Lynne Wong's PhD thesis

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Table 4.11. Comparison of moisture determination in fibre samples by halogen thermogravimetry and the standard drying method. Sample Moisture/% Halogen Oven Halogen Oven Halogen Oven Halogen Oven Halogen Oven Mean halogen Mean oven Stalk fibre 3.68 1.79 4.31 2.51 3.35 2.71 3.07 3.27 4.19 2.45 3.72 2.55 Stalk pith 2.76 3.58 2.52 1.92 2.26 3.42 2.15 2.10 2.45 2.13 2.43 2.63 Rind fibre 2.00 3.05 2.39 2.90 2.65 2.40 2.05 2.28 2.22 2.18 2.26 2.56 Rind fines 2.46 2.55 2.12 1.83 2.12 2.58 1.79 1.11 1.88 1.02 2.07 1.82 Top 3.79 3.18 2.79 3.03 3.70 3.03 3.34 3.57 3.10 1.59 3.34 2.88 Dry leaf fibre 2.55 2.86 2.62 3.21 2.18 2.72 2.43 2.90 2.34 1.47 2.42 2.63 Dry leaf fines 2.29 2.04 2.08 2.12 1.57 2.92 1.56 1.29 2.06 2.05 1.91 2.08 Green leaf fibre 3.10 2.13 2.00 1.93 2.44 1.99 2.34 2.47 2.18 2.45 2.41 2.19 Green leaf fines 2.09 1.88 1.70 1.92 1.57 1.66 1.58 1.58 1.68 2.62 1.72 1.93 2.48 2.36 138
value determined could be corrected for the residual moisture after the vacuum drying procedure. 4.4.7 Concentration of the contact solution By varying the concentration of the contact solution from 5 to 10 and 15° Brix sucrose solution, it was found that the Brix-free water in a rind fibre and stalk pith varied with a change in sucrose concentration (Table 4.12), and to increase with increased concentration of sucrose solution (Table 4.13) in a later experiment with a stalk fibre and a rind fibre. This is in contradiction to the findings of Qin and White (1991), Van der Pol et al. (1957) and Kelly and Rutherford (1957), who found that the Brix-free water values decreased as the concentration of the contact solution increased. With a 5° Brix sucrose solution, the increase in Brix after contacting would be smaller than 0.1 unit and hence difficult to detect, whereas with a 15° Brix solution, the stability of the sucrose would be doubtful after the long procedure of determination. It was therefore decided to adopt a 10° Brix sucrose solution as the contact solution, since it was also adopted by Mangion and Player (1991). 4.4.8 Ratio of the contact solution to sample size In this experiment, a 10° Brix sucrose solution was used and four samples were examined: two rind fibres and two stalk piths. The ratio of contact solution to sample mass was varied from 25 to 10. At a high ratio, e.g. 25, the errors became large as the increase in Brix after equilibration was less than 0.1 unit, and at a low ratio, e.g. 15, the volume of the solution obtained from pith samples after equilibration was not sufficient for the Brix determination. At a ratio of 5, pith samples were not completely wetted. It was therefore found that a ratio of 20 was most appropriate. The higher surface area of stalk pith as shown by scanning electron microscopy (Fig 3.24f) may explain its higher liquid absorption than sample of other cane components. Two samples showed a decrease in Brix-free water with decrease in the ratio of contact solution/sample, while one stalk pith showed the opposite (Table 4.14). Qin and White (1991) with their press cell method, however, found that this ratio does not affect the Brixfree water results, although the errors become larger at the higher juice/fibre ratios. 139
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THE BRIX-FREE WATER CAPACITY AND SO
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dissolved and hydrated waters, and
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ACKNOWLEDGEMENTS I am particularly
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Page 1.5 THE DELETERIOUS EFFECTS OF
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Page 2.2 THE PHENOMENON OF BRIX-FRE
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Page 3.4.3.3 Cane tops 83 3.4.4 Cha
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4.3.3 Temperature at which Brix-fre
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4.6.1 Materials 143 4.6.1.1 Samples
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CHAPTER 6. PROPERTIES OF THE SORBED
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APPENDIX 3. CALCULATIONS LEADING TO
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LIST OF FIGURES Page Figure 1.1. Fi
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Figure 3.1. Glucose and fructose an
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Figure 5.11. Residual plots for the
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total adsorbed water (m) and the pr
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Table 2.18. Moisture content in sug
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Page Table 4.4. Results of the dete
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Page Table 4.24. Analysis of varian
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Page Table 5.13. Table 5.14. Equili
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Table 6.3. Heat of sorption of the
