Journal of Food Engineering 125 (2014) 17–23

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Journal of Food Engineering

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Characterisation of fast dispersible fruit tablets made from greenand ripe mango fruit powders

0260-8774/$ - see front matter � 2013 Elsevier Ltd. All rights reserved.http://dx.doi.org/10.1016/j.jfoodeng.2013.10.014

⇑ Corresponding author. Tel.: +60 0389464425; fax: +60 389464440.E-mail address: yus.aniza@upm.edu.my (Y.A. Yusof).

M.Y. Ong a, Y.A. Yusof a,⇑, M.G. Aziz a,b, N.L. Chin a, N.A. Mohd. Amin a

a Department of Process and Food Engineering, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysiab Department of Food Technology and Rural Industries, Bangladesh Agricultural University, Mymensingh 2202, Bangladesh

a r t i c l e i n f o a b s t r a c t

Article history:Received 14 May 2013Received in revised form 30 August 2013Accepted 11 October 2013Available online 18 October 2013

Keywords:MangoCompactionFood tabletFruit tabletDissolutionVitamin C

This study was performed to assess the compressibility and dissolution of binary fruit tablets preparedfrom whole green and ripe mango powder influenced by disintegrants. Mango powder was preparedby freeze-drying mango pulps. Green mango powder exhibited medium flow and was poorly compress-ible compared with ripe and mixed mango powders. Tabletting of powders was performed using a uni-axial die compaction machine and dissolution tester with a moving paddle for the dissolution study.Among five formulations, the tensile strength of the mixed tablets was higher than the individual andmixed-fruit tablets. The dissolution kinetics revealed that the dissolution rate of the mixed-fruit tabletswas highly influenced by the disintegrant content. In conclusion, mixed mango tablets can be used as aneffective vitamin C supplement if the formulation is optimised with balanced sweetness and acidity andcan easily be consumed by chewing or by dissolving in water.

� 2013 Elsevier Ltd. All rights reserved.

1. Introduction

Large amounts of fruits, including the mango, are produced intropical and subtropical countries, which may be attractive froma commercial perspective. Mangos exhibit a high water contentin a mature state and are easily decomposed by microorganismsand chemical or enzymatic reactions. Fresh mangos are extremelyperishable and cannot be marketed or exported as fresh produceover long periods (Milton et al., 2005). The conversion of mangofruits into a dry particulate, which results in reduced volume andlonger shelf life, is commonly practised to overcome the problemsassociated with decomposition. Mango fruits can be found yearround in Malaysia and worldwide. However, due to their perish-able nature, mangos cannot be marketed as fresh produce for longperiods. Thus, the availability of mangos is limited. To meet the de-mand of the market throughout the year in all areas, mangos arepreserved as mango powder, which may be marketed as a fruitdrink. Mango powders can be stored for longer periods of timethan the fresh fruit.

Dehydration via freeze-drying is a common technique used inthe food industry to produce powder. Freeze-drying tends to re-duce nutrient loss during processing. Under optimal processingconditions, freeze-drying is an effective method for obtaining man-go powder to be marketed as a fruit drink powder in the dairy

industry and in baby food formulations (Nanjundaswamy, 1998).These dried foods are also can be used for instant foods, such assoup mixes, in which good reconstitution properties are highly de-sired. Good reconstitution properties include regaining the originalshape and structure rapidly after the addition of liquid and exhib-iting characteristics similar to the fresh products (Mellor, 1978).However, most sugar-rich powders, such as fruit powders, areamorphous and are frequently associated with problems causedby hygroscopicity, stickiness, or agglomeration due to the natureof the changing phase at the glass transition temperature (Tg)(Bhandari et al., 1997). Fruit powders are sensitive to the surround-ing environment and careful and costly packaging is essential formarketing and long-time storage of fruit powders. The compactionof fruit powder into tablets might be an excellent alternative forpost-processing, handling, packaging, and storage of fruit powder.

Aqueous solubility is a key determinant in using tablets asready-to-serve juices and drinks for refreshment. In pharmaceuti-cals, disintegrating agents are commonly incorporated in the tabletmatrix to improve the dispersibility and bioavailability of the ac-tive ingredients (Shailendra and Priti, 2011). Superdisintegrant,which is a fast-dissolving disintegrant, is added to pharmaceuticaltablet formulations to cause the compressed tablet to break apartwhen placed in an aqueous medium. Effervescent agents, whichare a mixture of sodium bicarbonate and citric acid, are used forthe same purpose and help dissolve the tablet, with carbon dioxideproduced during the reaction with water (Shailendra and Priti,2011). In this study, the effects of a superdisintegrant (Kollidon

18 M.Y. Ong et al. / Journal of Food Engineering 125 (2014) 17–23

CL) and an effervescent agent on the compaction and dissolution offreeze-dried mango powder were investigated.

2. Materials and methods

2.1. Materials

Ripe and green mango fruits were purchased from a fruit stall inSeri Kembangan, Selangor, Malaysia. The mango fruits were storedin the laboratory freezer at �20 �C before the experiment. Themango fruits were washed, and the seeds were removed beforethe fruits were cut into cubes and blended together with peelsusing a laboratory fruit juice blender (Panasonic MX-799S, Malay-sia). The pulps generated from fruits with peels were termed wholefruit pulp (WFP). The pulps were stored in a �20 �C freezer untilfreeze-drying.

2.2. Methods

2.2.1. Freeze-drying the whole fruit pulpThe WFP of ripe and green mango fruits was poured into rectan-

gular plastic containers and covered with lids. The contents of thecontainers were frozen in a 20 �C freezer for two days. The frozensamples were transferred to a vacuum freeze-dryer (BEW HAY/SB4, United Kingdom) and dried at �11 �C for 48 h at 0.27 MPapressure. After the freeze-drying process, the containers were re-moved from the drying chamber of the freeze-dryer, and the pow-der was stored in an air-tight container at ambient temperature forfurther analysis.

