Food Chemistry 169 (2015) 478–483

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Food Chemistry

journal homepage: www.elsevier .com/locate / foodchem

Effect of protic ionic liquid on the volumetric properties and tastebehaviour of sucrose

http://dx.doi.org/10.1016/j.foodchem.2014.08.0230308-8146/� 2014 Elsevier Ltd. All rights reserved.

⇑ Corresponding author. Tel.: +91 44 2257 4248; fax: +91 44 2257 4202.E-mail address: gardas@iitm.ac.in (R.L. Gardas).URL: http://www.iitm.ac.in/info/fac/gardas (R.L. Gardas).

Vickramjeet Singh, Pratap K. Chhotaray, Ramesh L. Gardas ⇑Department of Chemistry, Indian Institute of Technology Madras, Chennai 600 036, India

a r t i c l e i n f o

Article history:Received 3 March 2014Received in revised form 9 June 2014Accepted 7 August 2014Available online 18 August 2014

Chemical compounds studied in this article:Sucrose (PubChem CID: 5988)Acetic acid (PubChem CID: 176)3-Amino-1-propanol (PubChem CID: 9086)

Keywords:Protic ionic liquidSucrosePartial molar volumeHydration numberTaste quality

a b s t r a c t

The volumetric properties and taste behaviour of sucrose in aqueous solutions of a protic ionic liquid(3-hydroxypropylammonium acetate) have been studied at temperatures, T = (293.15–318.15) K and atatmospheric pressure. Apparent molar volumes, V2,/, apparent specific volumes, ASV, apparent molarisentropic compressibilities, Ks,2,/, and apparent specific isentropic compressibilities, ASIC, werecalculated from measured density, q and speed of sound, u data. Partial molar volumes, V2

� , and partialmolar isentropic compressibilities, Ks,2

� at infinite dilution, transfer parameters (DtV2� and DtKs,2

� ),expansion coefficients, [(@V2

� /@T)P and (@2V2� /@T2)P], interaction coefficients, (YAB and YABB) and hydration

numbers, Nw, were also evaluated and discussed in terms of solute–cosolute interactions. Further, theeffect of protic ionic liquid on the taste behaviour of sucrose has been discussed from ASV and ASICparameters, as these parameters, which are sensitive to solvation behaviour of solute, are divided intofour basic taste qualities occupying certain ranges.

� 2014 Elsevier Ltd. All rights reserved.

1. Introduction

Saccharides and their derivatives play an important role in var-ious aspects of chemistry, biochemistry and biotechnology. Theyact as a source of building blocks for cofactors or biomolecules,and are used in the design of biocompatible and biodegradablematerials (Ma, Sun, Chen, Zhang, & Zhu, 2014; Ramesh &Tharanathan, 2003). Saccharides are also used in pharmaceuticals,foods, and biomedical applications (Bordat, Lerbret, Demaret,Affouard, & Descamps, 2004; Ribeiro et al., 2011). Binary andternary aqueous solutions containing saccharides (e.g., sucrose,glucose, and fructose) and additives (ethanol, glycerol, salts, etc.)have been widely used as a suitable immersion media for freezingfruits (Banipal, Singh, & Banipal, 2010; Pincu, Brauver, Gerber, &Buch, 2010). The thermochemical methods of energy productionfrom sucrose biomass are gaining much interest and recently thefeasibility of hydrogen production from the catalytic reforming ofsucrose biomass has been reported (Tanksale, Wong, Beltramini,& Lu, 2007).

Ionic liquids (ILs) are molten salts composed of cations andanions. They are considered as ‘‘green benign solvents’’ promisingwide-spread industrial applications, possibly replacing conven-tional organic solvents (Elyasi, Khalilzadeh, & Karimi-Maleh,2013; Freire et al., 2008; Singh, Chhotaray, & Gardas, 2014). ILsare also employed for chemical and enzymatic modifications ofpolysaccharides into useful chemicals and materials, having poten-tial applications in the field of glycobiology, glycochemistry andglycotechnology. As a solvent, ILs are capable of dissolving variouspolar and non-polar compounds. Recently, imidazolium based ILswere used for cellulose dissolution (Murugesana & Linhardt,2005; Swatloski, Spear, Holbrey, & Rogers, 2002; Zhang, Wu,Zhang, & He, 2005). Further, mixed solvent systems containingILs are regarded as more efficient solvent for solubilising cellulose,as these solvents disrupt the hydrogen bonding network present incellulose.

The application of ILs in carbohydrate chemistry is rapidly grow-ing, both for their functionalization and dissolution, which can bringabout attractive new methodologies and enhanced procedures forsolution processing of lignocellulosic materials. Most of the pub-lished work (Conceicao, Bogel-Lukasik, & Bogel-Lukasik, 2012;Swatloski et al., 2002; Xu, Zhang, Zhao, & Wang, 2013) focus mainlyon the dissolution and homogenous modification of cellulose,

V. Singh et al. / Food Chemistry 169 (2015) 478–483 479

starch, lignin, etc. or direct wood dissolution. The physicochemicalproperties of simple saccharides (mono-, di- or tri-saccharides) inthe presence of ILs particularly, protic ionic liquids (PILs) are muchless studied (Jin & Chen, 2011; Singh et al., 2014; Wu, Zhang, &Wang, 2009; Wu, Zhang, Wang, & Yang, 2008).

