Interfacial and emulsifying properties of sucrose ester in coconut milk

emulsion in comparasion with tween

Suwimon Ariyaprakai, Tanachote Limpachoti, Pasawadee Pradipasena

-Thailand-

IntroductionCoconut Milk Food emulsion

Improve stability??

Adding additional surfactant

Example of surfactant:1. Tweens2. Sodium dodecyl

sulfate3. Sucrose esters

Aim of reasearch:Understanding the relationship between interfacial properties and stability of coconut milk emulsions after addition of sucrose ester and tween 60.

Comparasion structure of sucrose monostearate and ethoxylated sorbitan monostearate (tween 60)

• Comparative interfacial properties and emulsifier properties between SE and TW

• Difference between carbohydrate and ethoxylate headgroups

Material and Methods

Material: Sucrose ester (50-53% sucrose monostrearate, 18-

20% sucrose disterate, 12-14% sucrose dipalmitate, 5-10% sucrose alkylate) Mitsubishi Kagaku Food Corp.

Tween 60 (Polyoxyethylene sorbitan monostearate) Sigma

Coconut oil & Soybean oil Tropicana OilGround coconut meat purchased locally

Material and Methods (continued)

Coconut Milk Emulsion Preparation

Minced ground coconut meat(1)

mixed

Distilled water (2)

Pressed & filtered

Coconut milk

Solid residue

mixed

Distilled waterOr

Surfactant aqueous solution (0.25 wt%)

Homogenized(11.200 rpm, 3 min)

Sodium azide 0.02 wt%

1. Coconut milk (B)2. Coconut milk (SE)3. Coconut milk (TW)

Measurement• Coconut oil-water interfacial tension

measurement digital tensiometer at 25o C• Measurement of emulsion properties Droplet size measurement Laser diffraction particle size

analyzer Zeta-potential measurementParticle electrophoresis

instrument Optical MicroscopyStandard optical microscope Visual appearance and creaming index measurement photo

• Coconut milk emulsion stability Emulsion stability against pH and salt concentration Emulsion thermal stability

Material and Methods (continued)

Coconut oil-water interfacial behavior

• Minimum interfacial tension SE < 2 mN/mto small better ability than TW in reducing oil-water interfacial tension

• Minimum interfacial tension TW 8 mN/m

All types of emulsions appeared as white creamy emulsions

Emulsion thermal stability

• All types of emulsions appeared coagulated white solid particles denatured proteins (lesser in 100 C)

• Extra population of emulsion population

• SE surfactant more heat stable than TW surfactant

No oil layer on SE coconut milk

Particle size TW<SE<kontrol

• solid substance in optical micrographs

• SE and TW still small droplets but control became large coalesced oil drops

SE emulsifier revealing good emulsion stability

Emulsion thermal stability (continued)

Emulsion thermal stability (continued)

Emulsion thermal stability (continued)

Presence sucrose made coconut milk SE most stable after freeze thaw

Emulsion thermal stability (continued)

Emulsion stability against pH and salt concentrations

Emulsion stability on pH (continued)

Zero droplet charge flocculated

Emulsion stability on pH (continued)

Higest creaming index at pH 4, because zero droplet charged

Creaming index SE lowest beneficial as creaming stabilizer

Emulsion stability on pH and salt (continued)

Emulsion sensitive with salt

Conclusion

• SE slightly better in lowering interfacial tension between coconut oil and water interface

• SE were more thermally stable than TW