2.2.2. Powder propertiesThe physical properties, such as densities and particle sizes, of

both powders and a mixture (1:1) of the powders were determinedby the methods described by Ng et al. (2012). The absolute, tap andbulk densities of the powders were measured. The Hausner ratio(1967) and Carr index (1965) were used to indicate the flow prop-erties of the powders using the values of the bulk density and tapdensity. The absolute density was determined using a gas pycnom-eter (AccuPyc II 1340, Micromeritics, Norcross, USA). The particlesize of the ripe and green mango fruit powders was determinedusing a particle size analyser (Malvern Mastersizer 2000, MalvernInstrument Ltd., UK).

2.2.3. Compression of fruit powderThe Instron Universal Testing 5566 Machine (Canton MA, USA)

equipped with a cylindrical 20 ± 0.1 mm diameter hardened stain-less steel die was used to study the compaction behaviour of themango fruit powders. A 2 g sample of powder was compacted tovarious ultimate applied stresses in the dies. The powder of eachtablet was weighted using a digital balance with an accuracy rangeof ±0.001 g. The applied force and the cross-head displacementwere recorded by computer software. All the tablets were com-pacted by an ultimate force of 1, 3, 5, 7, and 9 kN. The compactionof the powder was performed according to the method describedby Yusof et al. (2012). The procedure was finished by unloadingand removing the bottom punch and ejecting the tablet from thedie. The height of the tablets was measured to calculate the densityof the tablet. To calculate the tensile strength, the tablet was placedbetween two flattening plates, and force was applied with the In-stron Universal Testing 5566 Machine at a speed of 10 mm/minwith ad force of 9.8 kN until a clear crack was visible on the com-pacted tablet. The tensile strength was calculated using the follow-ing formula (Fell and Newton, 1970):

rt ¼2F

pHDð1Þ

where F is the crushing force or tensile force (N), D the compactdiameter (m), and H is the compact thickness (m).

The compressibility of the powders was measured using theKawakita and Lüdde (1970/71) and Heckel (1961) equations. Thefollowing represents the Kawakita and Lüdde (1970/71) equation:

PC¼ P

aþ 1

abð2Þ

where a and b are constant, and C is the degree of volume reductionunder applied pressure P, and C is calculated from the initial volumeV0 and the powder volume under pressure V.

C ¼ V0 � VV0

The following represents the Heckel (1961) equation:

ln1

1� qr

� �¼ KP þ A ð3Þ

where qr is the relative density calculated from the ratio of theapparent density to the true density; K, the slope of the equation,is the reciprocal of the yielded pressure Py of the powder; and A isthe constant, which is a function of the original compact volume.

2.2.4. Dissolution of fruit tabletsBoth in vitro dissolution and erosion tests were performed to

evaluate the dissolution of mixed mango fruit powders. The ero-sion of tablets in different solvents was performed according tothe method described by Adiba et al. (2011). Distiled water, 0.1 Nhydrochloric acid and citrate buffer (pH 4) were used as solvents.Three mixed-fruit tablet formulations, including one formulationwith no disintegrant agent (NSD), one formulation with 1% effer-vescent agent (EFA) (equal ratio of sodium bicarbonate and citricacid) and one formulation with 1% Kollidon CL (KCL), were usedto observe the erosion kinetics in the solvents. The erosion testwas performed at a controlled temperature (37 �C) until completedissolution, and the erosion percentage was calculated using thefollowing equation:

Ra ¼Wb

WaX100 ð4Þ

where Ra is the erosion (%), Wb is the weight of the tablet beforeimmersion, and Wa is the weight of tablet after immersion.

In vitro dissolution of the mixed-fruit tablets was performedusing a dissolution tester (PT-DT8, Germany) on 5 tablets of eachtablet formulation in the 3 different medium solutions at37 �C ± 0.5 �C at 50 rpm. Approximately 500 ml of liquid mediumwas prepared and poured into the dissolution beaker, and 5 tabletswere simultaneously placed inside the dissolution beaker. At 10,20, 30, and 40 min intervals, 50 ml of liquid was withdrawn fromeach sample and replaced with an equal amount of fresh dissolu-tion medium. The liquid was filtered through filter paper (What-man No. 1, 0.45 lm) (Toyo Roshi Kaisha Ltd., Japan) beforestorage in a 50 ml centrifuge tube for further analysis. The dissolu-tion time was reached when 10 tablets were completely dissolvedin solution. The time was recorded using a stopwatch. The kineticrelease of vitamin C as influenced by disintegrant agents and sol-vents during dissolution was assessed. The DPPH (2,2-diphenyl-1-picryl hydrazyl) method was used to determine the antioxidantactivity according to the method described by Amin et al. (2006).TROLOX was used as a standard, and the results were expressedas the IC50. The vitamin C content in solution was measured bymeasuring the volume of the sample required to decolorise a solu-tion of DCPIP. The results were calibrated by comparison with aknown concentration of vitamin C, and the results were expressedin mg cm�3 (Anonymous, 2012). The kinetics of vitamin C release

M.Y. Ong et al. / Journal of Food Engineering 125 (2014) 17–23 19

was modelled using the Korsmeyer–Peppas equation (Eqs. (5) and(6)) (Korsmeyer et al., 1983).

dxdt¼ ktn ð5Þ

The equation also can be expressed in a logarithmic form:

logXt

Xo¼ logðkÞ þ n logðnÞ ð6Þ

where Xo is the vitamin C content at time 0; Xt the vitamin C contentat time t; k is the rate constant and n is the release exponent. Therelease mechanism is characterised based on the n value and its va-lue for cylindrically shaped matrices. All the analyses were per-formed in triplicate and reported as means ± standard deviation.

