PROTEIN RICH EXTRUDED SNACK FOODS USING HYDROLYZED PROTEINS

PROTEIN RICH EXTRUDED SNACK FOODS USING

HYDROLYZED PROTEINS





By

Heather M. Nelson




A Research Paper

Submitted in Partial Fulfillment of the
Requirements for the
Master of Science Degree
With a Major in

Food & Nutritional Sciences

Approved: 6 Semester Credits



___________________________________
Gour Choudhury, Investigation Advisor

Committee Members:

___________________________________
Janice Coker

___________________________________
John Crandall




The Graduate School
University of Wisconsin-Stout
August, 2003

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The Graduate School
University of Wisconsin-Stout
Menomonie, WI 54751


Abstract




Nelson
Heather
M.
(Writer) (Last
Name)
(First) (Initial)


Protein Rich Extruded Snack Foods Using Hydrolyzed Proteins
(Title)

Food & Nutritional Sciences Dr. Gour Choudhury August 2003
55
(Graduate Major)
(Research Advisor) (Month/Year) (No. of Pages)

American Psychological Association Style Manual 5th Edition

(Style Manual Used)


The effects of the degree of protein hydrolysis and feed concentration of protein were
tested on corn meal extrudates using a single screw extrusion system. Four different
concentrations of whey protein isolate (0%, 5%, 10%, and 15%) with differing levels of
hydrolysis (0%, 4.5%, 10.0%, and 14.9%) were mixed with corn meal and then extruded.
Samples of the extrudates were tested for breaking strength, apparent density, true
powder density, expansion ratios, and porosity. It was found that extrudates containing
the hydrolyzed proteins had physical characteristics similar to those of the 100% corn
meal samples. Many of the undesirable effects of adding unhydrolyzed protein to
extrusion feed mixtures either did not occur or occurred to a lesser extent when partially
hydrolyzed proteins were added. It was also found that as the degree of protein hydrolysis

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and as the protein concentration of the extrusion feed mixture increased the breaking
strength and the apparent density of the extrudate decreased to values that were lower
than the extrudate of the control corn meal. Extrusion runs that utilized hydrolyzed and
unhydrolyzed forms of the isolated soy proteins produced similar results which suggests
that changes in the physical properties of protein hydrolysate fortified corn meal
extrudates are independent of the protein source.

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Acknowledgements

To begin I would like to thank the University of Wisconsin-Stout for the use of
the facilities as well as equipment. I would like to thank Davisco Inc., Cargill Inc., Archer
Daniels Midland Company, and the Snack Food Association for their generous gifts of
materials and statistics of the snack food market without which this research would not
have been possible.

I would also like to thank several individuals for their support, contributions and
encouragement during the research process. First I would like to thank my committee
members Dr. John Crandall and Dr. Janice Coker for their assistance, suggestions, and
expertise. Their time and attention was greatly appreciated. I would also like to thank the
entire Food & Nutrition Department for their interest and encouragement throughout the
process, especially Vicki Weber for all of her support. I would like to thank Connie
Galep for her much appreciated help with the operation of the extruder and assistance
with sample measurement; this would not have been completed so quickly without her.
To Trudy Olson I would like to extend my gratitude for her encouragement and advice,
not only throughout the thesis process but throughout all of my years at the University of
Wisconsin-Stout, she always been there for me as a friend as well as my voice of reason
like a mother away from home. To my friends Laura, Sofyan, and Amie: thank you for
always listening and for always offering kind words of encouragement. I would also like
to thank my parents Alan and Nancy Picha and Peter Nelson as well as my sister Nicole
Nelson, without them I never would have had the courage and perseverance to reach this
goal. Finally I would like to extend my sincere thanks and gratitude to my advisor, Dr.
Gour Choudhury. He is truly an amazing individual who is always full of ideas and

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solutions. He encouraged me to achieve more and to realize my potential. I will always
be indebted to him for that.

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Table of Contents



Page
Abstract……………………………………………………………. ii


Acknowledgements…………………..……………………………. iv
List of Tables………………………………………………………
vii
List of Figures……………………………………………………...
viii

CHAPTER ONE…………………………………………………...
1

Statement of the Problem…………………………………...
2
Objectives.………………………………………………….
3


CHAPTER TWO..………………………………………………….
5
Extrusion……….……………………………………………
5
Whey Protein..………………………………………………
5
Hydrolyzed Protein..………………………………………..
6
Previous Studies………….…………………………………
7

CHAPTER THREE…………………………………………………
10

Materials..……………………………………………………
10

Extruder……………………………………………………..
11

Extrusion Experiments………………………………………
11

Response Variables………………………………………….
14
Data Analysis………………………………………………..
17

CHAPTER FOUR…………………………………………………..
18

Feed Composition…………………………………………..
18

Effects of Hydrolyzed Protein on Extrudate Densities……..
18

Effects of Hydrolyzed Protein on Extrudate Porosity………
28
Effects of Hydrolyzed Protein on Extrudate Expansion…….
33