Furthermore, the thermodynamic properties (apparent specificvolumes and apparent specific isentropic compressibilities) of dif-ferent sapid substances (including saccharides) have been studied(Aroulmoji, Hutteau, Mathlouthi, & Rutledge, 2001; Aroulmoji,Mathlouthi, Feruglio, Murano, & Grassi, 2012; Jamal, Khosa,Rashad, Bukhari, & Naz, 2014; Parke, Birch, & Dijk, 1999) in aque-ous and mixed aqueous solutions (Aroulmoji, Mathlouthi, & Birch,2000; Banipal, Singh, Banipal, & Singh, 2013; Seuvre & Mathlouthi,2010), in order to understand the role of water–solute interactionsand the influence of additives on the taste quality of these sub-stances (saccharides). Moreover, the role of water in sweet tastechemoreception has also been reported (Birch, 2002) because thechanges in the hydration layer and centre of hydration of solutein the solvent affects the transport of the solute to the taste epithe-lium (Parke et al., 1999).

The solvation and taste behaviour of sucrose has been reportedin the presence of various additives e.g., gluconate salts of sodium,potassium and magnesium (Aroulmoji et al., 2000) and sodium ace-tate (Banipal et al., 2013). Furthermore, the taste quality of aqueoussolutions of salts varies as the anionic part of salt is changed (‘‘anioneffects’’) (Delwiche, Halpern, & Desimone, 1999). So, in the presentwork, 3-hydroxypropylammonium acetate (3-HPAAc) was used asan additive to understand the effect of its cationic and anionic parton the volumetric properties of sucrose and its plausible tasteeffects. The choice of solute (sucrose) was based on the fact that ithas been used as a reference standard for sweet substances(Aroulmoji et al., 2000, 2001). The volumetric properties of sucrosein water and in mB (molality of 3-HPAAc) = (0.10, 0.20, 0.30, and0.40) mol kg�1 aqueous 3-HPAAc solutions have been studied attemperatures, T = (293.15–318.15) K, with 5 K interval and at atmo-spheric pressure. Various parameters such as partial molar expan-sion coefficients [(@V2

� /@T)P and second derivatives (@2V2� /@T2)P],

interaction coefficients (YAB and YABB), and hydration numbers, Nw

were also evaluated and analysed in terms of solute–solute and sol-ute–solvent interactions occurring between IL and sucrose. Thetaste behaviour of sucrose in presence of IL has been studied onthe basis of range covered by the apparent specific volume, ASVand apparent specific isentropic compressibility, ASIC parameters.

2. Materials and methods

2.1. Materials

Sucrose (CAS No. 50-99-7, 98%) was purchased from FinarChemical Ltd., India. Acetic acid (CAS No. 64-18-6, P95%) and3-amino-1-propanol (CAS No. 156-87-6, 99%) were purchased fromSigma Aldrich Chemical Co. Sucrose was used as such withoutfurther purification after drying in a vacuum desiccator at roomtemperature for 48 h. The 3-amino-1-propanol and acetic acidwere also used without further purification.

2.2. Synthesis of 3-hydroxypropylammonium acetate

3-Hydroxypropylammonium acetate was synthesised(Chhotaray & Gardas, 2014) by neutralization of equimolar3-amino-1-propanol with acetic acid. The reaction was carriedout with constant stirring, in a two necked round bottom flaskfitted with a dropping funnel (containing acetic acid) and con-denser. Acetic acid was added drop wise into 3-amino-1-propanolat a temperature below 283.15 K. On complete addition of acid, the

resultant mixture was continuously stirred for next 24 h at roomtemperature. The resulting viscous liquid was dried under highvacuum for 2 days at room temperature, so as to remove excessof reactant (if any) and moisture. The newly synthesised proticionic liquid was then stored under nitrogen atmosphere.

2.3. Apparatus and procedure

The simultaneous measurement of density, q, and speeds ofsound, u, of sucrose in water and in mB = (0.10, 0.20, 0.30, and0.40) mol kg�1 aqueous solutions of 3-HPAAc at temperatures,T = (293.15, 298.15, 303.15, 308.15, 313.15 and 318.15) K was car-ried out by using vibrating-tube digital density, and a sound velocitymeter (Anton Paar, DSA 5000 M). The density and sound velocitycells were temperature controlled by a built-in Peltier thermostat(PT-100) having an accuracy of ±0.01 K. Calibration of the instru-ment was done by millipore quality, freshly degassed water anddry air at atmospheric pressure. The uncertainty in the measurementof density is ±7 � 10�3 kg m�3 and for speed of sound is ±0.5 m s�1.

Fresh solutions were made on mass basis in air tight glass vialsby using a Sartorius balance (Model CPA225D), having a precisionof ±0.01 mg. Millipore quality freshly degassed water was used formaking solutions.