3. Results and discussion

3.1. Physical properties

Moisture content is used to measure the quantity of water con-tained in a unit mass of bulk powder as a percentage or fraction bymass. The mango fruit powders produced from freeze-drying exhi-bit moisture content less than 5%, as shown in Table 1. Accordingto Barbosa-Cánovas et al. (2005), the requirement of moisture con-tent of a food powder is between 4% and 6%. The powder producedin this study meets the moisture content requirement.

According to Table 1, ripe mango fruit powder exhibited highermoisture content than green mango powder, which was mostlydue to the hygroscopic characteristics of ripe mango powdersand its ability to easily absorb moisture when expose to air. Thehydroscopic nature of ripe mango powders was due to the high su-gar content of the ripe mango powder because low molecular-weight sugars in fruit juices yield powder with thermoplasticand hygroscopic properties (Bhandari et al., 1997). This propertymakes ripe mango powder stickier and reduces flow. The highestmoisture content of the mixed-fruit powder also reveals the hygro-scopicity, which might occur for a longer exposure to the air duringmixing. Longer exposures may lead to powder caking as the pow-der sticks together to form lumps in the powder bulk or solidifica-tion of a bed powder due to the formation of a solid bridge, whichcreates strong powder cohesion and reduced flowability (Fitzpa-trick, 2005).

The HR and CI values were calculated according to Hausner(1967) and Carr (1965) and are presented in Table 1. The resultsshow that the mixed mango fruit powder exhibited higher HRand CI values than the green or ripe mango powders. The greenmango powder was a medium-flowing powder, while the ripeand mixed mango fruit powders were poor flowing. All the pow-ders exhibited poor flow behaviours. The powders were easilycompressible and may form strong coherent junctions betweenthe particles (Yusof et al., 2005).

Particle size and shape are very important during particle for-mation and processing because they can directly affect the quality

Table 1The basic material properties of mango powders.

Material properties Green mango fruit powder

Moisture content (%) 4.26 ± 0.08Bulk density (kg/m3) 524.45 ± 1.35Tapped density (kg/m3) 680.30 ± 0.35True density (kg/m3) 1466.1 ± 4.36Mean particle size diameter, D50 (lm) 172.144Carr index, CI (%) Carr (1965) 22.91 ± 0.14Hausner ratio, HR Hausner (1967) 1.30 ± 0.01Flowability Carr (1965) and Hausner (1967) Medium flow

of the final products (Ma et al., 2000). Particle size also influencesthe flowability and segregation of powders (Fitzpatrick, 2007). Asshown in Table 1, the mean diameter of the particle sizes of theripe mango powder was smaller compared with the green mangopowder. The difference in particle size might due to the higher con-tent of high-molecular weight soluble particles, such as pectin andstarch, in green fruits compared with ripe mango fruits. Interest-ingly, upon mixing the ripe and green mango powders, the meandiameter of the particles became the highest in size. The increasedparticle size may due to the filling of the existing large void spacebetween the particles and the effect of contact surface area on sizedistribution (Eichie and Kudehinbu, 2009). According to Li et al.(2004), the particle size and shape can influence the contact sur-face area because a higher degree of size distribution results inmore contact surface area between the particles and increasesthe flowability of the powder. Therefore, upon reduction in particlesize, the powder appears to exhibit less flow because the surfacearea per unit mass increases (Fitzpatrick et al., 2004). Powders withsmaller particle sizes are more cohesive and exhibit poor flowproperties and handling problems (Davor, 2011).

3.2. Compressibility of mango fruit powder

3.2.1. Effect of tensile strength on compaction of mango powderIn general, the tensile strength of a compacted powder in-

creases with increasing compaction pressure. Tablets compressedat a higher compaction pressure exhibit higher tensile strength,lower tablet thickness and higher density compared with tabletscompacted with lower pressure. Thus, high-density tablets are dif-ficult to crush due to the strong inter-particle bonding in the tablet(Veen et al., 2000).

Fig. 1 shows the relationship between the tensile strength oftablets prepared from different mango powders by applying vari-ous pressures. The graph shows that with increasing pressure load,the tensile strength of all the tablet formulations increased. Asshown in Fig. 1, the tensile strength of the tablets prepared froman equal mixture of green and ripe mango powders was higherthan the tensile strength of the individual fruit tablets, whichwas due to the arrangement of particles in the tablets. The particleswere strongly bound in the mixture, which increased the adhesive-ness in the mixed powders. Single-fruit tablets exhibit poor inter-particle bonding and exhibit large voids between particles, whichcontribute to the decreased density (Eichie and Kudehinbu,2009). Low density can cause the tablet to break easily when a loadis applied during the determination of tensile strength. The ripemango fruit powder exhibited a smaller particle size than thegreen powder and can fill the voids within the green mango fruitpowder particles. The presence of inter-particle bonding in themixed tablet was stronger than the inter-particle bonding in thesingle-fruit tablets, which resulted in increases density and tensilestrength of the mixture tablet. In addition, the particle size itself af-fects the tensile strength of tablets. As the particle size decreases,the powder becomes more cohesive and the flow decreases, which

Ripe mango fruit powder Mixed mango fruit powder

4.31 ± 0.11 4.68 ± 0.09515.27 ± 0.28 519.27 ± 0.37682.00 ± 3.00 702.70 ± 2.521456.4 ± 0.49 1494.50 ± 2.0788.879 189.01024.45 ± 0.29 26.10 ± 0.211.32 ± 0.01 1.35 ± 0.01Poor flow Poor flow

Ten

sile

str

engt

h, M

Pa

Pressure, MPa

GMFP

Mixed + 1%EFA

Mixed + 1%KCL

Mixed (1:1)

RMFP

Fig. 1. Regression line of tensile strength against pressure applied. Error bar hasbeen drawn from three replications. GMFP and RMFP represent tablets from greenand ripe mango powder, respectively. Mixed (1:1), Mixed + 1% KCL and Mixed + 1%EFA represent tablets prepared from equal amount of GMFP and RMFP, mixed inaddition to 1% Kollidon CL and mixed in addition to 1% effervescent agent,respectively.