Effects of Hydrolyzed Protein on Extrudate Hardness……..
46

CHAPTER FIVE………………………………………………………
52

Summary………………………………………………………
52

Conclusions……………………………………………………
53


References
…………………………………………………………
54

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List of Tables












Page


Table 1:
Consumption of Snack Foods Over the Past Three Years…
2

Table 2:
Approximate Company Specifications of Ingredients…….
10
Table 3:
Particle Size Distribution of Corn Meal……………………
11

Table 4:
Moisture Determinations of Raw Ingredients………………
13
Table 5:
Composition of Extruded Mixes……………………………
14
Table 6:
True Density Values for Whey Protein Samples…………..
24
Table 7:
Mean Sum of Squares Data for Densities and Porosities
Whey
Protein
Samples…………………………………….
25
Table 8:
Analysis of Variance Data for Expansion Ratios of Whey
Protein
Samples……………………………………………
39
Table 9:
Analysis of Variance Data for Breaking Strengths of Whey
Protein
Samples……………………………………………
46

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List of Figures












Page


Figure 1:
Sales of Cheese Snacks…………………………………….
3
Figure 2:
Volume of Cheese Snacks Sold……………………………
4

Figure 3:
Single Screw Extruder…………………………………….
12
Figure 4:
Unhydrolyzed Whey Protein Samples…………………….
19
Figure 5:
4.5% Hydrolyzed Whey Protein Samples…………………
20
Figure 6:
10.0% Hydrolyzed Whey Protein Samples………………
21
Figure 7:
14.9% Hydrolyzed Whey Protein Samples……………….
22

Figure 8:
Soy Protein Samples………………………………………
23
Figure 9:
Apparent Density of Whey Protein Extrudates………….

27
Figure 10:
Apparent Density of Soy Extrudates…………………….

29
Figure 11:
Porosity of Whey Protein Extrudates……………………

30
Figure 12:
Porosity of Soy Protein Isolates…………………………

31
Figure 13:
Porosity versus Apparent Density for Whey Protein

Extrudates……………………………………………….
32
Figure 14:
Radial Expansion Ratios for Whey Protein Extrudates…

35
Figure 15:
Radial Expansion for Soy Protein Extrudates…………..

36
Figure 16:
Axial Expansion Ratios for Whey Protein Extrudates….

38
Figure 17:
Axial Expansion Ratios for Soy Protein Extrudates……

38
Figure 18:
Overall Expansion Ratios for Whey Protein Extrudates..

39

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List of Figures (continued)












Page
Figure 19:
Overall Expansion Ratios for Soy Protein Extrudates…

43
Figure 20:
Overall Expansion Ratio versus Apparent Density for
Whey Protein Extrudates………………………………

44

Figure 21:
Overall Expansion Ratio versus Porosity for Whey


Protein Extrudates…………………………………….

45

Figure 22:
Breaking Strength Values for Whey Protein Extrudates.

47
Figure 23:
Breaking Strength Values for Soy Protein Samples….

48
Figure 24:
Radial Expansion versus Breaking Strength for Whey
Protein
Samples………………………………………..
49

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CHAPTER ONE
Introduction
Extrusion is a means of shaping something by forcing it through an opening. In
food processing, extrusion combines heating with the act of extrusion to create a shaped
cooked product. Extrusion is accomplished by single screw and twin-screw extruders.
The choice of extruders is determined by the moisture content of the extrusion feed
mixture. Low moisture extrusion mixtures appropriate for a single screw extruder must
have a feed composition of less than 35% moisture. High moisture extrusion mixtures,
those with a moisture level of 35% or above, require the use of a twin-screw extruder.
The 13.5% (w/w) moisture content of the extrusion mixtures used throughout this study
was applicable to a single screw extruder.
There has been extensive ongoing research on the benefits of whey protein in the
diet. Some of the findings indicate that whey protein slows the growth of breast cancer,
boosts the immune systems of AIDS patients, reduces blood pressure, suppresses
appetite, reduces cholesterol, and the inhibits the formation of dental plaque and dental
caries. Benefits of whey protein exist for infants, active teens and healthy adults, athletes,
and the elderly. The addition of whey protein into a commonly consumed type of snack
food would increase the consumption of whey protein as well as possibly benefit the
health of many individuals (Pins & Keenan, 2002; Schmidl, Taylor, & Nordlee, 1994;
Ziegler, Nitenberg, Coudray-Lucas, Lasser, Giboudeau, & Cynober, 1998; Nelson,
Colker, Kalman, & Swain, 2002; Loimaranta, Laine, Soderling, Vasara, Rokka, Marnila,
Korhonen, Tossavainen, & Tenovuo, 1999).

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