Lynne Wong's PhD thesis

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Table 4.8. Brix-free water results for fibre samples which had either been vacuum or air dried for varying lengths of time prior to analysis. Sample Vacuum oven drying Brix-free water/% Sample Air oven drying Brix-free water/% Temperature/ o C Duration/h Temperature/ o C Duration/h Green leaf fibre 65 2 12.95 Rind fibre 65 1 9.90 Green leaf fibre 65 4 14.20 Rind fibre 65 4 11.86 Green leaf fibre 65 6 13.51 Rind fibre 65 6 11.93 Green leaf fibre 65 16 16.85 Rind fibre 65 15 13.56 Rind fibre 65 21 13.85 Green leaf fibre 80 3 17.42 Rind fibre 105 1 15.75 Green leaf fibre 80 4 17.33 Rind fibre 105 3 15.56 Green leaf fibre 80 5 16.83 Rind fibre 105 6 17.01 Green leaf fibre 80 7 17.87 Rind fibre 105 14 16.82 Green leaf fibre 80 16 15.73 Rind fibre 105 20 17.37 130
The experiment was repeated with the remaining sub-samples after drying at 80 °C in a vacuum oven under 875 mbar vacuum for 3, 4, 5, 7 and 16 hours. Results obtained (Table 4.8) after vacuum drying at 80 °C for 3, 4, 5 and 7 hours are all comparable to those obtained after drying overnight for 16 hours at 65 °C (average of 17.4% c.f 16.9%). However, after overnight drying at 80 °C, the Brix-free water value obtained was much lower at 15.7%. Air-oven drying was tried on subsamples of a rind fibre at 65 °C and 105 °C for various lengths of time up to 21 hours. Results (Table 4.8) show that 65 °C was insufficient to dry the samples even after 21 hours whereas 105 °C yielded the highest Brix-free value of the sample after 6-20 hours. This means that at 105 °C after 6-20 hours, the Brix-free water originally in the sample has been completely driven out of the sample, enabling ‘new’ water to be adsorbed during analysis and determined as Brix-free water. However, it would be unwise to adopt this drying method prior to analysis, since many workers have warned against the use of high temperatures, notably Kollmann and Schneider (1963) who indicated that elevated temperatures reduce timber water adsorption capacity. From the data in Table 4.8, it was evident that after one hour of drying at 65 °C, the Brixfree water result of 9.9% represented more than half of the maximum value of 17.37% achieved after 20 hours of drying at 105 °C. Hence it was thought reasonable to use one hour air-oven drying at 65 °C prior to vacuum drying to boost the drying process. Results for one hour air-oven drying at 65 °C followed by 65 °C or 80 °C vacuum-oven drying for various lengths of time are shown in Table 4.9. It appears that more consistent results are obtained after air-oven drying at 65 °C for one hour followed by overnight vacuum-oven drying for 16 hours at 65 °C under 875 mbar vacuum. (See also Section 4.4.6.). 4.4.6 Residual moisture in fibre samples prior to Brix-free water determination The Brix-free water values obtained for certain sugar cane component parts were in general lower than those obtained by Mangion and Player (1991), for example, 13 – 15% both for cane top and dry leaf fibres compared to those of Mangion and Player of 23 – 24% for cane top and 20 – 21% for dry leaf. It was therefore thought opportune to check the remaining moisture content of fibres after the method of vacuum oven drying at 65 °C for 16 hours under 875 mbar vacuum prior to the Brix-free water determination. Should there 131
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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
Page 131 and 132: The extraction of fibres starting f
Page 133 and 134: pre-treatment in a Jeffco cutter-gr
Page 135 and 136: Figure 3.19. Stalk cake washed free
Page 137 and 138: 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: Table 4.7. Results of the repeat de
Page 185 and 186: e any residual moisture in the samp
Page 187 and 188: By means of the same technique, Won
Page 189 and 190: was still hot. Since the filter was
Page 191 and 192: value determined could be corrected
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
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and on agricultural products such a
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Bruijn (1963) studied the mass incr
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After measuring the EMC of dry corn
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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
Page 349 and 350:
Madamba P.S., R.H. Driscoll and K.A
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Prinsen Geerligs, H.C. (1897). Stud
Page 353 and 354:
Sing K.S.W., D.H. Everett, R.A.W. H
Page 355 and 356:
Van der Pol C., C.M. Young and K. D
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Lynne Wong's PhD thesis

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