PAGE

Title Page i

Certification ii

Acknowledgements iv

Abstract v

Table of Contents vi

List of Figures ix

Chapter ONE

11 Introduction 1

12 Biology of Cassava and Maize 2

121 Cassava 2

122 Maize 6

13 Starch 8

131 Starch properties 8

132 Test for starch 10

133 Cassava starch 11

134 Starch synthesis 12

135 General biosynthesis of polysaccharides 12

136 Biosynthesis of a glycosidic bond 14

137 Structural alterations to sugar nucleotide before polysaccharide assembly 16

138 Starch hydrolysis (degradation) 17

139 Acid hydrolysis 17

1310 Enzyme hydrolysis of starch 19

14 Amylases 19

141 General properties of amylases 19

142 Sources of amylases 20

143 Plant amylases 20

144 Amylases production in germinating cereals 21

145 Maize amylases 22

15 Aims and objectives of research 23

Chapter TWO

21 Materials 24

211 Sample collection and location(s) 24

2111 Cassava varieties 24

2112 Maize varieties 24

212 Chemicals/Reagents/Samples 25

213 Apparatus 26

22 Methods 26

221 Preparation of buffers 26

222 Extraction of cassava starch 27

223 Glucose calibration curve 27

224 Enzyme extraction 27

225 Method of enzyme assay 27

226 Effect of germination on maize amylase activity 27

227 Effect of pH on maize amylase activity 28

228 Germination of maize 28

229 Determination of activity in 20 varieties of hydrid maize 28

2210 Assay of amylase activity in maize 28

2211 Effect of Ca

2+

ions on amylase activity 29

2212 Determination of protein concentration in all enzyme extracts 29

2213 Protein determination 29

2214 Maize amylase specific activity 30

2215 Activity of maize amylase on cassava starch 30

2216 Effect of pH on amylase activity using cassava starch as substrate 30

2217 Effect of substrate concentration on enzyme activity 30

23 Statistical Analysis 31

Chapter THREE

31 Effect of germination on amylase activity 32

32 Effect of pH on amylase activity 32

33 Amylase activity before imbibition at pH 55, 75 and 95 33

34 Amylase activity on day 3 after imbibition at pH 55, 75 and 95 34

35 Amylase activity on day 5 after imbibition at pH 55, 75 and 95 35

36 Protein determination 39

37 Maize amylase specific activity 41

38 Determination of maize variety with the highest amylase activity 45

39 Hydrolysis of cassava starch by enzyme extract from VARIF2 45

310 Effect of Ca

2+

on enzyme activity 45

311 Effect of substrate (starch) concentration on maize enzyme activity 45

312 Effect of pH on amylase activity using 1% cassava starch 46

Chapter FOUR

41 DISCUSSION 50

42 CONCLUSION 55

REFERENCES 57

APPENDICES 62