Browsing by Author "Suwimon Ariyaprakai"
Results Per Page
ItemFormation and stability study of flavor oil emulsions stabilized by polyglycerol esters and by sucrose esters(Assumption University, 2016-05) Suwimon AriyaprakaiIn this work, flavor oil emulsions contained 5 wt% oil and 0.75 wt% emulsifier were formulated by using different combinations between flavor oils and food emulsifiers. Orange oil (00), peppermint oil (PO), polyglycerol monostearate (PGE), and sucrose monostearate (SE) were employed to form emulsions by ultrasonic homogenization. Heat stability (storage at 100°C for 30 min) and freeze-thaw stability (storage at -20°C for 22 h. and at 30°C for 2 h.) of emulsions were investigated by observing droplets under a microscope, determining mean droplet sizes, and measuring amounts of destabilized oil. Ostwald ripening stability of emulsions was determined by measuring the droplet size distribution changes over 48 days of storage. The results showed that flavor oil emulsions stabilized by PGE and by SE were heat stable. Interestingly, flavo.r oil emulsions stabilized by PGE had better freeze- thaw stability compared to emulsions stabilized by SE. This property of PGE was suggested from polyglycerol interfacial layers reduced ice crystallization and reduced coalescence. The flavor oil emulsions stabilized by either PGE or SE underwent through Ostwald ripening destabilization and the ripening stability was improved by using mixed emulsifiers between PGE and SE. The information from this study could be useful for creating formulations of flavor oil emulsions that suitable for future applications in foods and beverages.
ItemFreeze–thaw stability of edible oil-in-water emulsions stabilized by sucrose esters and TweensThis work aimed to investigate freeze thaw stability of 20 wt% coconut oil (CtO) and corn oil (CnO)- in-water emulsions stabilized by 1 wt% of various types of sucrose esters and Tweens. Sucrose esters composed mainly of sucrose monostearate (S1670), sucrose monopalmitate (P1670), sucrose monolaurate (L1695), Tween 20 (TW20), Tween 60 (TW60), and Tween 80 (TW80) were used. After all emulsions were frozen at 20 ± 2 C and thawed to room temperature, their stability was analyzed from visual appearance, optical micrographs, amounts of destabilized oil, and average particle sizes. The CtO emulsions stabilized by S1670 and P1670 were very stable, the CtO emulsions stabilized by L1695 partly destabilized, and the CtO emulsions stabilized by TW20, TW60, and TW80 mostly destabilized into oil layers separated on top. The excellent stability of CtO emulsions stabilized by S1670 and P1670 was also confirmed from similar thermograms obtained from differential scanning calorimeter after three cooling–heating cycles (40 C to 40 C to 40 C at 5 C/min). It was proposed here that S1670 and P1670 affected the interfacial fat crystallization and their interfacial layers protected CtO emulsions against partial coalescence. Differently for the case of CnO emulsions, the CnO droplets remained liquid during freezing. All CnO emulsions stabilized by any emulsifiers destabilized by coalescence since these small surfactants could not provide enough interfacial barriers.
ItemInterfacial and emulsifying properties of sucrose ester in coconut milk emulsions in comparison with TweenIn this study, sucrose esters were presented as a promising alternative to petrochemically synthesized Tweens for application in coconut milk emulsions. The interfacial and emulsiﬁer properties of sucrose ester (SE), mainly sucrose monostearate, had been investigated in comparison with Tween 60 (TW), an ethoxylate surfactant. The interfacial tension measurement showed that SE had a slightly better ability to lower the interfacial tension at coconut oilewater interface. These surfactants (0.25 wt%) were applied in coconut milk emulsions with 5 wt% fat content. The effects of changes in pH, salt concentration, and temperature on emulsion stability were analyzed from visual appearance, optical micrograph, droplet charges, particle size distributions, and creaming index. Oil droplets in both SE and TW coconut milk emulsions extensively ﬂocculated at pH 4, or around the pI of the coconut proteins. Salt addition induced ﬂocculation in both emulsions. The pH and salt dependence indicated polyelectrolyte nature of proteins, suggesting that the proteins on the surface of oil droplets were not completely displaced by either added nonionic SE or TW. TW coconut milk emulsions appeared to be thermally unstable with some coalesced oil drops after heating and some oil layers separated on top after freeze thawing. The change in temperature had much lesser inﬂuence on stability of SE coconut milk emulsions and, especially, it was found that SE emulsions were remarkably stable after the freeze thawing.
ItemStability of Orange Oil-in-Water Emulsions Prepared by Multilayer MembranesDue to the small molecular size of orange oil, primary orange oil–in-water emulsion can easily undergo Ostwald ripening destabilization. To improve the stability of orange oil emulsion, multilayer emul- sion was prepared using Citrem as emulsifier and gelatin as coated biopolymer. Firstly, primary emulsion containing 20 wt% orange oil and 0.4 wt% Citrem was produced. Since Citrem was an anionic emulsifier, the primary emulsion had a negative charge of ~ -57mV. Then, the primary emulsion was suspended in 0.5 wt% gelatin aqueous solution at pH 3 with the ratio of primary emulsion to gelatin aqueous solution of 1:1. The gelatin that was positively charged at this pH condition coated around the primary emulsion and double layer emulsion (secondary emulsion) with a ζ-potential value of ~ +20 mV was Produced. The particle sizes of primary and secondary emulsions at various time intervals were detected using a laser diffraction particle analyzer. The results showed that the average particle size (d3,2) of secondary emulsion on the first day was 1.5 (± 0.02) microns and that after storage at room temperature (~25 °C) for 14 days was 1.5 (± 0.02) microns, indicating good emulsion stability. The particle size of the primary emulsion (d3,2) increased from 1.3 (± 0.02) microns to 1.8 (± 0.02) micron, or increased by a factor of 1.4.