Reham Mohamed Mohamed Abd El-kader

245 Pages·2012·4.19 MB·English

Faculty of Science
Microbiology department 
“ Development of safe juices for
immunocompromised patients by irradiation
alone or in combination with other
technologies” 

By  
Reham Mohamed Mohamed Abd El-kader
B. Sc. Microbiology – Biochemistry
(2007)
Faculty of Science, Ain- shams University
National Center For Radiation Research and Technology
Thesis
submitted in partial fulfillment of the requirement for
M. Sc. Degree in
Microbiology
Microbiology Department
Faculty of Science
Ain-Shams University
2012
Faculty of Science
Microbiology department 

“Development of safe juices for
immunocompromised patients by irradiation
alone or in combination with other
technologies” 

By  
Reham Mohamed Mohamed Abd El-Kader
B. Sc. Microbiology - Biochemistry
(2007)
National Center For Radiation Research and Technology

Supervised by: 
Prof. Khayria Abd El-Ghany Youssef
Professor of Microbiology, Faculty of Science, Ain Shams
University
Prof. Ali Ahmed Ibrahim Hammad
Professor of Food Science and Microbiology, Former Vice
Chairman of Egyptian Atomic Energy Authority
Dr. Hanan Hassan Abd El-Khalek
Lecturer of Microbiology, National Center for Radiation
Research and Technology (NCRRT), Atomic Energy Authority
2012
Faculty of Science 
Microbiology department 

Name: Reham Mohamed Mohamed Abd El-Kader
Title: 
“Development of safe juices for immunocompromised
patients by irradiation alone or in combination
with other technologies”

Supervised by: 

1-Prof. Khayria Abd El-Ghany Youssef……………
Professor of Microbiology, Faculty of Science, Ain Shams University. 

2-Prof. Ali Ahmed Ibrahim Hammad……………..
Professor of Food Science and Microbiology, Former Vice Chairman of Egyptian 
Atomic Energy Authority. 
3- Dr. Hanan Hassan Abd El-Khalek…………….
Lecturer of Microbiology, National Center for Radiation Research and Technology 
(NCRRT), Atomic Energy Authority(AEA).
Faculty of Science
Microbiology department 

“Development of safe juices for
immunocompromised patients by irradiation
alone or in combination with other
technologies”

By  
Reham Mohamed Mohamed Abd El-Kader
B. Sc. Microbiology - Biochemistry
(2007)
National Center For Radiation Research and Technology

Approved by: 
1-Prof. Mohie Eddin Zohier El-Fouly
Professor of Microbiology, National Center For Radiation
Research and Technology ( NCRRT ), Atomic Energy Authority
2-Prof. Mohamed Ghareeb Ibrahim Emaish
Professor of Microbiology, Faculty of Education, Ain Shams
University.
3-Prof. Khayria Abd El-Ghany Youssef
Professor of Microbiology, Faculty of Science, Ain Shams
University
4-Prof. Ali Ahmed Ibrahim Hammad
Professor of Food Science and Microbiology, Former Vice
Chairman of Egyptian Atomic Energy Authority

DEDICATION

To my mum Mrs.Nawal Mahmoud.
Your constant motivation and faith has always given
me hope. Now, this is was your dream, through me.
Thank You.

&
To my brother Islam Abdelkader for his supports
and encouragements. D
&
To my father soul, God bless him.
Finally, this thesis is dedicated to all those who believe
in the richness of learning.
ACKNOWLEDGEMENTS
All praises and thanks are for ALLAH who is the
entire source of all knowledge and wisdom endowed
to mankind

Prof. Khayria Abd El-Ghany Youssef, thank you for believing in me; for
your encouragement through kind words, support, your guidance, for
effective and helpful supervision, Fruitful discussion and valuable
advice.

Prof. Ali Ahmed Ibrahim Hammad, thank you for suggestion of the point,
assigning the work, kindly supplied me with all necessary facilities,
carefully editing this thesis and your attention to finer details, and
thanks for your encouragement, guidance, patience, time and expertise on
this work.

My heartfelt gratitude goes to Dr. Hanan Hassan Abd El-Khalek for all
her help, encouragement and dedication in helping me, support, patience,
and sincere advices, advance my knowledge and making this work
possible.

Prof Hussein Abd El-Kareem Head of Microbiology department, National
Center for Radiation Research and Technology (NCRRT).Atomic Energy
Authority(AEA).A cooperative and affectionate personality, special
thanks are extended to you for the care, impetus and encouragements.
Thanks to the head of Microbiology department Mohamed khaled
Ibrahim and to the faculty, staff and members of the Microbiology
department for their help and their academic advice.
My deepest graditude to all staff of Microbiology department,
National Center for Radiation Research and Technology for their
friendship and their advice.

Last, but not least my deep thanks are extended to my family and all my
friends, their love, understanding and unfailing support has made
everything possible.

I thank all those who, in different ways, have walked beside me along
the way; offering support and encouragement, challenging my thinking,
and teaching me to consider alternative views.
Name : Reham Mohamed Mohamed Abd El-Kader
Title of Thesis : Development of safe juices for immunocompromised patients by
irradiation alone or in combination with other technologies.
Degree: M.Sc.
Faculty : Science
University : Ain Shams
Department : Microbiology
Abstract
Fresh fruit and vegetable juices have become a new functional food
available for dietary and health. However, they have high microbial load and poses a
microbial hazard to consumer unless treated with a suitable method of food
preservation. Gamma irradiation, as non thermal process, is highly effective in
destruction of both spoilage and pathogenic microorganism in various foods without
arising its temperature, hence keeping its freshness and nutritional quality. In recent
years, it is used as a safe and alternative method for food preservation in many
countries.
In present study, pomegranate, tomato and carrot juices were irradiated at
different irradiation doses (1- 4.5 kGy). Yeasts, as the principle cause of juices
spoilage, were isolated and identified from unirradiated (control) juices. The
resistance of the identified yeasts to gamma radiation in the term of D - value was
10
investigated. It was found that Debaryomyces hansenii had the highest radiation
resistance ( D -value of 1.63 kGy ) while Candida tropicalis had the lowest
10
resistance to gamma radiation ( D -value of 0.98 kGy ).The effect of these
10
irradiation doses on the microbiological load, nutritional, physiochemical and
sensory properties were evaluated immediately after irradiation and during
subsequent refrigeration storage. Generally, irradiation doses of 1.0 kGy and above
were efficient and sufficient for complete elimination of coliform bacteria and E.coli
found in these juices without impairing the nutritional and sensory quality attributes.
Irradiation of pomegranate juice at 2.5 kGy greatly reduced its microbial
counts and extended the shelf-life to 14 days at refrigeration temperature (4°C±1)
with minimal changes in the anthocyanin content. Irradiation dose of 3.0 kGy could
improve the microbial quality, ensure safety and extend the shelf-life of tomato juice
to 15 days at refrigeration temperature without significant changes in lycopoene
content. Meanwhile, irradiation dose of 3.0 kGy in combination with
cinnamaldehyde (8µl/100 ml) greatly reduced the microbial load of carrot juice and
extended its shelf-life to 21 days at 4°C±1 without adverse effect on the sensory and
nutritional quality.
Key words : pomegranate juice, tomato juice, carrot juice, irradiation, nutritional
quality.