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Evaluating the desorption of oxygen from wine
Thesis (MScAgric)--Stellenbosch University, 2022.
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Stellenbosch : Stellenbosch University
2022
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| _version_ | 1867613995527045120 |
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| access_status_str | Open Access |
| author | Sutton, Steven |
| author2 | Du Toit, Wessel J. |
| author_browse | Du Toit, Wessel J. Sutton, Steven |
| author_facet | Du Toit, Wessel J. Sutton, Steven |
| author_sort | Sutton, Steven |
| collection | Thesis |
| dc_rights_str_mv | Stellenbosch University |
| description | Thesis (MScAgric)--Stellenbosch University, 2022. |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/124943 |
| institution | Stellenbosch University (South Africa) |
| language | en_ZA |
| last_indexed | 2026-06-10T12:45:00.328Z |
| license_str | Other β see source repository |
| provenance_str_mv | Harvested via OAI-PMH from SUNScholar β Stellenbosch University Repository |
| publishDate | 2022 |
| publishDateRange | 2022 |
| publishDateSort | 2022 |
| publisher | Stellenbosch : Stellenbosch University |
| publisherStr | Stellenbosch : Stellenbosch University |
| record_format | dspace |
| source_str | SUNScholar β Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019.1/124943 Evaluating the desorption of oxygen from wine Sutton, Steven Du Toit, Wessel J. Pott, Robert William M. Stellenbosch University. Faculty of AgriSciences. Dept. of Viticulture and Oenology. Wine and wine making -- Oxidation Desorption Wine processing Bubble column Dissolved oxygen removal Wine and wine making -- Microbiology Wine -- Composition Wine -- Protein content Antioxidants Mass transfer --Mathematical models UCTD Thesis (MScAgric)--Stellenbosch University, 2022. ENGLISH ABSTRACT: The removal of dissolved oxygen through desorption is commonly done in winemaking. Winemakers have indicated that under the same conditions, this process takes place at different rates, for different wines. The mass transfer of oxygen in six wines and various model wine solutions, was examined by evaluating the oxygen desorption volumetric mass transfer coefficient (ππΏ π), the Sauter mean bubble diameter (D32), gas holdup (π), the interfacial area (π), and the oxygen mass transfer coefficient (ππΏ). One of the wines used was split into two batches, with one half treated with bentonite, and the other not. A bubble column with a stone sparger was used for the experiments. The gassing out procedure and a 2nd order model was used to determine ππΏπ. Bubble imaging was done to determine the interfacial area, and subsequently the ππΏ. During oxygen desorption within wine, the ππΏπ values varied between 0.0125 s-1 and 0.0275 s-1 depending on the wine. The ππΏ π value during oxygen desorption within a 10 % ethanol solution was found to be 0.0275 s1. The addition of a small amount glycerol to this system reduced the ππΏπ to 0.0225 s-1. Further additions of organic acids did not affect the ππΏπ, while the addition of protein in the form of BSA and yeast extract reduced the ππΏπ to approximately 0.0175 s-1. The ππΏ π for during oxygen desorption within a wine that was protein unstable improved from 0.009 s1 to 0.015 s1 after being treated with bentonite. During desorption, there were no significant variations in the D32 and the interfacial area between systems containing wines or model wine solutions. Consequently, the variations between the ππΏπ values could all be ascribed to differences in the ππΏ. During oxygen desorption, the ππΏ values were found to be between 0.015 and 0.045 mm/s within the different wines. The ππΏ values were found to be between 0.03 and 0.04 mm/s within a 10% ethanol solution, and within the model wine solutions containing glycerol and organic acids. The ππΏ values dropped between 0.02 and 0.03 mm/s with the addition of protein to the model wine solution. Treating a protein unstable wine with bentonite increased the ππΏ value from 0.017 mm/s to 0.0225 mm/s. The combination of the reduction in the ππΏ when protein was added to a model wine solution, and the improvement of the ππΏ when wine was treated with bentonite, suggested that proteins in wine significantly affect oxygen desorption rates. It is suggested that winemakers can improve the oxygen ππΏ within their system by operating at higher gas flowrates to increase the turbulence during desorption. However, the most effective way of improving the desorption rate is by using a sparger that produces smaller