3. Results and discussion

3.1. Characterisation of 3-HPAAc

The proton NMR of 3-HPAAc was recorded on Brukar Avance500 MHz spectrometer using deuterated DMSO as solvent. 1HNMR: d = 4.1 ppm (broad, 4H, OH and NHþ3

N), d = 3.45 ppm (t, 2H,CH2AN), d = 2.72 ppm (t, 2H, CH2AO), d = 1.71 ppm (s, 3H, CH3AC),d = 1.60 ppm (qn, 2H, CH2AC)]. IR spectra were recorded on JASCOFT/IR- 4100 spectrometer. The characteristic ammonium peak, m(NAH) and m (OAH) stretching vibration appeared in the range of(3600–2600) cm�1. The characteristic carbonyl, m (C@O) stretchingand d (N-H) plane bending vibrations broad band appeared around1600 cm�1. An Analab Karl Fischer Titrator (Micro AquaCal 100)was used for determining water content of synthesised 3-HPAAcand was found to be �5538 ppm.

3.2. Volumetric properties and taste behaviour

The apparent molar volumes, V2,/ and apparent molar isentro-pic compressibilities, Ks,2,/ of sucrose in water and in (0.10, 0.20,0.30, and 0.40) mol kg�1 aqueous solutions of 3-hydroxypropylam-monium acetate (cosolute) at different temperatures were calcu-lated from the experimentally determined density, q, and speedof sound, u, data by using the following Eqs. (1) and (2):

V2;/ ¼ ½M=q� � ½ðq� qoÞ=ðm � q � qoÞ�; ð1Þ

Ks;2;/ ¼ ðjs �M=qÞ � ½ðj�s � q� js � qoÞ=ðm � q � qoÞ� ð2Þ

where q and qo are the densities of solution and solvent (water orwater + 3-HPAAc), M and m are the molar mass and molality ofthe solute (sucrose), js and js

� are the isentropic compressibilitiesof solution and solvent, respectively. The isentropic compressibili-ties, js were evaluated by using the Eq. (3):

js ¼ 1=u2 � q: ð3Þ

The q, V2,/, u and Ks,2,/ values in water and in aqueous solutionsof PIL at different temperatures are given in Supporting Information(Table S1). The standard uncertainty in V2,/ values resulting fromvarious experimentally measured quantities [u(m) = 5.2�10�6

mol kg�1, u(q) = 7.0�10�3 kg m�3, u(T) = 0.01 K] ranges from (0.108

480 V. Singh et al. / Food Chemistry 169 (2015) 478–483

to 0.033)�106 m3 mol�1 at low (60.05 mol kg�1) and high concen-tration ranges of sucrose, respectively, and the standard uncertain-ties in Ks,2,/ values ranges from (1.21 to 0.37)�10�15 m3 mol�1 Pa�1.The V2,/ and Ks,2,/ values of sucrose in water and in 3-HPAAcaqueous solutions increases with solute (sucrose) concentrationand with temperature. A representative plot for V2,/ versus molal-ity, m, of sucrose in water at different temperatures is shown inFig. 1.

Standard partial molar volumes at infinite dilution (V2� = V�

2,/)and standard partial molar isentropic compressibilities at infinitedilution (K�

s,2 = K�s,2,/) were calculated by least-squares fitting of the

following relation to V2,/ and Ks,2,/ data as Eqs. (4) and (5):

V2;/ ¼ V�

2 þ Sv �m ð4Þ

Ks;2;/ ¼ K�

s;2 þ SK �m ð5Þ

Fig. 1. Plot of apparent molar volumes, V/, versus molalities, m, of sucrose in wat

Table 1Standard partial molar volumes at infinite dilution, V2

� , of sucrose in water and in aqueou

mBa (mol kg�1) V2

� �106 (m3 mol�1

T/K = 293.15 298.15 303.15 3

Sucrose0.00 211.46 ± 0.01b (2.78)c 211.90 ± 0.01 (2.26)

[211.87d, 211.92e,f]212.27 ± 0.02(4.88)

22

0.10 212.05 ± 0.03 (2.58) 212.53 ± 0.01 (2.67) 212.93 ± 0.02(2.64)

2

0.20 212.12 ± 0.01 (1.94) 212.64 ± 0.01 (1.61) 213.06 ± 0.01(2.49)

2

0.30 212.40 ± 0.01 (2.51) 212.86 ± 0.01 (2.04) 213.32 ± 0.01(1.87)

2

0.40 212.49 ± 0.01 (1.42) 212.93 ± 0.01 (1.88) 213.43 ± 0.01(1.69)

2

a mB, molality of 3-HPAAc in water.b Standard deviation.c Sv/m3 kg mol�2.d Banipal, Singh, and Banipal (2010).e Banipal, Chahal, and Banipal (2009).f Banipal, Dhanjun, Sharma, Hundal, and Banipal (2008).

where Sv and SK are respective experimental slopes. The infinitedilution values (V2

� and K�s,2) of sucrose in water and their compari-

son with literature values (Banipal, Chahal, & Banipal, 2009;Banipal, Dhanjun, Sharma, Hundal, & Banipal, 2008; Banipal et al.,2010, 2013; Bernal & Hook, 1986; Hoiland & Holvik, 1978) have beengiven in Tables 1 and 2, respectively.

