Enhancing the availability of natural antioxidants in wheat

256 Pages·2007·1.29 MB·English

by  Matthew Hill

ABSTRACT
Title of Document: Enhancing the availability of natural antioxidants in wheat-
based food ingredients and food products through improved
post-harvest treatments and processing conditions.

Jeffrey Calvin Moore, Doctor of Philosophy, 2007

Directed By: Professor Liangli (Lucy) Yu
Department of Nutrition and Food Science

Wheat grain has significant antioxidant contents concentrated in the bran
fraction, most of which may not be bioavailable in humans because they are not
released from matrix materials during digestion. The present study developed solid-
state enzymatic and yeast post-harvest treatments, and investigated the effects of
these treatments and food processing on the extractable antioxidant properties of
whole-wheat based food ingredients and food products. Antioxidant properties
investigated in this study included scavenging capacities against cation ABTS
radicals, peroxyl radicals (ORAC), hydroxyl radicals, and DPPH radicals, and total
phenolic contents and phenolic acid compositions.
The first part of this research developed and validated a high-throughput
fluorometric hydroxyl radical scavenging capacity (HOSC) assay. The HOSC assay
utilized a Fe(III)/H O Fenton-like reaction to generate hydroxyl radicals, fluorescein
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as detector probe, trolox as an antioxidant standard, and area under the curve
measurements to quantify scavenging capacity. The hydroxyl radical purity and
potential solvent interference in the assay system were evaluated using electron spin
resonance. The HOSC assay was found to have acceptable performance
characteristics including linear range, accuracy, and reproducibility.
The second part of this study investigated the potential of solid-state enzyme
and yeast treatments to improve wheat bran antioxidant properties. Both enzyme and
yeast treatments were capable of increasing available wheat bran antioxidant
properties. Reaction parameters found to influence the effectiveness of these
treatments to enhance wheat bran antioxidant properties included enzyme preparation
and reaction moisture content for enzyme treatments, and yeast preparation along
with dose and treatment time for yeast treatments.
The final part of this research evaluated the effects of processing conditions
including bran particle size, fermentation time, and baking conditions on the
antioxidant properties of a whole-wheat pizza crust. Baking increased extractable
antioxidant properties up to 82%. Fermentation time caused some significant
increases, while bran particle size had no influence on extractable whole-wheat pizza
crust antioxidant properties.
This study suggests that post-harvest treatment of wheat bran and optimized
processing conditions for whole-wheat food products are potential approaches for
increasing their extractable antioxidant properties.
ENHANCING THE AVAILABILITY OF NATURAL ANTIOXIDANTS IN
WHEAT-BASED FOOD INGREDIENTS AND FOOD PRODUCTS THROUGH
IMPROVED POST-HARVEST TREATMENTS AND PROCESSING
CONDITIONS.

By

Jeffrey Calvin Moore

Dissertation submitted to the Faculty of the Graduate School of the
University of Maryland, College Park, in partial fulfillment
of the requirements for the degree of
Doctor of Philosophy
2007

Advisory Committee:
Professor Liangli Yu, Chair
Professor Thomas Castonguay
Professor Jose M. Costa
Professor Mark A. Kantor
Dr. Shiow Y. Wang
Dr. Jun-Jie Yin
© Copyright by
Jeffrey Calvin Moore
2007
Dedication
In memory of my grandfathers, Chester Walkowicz and Robert Moore.
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Acknowledgements
My tenure as a graduate student at the University of Maryland, College Park
from 2004 to 2007 proved to be some of the most exciting, challenging, and
productive years of my life. I have many people to thank for helping me achieve my
goals.
I am most grateful to my principal advisor, Dr. Liangli Yu. This research
would not have been possible without her tremendous vision, guidance, and support.
Her passion for science, leadership in her field, ambition and efficiency as a
researcher, encouragement as an advisor, and intellect as a professor, have provided
an incredible example for me to follow as a scientist.
I would also like to thank my committee members, Dr. Jun-Jie Yin, Dr.
Thomas Castonguay, Dr. Jose Costa, Dr. Shiow Wang, and Dr. Mark Kantor, for their
support through my research and their constructive and detailed comments on my
dissertation. I would especially like to acknowledge Dr. Yin for use of his ESR
facilities and expertise at FDA-CFSAN.
Many thanks to my wonderful present and past labmates including Dr. Kevin
Zhou, Dr. John Parry, Dr. Zhihong Cheng, Dr. Zhiliang Huang, Marla Luther, Shane
Ardo, Margaret Smitka, Lan Su, and Shuang Song. This research would not have
been possible without their encouragement, support, and critical evaluation. The
relationships built with these labmates provided many good conversations and laughs
that made our lab a pleasant and productive working environment. Also thanks to
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Victor (III) who proved to be an invaluable part of my research efficiency.
I would like to thank my family for their lifetime of support and
encouragement. I am especially grateful for my wonderful wife, Monali, whose love,
support, advice, and encouragement have helped me achieve my dreams.
Lastly, I would like to acknowledge former mentors and friends who helped
shape my career path in food science; Linda Law at Nestlé in Solon, OH and Dr. Kirk
Dolan at Michigan State University.
Financial support for this research was provided in part by USDA/CSREES-
NRI #2004-35503-14852, Maryland Grain Producers Utilization Board, and
Maryland Agricultural Experiment Station, which are gratefully acknowledged.
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Table of Contents

