Formulation and stability of water-in-virgin coconut oil microemulsion using ternary food grade nonionic surfactants

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1 Interntionl Food Reserh Journl 19: x-x (2012) Formultion nd stility of wter-in-virgin oonut oil miroemulsion using ternry food grde nonioni surftnts 1 Rukmini, A., 2 Rhrjo, S., 2 Hstuti, P. nd 2 Supriydi, S. 1 Deprtment of Food Tehnology nd Nutrition, Fulty of Agriulturl Tehnology, Widy Mtrm University, Ndlem Mngkuumen KT III/237, Yogykrt 55132, Indonesi 2 Deprtment of Food nd Agriulturl Produt Tehnology, Fulty of Agriulturl Tehnology, Gdjh Md University, Bulksumur, Yogykrt 55281, Indonesi Astrt:This study ws intended to otin formultion of wter-in-virgin oonut oil (w/o) miroemulsions nd to determine its stility. The stle w/o miroemulsions were prepred sed on the hydrophili lipophili lne (HLB) onept y using ternry nonioni surftnts omintion hving low, medium, nd high HLB vlues. Miroemulsions were formulted with ternry surftnts mixture onsisting of Spn 80, Spn 20 nd Tween 20 to hieve predetermined HLB vlues of 6.0, 6.5, 7.0, 7.5, nd 8.0. These vlues were susequently used to determine the proportion of wter, surftnt, nd oil to otin miroemulsions. These miroemulsions were sujeted to stility tests whih inlude entrifugtion, heting tretment, nd storge t room temperture. The results indited tht ler w/o miroemulsion ws suessfully formulted ontining 75% of oils portion. It required surftnt nd wter rtio of 4.5:1 or higher. When the miroemulsions were formulted to ontin 77.78% oils, the surftnt nd wter rtio is t lest 5.5 prt or higher. These miroemulsions remined stle during storge, even fter entrifugtion, ut they were not stle when sujeted to heting t 70 ºC or higher. This study onfirmed tht wter-in-virgin oonut oil miroemulsion is otinle nd suitle for rrying hydrophili iotive ompound in food pplition. Keywords: HLB vlue, w/o miroemulsion, virgin oonut oil, nonioni surftnt Introdution Wter-in-oil (w/o) miroemulsion is nno-sle droplets of wter tht re surrounded y oil medium. Aording to Lim (2006), these droplets re stilized y monolyer of surftnt nd/or o-surftnt moleules enveloped round these droplets. Nnodroplets formed when orret ompositions of surftnt, o-surftnt, wter, nd hydroron re mixed in the right sequene. Surftnts re ggregted in polr solvent with their polr heds direted towrd the ore of the ggregtes nd their hydrophoi tils direted outwrd, shielding the inner polr (wter) ore from the nonpolr (oil) medium. The o-surftnt is often required to lower the interfil tension of the interfe etween wter nd oil euse low interfil tension is essentil for produing miroemulsions (Lv et l., 2006). Moreover, the hin length omptiility of the surftnt nd the oil is n importnt ftor regrding the formtion of miroemulsions (Byrk nd Isn, 2005). Miroemulsions re thermodynmilly stle, trnsprent isotropi solutions with prtile sizes rnging from 5 to 10 nm, nd rise from the spontneous self-ssemly of the hydrophoi or hydrophili prts of surftnt moleules (Flngn nd Singh, 2006). Miroemulsions hve found numerous pplitions ut the pplition in foods is limited y the types of surftnts whih re used to filitte miroemulsion formtion. Mny surftnts re not permissile in foods; mny more my only e dded t low levels. Miroemulsion using osurftnts my not e suitle used in foods euse short- or medium-hin lohols n use toxiity nd irrittion (Flngn nd Singh, 2006). Also, osurftnts n led to destrution of miroemulsion upon dilution due to prtitioning of the o-surftnt out of the interfil region into the ontinuous phse (Wrisnoihroen