Infinite dilution partial molar volume can be analysed to under-stand the solute–solvent interactions, as at infinite dilution the sol-ute–solute interactions become negligible and V2

� providesinformation regarding solute–cosolute interactions. The V2

� valuesincrease with IL concentration and temperature, which indicate astrengthening of attractive interactions between 3-HPAAc andsucrose. Magnitude of K�

s,2 values for sucrose in water and in aqueousIL solutions are negative, which further decreases with concentrationof IL and temperature, indicating a reduction in the electrostrictionand as a result more water is released as the bulk water.

er at temperatures, T = (293.15, 298.15, 303.15, 308.15, 313.15 and 318.15) K.

s 3-HPAAc solutions at T = (293.15–318.15) K.

)

08.15 313.15 318.15

12.74 ± 0.02 (5.34) [212.75d,12.70e, 212.72f]

213.10 ± 0.01(5.82)

213.75 ± 0.01 (3.17) [213.80d,213.81e, 213.80f]

13.43 ± 0.02 (3.81) 213.82 ± 0.02(3.25)

214.59 ± 0.03 (3.25)

13.70 ± 0.01 (1.98) 214.11 ± 0.01(2.24)

214.79 ± 0.01 (1.78)

13.82 ± 0.02 (3.11) 214.24 ± 0.01(2.40)

214.93 ± 0.02 (2.74)

13.91 ± 0.01 (2.30) 214.34 ± 0.01(1.96)

215.03 ± 0.01 (2.08)

Table 2Standard partial molar isentropic compressibilities at infinite dilution, K�

s,2, of sucrose in water and in aqueous 3-HPAAc solutions at temperatures, T = (293.15–318.15) K.

mBa (mol kg�1) K�

s,2�10�15 (m3 mol�1 Pa�1)

T/K = 293.15 298.15 303.15 308.15 313.15 318.15

Sucrose0.0 �23.61 ± 0.01b (3.16)c �19.09 ± 0.03 (3.98)

[�18.74d, �18.90e,�17.80f]

�16.52 ± 0.02 (3.34) �15.17 ± 0.04 (2.65)[�15.88d]

�13.68 ± 0.02 (2.26) �12.09 ± 0.02 (2.67)[�12.25d]

0.10 �23.12 ± 0.03 (2.37) �17.78 ± 0.02 (3.28) �15.02 ± 0.02 (4.02) �13.52 ± 0.02 (3.73) �11.64 ± 0.02 (2.32) �9.40 ± 0.01 (3.59)0.20 �21.95 ± 0.03 (2.96) �17.23 ± 0.02 (2.56) �14.45 ± 0.03 (2.20) �12.78 ± 0.04 (2.09) �10.57 ± 0.02 (2.47) �8.35 ± 0.01 (1.96)0.30 �20.57 ± 0.02 (2.50) �15.75 ± 0.03 (3.09) �12.34 ± 0.02 (2.92) �10.67 ± 0.03 (2.27) �8.95 ± 0.01 (1.90) �7.18 ± 0.02 (2.40)0.40 �17.53 ± 0.01 (2.68) �12.62 ± 0.02 (3.68) �9.98 ± 0.03 (2.87) �8.54 ± 0.02 (2.74) �6.75 ± 0.02 (2.13) �4.86 ± 0.02 (2.61)

a mB, molality of 3-HPAAc in water.b Standard deviation.c Sv/m3 kg Pa�1.d Banipal, Singh, Banipal, and Singh (2013).e Bernal and Hook (1986).f Hoiland and Holvik (1978).

0

0.2

0.4

0.6

0.8

1

1.2

1.4

0 0.1 0.2 0.3 0.4mB/mol.kg-1

tVº 2. 10

6 /m3.

mol

-1

Δ

Fig. 2. Plots of standard partial molar volumes of transfer, DtV�2, versus molalities,

mB, of 3-HPAAc of sucrose at temperatures, T = �, 293.15 K; j, 298.15 K; N, 303.15 K;�, 308.15 K, *, 313.15 K, s, 318.15 K.

0

1

2

3

4

5

6

7

8

0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40mB/mol.kg-1

tKº s,

2/1015

. m3.

mol

-1. Pa

-1Δ

Fig. 3. Plots of standard partial molar isentropic compressibilities of transfer, DtK�s,2,

versus molalities, mB, of 3-HPAAc of sucrose at temperatures, T = �, 293.15 K; j,298.15 K; N, 303.15 K; �, 308.15 K, *, 313.15 K, d, 318.15 K.