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GLOSSARY OF TERMS Absorption is the
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Filterability of a raw sugar is mea
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Sorption is the generic term used w
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LIST OF MAIN SYMBOLS Symbol Descrip
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s c s Slope of Caurie I isotherm pl
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number of 255, and cane land covere
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Nouvelle Mon In Trésor ustrie and
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Figure 1.3. Cane sampling by core s
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In Mauritius, most of the sugar fac
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are: cane tops, dry and green leave
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1.4 TRENDS IN CANE QUALITY RECEIVED
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campaign was launched to encourage
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The level of extraneous matter in c
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In Australia (Cargill, 1976), cane
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The effect of soil on factory perfo
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leaves increased the level of impur
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• From 1976 to 1980, when the pro
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Clerget purity of molasses 40 Clerg
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CHAPTER 2. IMPACT OF EXTRANEOUS MAT
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Since the extrapolated purity of mo
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Figure 2.1. Jeffco cutter grinder.
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2.1.4 Results The analytical result
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Table 2.3. Analytical results of re
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Table 2.5. Composition of dry trash
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Table 2.7. Predicted factory perfor
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Boiling house recovery 91.0 89.8 89
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0 5 10 15 20 % EM in cane y = 0.572
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% EM in cane 0 5 10 15 20 0 -2 -4 -
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1 y = 0.020 (% D) R 2 = 1.00 = 0.03
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% EM in cane 0 5 10 15 20 0 -2 y =
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esulting in 0.015 unit sucrose loss
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2.2.1 Experimental procedure Cane m
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filter paper, rejecting the first f
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Table 2.9. Effect of increased addi
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Table 2.11. Effect of increased add
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Table 2.13. Effect of increased add
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various components such as stalk fi
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in the presence of dry leaves, if c
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Table 2.17. Moisture content in sug
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CHAPTER 3. SEPARATION OF THE SUGAR
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Table 3.1. It can be seen that the
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Table 3.2. Fibrous physical composi
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R 579 R 570 M 1557/70 M 1400/86 74
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loosen the fibre. The woody core is
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agitate the mixture in the pot, and
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Figure 3.7. Custom-built fibre-pith
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The extraction of fibres starting f
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pre-treatment in a Jeffco cutter-gr
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Figure 3.19. Stalk cake washed free
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not have many dry leaves attached t
Page 139 and 140: Table 3.5. Masses of cane samples a
Page 141 and 142: Table 3.7. Masses of cane samples a
Page 143 and 144: Table 3.9. Masses of cane component
Page 145 and 146: 3 57.6 126.3 23.7 97.2 31.1 53.8 11
Page 147 and 148: Table 3.12. Material loss (%) from
Page 149 and 150: 3.5.3 Fibre/pith ratios in cane com
Page 151 and 152: Table 3.15. Effect of extraneous ma
Page 153 and 154: Snow (1974) investigated the season
Page 155 and 156: from Figure 2.9 that the change in
Page 157 and 158: Table 3.18. Fibre % cane results by
Page 159 and 160: 110
Page 161 and 162: (a). Dry leaf (b). Green leaf (c).
