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Superficial scald on ‘Granny Smith’ – understanding commercial storage protocols and their limitations
Thesis (PhD)--Stellenbosch University, 2025.
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Stellenbosch : Stellenbosch University
2025
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| _version_ | 1867614110310465536 |
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| access_status_str | Open Access |
| author | Gerber, Monja |
| author2 | Crouch, E. M. |
| author_browse | Crouch, E. M. Gerber, Monja |
| author_facet | Crouch, E. M. Gerber, Monja |
| author_sort | Gerber, Monja |
| collection | Thesis |
| dc_rights_str_mv | Stellenbosch University |
| description | Thesis (PhD)--Stellenbosch University, 2025. |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/132187 |
| institution | Stellenbosch University (South Africa) |
| language | English |
| last_indexed | 2026-06-10T12:46:49.940Z |
| 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:10019.1/132187 Superficial scald on ‘Granny Smith’ – understanding commercial storage protocols and their limitations Gerber, Monja Crouch, E. M. Jooste, M. M. Crouch, I. J. Botes, W. J. Stellenbosch University. Faculty of AgriSciences. Dept. of Horticultural Science. Apple scald Apples -- Storage -- Diseases and injuries Apples -- Postharvest technology -- South Africa Apples -- Storage -- Quality control Oxidative stress Protective atmospheres UCTD Thesis (PhD)--Stellenbosch University, 2025. Gerber, M. 2025. Superficial scald on ‘Granny Smith’ – understanding commercial storage protocols and their limitations. Unpublished doctoral dissertation. Stellenbosch: Stellenbosch University [online]. Available: https://scholar.sun.ac.za/items/e71b5efb-3845-4d1c-b5cd-367bca935b5f ENGLISH ABSTRACT: Superficial scald is a major postharvest disorder induced by oxidative stress during the first 7 d after harvest, during short-term storage or shipment in a regular atmosphere (RA). The induction period is associated with ethylene-dependent processes and the accumulation of α-farnesene oxidation products like 6‑methyl‑5‑hepten‑one (MHO). Symptoms develop as bronze patches on the fruit peel on transferring the fruit from regular atmosphere (RA) or low-oxygen storage to shipment and shelf‑life conditions. Incidence of more than 1 % on arrival in the overseas market may lead to claims and significant economic losses. This study assessed the efficacy of storage techniques and their combinations used by the South African export industry to control superficial scald. ