Naringinase from probiotic bacteria and its application in production of probiotic citrus juices: Doctoral Dissertation - Major: Food science

Naringinase from probiotic bacteria and

its application in production of probiotic

citrus juices

Doctoral (PhD) Dissertation

Tran Thi Mai Anh

Gödöllő

2019

Acknowledgement

Firstly, I would like to express my sincere gratitude to my supervisor Prof. Nguyen Duc

Quang for the continuous support of my Ph.D. study and related research, for his patience,

motivation, and immense knowledge. His guidance helped me in all the time of research and

writing of this thesis.

I am grateful to my co-supervisor Assoc. Prof. Dam Sao Mai for introducing me to the

world of science and for helping me during research as well.

Besides my supervisors, I would like to thank all members of the Department of

Distilling and Brewing: Rezessyné Dr. Szabó Judit, Prof. Hoschke Ágoston, and Hegyesné

Dr. Vecseri Beáta for supporting me and giving me encouragements during the study; Dr.

Bujna Erika for her encouragement as well as supporting me in the laboratory and research

facilities; Dr. Nagy Edina Szandra, Farkas Csilla, Dr. Kun Szilárd, Dr. Kun-Farkas

Gabriella, Kiss Zsuzsanna, Kilin Ákos for their help and share.

I thank my fellow lab mates Ta Phuong Linh, Koren Dániel, Pham Minh Tuan,

Truong Hoang Duy, Nguyen Bao Toan for their help, stimulating discussions, and for all the

fun we have had in the last four years.

My thankfulness goes to Professors in Faculty of Food Science, who gave me scientific

lectures. I have learned from them the means of working and study.

It is my fortune to gratefully acknowledge my friends for their support and generous care

throughout the research tenure. They were always beside me during the happy and hard moments

to push me and motivate me.

Finally, I acknowledge the people who mean a lot to me, my parents, my parent in-law,

and members of my big family. Although they hardly understood what I researched on, they

were willing to support any decision I made. I would never be able to pay back their love and

affection.

I owe thanks to very special persons, my beloved husband and lovely children for their

continued and unfailing love, support and understanding during my pursuit of Ph.D. degree that

made the completion of my thesis possible. I really appreciate my children, Linh and Phong, for

abiding my absence and the patience they showed during my study. Words would never say how

grateful I am to them.

I consider myself the luckiest in the world to have such a lovely and caring family,

standing beside me with their love and unconditional support.

Ph.D. School

Name: Food Science Doctoral School

Field: Food Science

Head: Prof. Livia SIMON-SARKADI D.Sc.

Department of Food Chemistry and Nutrition Science

Faculty of Food Science, Szent István University

Supervisor: Prof. Quang D. Nguyen Ph.D

Department of Brewing and Distilling

Faculty of Food Science, Szent István University

Assoc. Prof. Mai S. Dam Ph.D

Institute of Biotechnology and Food Technology

Industrial University of Ho Chi Minh City, Vietnam

The applicant met the requirements of the Ph.D. regulations of the Szent István

University and the thesis is accepted for the defense process.

……………………………….. ……………………………..

Signature of Head of Doctoral School Signature of Supervisor

Table of Contents

Abbreviations............................................................................................................................................... i

List of figures.............................................................................................................................................. ii

1. INTRODUCTION AND OUTLINE.....................................................................................................1

1.1. Introduction ....................................................................................................................................1

1.2. Outline of dissertation....................................................................................................................3

2. LITERATURE REVIEW......................................................................................................................4

2.1. Citrus fruits.....................................................................................................................................4

2.1.1. General introduction ..............................................................................................................4

2.1.2. Nutritional value .....................................................................................................................5

2.2. Flavonoids concentrations of grapefruit juices............................................................................7

2.2.1. Bitterness.................................................................................................................................9

2.2.2. Debittering technology .........................................................................................................10

2.2.2.1. Physical methods...........................................................................................................11

2.2.2.2. Chemical methods.........................................................................................................11

2.2.2.3. Biotechnological methods.............................................................................................12

2.3. Naringinase ...................................................................................................................................13

2.3.1. General information .............................................................................................................13

2.3.2. Sources...................................................................................................................................14

2.3.2.1. Fungal naringinase........................................................................................................15

2.3.2.2. Bacterial naringinase ....................................................................................................18

2.3.3. Molecular and structural characteristics of naringinase ..................................................20

2.3.4. Assay of naringinase activity ...............................................................................................23

2.3.5. Characterization of naringinase ..........................................................................................25

2.3.6. Application of naringinase ...................................................................................................29

2.3.6.1. Debittering of fruit juices.............................................................................................29

2.3.6.2. Enhancement of wine aroma........................................................................................31

2.4. Probiotic microorganism .............................................................................................................32

2.4.1. Introduction...........................................................................................................................32

2.4.2. Benefits of probiotic..............................................................................................................33

2.4.3. Properties essential for effective and successful probiotics...............................................33

2.5. Probiotic beverage ........................................................................................................................34

2.6. Factors affecting lactic fermentation..........................................................................................35

2.6.1. Nutritional requirements .....................................................................................................35

2.6.2. pH...........................................................................................................................................35

2.6.3. Temperature..........................................................................................................................36

2.6.4. Substrate inhibition ..............................................................................................................36

2.6.5. Product inhibition.................................................................................................................36

3. MATERIALS AND METHODS ........................................................................................................37

3.1. Chemicals......................................................................................................................................37

3.2. Screening naringinase production of probiotic bacteria...........................................................37

3.3. Effect of some factors on naringinase production by L. fermentum D13.................................37

3.3.1. Effect of inoculum ratio of bacteria ....................................................................................37

3.3.2. Effect of different pH............................................................................................................38

3.3.3. Effect of naringin concentration..........................................................................................38

3.3.4. Effect of carbohydrate sources............................................................................................38

3.3.5. Effect of metal ions ...............................................................................................................38