Optimization of Oil-in-Water Emulsion Using Coconut Oil with Soy Lecithin or Soy Protein Isolate and the Determination of its Emulsion Stability

Lim, Kenneth Kai Lun (2020) Optimization of Oil-in-Water Emulsion Using Coconut Oil with Soy Lecithin or Soy Protein Isolate and the Determination of its Emulsion Stability. Final Year Project (Bachelor), Tunku Abdul Rahman University College.

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Abstract

Coconut oil in water emulsion with soy lecithin or soy protein isolate as the stabilizer can be utilized as a vegan and organic alternative to some common food products such as whipping cream. However like many other emulsions, the coconut oil in water emulsion might be prone to emulsion instabilities in the form of coalescence, Ostwald ripening, creaming and many more. Therefore, this research is conducted to optimize certain aspects of the emulsion in order to produce a shelf stable emulsion. The comparison between soy lecithin and soy protein isolate as the stabilizer, using different concentrations (1.0%, 2.0%, 3.0%, 4.0%, 5.0%) of stabilizers, and comparing the storage condition in room temperature (25 ˚C) and cold temperature (5 ˚C) is performed by analysing the coconut oil in water emulsion’s creaming index, pH value, microscopic observation of emulsion particles, emulsion droplet size, particle size distribution, and rheology to determine the emulsion stability. The optimized formulation for the emulsion is using 2% soy protein isolate and using cold temperature as the storage condition. This optimized formulation exhibited 0% of creaming index based on both centrifugation method and gravitational method after storing for 7 days at cold temperature (5 ˚C). The pH value was measured at 7.59 ± 0.03 for the fresh sample and 7.12 ± 0.03 after storing at cold temperature for 7 days. The particle size was measured at 2.54 ± 0.07 μm for fresh samples, while the particle size was measured at 2.56 ± 0.06 μm, 2.22 ± 0.05 μm, 2.98 ± 0.01 μm, and 2.90 ± 0.00 μm after 1 day, 3 days, 5 days, and 7 days of cold temperature storage respectively. The particle distribution was reported as span with the measurement of 2.615 ± 0.004 for the fresh sample, 2.582 ± 0.010 after 1 day of cold storage, 2.411 ± 0.122 after 3 days of cold storage, 1.991 ± 0.004 after 5 days of cold storage, and 1.969 ± 0.008 after 7 days of cold storage. This optimized emulsion formulation is a shear-thinning fluid with flow behaviour index of 0.583 and consistency coefficient of 55.005 Pa.sn, where the flow behaviour index is 0.857 and consistency coefficient is 212.961 Pa.sn after storing at cold temperature for 7 days.