Dedication.....................................................................................................................ii
Acknowledgements......................................................................................................iii
Table of Contents..........................................................................................................v
List of Tables.............................................................................................................viii
List of Figures..............................................................................................................ix
Introduction...................................................................................................................1
Chapter 1: Literature Review........................................................................................3
1.1 Wheat’s Importance and Classifications.................................................3
1.2 Wheat’s Fractions and Their Nutritional Properties...............................5
1.3 Wheat and Evidence of its Health Promoting Properties........................6
1.4 Free Radicals, Oxidative Stress, and Human Health..............................9
1.5 Antioxidants and Human Health...........................................................11
1.6 The Antioxidant Contents of Wheat.....................................................14
1.7 The Antioxidant Properties of Wheat...................................................18
1.8 Functional and Nutraceutical Food Development and Antioxidants....24
1.9 Bioavailability of Phenolic Acids in Wheat..........................................26
1.10 Treatments to Improve the Bioavailability of Wheat Phenolic Acids 28
1.11 Effects of Processing on Antioxidants in Food Systems....................31
1.12 Effects of Processing on Antioxidants in Non-Wheat Food Systems.33
1.13 Effects of Processing on Antioxidants in Wheat Food Systems.........38
1.14 In-vitro Methods to Assess the Antioxidant Properties of Wheat......42
1.14.1 Phenolic Acid Composition Analysis..........................................42
1.14.2 Carotenoid and Tocopherol Composition Analysis.....................43
1.14.3 Total Phenolic Contents (TPC) Assay.........................................44
1.14.4 Total Flavonoid Content Assay...................................................45
1.14.5 DPPH Radical Scavenging Capacity Assay................................45
1.14.6 ABTS Cation Radical Scavenging Capacity Assay.....................46
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1.14.7 Superoxide Anion Radical Scavenging Capacity Assay.............46
1.14.8 Oxygen Radical Absorbing Capacity (ORAC) Assay.................48
1.14.9 Peroxyl Radical Scavenging Capacity (PSC) Assay...................49
1.14.10 Total Oxyradical Scavenging Capacity (TOSC) Assay.............49
1.14.11 Hydrogen Peroxide Scavenging Capacity Assay.......................50
1.14.12 Hydroxyl Radical Scavenging Capacity Assays........................50
1.14.13 Iron (II) Chelating Capacity Assay............................................51
1.14.14 Copper (II) Chelating Capacity Assay.......................................52
1.14.15 Assays Measuring Inhibition of Lipid Peroxidation..................52
Literature Cited...........................................................................................56
Chapter 2: Novel Fluorometric Assay for Hydroxyl Radical Scavenging Capacity
(HOSC) Estimation.....................................................................................................86
2.1 Abstract.................................................................................................86
2.2 Introduction...........................................................................................87
2.3 Materials and Methods..........................................................................91
2.4 Results and Discussion.........................................................................96
2.5 Conclusion..........................................................................................115
2.6 Literature Cited...................................................................................115
Chapter 3: Effects of Solid-State Enzymatic Treatments on the Antioxidant Properties
of Wheat Bran...........................................................................................................125
3.1 Abstract...............................................................................................125
3.2 Introduction.........................................................................................126
3.3 Materials and Methods........................................................................128
3.4 Results and Discussion.......................................................................135
3.5 Conclusion..........................................................................................163
3.6 Literature Cited...................................................................................164
Chapter 4: Effects of Solid-State Yeast Treatment on the Antioxidant Properties, and
Protein and Fiber Compositions of Common Hard Wheat Bran..............................172
4.1 Abstract...............................................................................................172
4.2 Introduction.........................................................................................173
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4.3 Materials and Methods........................................................................175
4.4 Results and Discussion.......................................................................182
4.5 Conclusion..........................................................................................203
4.6 Literature Cited...................................................................................205
Chapter 5: Effects of Baking Conditions, Dough Fermentation, and Bran Particle
Size on the Antioxidant Properties of Whole-Wheat Pizza Crust............................210
5.1 Abstract...............................................................................................210
5.2 Introduction.........................................................................................211
5.3 Materials and Methods........................................................................212
5.4 Results and Discussion.......................................................................219
5.5 Conclusion..........................................................................................235
5.6 Literature Cited...................................................................................236

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