| Summary: | 碩士 === 國立海洋大學 === 食品科學系 === 87 === The objectives of the study are to explore the effects of using water-soluble chitosan obtained by microfluidizing treatment in W/O/W multiple emulsion lotions which carry the lactic acid and vitamin E. The study includes 1. To determine the changes of molecular weight and degree of deacetylation of water-soluble chitosan with conditions and cycles of microfluidization treatment, 2. To explore the effect of adding water-soluble chitosan on the yield, stability, and average droplet size of the W/O/W multiple emulsion prepared. 3. To explore the rheological properties, skin moisture content, pH value and safety of W/O/W multiple emulsion lotion containing water-soluble chitosan. The results obtained are:
The molecular weight of water-soluble chitosans obtained by microfluidizier treatment for 1, 3 and 7 cycles are 1.75 x 106, 1.35 x 106 and 1.00 x 106 Dalton respectively. Degree of deacetylation are around 75%.
The yield of W/O/W multiple emulsion containing water-soluble chitosan is higher than that containing xanthan gum and the yield of preparation increased with increasing molecular weight of water-soluble chitosans used. But the stability of the W/O/W multiple emulsion lotions containing water-soluble chitosans are less than that containing the xanthan gum. The average droplet size were between 2- 4μm. The average droplet of the lotions containing water-soluble chitosan of 1.79 x 106 Dalton are smaller than that prepared from the other two molecular weight water-soluble chitosans.
All the lotions prepared in the studies were pseudoplastic fluids. The pseudoplastic characteristic of the lotions such as shear thinning properties were more pronounced for those lotions containing xanthan gum in the external phase than that containing water-soluble chitosan . The apparent viscosity of the multiple emulsion is mainly affected by the changes of viscosity of the external continuous phase, and is less affected by the changes of the viscosity of the internal phase. The viscosity of the lotion containing xanthan gum in the external phase is higher than that containing water-soluble chitosan. The apparent viscosity of the lotion increased with increasing molecular weight of the water-soluble chitosan in the external continuous phase.
Skin moisture content were higher for those lotions containing the water-soluble chitosan in the inner and/or external phase than that containing xanthan gum. Lotions containing W/O/W multiple emulsion carry lactic acid and vitamin E are a long last moisturizer. The effect of molecular weight of the water-soluble chitosan on skin moisture content become no significant different as the water-soluble chitosan was added in the inner phase. However skin moisture content increased with increasing molecular weight of the water-soluble chitosan added in the external phase at the first 40 minute after applying the lotion. Skin moisture content were independent to the molecular weight of water-soluble chitosan used after 40 minute.
Decreasing of the skin pH value was lower for the W/O/W multiple emulsion lotions containing water-soluble chitosan in the inner and/or the external phase than that containing xanthan gum as control. The effect of molecular weight of the water-soluble chitosan used on skin moisture content was not significant. Decreasing of the skin pH value was the lowest for those W/O/W multiple emulsion lotions containing water-soluble chitosans in the inner and the external phase. It may due to the protonation of water-soluble chitosan in acidic solution which alleviated the decrease in free hydrogen ion resulted in less pH lowering of the lotion therefore less lowering in the skin pH value.
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