Smoke in food processing

169 Pages·2018·18.023 MB·English

by  Maga, Joseph A

Smoke
in
Food
Processing
Author
Joseph A. Maga
Professor
Department of Food Science and
Human Nutrition
Colorado State University
Fort Collins, Colorado
Boca Raton London New York
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First published 1988 by CRC Press
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Reissued 2018 by CRC Press
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Library of Congress Cataloging-in-Publication Data
Maga, Joseph A.
Smoke in food processing.
Includes bibliographies and index.
1. Meat, Smoked. 2. Fish, Smoked. I. Title.
TP371.44.M34 1988 664’ .0286 87-24231
ISBN 0-8493-5155-3
A Library of Congress record exists under LC control number: 87024231
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PREFACE
Smoking was one of the first forms of food processing, and through the centuries the
chemistry of smoke has slowly evolved. It is now known that wood and food composition
can significantly influence smoke composition, as well as the resulting textural, sensory,
nutritional, antioxidative, and antimicrobial properties of the smoked food.
Aside from beneficial properties, one must also consider potential health concerns asso
ciated with certain woods and their resulting smoke.
THE AUTHOR
Joseph A. Maga, Ph.D., is Professor of Food Science and Director of the Food Research
and Development Center in the Department of Food Science and Human Nutrition at Colorado
State University, Fort Collins, Colorado.
Dr. Maga received his Ph.D. in Food Science from Kansas State University and his M.S.
and B.S. in Dairy Manufacturing from The Pennsylvania State University. His industrial
experience includes being a Group Leader in the Research and Development Group at Central
Soya and a Project Leader with Borden Foods Company.
Dr. Maga's area of specialization is flavor chemistry with special emphasis on the role
of food processing and storage. Current research areas include flavor formation during
thermal degradation of by-products and flavor formation and retention during food extrusion.
He is a professional member of the American Dairy Science Association, American
Association of Cereal Chemists, American Chemical Society, and the Institute of Food
Technologists of which he is currently President of the Rocky Mountain Section and a
member of the Board of Editors for the Journal of Food Science.
Dr. Maga is the author of over !50 publications including numerous extensive reviews
appearing in CRC Press publications.
TABLE OF CONTENTS
Chapter 1
Wood Composition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
I. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
II. Cellulose .......................................................................... 2
III. Hemicellulose ..................................................................... 3
IV. Lignin ............................................................................. 4
V. Miscellaneous Compound Classes ................................................ 5
A. Volatile Oils ............................................................... 5
B. Terpenes and Related Compounds ......................................... 5
C. Fatty Acids ................................................................ 6
D. Carbohydrates ............................................................. 6
E. Polyhydric Alcohols ....................................................... 6
F. Nitrogen Compounds ...................................................... 6
G. Phenolic Compounds ...................................................... 6
H. Inorganic Constituents ..................................................... 7
VI. Bark Composition ................................................................. 7
VII. Hardwoods vs. Softwoods ........................................................ 9
VIII. Heartwoods vs. Sapwood ......................................................... 9
References ............................................................................... 27
Chapter 2
Thermal Reactions of Wood ........................................................... 29
I. Introduction ...................................................................... 29
II. Thermal Decomposition of Hemicellulose ....................................... 29
III. Thermal Decomposition of Cellulose ............................................ 30
IV. Thermal Decomposition of Lignin ............................................... 34
V. Combustion ...................................................................... 36
References ............................................................................... 37
Chapter 3
Smoke Generation Technology ........................................................ 39
I. Introduction ...................................................................... 39
II. Smoldering ....................................................................... 39
III. Friction .......................................................................... 40
IV. Wet Smoke ...................................................................... 40
V. Fluidization ...................................................................... 40
VI. Two Stage ....................................................................... 41
VII. Carbonization .................................................................... 41
VIII. Hot vs. Cold Smoking ........................................................... 42
IX. Electrostatic Smoking ............................................................ 42
X. Miscellaneous Technologies ..................................................... 44
A. Gas-Phase Smoke ........................................................ 44
B. Closed Smoking .......................................................... 44
C. Indirect Smoking ......................................................... 44
D. Liquid Smoke ............................................................ 44
References ............................................................................... 46
Chapter 4
Flavor Chemistry of Wood Smoke .................................................... 49
I. Introduction ...................................................................... 49
II. Important Flavor Compound Classes ............................................. 50
A. Phenols ................................................................... 50
I. Sensory Properties ................................................ 51
2. Formation Pathways .............................................. 52
B. Furans .................................................................... 53
C. Carbonyls ................................................................ 53
D. Others .................................................................... 53
III. Wood Source .................................................................... 54
IV. Generation Conditions ........................................................... 57
A. Temperature .............................................................. 57
B. Air ....................................................................... 58
C. Wood Moisture Content .................................................. 59
D. Wood Particle Size ....................................................... 59
V. Smoking Procedure .............................................................. 59
VI. Storage ........................................................................... 60
References ............................................................................... 86
Chapter 5
Textural Changes in Smoked Foods ................................................... 89
I. Introduction ...................................................................... 89
II. Protein Interactions .............................................................. 89
III. Smoke Source ................................................................... 89
IV. pH and Water-Holding Capacity (WHC) ......................................... 90
A. pH ........................................................................ 90
B. WHC ..................................................................... 9I
References ............................................................................... 9I
Chapter 6
The Nutritional Quality of Smoked Foods ............................................ 93
I. Introduction ...................................................................... 93
II. Amino Acid Composition ........................................................ 93
A. Available Lysine ......................................................... 93
B. Methionine ............................................................... 94
III. Protein Digestibility .............................................................. 94
IV. Protein Alteration ................................................................ 95
V. Vitamins ......................................................................... 95
References ............................................................................... 96
Chapter 7
The Antioxidative Properties of Wood Smoke ........................................ 99
I. Introduction ...................................................................... 99
II. Reactive Compounds ............................................................. 99
III. Smoke Source ................................................................... 99
References .............................................................................. I 00
Chapter 8
Smoke and Food Color ............................................................... I 03
I. Introduction ..................................................................... 10 3
II. Compounds Involved ........................................................... I 03
A. Carbonyls ............................................................... I03
B. Phenols .................................................................. I 03
III. Reaction Mechanisms ........................................................... 104
IV. Factors Influencing Rate of Color Formation ................................... I 05
A. Concentration of Reactants .............................................. I 05
B. Temperature ............................................................. 105
C. Moisture Level .......................................................... 105
D. Method of Smoke Application ........................................... 105
V. Miscellaneous Methods of Smoke Coloring ..................................... 105
A. Steam-Generated Smoke ................................................. 105
B. Electrostatic Deposition ................................................. I 06
C. Dyes ..................................................................... 106
D. Infrared Radiation ....................................................... 106
References .............................................................................. I 06
Chapter 9
Antimicrobial Properties of Smoke ................................................... 10 7
I. Introduction ..................................................................... 107
II. Antibacterial Aspects ........................................................... I 07
Ill. Antifungal and Yeast Aspects ................................................... 110
References .............................................................................. Ill
Chapter 10
Potential Health Concerns Associated With Smoke .................................. 113
I. Introduction ..................................................................... 113
II. Smoking Methods vs. PAH Concentration ...................................... 113
III. PAH in Wood Smoke ........................................................... 119
IV. PAH in Foods .................................................................. 121
V. Methods of PAH Analysis ...................................................... 130
VI. PAH Metabolism ............................................................... 133
VII. PAH Stability ................................................................... 134
VIII. Nitrosamines .................................................................... 135
IX. Toxicological Properties of Wood Smoke ....................................... 136
X. Mutagenic Properties of Wood Smoke .......................................... 137
References .............................................................................. 138
Chapter 11
Tobacco Smoke ........................................................................ 145
I. Introduction ..................................................................... 145
II. The Tobacco Combustion Process .............................................. 145
III. Tobacco Forms ................................................................. 146
IV. Major Tobacco Smoke Constituents ............................................. 148
V. Mainstream vs. Sidestream Tobacco Smoke .................................... 152
References .............................................................................. 153
Index ................................................................................... 155

