i

DECLARATION

I do hereby declare that the work reported in this dissertation was exclusively carried

out by me under the supervision of Ms. Hemani Gunathilake. It describes the results

of my own independent research except where due reference has been made in the

text. No part of this dissertation has been submitted earlier or concurrently for the

same or any other degree.

Date: .... .

Signature of the Candidate

Faculty of Science & Technology

Uva Wellassa University

Badulla

We/I endorse the declaration by the candidate.

. ...

Ms. Hemani Gunathilake Ms. Maheshi peries

Supervisor Supervisor

Date: Date:

..

Dr. K.B Wijesekara

Research Coordinator

Date: .

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Abstract

The aim of this study was determine the optimum levels of enzymes (amylase, glucose

oxidase, Lipase, xylanase) for bakers flour which containing hard and medium wheat

flour in chosen proportions. In order to have general over view of enzyme effect on

wheat flour, enzymes were chosen in different concentration levels (low, medium,

high) and supplemented with flour. The effect of different enzymes on, gluten quality,

gluten amount, gluten index, dough rheology, water absorption, falling number and

final quality of bread was investigated with control. The effect of enzymes on gluten

quality was evaluated concerning amount of wet and dry gluten. Water absorption,

stability, development time, was analyzed using farinograph test. Dough rheology

(extensibility, resistance) was analyzed using extensograph.

It was found that water absorption and development time of wheat flour was

decreased when adding amylase enzyme and water absorption was increased with

xylanase, glucose-oxidase. Development time was increased with glucose-oxidase

concentration. According to farinograph stability of wheat flour was increased with

glucose oxidase and decreased with amylase. Extensibility of wheat flour was

decreased with glucose oxidase and increased with amylase, lipase and xylanase. Also

it was observed flour with enzymes was shown no significant difference on gluten

quality and amount and it was observed with amylase and xylanase enzymes were

reduced the falling number on wheat flour.

In order to find optimum levels of enzymes for hard and medium flour blend, flour

was treated with four enzyme combinations in recommended dosage levels. Enzyme

combinations activity was evaluated by the measurement of loaf volume and in

addition to that sensory analysis was done for evaluate bread quality with reference.

Enzymes had positive effect on wheat flour by dough strengthening, conditioning

dough rheology and water absorption. Regarding the effect on final baked product,

enzymes improve the quality of bread by improving volume and other sensory

characteristics (overall appearance, crust colour. symmetry of form, texture, grains,

mouth feel, and overall acceptability.).Except treatment1 all other enzyme treatments

were shown no significant difference from the reference. So that according

comparison cost of treatments it was found that amylase 6ppm, glucose-oxidase

15ppm, lipase 25ppm and xylanase 40ppm combination was the cheapest and best

enzyme treatment for hard and medium flour blend.

Key Words: Wheat flour, Enzymes, dough rheology, water absorption, bread flour

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ACKNOWLEDGMENT

I would sincerely like to express my most profound thanks to my supervisor Ms.

Hemani Gunathilake at Serandib Flour mills (pvt) Ltd, for her dedicative continuous

support, guidance, encouragement, expertise, and invaluable advice throughout the

research period without her the work would never have been undertaken.

Grateful thanks are also extended to Dr. Kolitha B. Wijesekara, Ms. Maheshi peries at

Uva Wellassa University for help and suggestions throughout the research period.

Also my thanks go to all other academic staff members of Science and technology

faculty.

I would like to thank Mr.Pethum Eranga, Mr.Ajith Priyankara, Ms.Laavanya

Siththapalanadan, laboratory staff and all the members at Serandib Flour Mills (Pvt)

Ltd who helped me to succeed my research.

I deeply appreciate the helps of my friends and colleagues who have not been

mentioned here individually for being my side in making this task a success.

I will be ever grateful for the unconditioned love of my heroic parents for being with

me throughout this research period.