V. Singh et al. / Food Chemistry 169 (2015) 478–483 481

Standard partial molar volumes of transfer, DtV2� , and standard

partial molar isentropic compressibilities of transfer, DtK�s,2 of

sucrose from water to aqueous solutions of 3-HPAAc were calculatedby using following Eq. (6):

DtX�

2 ¼ X�

2ðin aqueous 3-HPAAc solutionsÞ � X�

2ðin waterÞ ð6Þ

where DtX�

2 ¼ ðDtV�

2 or DtK�

s;2Þ; X�

2 ¼ ðV�

2 or K�

s;2Þ:

The plot of DtV2� versus mB is represented in Fig. 2 and DtK

�s,2

versus mB in Fig. 3. The magnitude of DtV2� and DtK

�s,2 for sucrose

in presence of 3-HPAAc is found to be positive, which increase withcosolute concentration and temperature.

The co-sphere overlap model (Gurney, 1953) can be used tointerpret the magnitude transfer volumes (DtV2

� or DtK�s,2) in terms

of the various interactions occurring in ternary solutions (sucrose +water + 3-HPAAc). The possible types of interactions between soluteand cosolute in ternary solutions are: (1) hydrophilic–ionic interac-tions between the (AOH, AC@O, and AOA) groups of sucrose and theions (ANH3

+, CH3COO�) of IL; (2) hydrophobic–ionic interactionsbetween hydrophobic parts of sucrose and the ionic parts of IL, (3)

hydrophobic–hydrophobic interactions between the hydrophobicgroups of sucrose and IL, (4) hydrophilic–hydrophobic interactionsbetween the hydrophilic groups of sucrose and the hydrophobicparts of 3-HPAAc. According to the co-sphere overlap model(Gurney, 1953), the overlap of hydration co-spheres of hydrophilicsites and ionic species (type 1 interactions) results in positive DtX2

�

values, whereas the overlap of hydration co-spheres of hydrophobicparts and ionic species (type 2, 3 and 4 interactions) results in neg-ative transfer volumes. The positive magnitude of transfer volumesindicates that type 1 interactions predominate over the type 2, 3and 4 interactions. The dominance of type 1 interactions betweensucrose and IL causes the reduction of electrostriction of water mol-ecules in the vicinity of sucrose molecules and consequently contrib-ute positively to DtV2

� and DtK�s,2 values. In presence of 1-butyl-3-

methylimidazolium tetrafluoroborate (IL) positive DtV2� values for

sucrose have been reported in literature (Wu et al., 2009). Similarly,Jin and Chen (2011) also reported positive magnitude of DtV2

� valuesfor sucrose in presence of 1-allyl-3-methylimidazolium chloridesolutions. Positive magnitude of DtV2

� values for sucrose obtainedin these ILs were explained on the basis of the structural interactionmodel and the group additivity model (Jin & Chen, 2011), which alsosuggest the dominance of hydrophilic–ionic interactions between

482 V. Singh et al. / Food Chemistry 169 (2015) 478–483

the cations of ILs and the hydrophilic sites (AOH, AC@O, AOA) ofsucrose.

Shahidi’s Eq. (7) (Shahidi, Ferrell, & Edwards, 1976) can be usedto explain the magnitude of V2

� values as:

V�

2 ¼ Vv:w þ Vvoid � V shrinkage ð7Þ

where Vv.w is the van der Waal’s volume, Vvoid is the associated voidvolume and Vshrinkage, is the volume of shrinkage, caused by theinteractions of hydrogen bonding groups of solute with water mol-ecules. If it is assumed, that Vv.w and Vvoid are not significantlyaffected by the presence of 3-HPAAc, the positive DtV2

� valuesobtained for sucrose may be due to a decrease in the Vshrinkage.

The expansion coefficients, (@V2� /@T)P and its derivative, (@2V2

� /@T2)P were calculated by using the following Eq. (8):

V�

2 ¼ m0 þ m1T þ m2T2; ð8Þ

where m0, m1 and m2 are constants. The expansion coefficient, (@V2� /@T)P

for sucrose in water agrees well with literature values (Banipal et al.,2009, 2010; Bernal & Hook, 1986). The (@V2

� /@T)P values of sucrose inwater and in 3-HPAAc solutions are positive and increase with tem-perature (Supporting Information Table S2). The judgment regardingthe structure-making or structure-breaking ability of an ion in solu-tion can be explained by considering relation suggested by theHepler (1969) as: (@Cp,2

� /@P)T = �T (@2V2� /@T2)P. The positive (@2V2

� /@T2)P values obtained for sucrose in water and in 3-HPAAc aqueoussolutions suggest that sucrose acts as structure maker.

The hydration numbers, Nw, i.e. the average number of watermolecules affected by the presence of solute–solvent interactions,resulting an observable change in physical property of solution,were evaluated using the method reported by Millero, Antonio,and Charles (1978) by using the following relation (9):

Nw ¼ �½K�

s;2 ðelectÞ=ðK�s � V�

1Þ� ð9Þ

where K�s is the compressibility of bulk water or bulk solvent, and K�

s,2

(elect) is the electrostriction partial molar compressibility, V�1 is the

molar volume of bulk water or bulk solvent. The hydration numbers,Nw (Table 3) of sucrose in water agree well with the literature values(Banipal et al., 2013; Gaida, Dussap, & Gros, 2006; Shiio, 1958). Fur-ther, the magnitude of Nw values of sucrose in aqueous 3-HPAAcsolutions are lower as compared to their values in water, which indi-cates an increase in sucrose-IL interactions and thus a reduction inthe electrostriction.

