.

The development of methods and techniques suitable for powder analysis meets these requirements. This book contributes to this overall strategy by outlining all the relevant measures to effectively carry out the drying and quality control of powders.

Chapter 1 deals with dehydration processes in general and their influence on powder properties. Chapters 2 to 6 (Part 1) outline a set of tools and biochemical methods while Chapters 7 to 13 (Part 2) outline the physicochemical methods with the aim of providing a more accurate characterisation of powders as well as a more precise definition of their specifications. These tools and methods have been described in detail by providing comments, remarks and suggestions for improvement with regard to their implementation and the formulation of analytical results. For illustrative purposes, these methods were tested in triplicate on ten commercial dairy powders obtained by spray drying, including:

skimmed milkmilk with 26% fat in dry matter (milk 26% fat)micellar casein obtained by microfiltration of skimmed milk (micellar casein)calcium and sodium caseinates obtained by neutralising an acid curd with calcium and sodium hydroxide, respectivelysweet whey obtained from the manufacture of hard pressed cheese (whey) and fat-filled whey with 40% fat using coconut oil (whey 40% fat)ultrafiltration permeate of milk (UF permeate)whey protein concentrate with 35% protein in dry matter obtained by ultrafiltration of whey (WPC 35)whey protein isolate with 90% protein in dry matter obtained by ultrafiltration of milk microfiltrate (WPI 90)

and 15 commercial non-dairy food powders obtained by spray drying, including:

maltodextrins with different dextrose equivalents (DE): two powders with DE 12 (MD DE 12 (1) and (2)), one with 19 (MD DE 19) and a glucose syrup with DE 39 (GS DE 39)polyols, as sorbitol and maltitolapple extracts (apple (1) and (2))chicory extracts (chicory (1) and (2))egg products: whole egg, egg yolk and white eggpet foodgelatin.

The analytical results obtained are individually discussed at the end of each chapter. Finally, a comprehensive analysis was conducted to identify the correlations between the analysed properties (Chapter 14).

Dr Pierre SchuckPr Romain JeantetPr Gérard Brulé Dr Jean-Louis Maubois

Chapter 1

Dehydration Processes and their Influence on Powder Properties

Most microbial and biochemical changes that alter the quality of food occur in the aqueous phase. Water plays a dual role:

As a solvent, it ensures the transfer of substrates, growth promoters, biological agents and reaction products, which allows reactions to take place in optimal conditions.As a reaction substrate, it is involved in hydrolysis reactions (proteolysis, lipolysis).

This dual action requires that water is available, which can be characterised by its water activity (aw; cf. 1.2.1.2), i.e. the ratio between the partial pressure of the water vapour of the product and the partial pressure of pure water vapour at the same temperature. Any process that reduces this availability also slows down reaction times.

Water activity can be lowered by the crystallisation of solvent water (freezing) or by the addition of highly hydrophilic solutes that bind water molecules through hydrogen or dipolar interactions (salting, sugaring). It can also be lowered by eliminating the available water (concentration, evaporation and drying); in this case the inhibition generated is removed by dilution or rehydration.

This book deals with the properties of food powders obtained through drying. This preservation method only slightly alters the nutritional and organoleptic qualities during dehydration and any pre-treatments are well controlled with regard to heat and mass transfer.