PROCESS EVALUATION AND QUALITY OPTIMIZATION OF APPLE SNACK By Navpreet Kaur Gill ...

114 Pages·2013·1.61 MB·English

PROCESS EVALUATION AND QUALITY OPTIMIZATION OF
APPLE SNACK

By

Navpreet Kaur Gill

Department of Food Science and Agricultural Chemistry
Macdonald Campus, McGill University
Montreal, Canada

April 2013

A thesis submitted to McGill University in partial fulfilment of the
requirements for the degree of Master of Science

© Navpreet Kaur Gill, 2013
Dedicated to my family and my supervisor
ABSTRACT

The decline of formal lunchtime eating is creating a new market segments and strong growth in
the snack food market. Busy modern life with lunch at desks and night in front of computers is
for snack food consumption. The unhealthy snacks are composed of sugars and fats and
considered as “junk” increasing body weight whereas if these unhealthy snacks are supplemented
or enriched with well-balanced nutrients, we can have healthy life with enhanced health benefits
and consumer satisfaction. Such enrichments can be accomplished by naturally supplementing
these foods with proteins, fiber and antioxidants. My thesis research aims to enhance the value of
apple fruit snacks by adding soy protein, orange fiber and grape juice concentrate.
The two methods were employed for preparing the fruit snack - direct sheet drying and
extrusion-drying. Experimental procedure includes drying (fruit leather) and extrusion process
(apple extrudates) of apple fruit to obtain apple fruit snack. This was further enhanced with (0-
10%) fibre, (0-10%) antioxidant and (0-20%) protein. These three were varied within the range
using a CCRD design and the balance was supplemented by applesauce to make it 100%.
Nutritional assessment of snack bars was based on the total antioxidant, protein, water activity,
Hunter L∗ a∗ b∗ colour, hardness, phenolic composition and sensory quality. The water activity
values (<0.75) suggested that the resultant snack bars would possess a good shelf life.

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RÉSUMÉ
Le déclin actuel du dîner formel est en train de créer des nouveaux secteurs de marché autant
qu’une forte croissance dans le marché des collations. La vie modern occupée, avec ses dîners
devant le bureau et ses nuits devant l’ordinateur, est devenue propice à la consommation des
collations. Ces collations malsaines contiennent des sucres et du gras et sont considérées comme
de la « malbouffe ». En revanche, si ces mêmes aliments étaient supplémentés ou enrichis avec
des éléments nutritifs bien équilibrés, nous pourrions jouir d’une vie saine avec plus de bénéfices
pour la santé et une meilleure satisfaction du consommateur. De tels enrichissements peuvent
être obtenus en enrichissant ces aliments naturellement avec des protéines, de la fibre et des
antioxydants. Ma recherche de thèse vise à améliorer la valeur des barres aux fruits aux pommes
en y ajoutant des protéines de soya, de la fibre d’orange et du concentré de jus de raisin.
Le processus expérimental inclut le séchage (pour produire une pâte de fruits) et l’extrusion du
fruit pour obtenir une barre aux fruits aux pommes. Le produit est ensuite enrichi avec de la fibre
(0 à 10 %), des antioxydants (0 à 10 %) et des protéines (0 à 20 %). L’analyse nutritionnelle des
barres aux fruits est basée sur la teneur totale en antioxydants, en protéines et en humidité, autant
que sur la couleur (Hunter L*a*b*), la dureté, la composition phénolique et la qualité sensorielle.
L’activité de l’eau suggère que les barres aux fruits produites ainsi seront munies d’une durée de
conservation adéquate. Les résultats de l’analyse spectrophotométrique donnèrent des résultats
comparables et fortement corrélés (p < 0,05). Les barres aux fruits enrichies avec des éléments
nutritifs peuvent donc être des aliments fonctionnels qui offrent une bonne source de protéines,
d’antioxydants et de polyphénols.