Page 163 and 164: dry fibre, or a factor, is used in
Page 165 and 166: Steuerwald (1912) applied sucrose s
Page 167 and 168: solution/fibre ratio was lowered fr
Page 169 and 170: leave some residual moisture on the
Page 171 and 172: instead of 150 g of 10° Brix sucro
Page 173 and 174: Table 4.2. Determination of Brix-fr
Page 175 and 176: Table 4.3. Comparison of Brix-free
Page 177 and 178: Table 4.4. Results of the determina
Page 179 and 180: In order to test for homogeneity of
Page 181 and 182: Table 4.7. Results of the repeat de
Page 183 and 184: The experiment was repeated with th
Page 185 and 186: e any residual moisture in the samp
Page 187 and 188: By means of the same technique, Won
Page 189: was still hot. Since the filter was
Page 193 and 194: Qin and White’s finding was confi
Page 195 and 196: A sample size of 3.5 g with 75 g co
Page 197 and 198: Figure 4.4. Fibre samples drying in
Page 199 and 200: - One large fibre sample (rind) of
Page 201 and 202: Table 4.18. Brix-free water values/
Page 203 and 204: Table 4.20. Brix-free water values/
Page 205 and 206: 4.7.3 Statistical analysis It is es
Page 207 and 208: Table 4.23. Analysis of variance (B
Page 209 and 210: pointing out that at 52 weeks old,
Page 211 and 212: The crop of R 570 sampled in 2001 w
Page 213 and 214: 4.7.4. Estimated Brix-free water co
Page 215 and 216: The main difference in the two sets
Page 217 and 218: Table 4.27. Predicted Brix-free wat
Page 219 and 220: 4.8 SUMMARY AND CONCLUSIONS An anal
Page 221 and 222: component parts, and verify the Bri
Page 223 and 224: 3) Thermodynamic, water in equilibr
Page 225 and 226: Langmuir (1916, 1917, 1918) propose
Page 227 and 228: to determine the moisture sorption
Page 229 and 230: Table 5.1. Some commonly used isoth
Page 231 and 232: Lomauro et al. (1985) found that wi
Page 233 and 234: and on agricultural products such a
Page 235 and 236: Bruijn (1963) studied the mass incr
Page 237 and 238: After measuring the EMC of dry corn
Page 239 and 240: approached, that is, either by adso
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Table 5.4. Water activity (a w ) of
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5.6.3 Procedure to determine equili
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5.6.4 Results and discussion An exa
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Table 5.8. Equilibrium moisture con
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Table 5.10. Equilibrium moisture co
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Table 5.12. Equilibrium moisture co
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30 o C 45 o C 55 o C 60 o C Water w
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m/m of 96% activity, a w (g/100g dr
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vaporisation generally decreases fr
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30 o C isotherm 45 o C isotherm 55
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4 0 Stalk fibre 5 0 Stalk pith 5 0
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5.6.4.4 Fitting of sorption models
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Table 5.19. Parameters of the sorpt
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Modified GAB Kuhn Iglesias - Chirif
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Table 5.28. Classification of resid
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Stalk fibre Stalk pith Rind fibre 4
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5.6.4.5 Calculated EMC values of re
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Table 5.30. Calculated equilibrium
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m/m of 96% Table 5.32. Calculated e
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Table 5.33. Parameters of the Hailw
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CHAPTER 6. PROPERTIES OF THE SORBED
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where m is the equilibrium moisture
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6.2 THE NUMBER OF ADSORBED MONOLAYE
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6.3 TOTAL SOLID SURFACE AREA AVAILA
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Thus, for each cane component of ea
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abscissa. For each moisture level (
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A similar procedure was followed to
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10 0 Stalk fibre Stalk pith Rind fi
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Moreover, if T β > T hm the proces
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Table 6.5. Characteristic parameter
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Binding energy/kJ (kg mol) -1 2 0 0
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6.8 CALCULATION OF BOUND WATER AND
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The values of K 1 , K 2 and W were
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Table 6.7. Separation of the total
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Table 6.7. (Contd.) Sample 30 o C 4
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3 0 S talk fibre 4 0 Stalk pith 3 0
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3 0 Reconstituted cane at 30 o C 3
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when water is added to dry wood, wh
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It is evident that in some cases ma
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The number of adsorbed monolayers,
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Data in Tables 2.9 and 2.11 show th
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particular fibre is systematically
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Anon. (1985b). Laboratory manual fo
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Blanchi R.H. and A.G. Keller (1952)
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Day D.L. and G.L. Nelson (1965). De
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Heyrovsky J. (1970). Determination
Page 347 and 348:
Kuhn I.J. (1964). A new theoretical
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Madamba P.S., R.H. Driscoll and K.A
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Prinsen Geerligs, H.C. (1897). Stud
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Sing K.S.W., D.H. Everett, R.A.W. H
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Van der Pol C., C.M. Young and K. D
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Lynne Wong's PhD thesis

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