摘要：Ultrasound has been an extraction technique received much attention in recent years. This technique is proven to be able to increase extraction efficiency, shorten extraction time and maintain the activity of antioxidants especially polyphenols. Liquid state of the antioxidant mixture after extraction reduces the application of extracts containing bioactive compounds. This is due to the rapid decline in activity over time and higher transport costs for the liquid extracts with a large amount of water. Therefore, this study was focused on extraction process assisted by microwave to obtain the guava extracts and capsulated these extracts by the suitable carrier to remain the polyphenol activity. It could be seen that microwave was a potential method to extract the polyphenols in comparison with solid-liquid extraction. The cell structure of plant materials was significantly destroyed by microwave in order to release more polyphenols from inner parts of guava leaves. The total phenolic and flavonoid content were increased 12.7% and 36.5% when microwave applied in comparison with the solid-liquid extraction. The combined 20% maltodextrin and 10% arabic gum was the best way to maintain the polyphenol activity. The polyphenols were encapsulated by the combined maltose dextrin and arabic gum was 5.2% more than those of maltodextrin only. Color indices such as L*, a*, b* were significantly different between the powders capsulated by the maltose dextrin and the combined maltose dextrin and arabic gum.
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