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CONTRIBUTIONS OF AUTHORS
Several parts of the thesis research have been presented at scientific conferences and manuscripts
have been prepared for publication. Hence, the thesis is written in the manuscript style so that the
three chapters highlighting the thesis research could be suitably edited for publication. Two
authors have been involved in the thesis work and their contributions to the various articles are as
follows:
Navpreet Kaur Gill is the M.Sc. candidate who planned and conducted all the experiments, in
consultation with his supervisor, gathered and analyzed the results and drafted the thesis and the
manuscripts for publications.
Dr. Hosahalli S. Ramaswamy is the thesis supervisor, under whose guidance the research was
carried out, and who assisted the candidate in planning and conducting the research, as well as in
correcting, reviewing and editing the thesis and the manuscript drafts for publication.

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LIST OF PUBLICATIONS AND PRESENTATIONS
Parts of this thesis have been prepared as manuscripts for publications in refereed
scientific journals:
Gill, N and Ramaswamy, H. S., 2013. Evaluation of quality parameters and optimization of
apple fruit snack prepared with the drying process (draft prepared)

Gill, N and Ramaswamy, H. S., 2013. Evaluation of quality parameters and optimization of
apple fruit snack prepared formed by extrusion process (draft prepared)

Parts of this thesis have also been presented at the following scientific conferences:

Gill, N; Thotakura, S and Ramaswamy, H. S 2012. Quality evaluation of enriched products
formed with the extrusion process. Conference of Food Engineering (COFE), Leesburg,
Virginia, USA, April 2012.
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ACKNOWLEDGEMENTS
It is my proud privilege and distinct honor to acknowledge my sincere and humble gratitude to
my thesis advisor Dr. Hosahalli S. Ramaswamy for giving me the opportunity to work under his
supervision. I would like to express a deep sense of thanks for his continuous guidance,
invaluable advice, affectionate encouragement, financial support and help during my course of
study. His truly scientist intuition has made him as a constant oasis of ideas and passions in
science, which phenomenally inspire and enrich my growth as a student. I am indebted to him
more than he knows.
Sincere thanks to all the Faculty members of Department of Food Science and Agricultural
Chemistry, especially to Dr. Benjamin K. Simpson for being in my supervisory committee. I
would also like to thank Ms. Leslie Ann La Duke and Ms. Diane Chan-Hum, Food Science
Department secretaries, for all their administrative and secretarial help.
I would like to extend my appreciation to all my friends in the food processing group at McGill
University for their assistant and continuous motivation.
I would like to thank Dr. Ajaypal Singh, Research Associate in our Food Processing Group, for
the technical help in the experimental design and data analysis. I would also like to thank my
close friends Venu, Sushanth, Surinder, Kirupa, Ankur, Ravneet and Prabhjot for their support
and encouragement. It was impossible without their invaluable assistance. I feel proud to have
friends like you. I offer my regards and blessings to all of those who supported me in any respect
during the completion of my study.
I would like to deeply thank my parents for their continued love and moral support they gave me
throughout my life. I want to specially thank my brothers for always being with me. I want to
dedicate this work to all members of my family. Finally, I would like to thank God for blessing
such a beautiful life.

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TABLE OF CONTENTS
ABSTRACT i
RESUME ii
CONTRIBUTION OF AUTHORS iii
LIST OF PUBLICATIONS iv
ACKNOWLEDGEMENTS v
CHAPTERS vi
LIST OF TABLES ix
LIST OF FIGURES xi

CHAPTER I: INTRODUCTION ................................................................................................ 1

