13 Nippon Shokuhin Kagaku Kogaku Kaishi Vol. //, No. /,,+/,,- (,**2)

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1 13 Nippon Shokuhin Kagaku Kogaku Kaishi Vol. //, No. /,,+/,,- (,**2) 215 OW WO Attempt at Measuring Thermal Conduction in O/W and W/O Emulsions Prepared by Using Edible-type Emulsifiers during Heating Tamako Mizu and Keiko Nagao Faculty of Home Economics, Tokyo Kasei University, Itabashi, Tokyo +1-20*, An attempt was made to measure thermal conduction in a series of O/W- and W/O-emulsions prepared by using edible-type emulsifiers such as deca-glyceryl mono-fatty acid ester for the O/W samples and sorbitan mono-fatty acid ester for the W/O samples. The size distribution of dispersed globules in prepared emulsions could be characterized as being negatively skewed with the highest frequency diameter being,/. m in O/W systems and -0. m in W/O systems. The emulsions were also characterized as being a plastic body with Casson s yield values in a range of higher concentrations of the dispersed phases. Thermal conductivity of all the emulsions heated in a cylindrical metal vessel was detected along a one-dimensional axis from the heating plane in the sample within a range of +* mm. The increasing temperature vs. heating time curve for all the emulsions tested conformed to an exponential equation as did other foodstu# s based on the assumption that retardation phenomenon plays a significant role in thermal conduction. A power relationship was also found in a double logarithmic plot of the reciprocal of the retardation time in the exponential equation vs. thermal di# usivity of each emulsion sample. (Received Nov. +.,,**1 ; Accepted Feb. 1,,**2) Keywords : edible-emulsifier, emulsion, thermal conduction, thermal di# usivity, plastic flow, Casson s yield value : Casson OW W + 3 O OW +* HLB Hydrophile-Lipophile-Balance ++ OW W ++ +, O *, Corresponding author nagao@tokyo-kasei.ac.jp + + OW HLB

2 216 // /,**2 / 14 Table + Composition of O/W-type and W/O-type emulsions to be tested in this study Dispersed phase Dispersed phase Oil phase Aqueous phase Volume fraction ( ) *4. *4/ *40 *41 *42 *43 +* wt polyglycerin fatty acid ester in aqueous phase konnyaku flour in aqueous phase Volume fraction ( ) *4- *4. *4/ *40 *41 *42 +* wt sorbitan monooleate in oil phase o w OW + Q-+, S HLB +/./ OW HLB OW /* WO +* wt Tadros +. +*. +-. wt OW M BX/+ Win Roof +1 T.K. Mk., +* *** rpm, f *.. *3. OW 0 Table + Casson, WO Span OW WO Span 2* HLB 0. - TVE,* -L WO TVE,* -H,/,.. mm, + -. Casson F, + dg dt +* wt Span 2* N m s +- ml +* *** rpm +2 SMP-,+ EYELA Casson ko F k k d d f *-. *2. k 0 WO +/ +0 Table + JA Daiagnostic SPOT Insight. w o +, +, o + g t +* wt, OW WO

3 15 : 217 Fig. + Cross-section of the devices provided for detecting temperature along the one-dimensional axis ( x axis) in foodstu# s during heating in a metal vessel (Pan broiling) +*, pan broiling boiling - + +*,+,- l kj s m K kj kg K Cp - r kg m, + a -, +* m alc r p,+* +*/ + l +* mm Fig. + +*,* + +.,. kj kg K + +,*. kj kg K + +,. +*,* * * - - kg m rf : kg m t t t - rp : +.** kg m * mm x + - / 1 C AM-1**, K C C X C X C X p pw w pf F ps s f t t W, F, S X x,* +-. kj kg K r fttt T T r+ Xr + expttx i i X,* r : T, T, T f t + *** 3** * * W. t x x t t frying m s Fig. + +,/. p * -

, *1. WO Fig. - Size distributions of the dispersed liquid globules in the freshly prepared O/W-type and W/O-type Fig.

4 218 // /,**2 / 16 Fig., Photomicrographs of the freshly prepared O/W-type and W/O-type emulsions xf t f *. 0-, + + e e :,. 1+2,2 + */. OW WO Fig., *1. WO Fig. - Size distributions of the dispersed liquid globules in the freshly prepared O/W-type and W/O-type Fig. - + m emulsions analyzed by use of the software Win- + m Roof (made by Mitani Syoji) Fig. - OW,/. m, WO -0. m WO OW,/ Casson Fig. /, WO *.. DLVO,1-* OW Fig.. WO WO Casson,0 + +3* s O W Fig. / Casson - Table,

5 17 : 219 Fig.. Correlation between the shear rate and the shearing stress of the O/W-type and W/O-type emulsions. Measured temperature :,/ C. Fig. / E# ect of the volume fraction of O/W-type and W/O-type emulsions on the apparent viscosity + + at low shear rate ranging from +3. s to -2. s and on the Casson s yield value at,/ C l r : *.. : *0. : */. : */. C p w o w o Table, OW a Fig. 0 WO,3 OW OW WO /-. WO Fig.. Fig. / OW WO

