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Grape pomace : an investigation into extraction techniques to enrich for different compound classes and the assessment of their biostimulant activity towards plants
Darren Nicholas, Maree. 2023. Grape pomace : an investigation into extraction techniques to enrich for different compound classes and the assessment of their biostimulant activity towards plants. Unpublished masters thesis. Stellenbosch: Stellenbosch University [online]. Available: https://scholar.s...
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Stellenbosch : Stellenbosch University
2023
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| access_status_str | Open Access |
| author | Darren Nicholas, Maree |
| author2 | Kaschula, Catherine H. |
| author_browse | Darren Nicholas, Maree Kaschula, Catherine H. |
| author_facet | Kaschula, Catherine H. Darren Nicholas, Maree |
| author_sort | Darren Nicholas, Maree |
| collection | Thesis |
| dc_rights_str_mv | Stellenbosch University |
| description | Darren Nicholas, Maree. 2023. Grape pomace : an investigation into extraction techniques to enrich for different compound classes and the assessment of their biostimulant activity towards plants. Unpublished masters thesis. Stellenbosch: Stellenbosch University [online]. Available: https://scholar.sun.ac.za/items/788e4383-b45d-4107-b887-57e421112e8a |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/128451 |
| institution | Stellenbosch University (South Africa) |
| language | English |
| last_indexed | 2026-06-10T12:43:53.285Z |
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| provenance_str_mv | Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository |
| publishDate | 2023 |
| publishDateRange | 2023 |
| publishDateSort | 2023 |
| publisher | Stellenbosch : Stellenbosch University |
| publisherStr | Stellenbosch : Stellenbosch University |
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| source_str | SUNScholar — Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019.1/128451 Grape pomace : an investigation into extraction techniques to enrich for different compound classes and the assessment of their biostimulant activity towards plants Darren Nicholas, Maree Kaschula, Catherine H. Nokwanda P, Makunga De Villiers, Andre J. Stellenbosch University. Faculty of Science. Dept. of Chemistry and Polymer Science. Extraction (Chemistry) -- South Africa Agricultural wastes -- South Africa Plants -- Effect of chemicals on -- South Africa Polyphenol oxidase -- South Africa UCTD Darren Nicholas, Maree. 2023. Grape pomace : an investigation into extraction techniques to enrich for different compound classes and the assessment of their biostimulant activity towards plants. Unpublished masters thesis. Stellenbosch: Stellenbosch University [online]. Available: https://scholar.sun.ac.za/items/788e4383-b45d-4107-b887-57e421112e8a Thesis (MSc)--Stellenbosch University, 2023. ENGLISH ABSTRACT: The global agriculture industry is moving towards greener and more sustainable farming practices that include the use of plant biostimulants for crop production. Grape pomace is an agro-industrial waste that contains beneficial compounds including polyphenolics. These compounds may be valorised by extracting them out of the pomace using conventional and unconventional extraction techniques, as well as an alkaline hydrolysis extraction. Conventional solid-liquid extraction (SLE) using hexane, acetone and 70% MeOH/H2O was found to generate chemically distinct extracts from grape pomace based on their increasing polarity. Among the four post-fermentation pomaces investigated with the sequential SLE (Barbera, Nebbiolo, Cabernet Sauvignon South Africa (CSSA), Cabernet Sauvignon Italy (CSI)), the CSSA was found to exhibit the largest hexane and 70% MeOH/H2O extractable fraction, whilst Nebbiolo was found to have the largest acetone extractable fraction. The CSSA 70% MeOH/H2O extract was found to also exhibit the most favourable phenolic enrichment and antioxidant activity (DPPH•/TPC). The most apolar portion of the hexane extract from CSSA was found by spectroscopic methods to contain a triacylglycerol, glyceryl linoleate. Under plant growth tissue culture conditions, the hexane extract was found to exhibit an inhibitory effect on tomato seed germination and seedling growth under standard and drought stressed conditions, especially at the 1000 mg/L concentration, and induce a change in the germination morphology with a decreased stem:root ratio. This suggests that compounds in the hexane extract may affect seed development and could be considered for the development of a plant growth inhibitor. In contrast, the 4 mg/L acetone extract caused a restorative effect on dry mass accumulation of drought stressed seeds. Seed germination was stimulated by the 1000 mg/L 70% MeOH/H2O extract, whilst the 100 mg/L concentration caused a significant restorative increase in the dry mass