Kornvalai Panpae 2

8/19/2019 Kornvalai Panpae 2

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The Malaysian Journal of Analytical Sciences, Vol 12, No 3 (2008): 513 - 519

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MINIMIZATION OF SUCROSE LOSSES IN SUGAR INDUSTRY BY pHAND TEMPERATURE OPTIMIZATION

Kornvalai Panpae1*, Wasna Jaturonrusmee1, Withawat Mingvanish1 , Chantana Nuntiwattanawong2, Surapon

Chunwiset 2

, Kittisak Santudrob1

and Siriphan Triphanpitak1

1 Department of Chemistry , Faculty of Science , King’s Mongkut’s

University of Technology Thonburi, Bangkok 10140, Thailand2Chaimongkol Refined Sugar Company, Limited.( U-Thong Factory ),

Supanburi Province 72160, Thailand

* Corresponding author: [email protected]

AbstractInvert sugar has several disadvantage properties that play an important role in many food applications. It has a high affinityfor water and is the cause of making products retain moisture.Invert sugar also affects the caramelization process , producinga browning effect. In this study, the possibility of minimization of sucrose inversion during the industrial production ofsugar cane was investigated by the variation of the important parameters, i.e. temperature and pH of sugar cane juice foreach of samples. The amounts of sucrose and reducing sugar alerting during the sucrose inversion process were determinedby the values of % Pol and % reducing sugar (% RS), respectively. Starting with the study of temperature and pH effects ofthe sucrose solution with the concentration of 16 Brix, used as a sample model, it was found that no change in amounts ofreducing sugar and sucrose was observed at room temperature (34oC) in the pH range of 5-11.

At pH 3, the amounts of reducing sugar increased and the amount of sucrose decreased as the time increased. Theseindicated that the process of sucrose inversion should better occur in more acidic solutions. Compared to the roomtemperature, it was found that the increment of temperature led to enhance the process of sucrose inversion. This wasdepicted by higher values of %RS and lower value of % Pol as the temperatures were elevated. The experiments were alsodone with real sugar cane juice, i.e. first, last, and mixed juice. The tendency of changes of the amounts of reducing sugarand sucrose in sugar cane samples by varying temperature and pH were found to resemble to those for the sample model.The increment of temperatures have also affected on a reduction of amounts of sucrose in each sugar cane juice. In addition,it could be concluded that the acidity of the solution affects sucrose easier to be broken down to glucose and fructosemolecules.

Keywords : Sugar industry , Sugar cane juice , Sucrose inversion , Reducing sugar,Inverted sucrose

IntroductionIndustrial processes aim at maximizing their production capacities while simultaneously improving the productquality and reducing operating costs. Usually, there exists a trade off between these requirements. This isparticularly true in the production of high quality sugar from sugar cane crushing factory where highproductivity at minimizing invert sugar is the most important issue. Sugar cane must be crushed to extract the juice. The crushing process must break up the hard nodes off the cane and flatten the stems. The juice iscollected, filtered and sometimes treated and then boiled to drive off the excess water. In the process of juicetreatment, juice should be filtered through a cloth before boiling in order to remove any solids such as dirt orparticles of cane. The juice is neutralized with lime (Ca(OH)2) and then is boiled. After removal from the heat,

the pans of juice are usually stirred rapidly to incorporate air and promote an even crystallization. For thosewith access to simple sugar measuring devices, this usually corresponds to a Brix (sugar content) of 90-95%.The schematic representating process of sugar production is shown in Figure 1.

Monitoring of total reducing sugar (reducing sugars plus hydrolyzed sucrose (Alves et al., 2006)) is veryimportant in relation to the sugar cane agro-industry, as it may provide information for evaluation of the rawmatter and for quality control of the sugar manufacturing process. The inversion reaction is shown in Figure 2.Invert sugar syrup, an equimolecular mixture of glucose and fructose, is a valuable sweetener and is require bythe food and pharmaceutical industries. High fructose syrups are in great demand as food and soft drinksweeteners. However, inversion of sucrose, an irreversible reaction, and thus the reaction rate is not influencedby the product accumulation, is, therefore, a major problem on sucrose losses, across unit processes in the sugarindustry.


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Kornvalai Panpae et al: MINIMIZATION OF SUCROSE LOSSES IN SUGAR INDUSTRY BY pH ANDTEMPERATURE OPTIMIZATION

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Figure 1 The process diagram of sugar production.

Fig. 1: The process diagram of sugar production.

Fig. 2: The inversion of sucrose.

In the sugar refinery, determination of reducing sugars commonly relies on the Lane-Eynon titration or on theSomogyi-Nelson spectrophotomatric procedure, both relying on sugar oxidation by Cu2+ ion (Alves et al.,2006). There are a number of publications focusing on the determination and/or preventation of “sucroseinversion” (Khan and Rahman, 1996 ; Wienen and Shalleuberger, 1988 ; Eggleston et al.,2002 ; Eggleston andMonge, 2005 : Alves et al.,2006) as well as using enzymatic reactions (Almeida et al.,2005 ; Kurup et al.,2005).