20 M.Y. Ong et al. / Journal of Food Engineering 125 (2014) 17–23

results in greater inter-particle friction, more energy required toovercome the friction, and increased tensile strength. This findingis similar to the results of Yusof et al. (2009) for the compressivebehaviour fine maize, coarse maize and Avicel powders. The tensilestrengths of the mixed tablets with effervescent agent and withKollidon CL were slightly lower than the tensile strength of themixed tablets without disintegrant. The mixed-fruit tablet contain-ing effervescent agent represented the lowest tensile strengthcompared with the tablet containing Kollidon CL and the mixed-fruit tablet with a disintegrant. The result was unexpected becausehigher tensile strength should be associated with smaller particlesizes of the disintegrant. The particles of both disintegrants weresmaller than the mango fruit powder and were not closely packed,which might have caused higher porosity and decreased density.The lower density resulted in lower tensile strength.

Moisture content also influenced the tensile strength of the tab-let. When the moisture content in the sample increases, the tensilestrength of the tablet increases. As shown in Table 1, the moisturecontent in the mixed-fruit powder was high, and the tensilestrength was also high compared with the single-fruit tablets.The difference in the moisture content was likely due to the mois-ture present in the sample absorbed as water vapour. Moisture in-creases the intermolecular attraction forces among the particlesand ultimately influences the tensile strength (Ahlneck and Alder-born, 1989).

From the result showed in Fig. 1, the regression values, R2, formost of the trend lines were reliable (R2 > 0.972). The regressionvalue for the trend line of 100% ripe mango powder is 0.973, whichis slightly lower than the 100% green mango. The slope values ofthe tensile strength–pressure lines of the tablets from the single-fruit powder are lower than the slope values of the mixed-fruitpowder; the green mango powder exhibited the lowest slope val-ues. The slope value of the trend lines decreased with the additionof superdisintegrant and effervescent agents compared with theslope of the trend line of the mixed-fruit tablet with disintegrant.The intercept of the trend lines indicated the die filling value inthe initial stages of rearrangement (Itiola, 1991). As shown inFig. 1, the mixed-fruit powder exhibited the highest die filling va-lue, and the green mango powder exhibited the lowest value. In thebulk state, the close packing of particles depends on the initialrearrangements. Powder particles undergo plastic deformation athigher compression pressures, and greater slopes indicate higherplasticity and compressibility (Ilkka and Paronen, 1993). Themixed-fruit tablets are more compressible than the single- or

mixed-fruit tablets containing disintegrants; the green mango fruittablets are approximately 3 times less compressible than themixed fruit tablets.

3.2.2. Pressure–volume relationshipThe most common equation used to describe pressure–volume

relationships in compaction is the Kawakita and Lüdde (1970/71)formula. This equation predicts a linear relationship between P/Cand P. The slope and intercept allow the constant ‘a’ and ‘b’ to beeasily evaluated. In addition to the Kawakita and Lüdde (1970/71) analysis, the data were also analysed by the Heckel (1961)equation. Table 2 shows the results calculated from the Kawakitaand Lüdde and Heckel equations. The plot of the raw data fromthe Kawakita and Lüdde equation is shown in Fig. 2. All the tabletsexhibited regression of R2 > 0.94.

From Table 2, the green mango tablet shows a higher value ofconstant ‘a’. Higher particle arrangement occurs in this formulationbecause of loose packing of powder before compression. Puregreen mango powder has the highest porosity due to its larger par-ticles, while ripe mango powder has smaller particles and lessporosity. For the mixed-fruit tablets, smaller particles of disinte-grants (sodium bicarbonate and Kollidon CL) can fill the pores be-tween mixtures and decrease the initial porosity and increase thepacking (Podczek and Sharma, 1996). Thus, the values of constant‘a’ of the mixed-fruit tablets with superdisintegrant and efferves-cent agent are lower than the single powder tablets.

The constant ‘b’ is related to the resistance of force of the pow-der particle (Pitt and Sinka, 2007) or the pressure needed to com-press the bed powder to one half of the total volume (Shivanandet al., 1991). Higher values of ‘b’ correspond to low pressure re-quired to form high tensile strength tablets. As shown in Table 2,the green mango powder tablet exhibited a lower value of ‘b’,which is due to the high porosity and high pressure required tocompact the powder to half of the volume and results in low ten-sile strength. Mixed-fruit tablets with effervescent agent exhibiteda lower value of ‘b’, which indicates that mixed-fruit tablets witheffervescent agents exhibit lower tensile strength and good disin-tegrant properties. Nicklasson and Alderborn (2000) stated in theirstudy that a higher value ‘b’ could be related to the formation oftablets with closed pore structure and higher tensile strength.According to Table 2, all mixture tablets have higher values of ‘b’compared with pure mango tablets, which indicated the highertensile strength of mixed-fruit tablets. The results were similar tothe study by Yusof et al. (2009), in which the same compactionmodel was used to find the values of ‘a’ and ‘b’ for fine maizeincluding starch, lactose, and paracetamol. All the values aredependent on the material properties of the powders.

