- Title
- Maximisation of extraction of phytochemicals from Salacia chinensis L. and encapsulation of its enriched extract
- Creator
- Ngo, Thanh
- Relation
- University of Newcastle Research Higher Degree Thesis
- Resource Type
- thesis
- Date
- 2020
- Description
- Research Doctorate - Doctor of Philosophy (PhD)
- Description
- Salacia chinensis L., a common species in genus Salacia, is distributed in many Asian countries, such as China, Vietnam, India and Sri Lanka. For thousands of years, S. chinensis has been used for the prevention and treatment of various illnesses including arthritis, inflammation, diabetes, obesity and liver disorders. Studies have shown that S. chinensis has relatively high content of bioactive compounds, such as total phenolics and total flavonoids as well as strong antioxidant properties. Numerous individual compounds, isolated and identified from S. chinensis such as mangiferin, catechins, salacinol and kotalanol, have been linked with therapeutic potential against various diseases, such as diabetes and certain common types of cancers. However, the conditions for maximum recovery of bioactive compounds from this plant material have not been thoroughly assessed. In addition, encapsulation to stabilise the extract and make it more available and convenient for further applications has not been conducted previously. Therefore, overall aim of this study was to optimise the conditions for maximum extraction of bioactive compounds from S. chinensis and further encapsulation of its enriched extract to improve the stability. To achieve this overall aim, four specific objectives were addressed as follows: (1) to compare bioactive compounds in different parts of S. chinensis to determine the most suitable part for further extraction of bioactive compounds; (2) to study the impact of different solvents on extraction efficiency of bioactive compounds from S. chinensis to identify the most suitable solvent for further extraction; (3) to optimise conditions for maximum extraction of total bioactive compounds and mangiferin, the major bioactive compound from S. chinensis; and (4) to investigate the optimal encapsulation conditions for improving stability of S. chinensis enriched extract. The results are presented in six research articles through four chapters (chapter 3 to chapter 6). Firstly, we found that the root of S. chinensis had higher levels of phenolics, flavonoids, proanthocyanidins and saponins as well as antioxidant capacity as compared to those of its stem and leaf (Chapter 3). Therefore, the root of S. chinensis was used in subsequent experiments for further extraction and isolation. The impact of different solvents on extraction efficiency of bioactive compounds from S. chinensis root was tested and the results (Chapter 4) revealed that solvents significantly affected extraction efficiency of bioactive compounds from S. chinensis root. Absolute organic solvents and water were found to be ineffective, but 50% ethanol and 50% acetone were effective for extraction of bioactive compounds and antioxidant capacity from S. chinensis root. Mixtures of ethanol or acetone with water were then applied for opimisation of ultrasound assisted extraction (UAE) conditions. Extraction efficiency of UAE was compared with continuous shaking extraction and decoction, which is known as the traditional method for preparation of extracts from S. chinensis. The optimal UAE conditions for maximum extraction of phenolic compounds, flavonoids, proanthocyanidins, and saponins with high antioxidant activities were an ethanol concentration of 50%, extraction time of 60 min, temperature of 50 ºC and ultrasonic power of 250 W; whereas, optimal UAE conditions for maximum extraction of mangiferin were 40% acetone, temperature of 50 ºC, 60 min extraction time, and 250W. In comparison with the two most common conventional extraction methods: decoction and continuously shaking extraction, UAE had comparable extraction yields of total bioactive compounds to continuously shaking extraction, but had significantly higher extraction yields than the decoction method. In addition, UAE could extract 3% and 57% more mangiferin in comparison with continuously shaking extraction and decoction, respectively (Chapter 5). UAE was then employed to prepare the enriched extract for further encapsulation. Encapsulating conditions such as maltodextrin to extract ratio, inlet spraying temperature, and feed rate were found to significantly affect recovery yields of powdered extract and its quality. The optimal conditions for encapsulation were maltodextrin to extract ratio of 20/100 (g/mL), inlet temperature of 130ºC and feed rate of 30% (9 mL/min). In comparison with freeze drying, encapsulation using spray drying produced the powder with comparable contents of total phenolics and mangiferin as well as antioxidant properties (Chapter 6). As it is more cost effective than freeze drying, these conditions are recommended for preparation of S. chinensis extract enriched with bioactive compounds for further applications.
- Subject
- Salacia chinensis L.; phytochemicals; mangiferin; antioxidant; encapsulation; thesis by publication
- Identifier
- http://hdl.handle.net/1959.13/1411330
- Identifier
- uon:36325
- Rights
- Copyright 2020 Thanh Ngo
- Language
- eng
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| Thumbnail | File | Description | Size | Format | |||
|---|---|---|---|---|---|---|---|
| View Details Download | ATTACHMENT01 | Thesis | 22 MB | Adobe Acrobat PDF | View Details Download | ||
| View Details Download | ATTACHMENT02 | Abstract | 575 KB | Adobe Acrobat PDF | View Details Download |