et l., 2000). Severl studies hve resulted in o-surftnt free oil-in-wter (o/w) miroemulsions using nonioni surftnts. Polyoxyethylene n-lkyl ether surftnts hve een extensively studied for prepring o/w miroemulsions without the id of o-surftnts for phrmeutil pplitions (Wrisnoihroen et l., 2000). However, polyoxyethylene ether surftnts, suh s Brij 96, re not food grde (Flngn nd Singh, 2006). Cho et l. (2008) reported tht o-surftnt free of o/w miroemulsion n e formulted y using nonioni surftnt mixtures. They used omintion of hydrophoi (Spn 20, 40, 60, nd 80) nd hydrophili (Tween 20, 40, 60, nd 80) surftnts. *Corresponding uthor. Emil:mr_rukmini@yhoo.o.uk Tel: , Fx: All Rights Reserved

2 60 Rukmini, A., Rhrjo, S., Hstuti, P. nd Supriydi, S. Polyoxyethylene soritn esters (Tweens) hve miniml toxiity nd re ommerilly inexpensive, so they re widely used in food, osmetis, nd phrmeutil pplitions (Yghmur et l., 2002; Cmpo et l., 2004). Miroemulsion ontining Tween 20 in omintion with soritn monolurte (Spn 20) hs een investigted s potentil iotive ompound delivery systems (Lv et l., 2006). Moreover, the omined use of surftnts showed the promise in generting desired self-emulsifying miroemulsions with smll prtile size, inresed iotive ompound loding, nd improved physil stility (Li et l., 2005). This study ws intended to otin wter-in-virgin oonut oil (w/o) miroemulsion sed on the hydrophili-lipophili lne (HLB) onept y using ternry nonioni surftnts omintion hving low, medium, nd high HLB vlues nd to determine their stility. Mterils nd Methods Mterils A freshly prepred virgin oonut oil (VCO) otined from lol VCO produer ws filtered using filter pper in the presene of nhydrous N 2 SO 4 to otin the dehydrted VCO. It ws then used s the ontinuous phse. Low HLB surftnt, i.e. soritn monoolete (Spn 80, HLB = 4.3) nd medium HLB surftnt, i.e. soritn monolurte (Spn 20, HLB = 8.6) were purhsed from Sigm Chemil Compny (St. Louis, MO), nd high HLB surftnt, i.e. polyoxyethylene soritn monolurte (Tween 20, HLB = 16.7) ws purhsed from Merk (Drmstdt, Germny). Deionized wter ws used s the disperse phse. Determintion of HLB vlue of w/o miroemulsion In this study, the miroemulsion systems were prepred with ternry surftnts mixture onsisting of Spn 80, Spn 20 nd Tween 20 to hieve predetermined HLB vlues of 6.0, 6.5, 7.0, 7.5, nd 8.0. Briefly, deionized wter nd omintion of ternry surftnts with rtio of 1:4 (w/w) were mixed on hot-plte stirrer (SRS 710 HA, Advnte, Jpn) t medium speed nd the temperture ws kept t 40 ± 2ºC. After 10 min, dehydrted VCO ws dded dropwise while stirring t high speed. The formtion of miroemulsion system ws hrterized y the presene of ler nd trnsprent solutions. Determintion of wter/surftnt/oil rtio Bsed on the seleted HLB vlue of surftnt mixtures, the rtio of wter/surftnt/oil ws determined. The miroemulsion ws prepred y mixing wter nd omintion of surftnts nd then dehydrted VCO ws dded dropwise s previously desried. The presene of trnsprent miroemulsion mixtures reveled tht the optimum rtio of wter/surftnt/oil ws otined. These miroemulsion smples were llowed to equilirte t room temperture (30 ± 1 C) for t lest 24 h efore further mesurements on visosity, ondutivity, nd interfil tension were performed. The visosity mesurements were tken using Brookfield visosimeter model LVT. The ondutivity mesurements were tken with ondutivity proe (Vernier Con-BTA) nd the drop method ws used to perform the interfil tension mesurements. Stility test of w/o miroemulsion The stility of miroemulsions during storge t room temperture nd under extreme onditions ws exmined