In the Heckel analysis, all the formulations showed linearityfrom the early stages of compression with low slopes (<0.1) (figurenot shown). Ripe mango powder exhibited the highest intercept(0.89), which corresponded with the highest die filling value. Thesefeatures could result in the formation of bridges and arches, whichcould prevent close packing of particles in the bulk state. The slope(K) of ripe mango powder is the highest (0.072) and the slope of themixture of green and ripe mango powder is the lowest (0.044).Greater slopes indicate a greater degree of plasticity and compress-ibility (Satya Prakas et al., 2011), which is also confirmed by thelower mean yield pressure Py of ripe mango powder (13.88).

3.3. Dissolution of mixed-fruit tablets

3.3.1. Erosion testMixed-fruit tablets prepared with two disintegrants and tab-

leted with 5 kN of load were used to perform the erosion study.The erosion study was performed to investigate the ability of tab-lets to swell in the medium. The tablets were dissolved in three dif-

Table 2Compressibility analysis of mango powders using Kawakita and Heckel equations.

Tablet composition Parameters of Kawakita analysis Parameters of Heckel analysis

a b R2 K A Py R2

100% GM 0.579 0.214 0.997 0.059 0.79 16.95 0.986100% RM 0.578 0.217 0.996 0.072 0.89 13.88 0.957GM + RM (1:1) 0.554 0.284 0.998 0.044 0.85 22.72 0.987GM + RM (1:1)+1% KL 0.579 0.238 0.995 0.061 0.86 16.39 0.95GM + RM (1:1) + 1% EA 0.572 0.229 0.995 0.057 0.84 17.54 0.94

GM stands for green mango, RM for ripe mango, KL for Kollidon CL and EA for effervescent agent, a is the compatibility, the reciprocal of b is the cohesiveness, K is the slope ofHeckel equation, which is reciprocal of yield pressure Py and A is the intercept indicating compact volume.

0.60

0.80

1.00

1.20

1.40

1.60

1.80

0 2 4 6 8 10 12

In(1

/(1-ρ r

))

Pressure, MPa

100% GM100% RMMixed (1:1)Mixed (1:1) 1%KLMixed (1:1) 1% EA

Fig. 2. Compression behaviour of mango powder analysed by Heckel equation (qr isthe relative density of the compact, GM = green mango powder, RM = ripe mangopowder, KL = Kollidon CL and EA = effervescent agent).

Table 4Dissolution time for mixture tablets in three different medium solutions.

Mixed mangopowders + superdisintegrant

Dissolution time (min)

Distiledwater

0.1 MHCl

0.1 Mcitratebuffer

Simulatedsaliva

Without disintegrant 42.7 38.4 57.6 2.16Effervescent agent (1%) 38.9 34.4 46.4 1.18Kollidon CL (1%) 52.2 36.3 55.2 2.83

M.Y. Ong et al. / Journal of Food Engineering 125 (2014) 17–23 21

ferent solutions: distiled water, 0.1 M HCl and 0.1 M citrate buffer.The results in the various medium are provided as the percentageof erosion in Table 3. The erosion percentage reflects the amount oftablet dissolved in different media during the dissolution process.The erosion rate increased with the increasing swelling time. Adibaet al. (2011) reported a similar finding on date (Phoenix dactyliferaL.) and spirulina (Spirulina sp.) powders.

Concerning the effect of disintegrants on erosion, the efferves-cent agent exhibited a faster erosion rate in all the media com-pared with the superdisintegrant, Kollidon CL and withoutdisintegrants. The swelling of the tablet was improved by the addi-tion of disintegrants. This could be due to the low tensile strengthof the tablets with effervescent agent and the increased porosity oftablets during swelling. Cavities may increase the effectiveness ofthis material in tablets by increasing the swelling force of the dis-integrant within porous spaces.

The tablets dissolved fairly rapidly with essentially completeerosion within 40 min in 0.1 M HCl compared with the two othermedium solutions. The mango tablets exhibited a higher tendencyto be eroded and swell in acidic medium than in neutral medium(distiled water). However, independently of the disintegrant con-

Table 3Percentage of erosion in different mixtures tablets in distils water, 0.1 M HCl and 0.1 M citr

Middle Mixture tablets Erosion (%)

5 min

Distil water Without disintegrant 17.33 (0.15)Effervescent agent 31.08 (0.64)Kollidon CL 12.97 (0.21)

0.1 M HCl Without disintegrant 22.46 (0.61)Effervescent agent 40.42 (0.68)Kollidon CL 25.57 (0.40)

0.1 M CITRATE buffer pH4 Without disintegrant 13.47 (0.32)Effervescent agent 26.63 (0.61)Kollidon CL 15.78 (0.40)

tent, the tablets showed lower erosion and swelling rates in citratebuffer at pH 4. This may be due to the ionic strength effect in thelow pH solution (Hu et al., 2001). According to Adiba et al.(2011), tablet composition more strongly influenced erosion thanthe composition of the erosion media. The effects of different ero-sion media, such as water, 0.1 N HCl and phosphate buffer at pH6.8 were similar.

3.3.2. In vitro dissolutionTable 4 shows the results of the dissolution time for three types

of mixed-fruit tablets when dissolved in distiled water, 0.1 M HCl,0.1 M citrate buffer (pH 4), and simulated saliva fluid (SSF) (pH6.8). As shown in Table 4, the tablet dissolved fastest in SSF. Com-plete dissolution required a minimum of 10-fold less time in SSFthan in distiled water, HCl and buffer. The fast dissolution andswelling ability of SSF causes the tablets to dissolve very quickly.The dissolution time was further decreased by the addition ofsuperdisintegrant. Superdisintegrant is added to a tablet formula-tion to cause the compressed tablet to break apart when placedin an aqueous environment and to facilitate the rupture of bondsduring disintegration (Shangraw et al., 1980). Although the per-centage of added superdisintegrant is small (e.g., 1%) in the tablet,the dissolution time tends to be decreased significantly. Among thefirst three dissolution media, mixed tablets with the addition ofeffervescent agent and Kollidon CL were dissolved much fasterthan mixed tablets in distiled water and 0.1 M HCl. Bolhuis et al.(1997) have demonstrated that the dissolution behaviour of tablets

ate buffer solution. Standard deviations of three replications are given within bracket.

10 min 20 min 30 min 40 min

37.12 (0.19) 54.17 (0.33) 78.51 (0.15) 91.32 (1.08)46.79 (0.52) 59.13 (0.25) 76.41 (1.48) 100.00 (0.00)24.02 (0.23) 44.67 (0.59) 60.49 (0.66) 78.63 (0.45)

46.53 (0.48) 55.88 (0.77) 81.86 (1.11) 100.00 (0.0)47.52 (0.87) 69.13 (0.44) 89.23 (1.07) 100.00 (0.0)46.89 (0.27) 64.42 (0.73) 86.47 (1.23) 100.00 (0.0)

32.20 (0.30) 40.62 (0.49) 52.25 (0.44) 70.27 (0.16)47.40 (0.98) 62.89 (0.50) 77.84 (0.58) 86.35 (0.90)33.42 (0.72) 57.57 (0.45) 68.14 (0.74) 81.42 (0.66)

Table 5Effect of effervescent agent concentration on the dissolution rate of mango fruittablets in simulated saliva fluid at pH 6.8.

Sample (n = 5) Dissolution time (min) at effervescent agentconcentration of

0% 1% 10% 20%

100% Green mango 2.57 1.50 1.16 1.07100% Ripe mango 2.14 2.05 1.52 1.141:1 Mixed mango 2.16 1.18 0.57 0.41

Table 6Constants of Korsmeyer–Peppas equation applied (n = 5).

Medium Mixed mango fruittablet +

R2 k n Releasetype

Distil water Without disintegrant 0.984 0.054 0.37 FickianEffervescent agent 1% 0.979 0.133 0.19 FickianKollidon CL 1% 0.999 0.033 0.21 Fickian

0.1 M HCl Without disintegrant 0.963 0.083 0.31 FickianEffervescent agent 1% 0.976 0.181 0.22 FickianKollidon CL 1% 0.987 0.097 0.30 Fickian

0.1 M citratebuffer

Without disintegrant 0.949 0.048 0.23 FickianEffervescent agent 1% 0.975 0.119 0.26 FickianKollidon CL 1% 0.976 0.050 0.26 Fickian

22 M.Y. Ong et al. / Journal of Food Engineering 125 (2014) 17–23

with poor aqueous solubility could be improved by adding super-disintegrant as a swelling carrier.

Dissolution of tablets can be caused by the pore structure andbonding structure within the tablet. The bonding strength withinthe bonding structure in the tablet can affect the penetration ofwater into the tablet. The bonding between particles is decreasedwhen superdisintegrants are added. When the tablet exhibits low-er bonding strength, the water penetrates easily to the tablet andfacilitates faster tablet breakdown. Thus, tablets containing disin-tegrants swell rapidly due to the low tensile strength, which affectsthe existing bonds between particles and causes the tablet to breakup. In the case of effervescent agents, the reaction of sodium car-bonate and citric acid results in the formation of carbon dioxide,which helps to break up and dissolve the tablet faster. Althoughthe tensile strength of mixed tablets containing Kollidon CL is low-er than that of the mixed tablets without disintegrant, the dissolu-tion time in distiled water is much longer compared with thetablets with disintegrant. When mixed tablets containing KollidonCL are exposed to water, stress builds, and the strain of the tabletsis increased and causes swelling and lower dissolution. Khan andRhodes (1975) found that when a tablet containing a disintegrantis exposed to water vapour, stress builds slowly, and the tablet ab-sorbs some of the strain as the tablets lose some absorption andswelling ability and exhibit poorer disintegration and dissolution.

Superdisintegrant particle size can affect the dissolution time.The smaller particle size of effervescent agent causes faster disso-lution compared with the larger Kollidon CL particles in all med-ium solutions. This is due to smaller particles, which are easier tobreak when dissolved in medium. The effervescent agent takes lesstime to dissolve than Kollidon CL, which allows the effervescentagent to be an effective superdisintegrants.

Increasing concentrations of effervescent agents decreased thedissolution time drastically as shown in Fig. 3 and Table 5. The dis-solution time reduced to 2.5 min from 38.9 min upon increasingthe effervescent agent concentration from 1% to 5%, respectively.The time further reduced to 1 min when the effervescent agent(EF) concentration was increased to 20%. The same tablet (mixedwith 20% EF) dissolved in simulated saliva fluid required only 41s to dissolve completely (Table 5). However, the effect of the EFconcentration beyond 1% on the dissolution time is insignificant.Lower dissolution time will help formulate ready-to-drink tablets.