1
Chapter 1
WOOD COMPOSITION
I. INTRODUCTION
Before one can begin to understand the various chemical and physical interactions of
wood smoke with foods, one should have an initial understanding of the basic composition
of wood.
Botanically, wood used as a smoke source falls into two broad categories, namely hard
woods and softwoods, which in some cases does not correlate with the actual physical
hardness of wood. For example, some hardwoods are actually quite soft (aspen and cotton
wood), while certain softwoods are quite hard (Douglas fir).
The two species can be distinguished by the fact that hardwoods produce woody, two
seed leaves (dicotyledenous) and their seeds are borne in a fruit structure. Thus, they are
classified as angiosperms. In addition, the leaves of hardwoods are usually broad or blade like
and in most climates they are deciduous in that they shed their leaves at the end of each
growing season.
On the other hand, the softwoods are classified as gymnosperms, since their seeds are
borne naked. Softwoods have also been called conifers, since many produce seed cones,
pollen cones, or a combination of both. This species has needlelike (pine) or scalelike (cedar)
leaves that are commonly called evergreen, since with the exception of larches and bald
cypress, the leaves are retained for up to several years. Some typical American hardwood
and softwood species are summarized in Table 1. *
Wood is essentially a plant tissue composed of various types of cells. In mature wood,
most of these cells are dead and hollow. This structure is known as secondary xylem, with
the hollow interiors of the cells known as lumens. The orientation of cells and lumens differ
between hardwoods and softwoods. In softwoods, the cells, which make up to 90 to 95%
of the wood volume, morphologically appear to be fibrous in nature, and thus are called
fibers. In contrast, hardwoods are composed of much wider cells, which are called vessel
elements. Also, fiber volume can be quite variable for hardwood, but averages approximately
50%.
From a chemical standpoint, wood cells are composed of several organic polymers with
the structural key compound being cellulose. As seen in Table 2, it is a long-chain, linear
sugar molecule or polysaccharide composed of glucose units. In most normal wood tissue,
glucose, as a cellulose polymer, accounts for 40 to 45% of total dry weight.
Another major constituent of wood is callea hemicellulose, which serves as the matrix
substance for the cellulose superstructure. It has a lower molecular weight than cellulose
and may contain short side chains. The carbohydrate composition of hemicellulose can vary
and is usually composed of a combination of five-carbon sugars such as xylose and arabinose
and six-carbon sugars typified by glucose, mannose, and galactose.
The third major component of wood is lignin, which serves as a cementing material that
assists in the binding together of wood cells. Approximately 60% of total lignin is located
in the cell walls, with the remainder spread throughout the wood. Structurally, as seen in
Table 2, it is a three-dimensional, highly branched, polyphenolic molecule of complex
structure and high molecular weight. It should be noted that lignin generally is not reactive
with water, whereas hemicellulose and cellulose are just the opposite.
Another compositional distinction, the overall importance of which has not been evaluated
* Tables appear at the end of text.