Lynne Wong's PhD thesis

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shoots and tops, which contain a lot of melassigenic non-sugars, retaining more sucrose in the molasses. 1.5.3.4 Sugar quality Dry leaves will produce more colour initially in juice and eventually in sugar. Deterioration in sugar quality has been noted in recent years with respect to the decreasing raw sugar filterability, which is attributable to suspended solids from soil brought to the factories (Lee and Donovan, 1996). 1.6 OBJECTIVES OF THIS STUDY The objectives of this study were to devise experiments to quantify the effect of extraneous matter on cane, bagasse and juice quality and its impact on milling performance; to develop methods to separate the sugar cane plant into fibres of its various components; and to study certain chemical properties such as the water adsorbing power and adsorption isotherms of these separated fibres in order to explain some of the effects observed when extraneous matter especially trash is added to cane. 27
CHAPTER 2. IMPACT OF EXTRANEOUS MATTER ON CANE JUICE QUALITY AND MILLING PERFORMANCE, AND THE PHENOMENON OF BRIX-FREE WATER IN DRY LEAF With the increasing trend in mechanised loading of cane which started in Mauritius in the mid-1970s, more extraneous matter (EM) is now being sent with the cane to the mills. Extraneous matter in cane consists of dry and green leaves, immature cane tops, roots, dead stems, soil and any other non-cane material, all of which increase the costs of harvest and transport, as well as the cost of mill maintenance. Extraneous matter in cane may also necessitate investment in new equipment to cope with the increased crushing and milling capacity of the factory (Wong Sak Hoi and Autrey, 1997). It also lengthens the crushing season. It is therefore essential to investigate and quantify the effects of certain kinds of extraneous matter, in particular, dry leaves, green leaves and tops on cane and juice quality, on milling operations and on sugar recovery. As already mentioned in Section 1.3, the use of the term trash or dry trash will be used to refer to the dry leaves associated with cane stalks. In this chapter, experiments performed to study the effect of the controlled addition of extraneous matter to clean cane will be described and discussed. 2.1 EFFECT OF EXTRANEOUS MATTER ON CANE JUICE QUALITY AND MILLING PERFORMANCE In the present study, the effects of dry trash, green leaves and immature cane tops were investigated by adding each type of EM to sub-samples of clean cane so that it constitutes 5, 10 and 20% of the total mass, and applying maceration water at 33% on cane to obtain “mixed juice”, since the average maceration water used on cane in all Mauritian sugar factories in 2000 was 33.3% (Anon., 2001b). The extracted “mixed juice” samples were analysed, in particular, for fructose (F), glucose (G) and sulfated ash (Ash), to predict the sucrose loss in molasses by means of the target purity (TP) of molasses by using the South African equation (Rein and Smith, 1981):
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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
Page 23 and 24: Figure 3.1. Glucose and fructose an
Page 25 and 26: Figure 5.11. Residual plots for the
Page 27 and 28: total adsorbed water (m) and the pr
Page 29 and 30: Table 2.18. Moisture content in sug
Page 31 and 32: Page Table 4.4. Results of the dete
Page 33 and 34: Page Table 4.24. Analysis of varian
Page 35 and 36: Page Table 5.13. Table 5.14. Equili
Page 37 and 38: Table 6.3. Heat of sorption of the
Page 39 and 40: GLOSSARY OF TERMS Absorption is the
Page 41 and 42: Filterability of a raw sugar is mea
Page 43 and 44: Sorption is the generic term used w
Page 45 and 46: LIST OF MAIN SYMBOLS Symbol Descrip
Page 47 and 48: s c s Slope of Caurie I isotherm pl
Page 49 and 50: number of 255, and cane land covere
Page 51 and 52: Nouvelle Mon In Trésor ustrie and
Page 53 and 54: Figure 1.3. Cane sampling by core s
Page 55 and 56: In Mauritius, most of the sugar fac
Page 57 and 58: are: cane tops, dry and green leave
Page 59 and 60: 1.4 TRENDS IN CANE QUALITY RECEIVED
Page 61 and 62: campaign was launched to encourage
Page 63 and 64: The level of extraneous matter in c
Page 65 and 66: In Australia (Cargill, 1976), cane
Page 67 and 68: The effect of soil on factory perfo
Page 69 and 70: leaves increased the level of impur
Page 71 and 72: • From 1976 to 1980, when the pro
Page 73: Clerget purity of molasses 40 Clerg
Page 77 and 78: Since the extrapolated purity of mo
Page 79 and 80: Figure 2.1. Jeffco cutter grinder.
Page 81 and 82: 2.1.4 Results The analytical result
Page 83 and 84: Table 2.3. Analytical results of re
Page 85 and 86: Table 2.5. Composition of dry trash
Page 87 and 88: Table 2.7. Predicted factory perfor
Page 89 and 90: Boiling house recovery 91.0 89.8 89
Page 91 and 92: 0 5 10 15 20 % EM in cane y = 0.572
Page 93 and 94: % EM in cane 0 5 10 15 20 0 -2 -4 -
Page 95 and 96: 1 y = 0.020 (% D) R 2 = 1.00 = 0.03
Page 97 and 98: % EM in cane 0 5 10 15 20 0 -2 y =
Page 99 and 100: esulting in 0.015 unit sucrose loss
Page 101 and 102: 2.2.1 Experimental procedure Cane m
Page 103 and 104: filter paper, rejecting the first f
Page 105 and 106: Table 2.9. Effect of increased addi
Page 107 and 108: Table 2.11. Effect of increased add
Page 109 and 110: Table 2.13. Effect of increased add
Page 111 and 112: various components such as stalk fi
Page 113 and 114: in the presence of dry leaves, if c
Page 115 and 116: 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
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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
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Table 3.5. Masses of cane samples a
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Table 3.7. Masses of cane samples a
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Table 3.9. Masses of cane component
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3 57.6 126.3 23.7 97.2 31.1 53.8 11
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Table 3.12. Material loss (%) from
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3.5.3 Fibre/pith ratios in cane com
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Table 3.15. Effect of extraneous ma
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Snow (1974) investigated the season
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from Figure 2.9 that the change in
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Table 3.18. Fibre % cane results by
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110
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(a). Dry leaf (b). Green leaf (c).
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dry fibre, or a factor, is used in
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Steuerwald (1912) applied sucrose s
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solution/fibre ratio was lowered fr
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leave some residual moisture on the
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instead of 150 g of 10° Brix sucro
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Table 4.2. Determination of Brix-fr
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Table 4.3. Comparison of Brix-free
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Table 4.4. Results of the determina
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In order to test for homogeneity of
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Table 4.7. Results of the repeat de
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The experiment was repeated with th
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e any residual moisture in the samp
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By means of the same technique, Won
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was still hot. Since the filter was
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value determined could be corrected
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Qin and White’s finding was confi
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A sample size of 3.5 g with 75 g co
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Figure 4.4. Fibre samples drying in
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- One large fibre sample (rind) of
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Table 4.18. Brix-free water values/
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Table 4.20. Brix-free water values/
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4.7.3 Statistical analysis It is es
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Table 4.23. Analysis of variance (B
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pointing out that at 52 weeks old,
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The crop of R 570 sampled in 2001 w
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4.7.4. Estimated Brix-free water co
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The main difference in the two sets
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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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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
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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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