3.3.3. In vitro release of vitamin CModelling the kinetic release of antioxidant (vitamin C) was

achieved by plotting log (Xt/X0) against log (t), which is referredto as the Korsmeyer–Peppas plot, for different types of disinte-grants in different medium solutions (distiled water, 0.1 M HCl,and 0.1 M citrate buffer). Modelling the dissolution data in simu-lated saliva fluid was not possible due to difficulties in determiningthe vitamin C content in a compatible time interval because the

Dis

solu

tion

time

(min

)

Concentration of effervascent agent

RMPTGMPTMMPT

Fig. 3. Effect of effervescent agent concentration on the dissolution rate of mangofruit tablets. Dissolution was carried out in vitro in distiled water. (RMPT = Ripemango fruit tablet, GMPT = Green mango fruit tablet, and MMPT = Mixed mangofruit tablet).

tablets dissolved completely within 3 min. Table 6 shows theparameters obtained after plotting this model for experimentaldata for the dissolution time of 40 min in three other solutions.The linear regions of the plots are fitted to straight lines withregression coefficients of R2 > 0.9489 for the entire tested com-pound. The value of exponent time, n, indicates the overall mech-anism of solute release during dissolution. The kinetic constant forrelease, k, indicates the overall solute diffusion coefficient charac-teristics of the tablets with increased total solubility of the tabletsin solution (Korsmeyer et al., 1983).

Based in Table 6, the n values for the dissolution time of 40 minfor all the mixture tablets in distiled water, 0.1 M HCl solution and0.1 M citrate buffer solution are between 0.2 and 0.4. Therefore, thediffusion represents Fickian release in all the solutions. The releaseof solute from tablets is from areas of high concentration to lowconcentration caused by the concentration gradient of the tabletsand solvent. These results are similar with the result reported inthe study by Adiba et al. (2011), in which the diffusion of pure spi-rulina exhibited Fickian release in distiled water and 0.1 M HCl.However, the previous study observed non-Fickian release whentablets were dissolved in phosphate buffer at elevated pH (6.8).Lower values of n indicate that the mechanism of solute releaseduring dissolution is faster and decreases the dissolution time.However, the value of n of the effervescent agent-containing tab-lets dissolved in 0.1 M citrate buffer increased with low dissolutiontime, which may be due to the ionic strength effect in the pH solu-tion (Hu et al., 2001). As shown in Table 6, a comparison of thethree original powders shows that the mixed-fruit tablets witheffervescent agent exhibited the highest value of k, followed bymixed-fruit tablets with Kollidon CL and pure mixture tablets.The higher value of constant k of the effervescent agent-containingtablets results in better plastic deformation and faster dissolutioncompared with tablets containing Kollidon CL. The swelling ofthe tablets can be affected by the pH of the swelling solution,which may cause Fickian release (Hu et al., 2001).

4. Conclusions

Tablets with the strongest mechanical strength exhibit longerdissolution times because the interlocking particle bonds are

M.Y. Ong et al. / Journal of Food Engineering 125 (2014) 17–23 23

strong, and water penetration into tablets is lower. The addition ofsuperdisintegrant to mixture tablets can increase the dissolutionrate because superdisintegrants cause the compressed tablet tobreak apart when placed in an aqueous environment and facilitatesthe rupture of bonds during disintegration. The dissolution rates ofmixed-fruit tablets were faster in simulated saliva fluid, but theantioxidant and vitamin C content was optimum in 0.1 M HCl(pH 1.3). The dissolution of binary mixtures of mango powder tab-lets occurs better in acidic compared with neutral (distiled water)or buffered solutions. Effervescent agents dissolve tablets fasterthan Kollidon CL. A binary mixture of mango tablets can be usedas an effective vitamin C tablet supplements if its formulation isoptimised with balanced sweetness and acidity. The tablets caneasily be consumed by chewing or by dissolving in water. The dis-integrant content needs to be optimised for faster dissolution forthe application of mango powder in fruit drinks.

Acknowledgements

The authors would like to acknowledge the Ministry of Science,Technology and Innovation (MOSTI) for granting the project Sci-ence Fund: 5450582.

References

Adiba, B.D., Salem, B., Nabil, S., Abdel Hakim, M., 2011. Preliminary characterizationof food tablets from date (Phoenix dactylifera L.) and spirulina (Spirulina sp.)powders. Powder Technology 208, 725–730.

Ahlneck, C., Alderborn, G., 1989. Moisture adsorption and tabletting. I. Effect onvolume reduction properties and tablet strength for some crystalline materials.International Journal of Pharmaceutical 54, 131–141.

Amin, I., Norazaida, Y., Emmy Hainida, K.I., 2006. Antioxidant activity and phenoliccontent of raw and branched Amaranthus species. Food Chemistry 94, 47–52.

Anonymous, 2012a. Testing Food for Vitamin C. <http://www.foodafactoflife.org.uk/attachments/ff2caf4a-75e5-4aa129132873.pdf> (retrieved 07.07.12).

Barbosa-Cánovas, Gustavo, V., Ortega-Rivas, Enrique, PabloJuliano, Hong Yan, 2005.Food Powders. Kluwer Academic/Plenum Publishers, New York.

Bhandari, B.R., Datta, N., Howes, T., 1997. Problems associated with spray drying ofsugar-rich foods. Drying Technology 15, 671–684.

Bolhuis, G.K., Zuurman, K., Wierik, G.H.P., 1997. Improvement of dissolution ofpoorly soluble drugs by solid deposition on a super disintegrant. II. The choiceof super disintegrants and effect of granulation. European Journal ofPharmaceutical Sciences 5, 63–69.

Carr, R.L., 1965. Evaluating flow properties of powders. Chemical Engineering 72,163–167.

Davor, J., 2011. Assessment of powder flow characteristics in incoherent soupconcentrates. Advanced Powder Technology. http://dx.doi.org/10.1016/j.apt.2011.07.003.

Eichie, F.E., Kudehinbu, A.O., 2009. Effect of particle size of granules on somemechanical properties of paracetamol tablets. Journal of Biotechnology 8,5913–5916.

