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Preparation and performance evaluation of bio-based cryogels for micronutrient and bioactive compound encapsulation and sustained release
Khupe, C. G. 2025. Preparation and performance evaluation of bio-based cryogels for micronutrient and bioactive compound encapsulation and sustained release. Unpublished masters thesis. Stellenbosch: Stellenbosch University [online]. Available: https://scholar.sun.ac.za/items/4af4ee44-f007-4723-ba02...
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Stellenbosch : Stellenbosch University
2025
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| _version_ | 1867613865644130304 |
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| access_status_str | Open Access |
| author | Khupe, Coleman Given |
| author2 | Chimphango, Annie |
| author_browse | Chimphango, Annie Khupe, Coleman Given |
| author_facet | Chimphango, Annie Khupe, Coleman Given |
| author_sort | Khupe, Coleman Given |
| collection | Thesis |
| dc_rights_str_mv | Stellenbosch University |
| description | Khupe, C. G. 2025. Preparation and performance evaluation of bio-based
cryogels for micronutrient and bioactive compound
encapsulation and sustained release. Unpublished masters thesis. Stellenbosch: Stellenbosch University [online]. Available: https://scholar.sun.ac.za/items/4af4ee44-f007-4723-ba02-72b3ee48caf5 |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/132581 |
| institution | Stellenbosch University (South Africa) |
| last_indexed | 2026-06-10T12:42:55.322Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository |
| publishDate | 2025 |
| publishDateRange | 2025 |
| publishDateSort | 2025 |
| publisher | Stellenbosch : Stellenbosch University |
| publisherStr | Stellenbosch : Stellenbosch University |
| record_format | dspace |
| source_str | SUNScholar — Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019.1/132581 Preparation and performance evaluation of bio-based cryogels for micronutrient and bioactive compound encapsulation and sustained release Khupe, Coleman Given Chimphango, Annie Stellenbosch University. Faculty of Engineering. Dept. of Chemical Engineering. Bioactive compounds -- Biotechnology Biopolymers -- Biotechnology Drug delivery systems UCTD Khupe, C. G. 2025. Preparation and performance evaluation of bio-based cryogels for micronutrient and bioactive compound encapsulation and sustained release. Unpublished masters thesis. Stellenbosch: Stellenbosch University [online]. Available: https://scholar.sun.ac.za/items/4af4ee44-f007-4723-ba02-72b3ee48caf5 Thesis (MEng)--Stellenbosch University, 2025. ENGLISH ABSTRACT: The prevalence of degenerative ailments caused by oxidative stress has continued to grow year on year. Micronutrients and bioactive compounds such as Ferulic Acid (FA), Quercetin (QN), and Vitamin A (often provided as Retinyl Acetate, RA), possess the capability to reduce oxidative stress and subsequent degenerative ailments. However, instability and low bioavailability often limit their effectiveness thereby leading to innovative delivery methods such as encapsulation to curb these limitations. Thus, this study explored a new encapsulation method using bio-based, freeze-dried commercial high methoxyl pectin (HMP) cryogels for the in-vitro delivery of FA, QN, and RA. Cryogels were prepared by a systematic sol-gel formulation following a full factorial design approach. Three process variables were considered; HMP concentration (3, 6, 9% (w/v)), solution pH (1.5, 2.5, 3.5) and cross-linker concentration, CaCl2 (40, 60, 80 mg/g pectin) with a constant 3% (w/v) concentration of crystalline nanocellulose (CNC) added as a cosolute and measured against the storage (G’) and loss moduli (G”). Stable hydrogels were achieved at pH 3.5, 6% (w/v) pectin, and CaCl2 at 80 mg/g pectin after 48 hours gelation time and achieving 97.26 ± 1.97%, 93.78 ± 1.18%, and 96.69 ± 0.67% encapsulation efficiency for FA, QN, and RA respectively. The effect of different freezing temperatures (-20 ℃, -60 ℃, -80 ℃, and -196 ℃) on the properties of cryogels was evaluated through various analyses, including scanning electron microscopy (SEM) and pycnometry. The freezing rate of the hydrogels significantly affected the cryogel properties, which displayed porosities of 89-94%, bulk densities of 0.0925-0.1978 g/cm³, pore sizes from 0.31 to 18.36 μm, and surface areas (SBET) of 0.6555 to 4.11 m²/g. The mechanical properties indicated moderate robustness, with Shore A hardness values from 32.2 to 49.8 and 16.6 to 37.5 N compressive strengths, and up to 331.6 MPa stress resistance. Thermogravimetric analysis (TGA) showed virtually identical degradation profiles for all formulations similar to native pectin, with degradation occurring at 50-150 ℃, 150-300 ℃, and 300-600 ℃, irrespective of freezing conditions. Fourier-transform infrared (FTIR) spectroscopy showed strong interactions in the QN-loaded cryogel, while FA and RA showed minimal interactions in the characteristic OH-pectin band of 3200-3500 cm⁻¹. The release profiles of the encapsulated compounds were evaluated in-vitro using simulated gastric fluid (SGF), pH 1.2, and simulated intestinal fluid (SIF), pH 6.8. All cryogel formulations exhibited either anomalous or super Case II transport mechanisms when fitted to the Korsmeyer-Peppas model in the order (-196 ℃ > -80 ℃ > -20 ℃ > -60 ℃), enhanced solubility (250-422%), and sustained release for up to 210 minutes. Additionally, it was desired to streamline the process for the production of HMP cryogels from raw materials. Thus, HMP cryogels were produced using pectin extracted from waste orange peels and their performance compared to the cryogels prepared from commercial HMP. To this end, pectin (MAEP) was extracted from waste orange peels using a microwave-assisted extraction (MAE) method with aqueous acetic acid by adopting a central composite design (CCD), and optimising for both the pectin yield and degree of esterification (DE). The optimisation yielded 16.3 % HMP with 69.47 % DE and 79.66 % purity, comparable to the commercial HMP (77.47 % DE and 74.10 % purity). MAEP cryogels displayed similar FA release profiles to commercial HMP. Overall, this research highlights the potential of bio-based cryogels to improve nutrient delivery and bioavailability, offering sustainable solutions for nutritional deficiencies. It was also demonstrated that HMP could be effectively sourced from waste materials thereby leading to waste valorisation and material circularity. AFRIKAANSE OPSOMMING: Geen opsomming beskikbaar. Masters 2025-06-11T09:52:31Z 2025-06-11T09:52:31Z 2025-03 Thesis https://scholar.sun.ac.za/handle/10019.1/132581 Stellenbosch University xvii, 174 pages : illustrations application/pdf Stellenbosch : Stellenbosch University |
| spellingShingle | Bioactive compounds -- Biotechnology Biopolymers -- Biotechnology Drug delivery systems UCTD Khupe, Coleman Given Preparation and performance evaluation of bio-based cryogels for micronutrient and bioactive compound encapsulation and sustained release |
| title | Preparation and performance evaluation of bio-based cryogels for micronutrient and bioactive compound encapsulation and sustained release |
| title_full | Preparation and performance evaluation of bio-based cryogels for micronutrient and bioactive compound encapsulation and sustained release |
| title_fullStr | Preparation and performance evaluation of bio-based cryogels for micronutrient and bioactive compound encapsulation and sustained release |
| title_full_unstemmed | Preparation and performance evaluation of bio-based cryogels for micronutrient and bioactive compound encapsulation and sustained release |
| title_short | Preparation and performance evaluation of bio-based cryogels for micronutrient and bioactive compound encapsulation and sustained release |
| title_sort | preparation and performance evaluation of bio based cryogels for micronutrient and bioactive compound encapsulation and sustained release |
| topic | Bioactive compounds -- Biotechnology Biopolymers -- Biotechnology Drug delivery systems UCTD |
| url | https://scholar.sun.ac.za/handle/10019.1/132581 |
| work_keys_str_mv | AT khupecolemangiven preparationandperformanceevaluationofbiobasedcryogelsformicronutrientandbioactivecompoundencapsulationandsustainedrelease |