6 220 // /,**2 / 18 Table, The measured thermal conductivity and the calculated density, heat capacity at constant pressure of the O/W-type and W/O-type emulsions O/W-type emulsions Volume fraction Thermal conductivity l Heat capacity C Density r p oil phase [kj s m K ] +* [kj kg K ] [kg m ] ( ) Measured Calculated Calculated o *4. *4/ *40 *41 *42 *43 *4.3, *4**0 *4..- *4**0 *4-3* *4**0 *4-.+ *4**- *4,3- *4**1 *4,/2 *4**3-4-, -4+*,422,400,4.*,4,, 30, 3/, 3.- 3, * n0 W/O-type emulsion Volume fraction Thermal conductivity l Heat capacity C Density r p aqueous phase [kj s m K ] +* [kjkg K ] [kgm ] ( ) Measured Calculated Calculated w *4- *4. *4/ *40 *41 *42 *4-,, *4**2 *4-02 *4**1 *4.+- *4**3 *4.0/ *4**- *4/*2 *4**2 *4/02 *4**,,400,422-4+* -4-, -4/ , /, 30, * n0 Fig. 0 E# ect of the volume fraction of dispersed oil (or aqueous) phase on the thermal di# usivity a of the prepared O/W-type and W/O-type emulsions at,* C Fig. 0 0** s *.. OW Fig. 1

7 19 : 221 Fig. 1 Comparison of the curves of increasing temperature detected at * mm ( ), + mm ( ), -mm ( ), / mm ( ), 1 mm ( ), +* mm ( ) from heating plane Fig. 2 Interrelationship between the reciprocal time constant + / t ( x) in Eq. ( 0) and dispersed oil or aqueous phase in O/W-type and W/O-type emulsions at * mm ( ), + mm ( ), - mm ( ), / mm -, ( ), 1 mm ( ), +* mm ( ), respectively from the heating plane. S +.,/ +* [m ]. +-. wt Fig. 1 OW WO. +- Fig. 1 Fig. 1 HLB * mm + mm - mm / mm 1 mm +* mm t x a OW WO Fig. OW 2 a WO OW

8 222 // /,**2 / 20 Table - Values for constant k and n-th power of thermal di# usivity a in Eq 4 ( 0) foodstu# s and method of heating model k, + + n ( x- mm) [m s ] n r* Mayonnaise-type O/W emulsion O/W-type emulsion model W/O-type emulsion model Baking at Frying at Boiling at Steaming at Pan-broiling at - +* *,4** +* *40-0 *43// * 14+/ +* +4-,. *411. -, +** 342* +* +4,,0 *43/. - * +** /40/ +* *43+3 *43*0 -, +*/ 041* +* *40/, *4301 r* Correlation coe$ cient obtained by the method of least squares samples (semi-solid food) : wheat flour dough, rice flour dough, mashed potato, soybean curd, mannan gel +4-2 *43-. *43/ *43,3 * ,/ +4-,2 *4322 WO t x,. St x k a n OW,/. m, WO -0. m -, S +,/. +* m W O x k n a Casson WO OW - n Table - *. 0/, - +* O W n OW *. 3,3 WO +.-,2 OW *3-.. n + Nagao, K. and Matsumoto, S., Preparation of Food Models for Examining Heat Transfer in Cooking under the Control of Moisture, J. Cookery Sci., Japan, -,, +* +1 ( +333). OW, Nagao, K. and Matsumoto, S., Thermal Conduction Along by the One-Dimensional Axis in Food-Stu# s during Heating in a Metal Vessel, J. Home Econ. Japan, WO

9 21 : 223 /,,,.+,.3 (,**+). Estimating the Size Distribution of Oil Globules in - Nagao, K. and Matsumoto, S., Detection of the Thermal Emulsion Type Commercial Foods by Means of a Conduction Induced Close by the Heating Plane in Modified Centrifugal Photo-Sediment-Meter, J. Texture Food-Stu# s during Di# erent Procedures of Heating, J. Stud., /,,3.* ( +31. ). Home Econ. Japan, /., 0,-0-+ (,**-). +2 Casson, N., A Flow Equation for Pigment-Oil Suspen-. Nagao, K. and Matsumoto, S., Retardation Phenomenon sions of the Printing Ink Type, Rheology of Disperse Applied to the Thermal Conduction in Foodstu# s Systems, C.C. Mill ed., (Pargamon Press, London), pp. 2. during a Variety of Heating Procedures, Nihon Reoroji +*. ( +3/3). Gakkaishi ( J. Soc. Rheology, Japan) --, 3- +** (,**/). +3 / pp. +- / // ,**.,* 0, // /1- pp..+ /- +*12 /2*,**.,+ 1 /0 /31-1,2-,3+,**. 0*/,**/ 2,, -2./ /*,**/ ,**/ 3, ,**0 /1,,3,-1,**0 +* OW,. /2 /.+ //+,**1 / /,**1,/ Gopal, E.S.R., Principles of Emulsion Formation, Emulsion ++ Shinoda, K. and Friberg, S.E., Emulsions and Solubilization, Science, Sherman P. ed., (Academic Press, London), (John Wiley, New York), pp. ++ /- ( +320 ). pp., 1/ ( +302). +,,0 3 pp..3 / /+ 3*/ 3+,,*** +- Matsumoto, S. and Sherman, P., A DTA Technique for,1 Verwey, E. J.W. and Overbeek, J. Th. G., Theory of the Identifying the Phase Inversion Temperature of O/W Stability of Lyophobic Colloids, (Elsevier Publishing, Emulsions, J. Colloid Interface Sci., --,,3.,32 ( +31* ). Amsterdam), pp. +-/ +2/ ( +3.2). +. Tadros, T., Leonard, S. and Taelman, M.C., A Surfactant /,2 Dickinson, E., DLVO Biopolymer Stabilizer for Emulsions, Cosmetics and pp.,**,* Toiletries. +,*,.1 /. (,**/).,3 pp. +,. +/ Sherman, P., The Influence of the Emulsifying Agent on the Viscosity of Water-in-Oil Emulsions of High Water -* Content, J. Colloid Sci., +*, 0-1* ( +3// ) ,**- pp. 0, 0. pp.,0*, Matsumoto, S. and Fukushima, S., An Attempt at ,*, 1

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