accumulation, stem and root length, and leaf development of drought stressed seedlings. Furthermore, tested on mature tomato seedling explants in tissue culture, the 70% MeOH/H2O extract was found to exhibit an inhibitory effect on stem elongation and dry mass accumulation of unstressed plants, especially at 1000 mg/L. However, the 100 mg/L concentration caused a significant 34% increase in callus development of stressed explants compared to the drought control. Moreover, the 70% MeOH/H2O extract caused an increase in the phenolic content and antioxidant activity of unstressed explants but not on drought stressed explants. The KOH hydrolysis extracts from grape pomace offer an industry friendly approach to the large-scale valorisation of grape pomace for the enrichment of phenolics. These hydrolysates were not found to exhibit beneficial properties towards green pepper plants grown in a greenhouse pot trial under standard or drought stressed conditions. However, a 1-day hydrolysate extract caused a decrease in ABTS radical scavenging activity and an increase in polyphenol oxidase (POD) enzyme expression of unstressed plants, as well as a decrease in glutamine, proline and phenyl alanine levels. Unconventional microwave assisted extraction (MAE) and sub-critical water extraction (SCWE) offer greener and more efficient extraction methods for the enrichment of antioxidant phenolics from plant materials including grape pomace. SCWE on CSSA under conditions of 150 ˚C for 10 min and under 40 bar N2 was found to provide the highest phenolic enrichment (17.9 ± 1.47 mg GAE/g dry mass (DM)) and was the extract that contained the highest combined total phenolic content and DPPH• radical scavenging capacity (67.9 ± 1.32 mg GAE/g EXT and EC50 43.8 μg/mL extract (EXT)). Under MAE conditions, 70% EtOH/H2O was found to have the highest phenolic enrichment (12.9 ± 1.57 mg GAE/g DM) and generated the most favourable antioxidant extract (111 ± 0.69 mg GAE/g EXT, EC50 = 32.7 μg/mL extract EXT). Both of MAE and SCWE were also found to exhibit good up-scalability for industry friendly use with similar extraction yields, TPC and EC50 values compared their small-scale counterparts. Taken together, certain extracts from grape pomace were found to exhibit growth stimulatory effects towards seedling germination and/or growth under either standard or drought stress conditions. Some of the extracts affect antioxidant abilities of plants by altering phenolic biosynthesis and radical scavenging capacity, as well as redirecting important amino acids including proline and phenylalanine. Some of these extracts have the potential to be developed into value-added products supporting greener, circular, and more sustainable agricultural practices. AFRIKAANSE OPSOMMING: Die wêreldwye landboubedryf beweeg na groener en meer volhoubare boerderypraktyke wat die gebruik van plantbiostimulante vir gewasproduksie insluit. Druiwe-afval is 'n landbouindustriële by-produk wat voordelige chemiese komponente bevat, insluitend polifenole. Hierdie komponente kan ontwikkel word deur hulle uit die afval te onttrek deur gebruik te maak van konvensionele en onkonvensionele ekstraksie tegnieke, sowel as alkaliese hidrolise ekstraksie. Daar is gevind dat konvensionele vastestof-vloeistof-ekstraksie met behulp van heksaan, asetoon en 70% MeOH/H2O chemies verskillende ekstrakte van druiwe-afval genereer op grond van hul toenemende polariteit. Onder die vier na-fermentasie afvalstowwe wat ondersoek is met die opeenvolgende vastestof-vloeistof ekstraksie (Barbera, Nebbiolo, Cabernet Sauvignon Suid-Afrika (CSSA), Cabernet Sauvignon Italië (CSI)), is gevind dat die CSSA die grootste heksaan en 70% MeOH/H2O ekstraheerbare fraksie vertoon, terwyl gevind is dat Nebbiolo die grootste asetoon-ekstraheerbare fraksie het. Die CSSA 70% MeOH/H2Oekstrak het ook die gunstigste fenoliese verryking en antioksidantaktiwiteit (DPPH• /TPC) vertoon. Die mees apolêre gedeelte van die heksaan ekstrak uit CSSA is deur spektroskopiese metodes gevind om n triasielgliserol, gliseriellinoleaat, te bevat. Onder plant groei weefselkultuur toestande is gevind dat die heksaan ekstrak 'n inhiberende effek op tamatie saadontkieming en saailinggroei onder standaard- en droogtestresstoestande toon, veral by die 1000 mg/L konsentrasie. Die ekstrak het ook 'n verandering in die ontkiemingsmorfologie veroorsaak met 'n verminderde stam:wortel verhouding. Dit dui daarop dat verbindings in die heksaan ekstrak saadontwikkeling kan beïnvloed en oorweeg kan word vir die ontwikkeling as 'n plantgroei-inhibeerder. In kontras het die het die 4 mg/L asetoon ekstrak 'n herstellende effek op droëmassa-akkumulasie van sade veroorsaak onder droogte stres. Saadontkieming is gestimuleer deur die 1000 mg/L 70% MeOH/H2O-ekstrak, terwyl die 100 mg/L konsentrasie 'n beduidende herstellende toename in die droëmassa-akkumulasie, stam- en wortellengte, en blaarontwikkeling van saailinge veroorsaak onder