Firstly and foremost, I would like to thank almighty Allah (God) who created me and gave sound health throughout the research period. The first person I would like to thank is my supervisor Prof. Dr. Klaus Dieter Kulbe, Universität für Bodenkultur, Wien, for accepting me as Ph.D. student in this University. In short, he is an outstanding role model not only for research duration but also for my, as an academic, future life. I could not but remember the valuable suggestions, support and cordial feelings of Prof. Dr. Dietmar Haltrich, Head, Division of Food Biotechnology during my study. I would like to pay my tribute to Austrian Exchange Service (OEAD), for providing financial supports. I am thankful to my loving wife, Khadija Begum, who sacrificed valuable time of her post-marriage conjugal life implementing this long dream. Finally, I would like to dedicate this dissertation to my beloved parents, who are not only a sponsor of my study but also sponsor of my life and career and my sweet daughter, Wafia Binte Aziz, who is another outcome during my Ph.D. study. Vienna, September 2008