bubbles, so as to increase the interfacial area. It is suggested that desorption is performed after fining, as the ππΏ will be greater. AFRIKAANSE OPSOMMING: Die verwydering van opgeloste suurstof deur middel van desorpsie kom algemeen in wynbereiding voor. Wynmakers het aangedui dat, onder dieselfde toestande, hierdie proses teen verskillende tempoβs vir verskillende wyne plaasvind. Die massa-oordrag van suurstof in ses wyne en verskillende model-wynoplossings is ondersoek deur die volumetriese massa- oordragkoΓ«ffisiΓ«nt (ππΏ π) van suurstof desorpsie, die Sauter gemiddelde borreldeursnee (D32), gasvertraging (gas holdup) (π), die oppervlakte van die koppelvlak (π) en die suurstof massa- oordragkoΓ«ffisiΓ«nt (ππΏ) te evalueer. Een van die wyne wat gebruik is, is in twee verdeel, die een helfte waarvan met bentoniet behandel is en die ander nie. βn Borrelkolom met βn klip sprinkeltoestel (stone sparger) is vir die eksperimente gebruik. Die ontgassingsprosedure (gassing out) en βn tweede-orde model is gebruik om ππΏ π te bepaal. Borrel beelding (imaging) is gedoen om die oppervlakte van die koppelvlak, en gevolglik die ππΏ, te bepaal. Tydens suurstofdesorpsie in die wyn het die ππΏ π-waardes tussen 0.0125 s-1 en 0.0275 s-1 gewissel, afhangend van die wyn. Die ππΏπ-waarde tydens suurstofdesorpsie met βn 10% etanoloplossing was 0.0275 s1. Die toevoeging van βn klein hoeveelheid gliserol aan hierdie stelsel het die ππΏπ tot 0.0225 s-1 verminder. Verdere toevoegings van organiese sure het nie die ππΏπ geaffekteer nie, terwyl die toevoeging van proteΓ―en in die vorm van BSA en gis-ekstrak die ππΏπ tot ongeveer 0.0175 s-1 verminder het. Die ππΏπ tydens suurstofdesorpsie in βn wyn wat proteΓ―en-onstabiel was, het verbeter van 0.009 s1 tot 0.015 s1 nΓ‘ behandeling met bentoniet. Tydens desorpsie was daar geen betekenisvolle verandering in die D32 en in die oppervlakte van die koppelvlak tussen stelsels wat wyn of model-wynoplossings bevat het nie. Gevolglik kon die verskille in die ππΏπ-waardes almal aan verskille in die ππΏ toegeskryf word. Tydens suurstofdesorpsie was die ππΏ-waardes in die verskillende wyne tussen 0.015 en 0.045 mm/s. Die ππΏ-waardes was tussen 0.03 en 0.04 mm/s in βn 10% etanoloplossing, asook in die model- wynoplossings wat gliserol en organiese sure bevat het. Die ππΏ-waardes het met tussen 0.02 en 0.03 mm/s gedaal met die toevoeging van proteΓ―en aan die model-wynoplossing. Die behandeling van βn wyn wat proteΓ―en-onstabiel was met bentoniet het die ππΏ-waarde van 0.017 mm/s tot 0.0225 mm/s verhoog. Die kombinasie van die afname van die ππΏ toe proteΓ―en by βn model-wynoplossing gevoeg is en die verbetering van die ππΏ toe die wyn met bentoniet behandel is, suggereer dat proteΓ―ene in wyn die suurstofdesorpsie-tempoβs aansienlik beΓ―nvloed. Daar word voorgestel dat wynmakers die suurstof-ππΏ in hulle stelsel kan verbeter deur teen hoΓ«r gasvloeitempoβs te werk om die turbulensie tydens desorpsie te verhoog. Die doeltreffendste manier om die desorpsietempo te verbeter, is egter om βn sprinkeltoestel te gebruik wat kleiner borrels produseer om sodoende die oppervlakte van die koppelvlak te vergroot. Daar word ook voorgestel dat desorpsie nΓ‘ brei uitgevoer word, aangesien die ππΏ groter sal wees. Masters 2022-03-10T20:25:22Z 2022-04-29T09:42:37Z 2022-03-10T20:25:22Z 2022-04-29T09:42:37Z 2022-04 Thesis http://hdl.handle.net/10019.1/124943 en_ZA Stellenbosch University xi, 116 pages : illustrations (some color) application/pdf Stellenbosch : Stellenbosch University |
| spellingShingle | Wine and wine making -- Oxidation Desorption Wine processing Bubble column Dissolved oxygen removal Wine and wine making -- Microbiology Wine -- Composition Wine -- Protein content Antioxidants Mass transfer --Mathematical models UCTD Sutton, Steven Evaluating the desorption of oxygen from wine |
| title | Evaluating the desorption of oxygen from wine |
| title_full | Evaluating the desorption of oxygen from wine |
| title_fullStr | Evaluating the desorption of oxygen from wine |
| title_full_unstemmed | Evaluating the desorption of oxygen from wine |
| title_short | Evaluating the desorption of oxygen from wine |
| title_sort | evaluating the desorption of oxygen from wine |
| topic | Wine and wine making -- Oxidation Desorption Wine processing Bubble column Dissolved oxygen removal Wine and wine making -- Microbiology Wine -- Composition Wine -- Protein content Antioxidants Mass transfer --Mathematical models UCTD |
| url | http://hdl.handle.net/10019.1/124943 |
| work_keys_str_mv | AT suttonsteven evaluatingthedesorptionofoxygenfromwine |