| Summary: | 碩士 === 國立成功大學 === 化學工程學系 === 103 === Ascorbic acid is a beneficial material; for example, it helps the collagen forming, scavenges free radicals, inhibits the formation of melanin, and evens out skin complexion However, ascorbic acid is easily degraded due to its high reactivity. Therefore, the aim of this study is to develop encapsulating methods of ascorbic acid for delayed oxidation.
In order to prevent ascorbic acid from oxidation, references mentioned that microparticles and emulsion are some methods to storage. Emulsion is good for adsorption but possible demulsification. Microparticles are convenient to transport and have good storage ability but the process more complicated. In this study, microfluidic platform is chosen for fabrication because it only needs tiny amounts of sample and the cost during developing phase can be reduced dramatically. Micro-droplets containing mixture of alginate and ascorbic acid were produced and then the subsequently cured by immersion in calcium chloride solution to form alginate particles. After freeze drying, dehydrated alginate microparticles containing ascorbic acid and coated by oil are obtained. The alginate matrix and oil coating are expected to retard the contact of water and oxygen to ascorbic acid.
To find the condition of high encapsulation ratio and protection ability, different sizes of droplets with different alginate concentrations were fabricated. Moreover, microparticles are stored under room temperature (R.T.) and humidity (R.H.) or 37 oC and 100 % relative humidity (100 % RH) to test their abilities in reduced oxidation of ascorbic acid. From the results, we find that 1 wt% alginate particles prevent ascorbic acid from oxidation and the remained percentage of non-oxidized ascorbic acid is 20 % higher than unprotected powder in R.T.R.H. However, the 1 wt% alginate particles do not prevent well in 37 oC, 100 % RH environment. Therefore, astaxanthin is added in mixture of alginate and ascorbyl acid to help protection. In result, encapsulating ascorbic acid in 1 wt% alginate and 1 mM astaxanthin microparticles considerably delayed the oxidation and remained 43 % more than ascorbyl acid powder in R.T.R.H after one month. In addition, encapsulating ascorbic acid in 1 wt% alginate and 2 mM astaxanthin microparticles delayed the oxidation and remained 20 % more than ascorbyl acid powder in 37 oC, 100 % RH environment.
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