The mechanism of sweet taste chemoreception has beenadvanced by microscopic and macroscopic studies of solute–waterinteractions (Birch, 2002; Birch, Parke, Siertsema, & Westwell,1996). Among these, volumetric properties (apparent specific vol-ume and apparent specific isentropic compressibility) of solutesin aqueous and mixed aqueous solutions have been studied exten-sively (Aroulmoji et al., 2000; Birch, 2002; Birch et al., 1996; Parke

Table 3Hydration numbers, Nw, of sucrose in water and in aqueous 3-HPAAc solutions attemperatures, T = (293.15–318.15) K.

mB (mol kg�1) Nw

T/K = 293.15 298.15 303.15 308.15 313.15 318.15

Sucrose0.00 2.92 2.36

[2.33a,3.80b3.13c,1.30a]

2.07 1.92[2.01a]

1.75 1.55[1.57a]

0.10 2.84 2.21 1.89 1.72 1.49 1.210.20 2.72 2.15 1.83 1.63 1.36 1.080.30 2.56 1.98 1.57 1.37 1.16 0.930.40 2.18 1.59 1.27 1.10 0.87 0.63

a Banipal, Singh, and Banipal (2010).b Shiio (1958).c Gaida, Dussap, and Gros (2006).

et al., 1999; Seuvre & Mathlouthi, 2010). So, an attempt has beenmade to understand the variation in the basic taste quality ofsucrose in water and in presence of 3-HPAAc on the basis of rangecovered by apparent specific volumes, ASVs and apparent specificisentropic compressibilities, ASICs values. The ASVs and ASICs werecalculated by using the following Eqs. (10) and (11):

ASV ¼ V2;/=M ð10Þ

ASIC ¼ Ks;2;/=M ð11Þ

ASVs and ASICs values (data not given) for sucrose in water arein the sweet taste (Parke et al., 1999) range [(v/ = (0.52–0.71 cm3

g�1), K/,m = (�3.383 � 10�7 to �2.335 � 10�5 cm3 g�1 bar�1)].Aroulmoji et al. (2001) have also reported that the ASV of sucrosein aqueous solutions fall in the sweet taste range (0.626 cm3 g�1),suggesting a better fit of sucrose within the structure of water. Inaqueous 3-HPAAc solutions, ASV and ASIC values of sucroseincrease with cosolute concentration as well as with temperature,and fall in the sweet taste range. Similarly, in aqueous sodium ace-tate solutions (Banipal et al., 2013), the magnitude of ASV and ASICfor sucrose falls in the sweet taste range. This suggests that achange in the cationic part of the additive from sodium (Na+) to3-hydroxypropylammonium (+H3N OH), does not influencethe taste behaviour of sucrose, as the anionic part (CH3COO�) isthe same in these additives. Recently, we have also studied(Singh et al., 2014) the effect of protic ionic liquid (3-hydroxypro-pylammonium formate) on the solvation behaviour and taste qual-ity of the monosaccharides D(+)-glucose and D(�)-ribose. Thesestudies suggests the dominance of hydrophilic–ionic interactionsbetween saccharides and IL, resulting in positive transfer parame-ters (DtV2

� and DtK�s,2). However these interactions do not affect the

basic taste behaviour of the saccharide molecules.Volumetric and compressibility interaction coefficients were

calculated from the volume of transfer (DtV2� or DtK

�s,2) based on

the McMillan–Mayer theory of solutions (McMillan & Mayer, 1945)by using the Eq. (12):

DtY�

2 ¼ 2YABmB þ 3YABBm2B ð12Þ

where A and B denotes, respectively, sucrose and 3-HPAAc. Theconstants YAB (VAB or KAB) are pair volumetric interactioncoefficients and YABB (VABB or KABB) are triplet volumetric interactioncoefficients. Pair interaction coefficients, YAB, contributes positivelyand triplet coefficients, YABB, can contribute positively or negatively(Supporting Information, Tables S3 and S4). The pair volumetricinteraction coefficients, VAB, are positive and triplet interactioncoefficients, VABB are negative at all temperatures, whereas paircompressibility interaction coefficients, KAB and triplet coefficients,KABB (Supporting Information Table S3) are positive (except at318.15 K). Overall, the VABB values are small, which indicate thatthe interactions between sucrose and 3-HPAAc are mainly pairwise. Moreover, the positive values for both the VAB and KAB param-eters suggest that interactions occur due to the overlap in hydrationco-spheres of sucrose and ions of 3-HPAAc.

4. Conclusions

The density, q, and speed of sound, u, of sucrose in water and inaqueous solutions of 3-hydroxypropylammonium acetate (3-HPAAc) were measured at temperatures, T = (293.15–318.15) K.The transfer parameters (DtV2

� and DtK�s,2) were calculated from infi-

nite dilution standard partial molar volumes, V2� , and standard partial

molar isentropic compressibility, K�s,2 values. The DtV2

� and DtK�s,2 val-

ues are positive and increases with increasing concentration of IL andtemperature, which indicates the dominance of hydrophilic–ionicinteractions.

