- Title
- Recovery of bioactive compounds from Robusta coffee pulp waste (Coffea canephora) and encapsulation of its phenolic-enriched extract
- Creator
- Tran, Thy Minh Kieu
- Relation
- University of Newcastle Research Higher Degree Thesis
- Resource Type
- thesis
- Date
- 2023
- Description
- Research Doctorate - Doctor of Philosophy (PhD)
- Description
- Coffee pulp accounts for up to 30% of the coffee cherry weight and it is a major by-product generated during coffee bean preparation. Coffee pulp waste is generated when using wet or dry techniques. Wet coffee pulp has a high moisture content (>75%), so it is susceptible to rapid degradation due to microbial growth, which leads to challenges in further utilisation and environmental problems. Previous studies revealed that coffee pulp is a great source of pectin, fibre, phenolic compounds and caffeine. However, there is limited utilisation of coffee pulp as the waste has been typically discarded in landfills. The overall aim was to establish optimal drying and extraction conditions for bioactive compounds from wet coffee pulp. The components can then be encapsulated to produce a functional powdered extract for later use as a functional ingredient. The results showed that drying conditions significantly affected stability of bioactive compounds as water was removed from the wet coffee pulp. The most suitable condition for drying was identified as vacuum drying at 110 °C with a vacuum pressure of 55 mbar. Under this drying condition, most bioactive compounds could be retained in the dried coffee pulp, and pulp dried using this method was used for further extraction. The results indicated that extraction conditions significantly affected extractability of bioactive compounds. Optimal aqueous condition was found to be at a temperature of 100 °C, time of 60 min, and ratio of solid to solvent of 1: 100 g/mL. Under this condition, the aqueous extraction was more effective than organic solvent extraction. However, the results showed that ultrasonic assisted extraction (UAE) and microwave assisted extraction (MAE) were more effective to extract bioactive compounds from coffee pulp in comparison to the optimal aqueous extraction. The optimal UAE was identified to be time of 35 min, temperature of 60 °C, and power of 250 W, whereas the optimal MAE was radiation time of 85 min, sample to solvent ratio of 1:100 g/ mL, ethanol concentration 42.5 % (v/v), and MAE system power of 1000 W. MAE was more effective than UAE as more bioactive compounds could be extracted under optimal MAE condition. To improve stability and functionalities of the extract, the results showed that encapsulation condition, including ratio of wall material to coffee pulp extract, inlet temperature, feed rate and different wall materials significantly affected recovery yield and quality of the powdered extract. The most suitable encapsulation condition was identified to be the inlet temperature of 160 °C, ratio of wall material to extract of 18: 100 g/mL, feeding pump rate of 3 mL/min and maltodextrin with dextrose equivalent 18 as a wall material. Under this condition, a quality powdered extract can be produced with high bioactive compounds, good solubility, and potent antioxidant activity for further applications. However, future studies are needed to test the toxicity, stability, shelf life and to apply this extract as a functional ingredient in food, cosmetic and pharmaceutical products to provide more scientific evidence for better utilisation of the wet coffee pulp to add more value to the coffee industry.
- Subject
- coffee; coffee pulp; waste; by-products; application; bioactive compounds; antioxidants; thesis by publication
- Identifier
- http://hdl.handle.net/1959.13/1485793
- Identifier
- uon:51697
- Rights
- Copyright 2023 Thy Minh Kieu Tran
- Language
- eng
- Full Text
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| Thumbnail | File | Description | Size | Format | |||
|---|---|---|---|---|---|---|---|
| View Details Download | ATTACHMENT01 | Thesis | 6 MB | Adobe Acrobat PDF | View Details Download | ||
| View Details Download | ATTACHMENT02 | Abstract | 613 KB | Adobe Acrobat PDF | View Details Download |