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Table of Contents

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Chapter 1

INTRODUCTION

1. Review of the Literature ............................................................................................ 1

1.1.1 Wheat .................................................................................................................... 2

1.1.2 Types of Wheat ..................................................................................................... 2

1.1.3 Wheat Flour ........................................................ Error! Bookmark not defined.

1.1.3.1 Types of Wheat Flour ................................................................................ 4

1.1.4 Bread ..................................................................................................................... 5

1.1.5 Additives for wheat Flour ..................................................................................... 6

1.1.5.1 Enzymes as an additive .............................................................................. 7

1.1.6 Major Enzymes used in bakery industry and their functionality .......................... 8

1.1.6.1 Amylases .................................................................................................... 8

1.1.6.2 Xylanase ..................................................................................................... 9

1.1.6.3 Glucose Oxidase ...................................................................................... 10

1.1.6.4 Lipase ....................................................................................................... 11

1.1.7 The synergetic effects of enzymes ...................................................................... 11

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1.1.8 Other ingredients in bread making ...................................................................... 12

1.1.8.1 Yeast ........................................................................................................ 12

1.1.8.2 Fat / Shortening ........................................................................................ 13

1.1.8.3 Water ........................................................................................................ 13

1.1.8.4 Salt ........................................................................................................... 14

1.1.8.5 Ascorbic Acid .......................................................................................... 14

1.1.9 Water Absorption ........................................................................ 16

1.1.10 Summary ........................................................................................................... 16

1.2. Objectives ............................................................................................................. 17

1.2.1 Main objective ............................................................................................ 17

1.2.2 Specific objectives ...................................................................................... 17

Chapter2

MATERIALS AND METHADALOGY .................................................................. 18

2.1 Flour ....................................................................................................................... 18

2.2 Enzymes ................................................................................................................. 18

2.3 Ingredients .............................................................................................................. 18

2.4 Analysis of flour samples ....................................................................................... 18

2.4.1 Moisture (ICC no. 110/1) ............................................................................ 19

2.4.2 Protein (kjedal method) ............................................................................... 19

2.4.3 Wet gluten (ICC.13.7; AACC-3812.A) ...................................................... 19

2.4.5 Ash (AACC-8.03) ....................................................................................... 20

2.4.6 Falling number ............................................................................................ 20

2.4.7 Farinograph ................................................................................................. 20

2.4.7 Extensograph (ICC Standard No. 114/1). ................................................... 21

2.6 Methodology .......................................................................................................... 22

2.6.1 Bread making procedure ............................................................................. 24

2.6.2 Loaf volume ........................................................................................................ 25

2.7 Sensory Attributes .................................................................................................. 25

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2.7.1 Sensory Evaluation of bread ............................................................................... 25

vii

Chapter3 ................................................................................................................... 26

RESULTS AND DISSCUSSION

Sensory characteristic .......................................................................................... 36

Chapter 4.................................................................................................................. 37

CONCLUSIONS AND RECOMMENDATION ..................................................... 37

REFERENCES..........38

viii

List of Tables

Table 1.1: Annual wheat consumption patterns04

Table 2.1: Enzymes concentration levels supplemented with flour..21

Table 2.2: Enzyme combination for Bread preparation.23

Table 2.3: Bread formulation.24

Table 3.1: Test results of current bakers flour and chosen proportion of

Hard and medium wheat flour blend26

Table 3.2: Water absorption of flour for each enzyme in different level..27

Table 3.3: Farinograph results....29

Table 3.4: Extensograph results.32

Table 3.5: Amount of wet and dry gluten for each enzyme level..35

Table 3.6: Falling number for each enzyme level and control sample...35

ix

List of Figures

Figure 1.1: Wheat kernel............................................................................ 03

Figure 1.2: The effect of shortening and mono-glycerides on the firming

Rate of Bread . 13

Figure 1.3: Representation of disulphide-sulfhydryl interchange.. 15

x

List of abbreviations

C Degree Celsius

G: O Glucose Oxidase

ppm part per million

cm Centimeter

FU Farinograph unit

BU Brabender unit