However, most of the investigations are based on single objective optimization, incorporating several objectives


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with some weight factor. Single objective function optimization approach is not efficient and also has thedrawback of possibly losing certain optimal solution. Sometimes it is very difficult to ensure for more complex,real-life problems.

In this study, an attempt has been made to establish the optimum conditions to reduce invert sugar of sugar cane

juice in U-Thong Sugar Industry Factory by optimizing pH and temperature compared with pure cane sugar.

Materials and Methods

MaterialsMixed juice, limed juice and clear juice samples were obtained from an industrial sugar cane process line. Theexperiments were performed at the factory laboratory. Mixed juice was the first crushed juice mixed with juicefrom 4 crushings without chemical was added. Limed juice was the mixed juice which pH adjusted to neutral bylime. Other chemical : dry lead subacetate (Pb(CH3COO)2Pb(OH)2) ; Analytical grade, pure cane sugar(sucrose, C12H22O11); Analytical grade and methylene blue indicator solution C16H18N3SCl.2H2O) were obtainedfrom Asia Pacific Specialty Chemicals Co. Copper sulfate (CuSO4.5H2O) ; Analytical grade and Rochelle salt,sodium potassium tartate (COOK(CHOH)2COONa.4H2O) ; analytical grade were purchased from AjaxChemical Co.

ApparatusA polarimeter with sodium-vapor lamp, thermostat and circulating pump was use to determine % Pol of thesamples. The mean Brix of triplicate samples was measured using a Leica Abbe Mark II refractometer with acrosshair reticule. Brix is total dissolved solid in juice solution. The concentration (C) of sucrose in solution(g/100cm3) can be obtained by measuring brix of solution and value of C from “Table of brix and grammes ofsucrose per 100 cm3 of sugar solutions” of Bureau of Sugar Experiment Stations (1970).

Methods The pH of standard sucrose solution (16 Brix) and raw juice samples (pH 5.53) were adjusted from 3.0 to 11.0with 10% HNO3 and 20% lime solution at the same temperature. The thermal stability of standard sucrose wasstudied by heating and stirring at 34 (room temperature), 60, 70, 80 and 90 °C. For the juice, it was heated to 80°C only.

Quality evaluationAfter the experiments, the standard sucrose and the juice samples were characterized base on their Brix, % Pol,% RS (reducing sugar), TSS (total suspended solid) and TDS (total dissolved solid). All experiments wererepeated three times and the average value were used.

Results and Discussion

Analytical data of non-pH and temperature controlled sugar cane juicePhysical and Chemical characteristics of the non-pH and temperature controlled juice are presented in Table 1.

Table 1: Analytical data of mixed, lime and clear juice samples

Technical data mixed juice lime juice clear juice (mgL-1)

TS 86.36 270.04 131.01TSS 10.45 4.60 1.48TDS 64.26 280.04 104.46

After neutralization, TS and TDS values of lime juice were rather high since adding lime, for neutralization,increases in total solids in sugar cane solution.


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Effects of pH and temperature on the cane sugar (concentration 16 Brix)% RS and % Pol of the standard sucrose was studied at various pH (3.0, 5.0, 7.0 and 11.0) and temperatures at34, 60, 70, 80 and 90 °C. The selected results (at temperature 30, 70 and 80 °C) are shown in Figure 3-8.

Fig. 3: % RS of standard sucrose at 34 °C Fig. 4: % Pol of standard sucrose at 34 °C

Fig. 5: % RS of standard sucrose at 70oC Fig. 6: % Pol of standard sucrose at 70 °C

Fig. 7: % RS of standard sucrose at 80 °C Fig. 8: % Pol of standard sucrose at 80 °C

time (hours)

time (hours) time (hours)

time (hours)time (hours)

time (hours)


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Sucrose is dextrorotatory, but the resulting mixture of glucose and fructose is slightly levorotatory, because thelevorotatory fructose has s greater molar rotation than the dextrorotatory glucose. As the sucrose is used up andthe glucose-fructose mixture is formed, the angle of rotation to the right (as the observer looks into thepolarimeter tube) becomes less and less, and finally the light is rotated to the left (Scheme 1).

Scheme 1

At the temperature of higher 80 °C, it was found that the caramelization occurred to a significant extent as thethermal degradation of sugars. Under heat, caramelization transforms sugars from colourless, sweet compoundsinto substances ranging in brown colour.

pH effects on the sucrose inversion of mixed juice Table 2 shows analytical data of mixed juice at 34 (room temperature) and 70 °C and pH at5.35 (non-pH controlled), 6.0, 7.0 and 8.0

Table 2: Analytical data of pH and temperature controlled mixed juice.

pH 5.35 6.0 7.0 8.0data 34oC 70oC 34oC 70oC 34oC 70oC 34oC 70oC% RSBrixPol% Brix% Pol%Pur

1.3915.1747.9015.1711.7577.44

1.8717.3755.6317.3713.5377.89

1.3515.4848.2015.4811.8176.27

1.5616.7854.3216.7813.2478.91

1.5215.2448.1815.2411.8177.52

1.5616.8053.6216.8013.0777.79

1.3515.1148.6115.1111.9378.92

2.2416.2753.3416.2713.0380.07

Data based on three replications.