ording to Cho et l. (2008). All of the miroemulsions (10 g) smples were stored in disposle onil tues. Miroemulsions stility ws routinely monitored y turidity mesurements every two weeks t room temperture (30 ± 1 C). Stility tests under extreme ondition were onduted y sujeting the miroemulsion smples to the heting or entrifugtion test. For the heting stility test, 10 g miroemulsions were sujeted to mild up to high temperture ( C) for 5 h in drying oven (MOV-112, Snyo, Jpn). For the entrifugtion stility test, 10 g miroemulsions were entrifuged t 2,300 g for 15 min in entrifuge (EBA 3S Hettih, Germny). After the heting stility test or entrifugtion test, the miroemulsion ws monitored y visul inspetion, nd turidity mesurement using UV/Vis spetrophotometer (UV-1650 PC, Shimdzu, Jpn). Smples were put into qurtz uvettes with pth length of 1 m nd ll mesurements were oserved t wvelength of 502 nm. The turidity ws lulted s desried y Flether nd Morris (1995). Sttistil nlysis The dt were represented s the men vlue of three replites. Signifint differenes (P < 0.05) etween mens were determined using Dunn s multiple rnge tests. Results nd Disussion Interntionl Food Reserh Journl 19: 59-66

3 Wter-in-virgin oonut oil miroemulsion 61 Suitle HLB vlue for w/o miroemulsion The wter-in-vco miroemulsions in this study ws prepred y using surftnts omintion whih mthes the ftty id of the VCO, hving low, medium, nd high HLB vlue. It ws onduted euse of hoosing surftnt mixtures whih is the est mth with the oil nd proper HLB is mong neessry onditions for miroemulsion formtion. The HLB is one of the most ommon methods to orrelte surftnt struture with their effetiveness s emulsifiers. The HLB vlue indites how the surftnt will ehve in solution (Pilemnd, 2002) nd it s losely relted to its pility to soluilize sustnes (Kruglykov, 2000). Aording to Flngn nd Singh (2006), the surftnt, lso lled emulsifier or mphiphili ompound, plys n importnt role in miroemulsion formtion y reduing the interfil tension. They lso reported tht the surftnts mixture inresed the soluility of the iotive ompound in the miroemulsion. Moreover, the hemil struture of surftnt must e onsidered euse the hin length omptiility of surftnt nd oil is n importnt ftor in the formtion of miroemulsion (Byrk nd Isn, 2005; Fnun, 2009). The omintion of high nd low HLB vlues of surftnts provides the neessry onditions for the formtion of stle w/o miroemulsion (Osorne et l., 1988; Pilemnd, 2002; Grti et l., 2005; Li et l., 2005; Cho et l., 2008). It ws found tht the w/o miroemulsion formed only t the HLB vlue of 7.0 whih ws omposed of 16.6% of Tween 20, 15.0% of Spn 20, nd 68.4% of Spn 80. The trnsprent pperne of the w/o miroemulsion using surftnts hving the HLB vlue of 7.0 ws seleted for further experiments. Optimum formul of w/o miroemulsion The miroemulsion system n e formulted y pproprite proportions of wter, surftnts, nd oil. In order to determine the optimum formul of wter-in-vco miroemulsion, the omintions of wter/surftnts/vco t vrious rtios were prepred (Tle 1). Trnsprent w/o miroemulsions were formed when the rtios of wter nd surftnts mixture were of t lest 1:4.5. Upon ddition of dehydrted VCO s the ontinuous phse, ler pperne of the miroemulsions were otined when the rtio of wter/surftnt mixture nd VCO ws 1:3 (the system ontining 75% of VCO) s indited in formule 5, 6, 7, nd 8. However, when the VCO ws dded t higher rtio (i.e. 1:3.5 or 77.78%), trnsprent w/o miroemulsion ws not hievle s indited y formule 9 nd 10. The higher proportion of VCO ddition ould only form ler miroemulsions when the rtio of