V. Singh et al. / Food Chemistry 169 (2015) 478–483 483

The apparent specific volumes, ASV, and apparent specific isen-tropic compressibility, ASIC, parameters of sucrose in water and inaqueous solutions of 3-HPAAc have also been calculated. The ASVand ASIC values are in the sweet taste range, indicating that thepresence of IL does not affect the taste qualities of the studieddisaccharide.

Acknowledgements

Authors are thankful to Council of Scientific and IndustrialResearch (CSIR), India, Department of Science and Technology(DST), India and IIT Madras for their financial support. Dr. Vickram-jeet Singh acknowledges the financial support from CSIR throughhis post-doctoral fellowship.

Appendix A. Supplementary data

Supplementary data associated with this article can be found, inthe online version, at http://dx.doi.org/10.1016/j.foodchem.2014.08.023.

References

Aroulmoji, V., Hutteau, F., Mathlouthi, M., & Rutledge, D. N. (2001). Hydrationproperties and the role of water in taste modalities of sucrose, caffeine, andsucrose–caffeine mixtures. Journal of Agricultural and Food Chemistry, 49,4039–4045.

Aroulmoji, V., Mathlouthi, M., & Birch, G. G. (2000). Hydration properties of Na, K,Mg gluconates and gluconate/sucrose mixtures and their possible taste effect.Food Chemistry, 70, 471–482.

Aroulmoji, V., Mathlouthi, M., Feruglio, L., Murano, E., & Grassi, M. (2012). Hydrationproperties and proton exchange in aqueous sugar solutions studied by timedomain nuclear magnetic resonance. Food Chemistry, 132, 1644–1650.

Banipal, P. K., Chahal, A. K., & Banipal, T. S. (2009). Studies on volumetric propertiesof some saccharides in aqueous potassium chloride solutions over temperaturerange (288.15–318.15) K. The Journal of Chemical Thermodynamics, 41, 452–483.

Banipal, P. K., Dhanjun, H. S., Sharma, S., Hundal, H., & Banipal, T. S. (2008). Effect ofsodium sulphate on the volumetric, rheological and refractometric properties ofsome disaccharides in aqueous solutions at different temperatures. Zeitschriftfür Physikalische Chemie, 222, 177–204.

Banipal, P. K., Singh, V., & Banipal, T. S. (2010). Effect of sodium acetate on thevolumetric behavior of some mono-, di-, and tri-saccharides in aqueoussolutions over temperature range (288.15–318.15) K. The Journal of ChemicalThermodynamics, 42, 90–103.

Banipal, P. K., Singh, V., Banipal, T. S., & Singh, H. (2013). Ultrasonic studies of somemono-, di-, and tri-saccharides in aqueous sodium acetate solutions at differenttemperatures. Zeitschrift fur Physikalische Chemie, 227, 1707–1722.

Bernal, P. J., & Hook, W. A. V. (1986). Apparent molar volumes, isobaric expansioncoefficients, and isentropic compressibilities, and their HD isotope effects forsome aqueous carbohydrate solutions. The Journal of Chemical Thermodynamics,18, 955–968.

Birch, G. G. (2002). Role of water in sweet taste chemoreception. Pure and AppliedChemistry, 74, 1103–1108.

Birch, G. G., Parke, S., Siertsema, R., & Westwell, J. M. (1996). Specific volumes andsweet taste. Food Chemistry, 56, 223–230.

Bordat, P., Lerbret, A., Demaret, J.-P., Affouard, F., & Descamps, M. (2004).Comparative study of trehalose, sucrose and maltose in water solutions bymolecular modelling. Europhysics Letters, 65, 41–47.

Chhotaray, P. K., & Gardas, R. L. (2014). Thermophysical properties of ammoniumand hydroxylammonium protic ionic liquids. The Journal of ChemicalThermodynamics, 72, 117–124.

Conceicao, L. J. A., Bogel-Lukasik, E., & Bogel-Lukasik, R. (2012). A new outlook onsolubility of carbohydrates and sugar alcohols in ionic liquids. RSC Advances, 2,1846–1855.

Delwiche, J. F., Halpern, B. P., & Desimone, J. A. (1999). Anion size of sodium saltsand simple taste reaction times. Physiology & Behavior, 66, 27–32.

Elyasi, M., Khalilzadeh, M. A., & Karimi-Maleh, H. (2013). High sensitivevoltammetric sensor based on Pt/CNTs nanocomposite modified ionic liquidcarbon paste electrode for determination of Sudan I in food samples. FoodChemistry, 141, 4311–4317.

Freire, M. G., Carvalho, P. J., Gardas, R. L., Marrucho, I. M., Santos, L. M. N. B. F., &Coutinho, J. A. P. (2008). Mutual solubilities of water and the [Cnmim][Tf2N]hydrophobic ionic liquids. The Journal of Physical Chemistry B, 112, 604–1610.

Gaida, L. B., Dussap, C. G., & Gros, J. B. (2006). Variable hydration of smallcarbohydrates for predicting equilibrium properties in diluted andconcentrated solutions. Food Chemistry, 96, 387–401.

Gurney, R. W. (1953). Ionic processes in solution. New York: McGraw Hill.Hepler, L. G. (1969). Thermal expansion and structure in water and aqueous

solutions. Canadian Journal of Chemistry, 47, 4613–4617.Hoiland, H., & Holvik, H. (1978). Partial molal volumes and compressibilities of

carbohydrates in water. Journal of Solution Chemistry, 7, 587–596.Jamal, M. A., Khosa, M. K., Rashad, M., Bukhari, I. H., & Naz, S. (2014). Studies on

molecular interactions of some sweeteners in water by volumetric andultrasonic velocity measurements at T = (20.0–45.0 C). Food Chemistry, 146,460–465.

Jin, H. X., & Chen, H. Y. (2011). Volumetric properties for ionicliquid + sucrose + water systems. Journal of Chemical Engineering Data, 56,4392–4395.

Ma, C., Sun, Z., Chen, C., Zhang, L., & Zhu, S. (2014). Simultaneous separation anddetermination of fructose, sorbitol, glucose and sucrose in fruits by HPLC-ELSD.Food Chemistry, 145, 784–788.

McMillan, W. G., Jr., & Mayer, J. E. (1945). The statistical thermodynamics ofmulticomponent systems. Journal of Chemical Physics, 13, 276–305.

Millero, F. J., Antonio, L. S., & Charles, S. (1978). The apparent molal volumes andadiabatic compressibilities of aqueous amino acids at 25 �C. Journal of PhysicalChemistry, 82, 784–792.

Murugesana, S., & Linhardt, R. J. (2005). Ionic liquids in carbohydrate chemistry –Current trends and future directions. Current Organic Synthesis, 2, 437–451.

Parke, S. A., Birch, G. G., & Dijk, R. (1999). Some taste molecules and their solutionproperties. Chemical Senses, 24, 271–279.

Pincu, M., Brauver, B., Gerber, R. B., & Buch, V. (2010). Sugar–salt and sugar–salt–water complexes: Structure and dynamics of glucose–KNO3–(H2O)n. PhysicalChemistry Chemical Physics, 12, 3550–3558.

Ramesh, H. P., & Tharanathan, R. N. (2003). Carbohydrates – The renewable rawmaterials of high biotechnological value. Critical Reviews in Biotechnology, 23,149–173.

Ribeiro, A. C. F., Barros, M. C. F., Lobo, V. M. M., Sobral, A. J. F. N., Fangaia, S. I. G.,Nicolau, P. M. G., et al. (2011). Interaction between calcium chloride and somecarbohydrates as seen by mutual diffusion at 25 �C and 37 �C. Food Chemistry,124, 842–849.

Seuvre, A. M., & Mathlouthi, M. (2010). Solutions properties and solute–solventinteractions in ternary sugar–salt–water solutions. Food Chemistry, 122,455–461.

Shahidi, F., Ferrell, P. G., & Edwards, J. T. (1976). Partial molar volumes of organiccompounds in water. III. Carbohydrates. Journal of Solution Chemistry, 5,807–816.

Shiio, H. (1958). Ultrasonic interferometer measurements of the amount of boundwater. Saccharides. Journal of American Chemical Society, 80, 70–73.

Singh, V., Chhotaray, P. K., & Gardas, R. L. (2014). Solvation behaviour and partialmolar properties of monosaccharides in aqueous protic ionic liquid solutions.The Journal of Chemical Thermodynamics, 71, 37–49.

Swatloski, R. P., Spear, S. K., Holbrey, J. D., & Rogers, R. D. (2002). Dissolution ofcellulose with ionic liquids. Journal of the American Chemical Society, 124,4974–4975.

Tanksale, A., Wong, Y., Beltramini, J. N., & Lu, G. Q. (2007). Hydrogen generationfrom liquid phase catalytic reforming of sugar solutions using metal-supportedcatalysts. International Journal of Hydrogen Energy, 32, 717–724.

Wu, B., Zhang, Y. M., & Wang, H. P. (2009). Volumetric properties and conductivitiesof 1-butyl-3-methylimidazolium tetrafluoroborate + sucrose + water mixtures.Journal of Chemical Engineering Data, 54, 1430–1434.

Wu, B., Zhang, Y., Wang, H., & Yang, L. (2008). Temperature dependence of phasebehavior for ternary systems composed of ionic liquid + sucrose + water. TheJournal of Physical Chemistry B, 112, 13163–13165.

Xu, A., Zhang, Y., Zhao, Y., & Wang, J. (2013). Cellulose dissolution at ambienttemperature: Role of preferential solvation of cations of ionic liquids by acosolvent. Carbohydrate Polymers, 92, 540–544.

Zhang, H., Wu, J., Zhang, J., & He, J. (2005). 1-Allyl-3-methylimidazolium chlorideroom temperature ionic liquid: A new and powerful nonderivatizing solvent forcellulose. Macromolecules, 38, 8272–8277.