Temperature effects on the sucrose inversion of sugar cane juiceThermal stability of sucrose, measured in % RS and % Pol, was summarized in Table 3. It is found that thepercentage of inversion of % RS and % Pol values at 80 °C were significant extent, especially for the last juicein the time period of 40 min. Increasing solid content resulted in lower % Pol during heating at 80 °C. Allof the juice are more susceptible to temperature elevation during heating than during storage at roomtemperature.


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Table 3: Effect of temperature on % inversion of RS and Pol of first, last and mixed juice Samples

temperature 34oC 80oCsample data 20 min 40 min 20 min 40 min

first juice % RS 9.76 8.64 - 9.80% Pol 0.72 12.90 6.98 -62.96

last juice % RS 15.33 23.03 14.72 25.30% Pol -0.37 -1.29 6.77 11.12

mixed juice % RS 0.56 4.92 5.59 17.39% Pol 0.08 0.13 9.11 21.80

ConclusionThe measurement of sucrose inversion across unit processes in the sugar industry is notoriously difficult andhas meant that very limited diagnosis of process problems contributing to sucrose losses has occurred. Sucroseconcentrations are traditionally measured at the factory using polarization or optical rotation puritymeasurements. Results from this study showed that sucrose inversion in various sugar cane juice samplesstrongly depended on pH, temperature and also solid content. Increasing solid content (lime juice) , pH andtemperature during both heating and storage at room temperature, increased the rate of sucrose inversion. Thetendency of changes of the amounts of reducing sugar and sucrose in sugar cane samples by varyingtemperature and pH were found to resemble to those for the sample model. To minimize the total reducingsugar, we recommended that temperature was a critical factor controlling sucrose inversion whereas the anion(OH - from lime) at the higher pH had a slightly influence on physical and chemical properties of the juicecompared to the high stability and purity of pure cane sugar.

AcknowledgementsThis research was supported by Industrial Cooperative Learning Research, Faculty of Science, King Mongkut’sUniversity of Technology Thonburi, Bangkok 10140, Thailand. Many helpful information and sugar cane juicesamples provided by Chaimongkol Refined Sugar Co. Ltd. and providing of factory laboratory spaces as well asthe necessary instruments, from U-Thong Sugar Industry Factory, Supanburi Province,Thailand are highappreciated.

References1.

Alves, E.R., P.R. Fortes, E.P. Borges and E.A.G. Zagalto.2006. Spectrophotomatric flow- injectiondetermination of total reducing sugars exploiting their alkaline degradation. Analytical Chimica Acta 564 :231-235.

2.

Eggleston, G. and A. Monge.2005. Minimization of seasonal sucrose losses across Robert’s-typeevaporators in raw sugar manufacture by pH optimization. Journal of Agricultural and food chemistry 53 :6332-6339.

3. Eggleston, G., A. Monge and A. Pepperman.2002. Preheating and Incubation of cane juice prior to liming :A comparison of intermediate and cold lime clarification. Journal of Agricultural and food Chemistry 50 :

484-490.4.

Janthakasorn, N. and L. Meesuk. 2005. The use of expanded perlite to remove color and turbidity inindustrial sugar. Kasetsart Journal (Nat. Sci.) 39 : 188-193.

5. Khan, S.H. and K. Rahman. 1996. Inversion of sucrose solution by ion exchange : Evaluation of reactionrate and diffusivity. The chemical Engineering Journal and the Biochemical Engineering Journal 61 : 7-12.

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Kirca, A., M. Özkan and B. Cemeroglu. 2006. Effect of temperature, solid content and pH on the stabilityof black carrot anthocyanins. Food chemistry 101 : 212-218.

7. Kurup, A.S., H. J. Subramani, K. Hidajat and A. K. Ray. 2005. Optimal design and operation of SMBbioreactor for sucrose inversion. Chemical Engineering Journal 108 : 19-33.

8.

Lutin, F., M. Bailly and D. Bar. 2002. Process improvements with innovative technologies in the starch andsugar industries. Desalination 148 : 121-124.

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9. Santana de Almeida, A. C., L. Costade Aaujo, A. M. Costd, C. A. Moraes de Abreu, M.A.Gomes deAndrade Lima and M. De L.A.P.F Palha. 2005. Sucrose hydrolysis catalyzed by auto – immobilizedinvertase into intact cells of Cladosporium cladosporioides. Electronic Journal of Biotechnology 8 : 54-62.

10. Wienen, W.J. and R.S. Shallenberger. 1988. Influence of acid and temperature on the rate of inversion ofsucrose. Food Chemistry 29 : 51-55.

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