CHAPTER II: REVIEW OF LITERATURE ............................................................................ 7
2.1 Historical Perspective ............................................................................................................ 7
2.2 Snack Foods .......................................................................................................................... 7
2.3 Apple as a Snack food ........................................................................................................... 8
2.4 Apple Fruit Leather ............................................................................................................... 9
2.4.1. Drying of fruit puree ...................................................................................................... 9
2.4.2. Drying Principle .......................................................................................................... 10
2.4.3 Water activity (a ) ........................................................................................................ 10
w
2.4.4 Drying Curve ................................................................................................................ 12
2.4.5 Types of air flow in the dryers ...................................................................................... 14
2.4.6 Tray Dryer..................................................................................................................... 15
2.5 Extruded Snacks .................................................................................................................. 15
2.5.1 History of Extrusion ..................................................................................................... 17
2.5.2 Introduction to Food Extruders..................................................................................... 17
2.6 Ingredients to Enhance the Quality ..................................................................................... 18
2.6.1Protein ............................................................................................................................ 18
2.6.2 Fiber .............................................................................................................................. 18
2.6.3 Antioxidants .................................................................................................................. 19
2.7 Response Surface Methodology .......................................................................................... 20

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CHAPTER III: EVALUATION OF QUALITY PARAMETERS AND OPTIMIZATION OF
APPLE FRUIT SNACK PREPARED BY DRYING ............................................................... 23
3.1 Abstract ............................................................................................................................... 23
3.2 Introduction ......................................................................................................................... 23
3.3 Materials and Methods ........................................................................................................ 25
3.3.1 Fruit leather Preparation ............................................................................................... 25
3.3.2 Color ............................................................................................................................. 27
3.3.3 Texture .......................................................................................................................... 27
3.3.4 Total Polyphenol Content ............................................................................................. 28
3.3.5 Antioxidant Activity ..................................................................................................... 28
3.3.6 Protein Content ............................................................................................................. 29
3.3.7 Statistical Analysis ....................................................................................................... 29
3.3.8 Sensory Analysis .......................................................................................................... 29
3.4 Results and Discussions ...................................................................................................... 30
3.4.1 Typical Drying Curve ................................................................................................... 30
3.4.2 Effect of process variables on color ............................................................................. 32
3.4.3 Effect of Process Variables on Texture ........................................................................ 41
3.4.4 Effect of Process Variables on Polyphenols ................................................................. 44
3.4.5 Effect of Process Variables on Antioxidant activity .................................................... 47
3.4.6 Effect of Process Variables on Proteins ....................................................................... 50
3.4.7 Effect of process variables on Sensory quality ............................................................. 52
3.4.8 Optimisation of the process .......................................................................................... 55
3.5 Conclusion ........................................................................................................................... 56

CHAPTER IV: EVALUATION OF QUALITY PARAMETERS AND OPTIMIZATION OF
APPLE FRUIT SNACK PREPARED BY EXTRUSION ....................................................... 59
4.1 Abstract ................................................................................................................................... 59
4.2 Introduction ......................................................................................................................... 60
4.3 Materials and Methods ........................................................................................................ 61
4.3.1 Apple Extrudate Preparation ........................................................................................ 61
4.3.2 Color analysis ............................................................................................................... 63
4.3.3 Texture analysis ............................................................................................................ 63
4.3.4 Total Polyphenol Content ............................................................................................. 64
4.3.5 Antioxidant Activity ..................................................................................................... 64
4.3.6 Protein Content ............................................................................................................. 64
4.3.7 Statistical Analysis ....................................................................................................... 64
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4.3.8 Sensory Analysis .......................................................................................................... 64
4.4 Results and Discussions ...................................................................................................... 64
4.4.1 Effect of Process Variable on Color ............................................................................. 66
4.4.2 Effect of process variables on Texture ......................................................................... 75
4.4.3 Effect of process variables on Polyphenols .................................................................. 78
4.4.4 Effect of process variables on Antioxidant activity ...................................................... 81
4.4.5 Effect of process variables on Proteins ......................................................................... 84
4.4.6 Effect of Process Variables on Sensory Analysis ......................................................... 87
4.4.7 Optimisation of process ................................................................................................ 91
4.5 Conclusion ........................................................................................................................... 92

CHAPTER 5: GENERAL CONCLUSIONS AND RECOMMENDATIONS FOR FUTURE
STUDIES ..................................................................................................................................... 93
5.1 General Conclusion ............................................................................................................. 93
5.2 Recommendations for future research ................................................................................ 93

REFERENCES ............................................................................................................................ 94

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