wter nd surftnts mixture ws lso inresed to 1:5.5 or higher s indited in formule 11 nd 12. Formul Tle 1. Evlution of wter-in-virgin oonut oil miroemulsion formultion Rtio of wter/surftnts (w/s) Rtio of (w/s) : VCO Apperne 1 1 : : 3 Cloudy 2 1 : 2 1 : 3 Cloudy, seprte phse 3 1 : 3 1 : 3 Cloudy, seprte phse 4 1 : 4 1 : 3 Cloudy 5 1 : : 3 Trnsprent 6 1 : 5 1 : 3 Trnsprent 7 1 : : 3 Trnsprent 8 1 : 6 1 : 3 Trnsprent 9 1 : : 3.5 Cloudy 10 1 : 5 1 : 3.5 Slightly loudy 11 1 : : 3.5 Trnsprent 12 1 : 6 1 : 3.5 Trnsprent 13 1 : 4 1 : 4 Slightly loudy 14 1 : 5 1 : 4 Slightly loudy 15 1 : 6 1 : 4 Slightly loudy The formule of 1, 2, 3, nd 4 ould not form miroemulsions system euse of insuffiient surftnts in the systems. Aording to Ptel et l. (2009), the onentrtion of surftnts must e high enough to provide the numer of surftnt moleules needed to stilize the mirodroplets to e produed y n ultrlow interfil tension (< 10-3 mn/m). Moreover, the mixed surftnt hving low nd high HLB vlue ws le to ridge the hydrophili/lipophili gp etween the wter nd the oil phses, produing miroemulsions with sustntil soluiliztion nd ultrlow interfil tension. It ws very importnt to promote the formtion of miroemulsion system hving dimeter of the droplets in the rnge of nm. Besides the surftnts hving low nd high HLB vlue, we lso used surftnt with medium HLB vlue. Aording to Frierg nd Chiu (1992), the ehvior of the nonioni surftnt depended on the length of its polr hin. With low numer of oxyethylene groups, the nonioni surftnt ted s powerful osurftnt nd stilized the lmellr liquid rystl in the system. Thus, y omining these surftnt moleules, the intertion of the surftnt with wter nd oil provide more effiient wy to ridge the hydrophili-lipophili gp etween the surftnt nd wter or oil thn using single surftnt moleule. Aording to Hit nd Moulik (2002), in w/o Interntionl Food Reserh Journl 19: 59-66

4 62 Rukmini, A., Rhrjo, S., Hstuti, P. nd Supriydi, S. miroemulsion ontining osurftnt, the wter phse is linked with the oil y monolyer t the interfe. On the other hnd, the osurftnt essentilly prtitions etween the oil phse nd the interfil region. It my even modertely or wekly prtition etween the wter phse nd the interfe s well. In this study, the surftnt hving medium HLB vlue ted s osurftnt. This ternry system ws expeted to produe stle w/o miroemulsion. However, w/o miroemulsion n e destilized y extr ddition of oil to mke it nonhomogeneous nd turid or loudy. To stisfy prtition requirement there is depletion of surftnt t the oil-wter interfe. Higher ddition of the surftnt helped to restore the system to renewed stte of thermodynmi equilirium (De et l., 2010). These phenomen were lerly indited in formule 5, 6, 7, 8, 9, 10, 11 nd 12. Eonomilly, the use of lrge mount of surftnts is onsidered ineffiient. A higher level of surftnt ddition my lso result in disturne on sensory properties of the produts. Consequently, the trnsprent systems otined from the formule of 5, 6, 7, 8, 11, nd 12 were seleted nd used for further experiment nd were oded A, B, C, D, E, nd F. Chrteristi of w/o miroemulsion Aording to Flngn nd Singh (2006), miroemulsion hrteriztion n e divided into two min res, i.e. hrteriztion t the mirosopi nd mrosopi levels. The visosity, ondutivity, nd interfil tension (Tle 2) represented the mrosopi level mesurements. Tle 2. Physil hrteristi of wter-in-virgin oonut oil miroemulsions Formul Visosity (p) Chrteristi *) Condutivity (µs/m) Interfil tension (dyne/m) A ± ± ± 0.38 d B ± ± ± 0.00 C ± ± ± 0.00 D ± ± ± 0.62 E ± ± ± 0.39 f F ± ± ± 0.20 e Tle 2 indited tht ll of the miroemulsion formule hd no signifint (P > 0.05) differene on visosity nd ondutivity. However, the interfil tension signifintly (P < 0.05) deresed on inresing the surftnt mixtures rtio. Lim (2006) sid tht visosity or ondutivity n e used to detet the miroemulsion struturl hnges. Grti et l. (2005) reported tht visosity depends lrgely on the miroemulsion struture, i.e., the type nd shpe of ggregtes, onentrtion nd intertion etween dispersed prtiles. The ondutivity depends not only on droplet size ut lso on men droplet-to-droplet distne or droplet onentrtion (Bumjdd nd Estoe, 2004). Aording to Grí-Río nd Hervell (2007), the ondutivity of w/o miroemulsion is losely relted to the rte of mss trnsfer etween droplets. Referring to the sid studies, this result indited tht vrious surftnt mixtures rtio did not impt on miroemulsion struture ut ffeted the intertion etween wter nd oil whih ws reognized y interfil tension mesurement. Interfil tension is the surfe tension used y intermoleulr intertions t the surfe seprting two immisile fluids (Rosen, 1989). Under pproprite onditions the miroemulsion system is misile with oth the oil nd wter phses. However, the miroemulsion system prtitions into three phses, surftnt-rih phse, surftnt-rih wter phse, nd surftnt-rih oil phse. The surftnt-rih phse is lled middle phse miroemulsion. It is in the middle phse miroemulsion tht surftnt shows the gretest soluilizing power for oth wter nd oil; here it lso gives ultr smll vlues of interfil tension etween oil nd wter under proper ondition. For this reson, inresing surftnt mixtures rtio in this study ould result in deresing interfil tension. As reported y Cho et l. (2008), the surftnt mixtures were more effetive in lowering interfil tension thn the individul surftnt. They lso reported tht lowering interfil tension ws relted to higher storge stility. Stility of w/o miroemulsion The stility of w/o miroemulsion n e evluted y mesuring its turidity hnges during storge t room temperture nd under elerted (extreme) ondition s shown in Tle 3 nd Figure 1. The turidity is the most ommon wy to mesure the stility of miroemulsion euse it s proportionl to the verge prtile dimeter (Cho et l., 2008). Thus, the turidity hnges n e used to derive hnges in the prtile volume resulting from either lustering or growth of the miroemulsion droplets, Interntionl Food Reserh Journl 19: 59-66

5 Wter-in-virgin oonut oil miroemulsion 63 nd to otin informtion on stility hnges. Tle 3. Stility of wter-in-virgin oonut oil miroemulsion fter entrifugtion, heting, nd storge t room temperture Formul A B C D E F Turidity Index (%) *) Untreted After entrifugtion After heting t 60ºC -0.09± ± ± ± ± ± ± ± ± ± ± ±0.01 After 1 month storge t room temperture After 2 months storge t room temperture -0.17± ±0.00 d 0.14±0.00 e -0.16± ±0.01 d 0.09±0.01 e -0.18± ±0.01 d 0.14±0.00 e -0.08± ±0.01 d 0.10±0.01 e -0.14± ±0.01 d 0.08±0.01 e -0.15± ±0.01 d 0.09±0.00 e Note: *): verge of three replites Different letters in the sme row indite signifint differene (P<0.05) () () () Figure 1. Turidity index hnges fter entrifugtion (), fter heting t 60ºC (), nd untreted () wter-in-virgin oonut oil miroemulsion formule A, B, C, D, E, nd F during storge t room temperture (30 ± 1ºC) Tle 3 shows tht the turidity deresed fter heting, slightly inresed fter entrifugtion, nd gretly inresed fter 1 month storge t room temperture. In this study, the heting test ws performed under mild to high temperture (60-105ºC) for up to 5 hours nd the entrifugtion test ws onduted t 2,300 g for 15 min. The negtive vlues of turidity index indited tht the smples hve lerer