Sudan University of Science and Technology College of Graduate Studies Yoghurt Partially Supplemented with Barley Flour fermented with Probiotic Bifidobacterium longum BB536 الزبادي المدعم جزئيا بدقيق الشعير المخمر بالبكتريا الصديقة Bifidobacterium longum BB536 Dissertation Submitted to Sudan University of Science and Technology in Partial Fulfillment for the Requirements of the Degree of Master of Science in Food Science and Technology By Manal Ahmed Mustafa Mohammed B.Sc. (Honors) in Food Science and Technology, Sudan University of Science and Technology (2010) Supervisor Associated Professor Dr. Barka Mohammed Kabier Barka Department of Food Science and Technology, College of Agriculture Studies, SUST October 2017 2 اﻵية قال تعالي: )وَإِنَّ لَكُمْ فِي الْأَنْعَامِ لَعِبْرَةً نُسْقِيكُمْ مِمَّا فِي بُطُونِهِ مِنْ بَيْنِ فَرْثٍوَدَمٍ لَبَنًا خَالِصًا سَائِغًا لِلشَّاِِبِينَ( صدق اهلل العظيم سوِة النحل اﻵية )66( I Dedication this dissertation is dedicated to soul of my late father Ahmed Mustafa To dear my mother Nafisa Khalid To my dear Grandmother To my dear Aunts and Uncles To my dear Brothers and sisters To my all Relative for their kind helps and support II Acknowledgment First, almost grateful thanks to Allah for giving me health, patience, and assistance to complete this work. Thanks and all thanks to my supervisor, Dr. Barka Mohamed Kabeir Barka for supervising and nice cooperation and help. Especially thanks to my dear Ustaza Eshraga and all staff at animal production department for kind help and support. Finally thanks to my all friends. III Table of Contents Title Page No. I ................................................................................................................... اﻵية Dedication ...................................................................................................... II Acknowledgment .......................................................................................... III Table of Contents .......................................................................................... IV List of Tables ................................................................................................ VII List of Figure ................................................................................................ VIII Abstract ......................................................................................................... IX X ............................................................................................................. الملخص CHAPTER ONE ................................................................................................ 1 INTRODUCTION .............................................................................................. 1 CHAPTER TWO ............................................................................................... 4 LITERATURE REVIEW ....................................................................................... 4 2.1 Definition of milk .................................................................................. 4 2.2 The role of milk as a source of macronutrients ...................................... 5 2.3 Factors affecting milk composition........................................................ 5 2.4 Cow milk ............................................................................................... 5 2.5 History of fermentations ........................................................................ 6 2.6 Fermented milk ..................................................................................... 7 2.6.5 Other fermented milk ......................................................................... 8 2.7 History of Yoghurt ................................................................................ 8 2.8 Definition of Yoghurt: ........................................................................... 9 2.8.1 Type of Yoghurt: ................................................................................ 9 2.8.2 Yoghurt as a Functional Food ........................................................... 11 2.8.3 Nutritional and health benefit of yoghurt .......................................... 12 2.8.4 Flow diagram for yoghurt production ............................................... 13 2.8.4.1 Traditional method ........................................................................ 13 2.8.4.2 Improved process .......................................................................... 14 IV 2.8.4.1 Definition of Probiotics: ............................................................... 15 2.8.4.2 The history of probiotics ................................................................ 16 2.8.4.3 Health benefit of probiotics: .......................................................... 18 2.9 Criteria for classifying Microorganism as Aprobiotic: ......................... 19 2.10 Characteristics of probiotics: ............................................................. 19 2.10.1 Carrier of probiotics ...................................................................... 20 2.11 Lactobacillus ..................................................................................... 22 2.12 Bifidobacterium ................................................................................. 22 2.13 Cereals .............................................................................................. 23 2.14 The barley: ........................................................................................ 24 2.14.1 Scientific classification and Etymology: ......................................... 24 2.14.3 Classification of Barley: ................................................................. 25 2.14.4 Composition of Barley: ................................................................ 26 2.14.5 Health Benefit and utilization in food: .......................................... 27 CHAPTER THREE ........................................................................................... 29 MATERIALS AND METHODS .......................................................................... 29 3.1 Raw materials: ..................................................................................... 29 3.2 Starter culture: ..................................................................................... 29 3.3 Chemicals: ........................................................................................... 29 3.4 Microbiological Media and L-cysteine. ........................................... 29 3.6.1 Preparation of Barley powder: .......................................................... 29 3.6.2 Preparation of Starter culture: ......................................................... 30 3.6.3 Yoghurt processing steps: ................................................................. 30 3.6.4 Enumeration of viable cell: ............................................................... 31 3.6.5 Phsio-Chemical Analysis: ................................................................. 31 3.6.5.1 PH value: ....................................................................................... 31 3.6.5.2 Titratable Acidity: ......................................................................... 31 3.6.5.4 Determination of lactose: ............................................................... 32 3.6.5.4.1 Preparation of standard solution: ................................................ 32 V 3.6.5.4.1.1 Procedure: ................................................................................ 32 3.6.5.5 Moisture content: ........................................................................... 33 3.6.5.6 Chemical Determination of fat content: ......................................... 33 3.6.5.7 Chemical Determination of ash content ......................................... 33 3.6.5.8 Determination of protein content: ................................................ 34 3.6.5.9 Determination of crude fiber:......................................................... 35 3.7 Sensory evaluation of different yoghurt: .............................................. 36 3.8 Statistical analysis: .............................................................................. 36 CHAPTER FOUR ............................................................................................ 37 RESULTS AND DISCUSSION ........................................................................... 37 4.1 Chemical composition of raw material ................................................ 37 CHAPTER FIVE ............................................................................................... 49 CONCLUSION AND RECOMMENDATION....................................................... 49 Conclusion: ............................................................................................... 49 Recommendation: ..................................................................................... 49 It is recommended that more investigation are needed to:- ........................ 49 Appendices ................................................................................................... 57 VI List of Tables Table Title Page No. Table 1: Chemical composition of fresh cow milk and barley: ...................... 40 Table 2: Chemical composition of different yoghurt products ....................... 43 Table 3: Lactic acid bacteria and Bifidobacterium longum BB536 growth, pH, and acidity of different yoghurt products ........................................................ 46 Table 4: Scenery characteristic of