Fell, J.T., Newton, J.M., 1970. Determination of tablet strength by the diametricalcompression test. International Journal of Pharmaceutical 59, 688–691691.

Fitzpatrick, J.J., 2007. Particle properties and the design of solid food particleprocessing operations. Food and Bioproducts Processing 85, 308–314.

Fitzpatrick, J.J., 2005. Food powder flowability. In: Onwulata, C. (Ed.), Encapsulatedand Food Powders. CRC Press, Boca Raton, FL.

Fitzpatrick, J.J., Barringer, S.A., Iqbal, T., 2004. Flow property measurement of foodpowders and sensitivity of Jenike’s hopper design methodology to the measuredvalues. Journal of Food Engineering 61, 399–405.

Hausner, H.H., 1967. Friction conditions in a mass of metal powder. InternationalJournal Powder Metallurgy 3, 7–13.

Heckel, R.W., 1961. An analysis of powder compaction phenomena. Transaction ofMetallurgy Society AIME. Springer, Bonston, ISSN: 0543-5722.221.

Hu, J., Reyes-Cruz, G., Goldsmith, P.K., Spiegel, A.M., 2001. The Venus’s-flytrap andcysteine-rich domains of the human Ca2+ receptor are not linked by disulfidebonds. Journal of Biological Chemistry 276, 6901–6904.

Ilkka, J., Paronen, P., 1993. Prediction of the compression behavior of powdermixtures by the Heckel equation. International Journal of Pharmacy 94, 181–187.

Itiola, O.A., 1991. Compressional characteristics of three starches and themechanical properties of their tablets. Pharmaceutical World Journal 8, 91–94.

Kawakita, K., Lüdde, K.H., 1970/71. Some considerations on powder compressionequations. Powder Technology 4, 61–68.

Khan, K.A., Rhodes, C.T., 1975. Water sorption properties of tablet disintegrants.Journal of Pharmaceutics Science 65, 1636–1637.

Korsmeyer, R.W., Gurny, R., Doelker, E., Buri, P., Peppas, N.A., 1983. Mechanisms ofsolute release from porous hydrophilic polymers. International Journal ofPharmaceutical 15, 25–35.

Li, Q., Rudolph, V., Weigl, B., Earl, A., 2004. Interparticle Van der Waals force inpowder flowability and compatibility. International Journal of Pharmaceutics280, 77–93.

Ma, Z., Merkus, H.G., de Smet, J.G.A.E., Heffels, C., Scarlett, B., 2000. Newdevelopments in particle characterization by laser diffraction: size and shape.Powder Technology 111, 66–78.

Mellor, J.D., 1978. Fundamentals of freeze-drying. Academic Press, London.Milton, C.C., Stringheta, P.C., Ramos, A.M., Cal-Vidal, J., 2005. Effect of the carriers on

the microstructure of mango powder obtained by spray drying and itsfunctional characterization. Innovative Food Science and EmergingTechnologies 6, 420–428.

Nanjundaswamy, A.M., 1998. Processing. In: Litz, R.E. (Ed.), The Mango, BotanyProduction and Uses. CAB International, Wallingford, UK, pp. 509–544.

Ng, L.T., Han, C.P., Yusof, Y.A., Chin, N.L., Talib, R.A., Taip, F.S., Aziz, M.G., 2012.Physicochemical and Nutritional Properties of Spray-Dried Pitaya Fruit Powderas Natural Colorant. Food Science and Biotechnology 21, 675–682.

Nicklasson, F., Alderborn, G., 2000. Analysis of the compression mechanics ofpharmaceutical agglomerates of different porosity and composition using theAdams and Kawakita equations. Pharmaceutical Research 17, 949–954.

Pitt, K., Sinka, I.C., 2007. Tabletting. In: Salman, A.D., Hounslow, M.J., Seville, J.P.K.(Eds.), Granulation (Handbook of Powder Technology), 11. Elsevier B.V., pp.735–778 (Chapter 16).

Podczek, F., Sharma, M., 1996. The influence of particle size and shape componentsof binary powder mixtures on the maximum volume reduction due to packing.International Journal of Pharmaceutics 137, 41–47.

Satya Prakas, S., Nirangan, P., Chakrabarty, S., 2011. Studies on flowability,compressibility and in vitro release of Terminalia Chebula fruit powder tablets.Iran Journal of Pharmaceutical Research 10, 3–12.

Shailendra, B., Priti, T., 2011. Development of domperidone: polyethylene glycol6000 fast dissolving tablets from solid dispersions using effervescent method.Journal of Chemical and Pharmaceutical Research 3, 889–898.

Shangraw, R., Mitrevej, A., Shah, M., 1980. A new era of tablet disintegrants.Pharmaceutical Technology 4, 49–57.

Shivanand, P., Sprockel, Omar L., 1991. Compaction behavior of cellulose polymers.Powder Technology 69, 1168–1172.

Veen, B.V., Maarschalk, V., Bolhuis, G.K., Zuurman, K., Frijlink, H.W., 2000. Tensilestrength of tablets containing two materials with a different compactionbehavior. International Journal of Pharmaceutics 203, 71–79.

Yusof, Y.A., Mohd Salleh, F.S., Chin, N.L., Talib, R.A., 2012. The drying and tablettingof pitaya powder. Journal of Food Process Engineering 35, 763–771.

Yusof, Y.A., Smith, A.C., Briscoe, B.J., 2005. Roll compaction of maize powder.Chemical Engineering Science, 60. Pergamon Press, Amsterdam, pp. 3919–3931.

Yusof, Y.A., Smith, A.C., Briscoe, B.J., 2009. Uniaxial die compaction of food powders.Journal of The Institution of Engineers, Malaysia 70, 41–48.