pperne s ompred to the referene (distilled wter). This study indited tht t the mild temperture (60ºC), ll of miroemulsions remined stle. They were still trnsprent fter heting, nd it ws even lerer thn tht of untreted smples. However, they were unstle when heted t 70ºC or higher whih resulted in phse seprtion. The phse seprtion ould e due to the hnges in nonioni surftnts struture whih re likely to our during heting. Aording to Flngn et l. (2008), the hed-group size of nonioni surftnts in prtiulr is ffeted y hnges in temperture, therey indiretly ffeting their ility to soluilize oil. This study onfirmed tht the wter-in-vco miroemulsions were only suitle for food pplition involving mild heting. To evlute the physil stility of miroemulsions during storge, ll the smples were stored t room temperture (30 ± 1ºC) for up to 2 months fter heting or entrifugtion tretment. Visul oservtion indited tht ll of the miroemulsions did not suffer from signifint hnges in their pperne over the storge period. However, there were slight inreses in their turidity index, espeilly in the het treted miroemulsions (Figure 1). As explined efore, this ould e euse the nonioni surftnts were ffeted y heting nd resulted in hnges in their hed-group size (Flngn et l., 2006). However, the rte of inresing the turidity index of miroemulsions during storge t room temperture ws reltively negligile. Aording to Li et l. (2005), s opposed to the single surftnt, omined use of surftnts might hve provided etter surftnts HLB. As result, it enhned the flexiility of the surftnt lyer tht ws formed. It lso enhned the surftnts ility to prtition t higher levels into the wter-oil interfe, oth of whih stilized the miroemulsion system. This ws the reson for its stilizing effet on the wter-in-vco miroemulsion during storge, even fter entrifugtion or heting t mild temperture. Although there were signifint differenes (p<0.05) on the turidity index (Tle 3), ll of these smples hd trnsprent pperne (Figure 2). Aording to Cho et l. (2008), the miroemulsion with trnsprent pperne nd turidity vlue of less thn 1% ws defined s stle miroemulsion. Thus, ll of the miroemulsion formule in this study ould e delred s stle miroemulsions nd re suitle Interntionl Food Reserh Journl 19: 59-66

6 64 Rukmini, A., Rhrjo, S., Hstuti, P. nd Supriydi, S. for further food pplitions. () New formul () After 2 months storge t room temperture (30 ± 1 ºC) Conlusion After entrifugtion () Stle w/o miroemulsions ould e otined y utilizing ternry nonioni surftnts omintion with the following proportion: 16.6% of Tween 20, 15.0% of Spn 20, nd 68.4% of Spn 80. Trnsprent w/o miroemulsion n only e formed when the rtio of wter nd surftnts ws t lest 1:4.5 nd the rtio of wter/surftnts nd VCO ws not more thn 1:3.5. These miroemulsions hd no signifint (P > 0.05) differene on their visosity nd ondutivity, ut their interfil tension signifintly (P < 0.05) deresed with the inresing level of surftnt mixtures proportion. All of the miroemulsions remined stle during storge t room temperture, ut they were not stle when sujeted to heting t 70 ºC or higher. Aknowledgement This reserh ws finnilly supported y the Disserttion Reserh Grnt for the Dotorte Degree in 2010 from the Diretorte Generl of Higher Edution, the Ministry of Ntionl Edution Repuli of Indonesi. After heting t 60 ºC Interntionl Food Reserh Journl 19: 59-66