droogte stres. Verder, getoets op volwasse tamatie saailinge in weefselkultuur, is gevind dat die 70% MeOH/H2O-ekstrak 'n inhiberende effek op stamverlenging en droëmassa-akkumulasie van ongestremde plante toon, veral by 1000 mg/L. Die 100 mg/L konsentrasie het 'n beduidende 34% toename in kallus ontwikkeling van eksplante onder stress veroorsaak in vergelyking met die droogte kontrole. Boonop, het die 70% MeOH/H2O-ekstrak 'n toename in die fenoliese inhoud en antioksidantaktiwiteit van ongestremde eksplante veroorsaak, maar nie op droogte gestremde plant materiaal. Die KOH-hidrolise ekstrakte van druiwe-afval bied 'n industrievriendelike benadering tot die grootskaalse prossesering van druiwe-afval vir die verryking van fenole. Daar is nie gevind dat hierdie hidrolisate voordelige eienskappe toon teenoor groenrissie plante wat in 'n kweekhuis potproef gekweek is onder standaard- of droogte gestremde toestane nie. 'n 1-dag hidrolise ekstrak het egter 'n afname in ABTS radikaal opvangkapasiteit en 'n toename in polyphenol oxidase (POD) ensiem uitdrukking van ongestreste plante veroorsaak, asook 'n afname in glutamien, prolien en feniel alanien vlakke. Onkonvensionele mikrogolf-ondersteunde ekstraksie (MAE) en sub-kritiese water ekstraksie (SCWE) bied groener en meer doeltreffende ekstraksie metodes vir die verryking van antioksidant aktiewe fenole van plantmateriaal, insluitend druiwe-afval. SCWE op CSSA onder toestande van 150 ˚C vir 10 min en onder 40 bar is N2 is gevind om die hoogste fenoliese verryking (17.9 ± 1.47 mg GAE/g droë massa (DM)) te verskaf en was die ekstrak wat ook die hoogste totale fenoliese inhoud en DPPH• radikale opvangkapasiteit bevat (67.9 ± 1.32 mg GAE/g EXT en EC50 43.8 µg/mL ekstrak (EXT)). Onder MAE toestande is gevind dat 70% EtOH/H2O die hoogste fenoliese verryking vertoon (12.9 ± 1.57 mg GAE/g DM) en het die mees gunstige antioksidant-ekstrak verhouding gegenereer (111 ± 0.69 mg GAE/g EXT, EC50 = 32.7 µg/mL extract). Daar is ook gevind dat beide MAE en SCWE goeie opskaalbaarheid toon vir bedryfsvriendelike gebruik met soortgelyke ekstraksie opbrengste, TPC en EC50 waardes in vergelyking met hul kleinskaalse eweknieë. Gesamentlik, is gevind dat sekere ekstrakte van druiwe-afval groeistimulerende effekte ten opsigte van saailingontkieming en/of groei onder standaard- of droogte toestande toon. Sommige van die ekstrakte beïnvloed die antioksidantvermoë van plante deur fenoliese biosintese en radikaal opvangkapasiteit te verander, asook om belangrike aminosure, insluitend prolien en fenielalanien, te herlei. Sommige van hierdie ekstrakte het die potensiaal om ontwikkel te word tot produkte met toegevoegde waarde wat groener en meer volhoubare landboupraktyke ondersteun. Masters 2023-03-07T10:20:30Z 2023-08-30T13:09:48Z 2023-03-07 2023-03-07T10:20:30Z 2023-08-31T09:18:45Z 2023-03-07T10:20:30Z 2023-08-31T09:18:45Z 2023-03 Thesis https://scholar.sun.ac.za/handle/10019.1/128451 en Stellenbosch University application/pdf xv, 139 pages : illustrations application/pdf Stellenbosch : Stellenbosch University |
| spellingShingle | Extraction (Chemistry) -- South Africa Agricultural wastes -- South Africa Plants -- Effect of chemicals on -- South Africa Polyphenol oxidase -- South Africa UCTD Darren Nicholas, Maree Grape pomace : an investigation into extraction techniques to enrich for different compound classes and the assessment of their biostimulant activity towards plants |
| title | Grape pomace : an investigation into extraction techniques to enrich for different compound classes and the assessment of their biostimulant activity towards plants |
| title_full | Grape pomace : an investigation into extraction techniques to enrich for different compound classes and the assessment of their biostimulant activity towards plants |
| title_fullStr | Grape pomace : an investigation into extraction techniques to enrich for different compound classes and the assessment of their biostimulant activity towards plants |
| title_full_unstemmed | Grape pomace : an investigation into extraction techniques to enrich for different compound classes and the assessment of their biostimulant activity towards plants |
| title_short | Grape pomace : an investigation into extraction techniques to enrich for different compound classes and the assessment of their biostimulant activity towards plants |
| title_sort | grape pomace an investigation into extraction techniques to enrich for different compound classes and the assessment of their biostimulant activity towards plants |
| topic | Extraction (Chemistry) -- South Africa Agricultural wastes -- South Africa Plants -- Effect of chemicals on -- South Africa Polyphenol oxidase -- South Africa UCTD |
| url | https://scholar.sun.ac.za/handle/10019.1/128451 |
| work_keys_str_mv | AT darrennicholasmaree grapepomaceaninvestigationintoextractiontechniquestoenrichfordifferentcompoundclassesandtheassessmentoftheirbiostimulantactivitytowardsplants |