Lynne Wong's PhD thesis

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Qin and White (1991) dried well-washed and sieved bagasse at 60 °C in an atmospheric oven for 8 hours and stored it in a desiccator. A weighed amount (8 g) of dry washed fibre was transferred to the cylinder of the hydraulic press (see Fig 4.1) and a weighed mass (24 g to 48 g) of sucrose solution of known Brix was added. The fibre was then compressed by the press causing liquid to appear through the open cylinder. When the hydraulic pressure was released, the fibre stayed as a compressed plug and needed to be released by digging with a small fork. The pressing and forking procedure was then repeated for the required number of pressings. A sample of the final juice was taken with a syringe, filtered and analysed in a refractometer. The same equation as that of Mangion and Player above applies. Qin and White (1991) found significant differences in Brix-free water values for rind fibre, stalk fibre and stalk pith fractions in the test bagasse; they were 11.9, 18.3 and 22.1% respectively when a 5° Brix sucrose solution was used as the contact solution. 4.3 VARIABLES THAT AFFECT BRIX-FREE WATER DETERMINATIONS Factors which affect the Brix-free water values are numerous and have been investigated by various research workers. They are enumerated in the following section. 4.3.1 Concentration of contacting solution Qin and White (1991) found that the Brix-free water of cane fibre decreased as the concentration of the contacting sucrose solution increased. Also the analytical errors decreased because the concentration change became larger. This trend agreed with the observations of Van der Pol et al. (1957) and Kelly and Rutherford (1957), although the absolute values found by Qin and White for sieved bagasse were lower than their values for cane fibres (with higher temperature fibre drying). The values obtained by Kelly and Rutherford varied with the cane variety, with Brix-free water values up to 130% for one cane variety. 4.3.2 Drying temperature of fibre The morphological history of the fibre is reported to have considerable effect on the Brixfree water value. Van der Pol et al. (1957) found a difference of five units in the Brix-free water values for cane dried at 60 °C (over phosphorus pentoxide and under vacuum) compared to the higher value obtained for the same fibre at 125 °C. Drying at 60 °C may 116
leave some residual moisture on the fibres; on the other hand, high temperature drying could have altered the characteristics of the fibre, e.g. activating it. Qin and White (1991) dried the fibres at 60 °C in an atmospheric oven for eight hours. Mangion and Player (1991) vacuum dried the fibres at 80 °C before performing the Brix-free water determination. 4.3.3 Temperature at which Brix-free water is measured Qin and White (1991) changed the temperature of the controlled atmosphere cabinet, and tests carried out at three temperatures with a 5° Brix sucrose solution and at a 4:1 contact solution/fibre ratio showed no trend. 4.3.4 Method of sample preparation Mangion and Player (1991) used three different types of equipment to extract fibre: a wet disintegrator, a Jeffco cutter-grinder and a gyratory-type machine grinder. The fibre obtained from the first two devices looked similar and gave comparable Brix-free water values, while that from the last device looked finer and yielded a higher Brix-free water value by 5 units. They attributed the higher value to an increased sample surface area per unit mass. 4.3.5 Methods of measurement Mangion and Player (1991) also showed that Brix-free water results depend on the analytical techniques used to detect the change in concentration of the contacting solution after mixing with the fibre. They found parallel results on 13 analyses by a refractometric technique gave values two units higher than a polarimetric measurement (22.1% compared to 19.8%). 4.3.6 Cane variety Mangion and Player (1991) carried out 20 analyses each of six cane varieties in the same region, and obtained values ranging from 17.0 to 20.3% Brix-free water. They attributed the variation in results to possible differences in fibre/pith ratios in the samples analysed and errors associated with the Brix measurements. 4.3.7 Pith and rind Qin and White (1991) separated fibre, pith and rind from bagasse samples by sieving and manual selection. Brix-free water results, obtained with a 5° Brix sucrose contacting 117
Page 1 and 2:
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
Page 117 and 118: CHAPTER 3. SEPARATION OF THE SUGAR
Page 119 and 120: Table 3.1. It can be seen that the
Page 121 and 122: Table 3.2. Fibrous physical composi
Page 123 and 124: R 579 R 570 M 1557/70 M 1400/86 74
Page 125 and 126: loosen the fibre. The woody core is
Page 127 and 128: agitate the mixture in the pot, and
Page 129 and 130: 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: solution/fibre ratio was lowered fr
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 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
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4.8 SUMMARY AND CONCLUSIONS An anal
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component parts, and verify the Bri
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3) Thermodynamic, water in equilibr
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Langmuir (1916, 1917, 1918) propose
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to determine the moisture sorption
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Table 5.1. Some commonly used isoth
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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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Page 273 and 274:
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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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