7 Wter-in-virgin oonut oil miroemulsion 65 Referenes Byrk, Y. nd Isn, M Studies on the phse ehvior of the system non-ioni surftnt/lohol/lkne/ H2O. Colloids nd Surfes A: Physiohemil Engineering Aspets 268: Bumjdd, A. nd Estoe, J Condutivity of mixed surftnt wter-in-oil miroemulsions. Physil Chemistry nd Chemil Physis 6: Cmpo, I., Yghmur, A., Grti, N., Leser, M. E., Folmer, B., nd Gltter, O Five omponent food-grde miroemulsions: struturl hrteriztion y SANS. Journl of Colloid Interfe Siene 274: Cho, Y. H., Kim, S., Be, E. K., Mok, C. K. nd Prk, J Formultion of osurftnt-free o/w miroemulsion using nonioni surftnt mixtures. Journl of Food Siene 73(3): E115-E121. Constntinides, P. P. nd Slrt, J. P Formultion nd physil hrteriztion of wter-in-oil miroemulsions ontining long- versus medium-hin glyerides. Interntionl Journl of Phrmeutis 158: De, M., Bhtthry, S. C., Moulik, S. P. nd Pnd, A. K Interfil omposition, struturl nd thermodynmi prmeters of wter/(surftnt+nutnol)/n-heptne wter-in-oil miroemulsion formtion in reltion to the Surftnt Chin Length. Journl of Surftnts nd Detergents 13: Fnun, M Miroemulsions : properties nd pplitions. CRC Press, New York. Flngn, J. nd Singh, H Miroemulsions: potentil delivery system for iotives in food. Critil Reviews in Food Siene nd Nutrition 46: Flngn, J., Kortegrd, K., Pinder, D. N., Rdes, T. nd Singh, H Soluilistion of soyen oil in miroemulsions using vrious surftnts. Food Hydroolloids 20: Flether, P. D. I. nd Morris, J. S Turidity of oil-inwter miroemulsion droplets stilized y nonioni surftnts. Colloids Surftnt A: Physiohemil Engineering Aspets 98: Frierg, S. E. nd Chiu, M Phse digrms of wter nd sodium dodeyl sulfte omined with four ommeril nonioni surftnts. Journl of the Amerin Oil Chemist Soiety 69(7): Grí-Río, L. nd Hervell, P Applition of the pseudophse ion-exhnge model to retivity in qurternry wter in oil miroemulsions. New Journl of Chemistry 31: Grti, N., Spernth, A., Aserin, A. nd Lutz, R Nno-sized self-ssemlies of nonioni surftnts s soluiliztion reservoirs nd miroretors for food systems. Soft Mtter 1: Hit, S. K. nd Moulik, S. P Interfil omposition nd thermodynmis of formtion of wter/isopropyl myristte wter-in-oil miroemulsions stilized y utn-1-ol nd surftnts like etyl pyridinium hloride, etyl trimethyl mmonium romide, nd sodium dodeyl sulfte. Lngmuir 18: Kruglykov, P. M Hydrophile-Lipophile Blne of surftnts nd solid prtiles: physiohemil spets nd pplitions, First edition. Elsevier Siene B.V,.Amsterdm, Netherlnds. Li, P., Ghosh, A., Wgner, R. F., Krill, S., Joshi, Y. M. nd Serjuddin, A. T. M Effet of omined use of nonioni surftnt on formtion of oil-inwter miroemulsions. Interntionl Journl of Phrmeutis 288: Lim, W. H Phse digrm, visosity nd ondutivity of α-sulfonte methyl esters derived from plm sterin/1-utnol/lkne/wter systems. Journl of Surftnts nd Detergents 9(4): Lv, F. F., Zheng, L. Q. nd Tung, C. H Studies on the stility of the hlormphenil in the miroemulsion free lohols. Europen Journl of Phrmeutis nd Biophrmeutis 62: Osorne, D. W., Middleton, C. A. nd Rogers, R. L Alohol-free miroemulsions. Journl of Dispersion Siene Tehnology 9: Ptel, M.R., Ptel, R. B., Prikh, J. R., Bhtt, K. K. nd Kundwl, A. J Miroemulsion : s novel drug delivery vehile. html on 1/1/2009. Pilemnd, C Surftnts: Their ilities nd importnt physio-hemil properties. Arejdsmiljøinstituttet, Køenhvn. Rosen, M. J Surftnts nd interfil phenomen, 2nd edn. Wiley, Cnd, pp Wrisnoihroen, W., Lnsley, A. B. nd Lwrene, M. J Nonioni oil-in-wter miroemulsions: the effet of oil type on phse ehvior. Interntionl Journl of Phrmeutis 198: Yghmur, A., Aserin, A. nd Grti, N Phse ehvior of miroemulsions sed on food-grde nonioni surftnts: effet of polyols nd short-hin lohols. Colloids nd Surfes A: Physiohemil Engineering Aspets 209: Interntionl Food Reserh Journl 19: 59-66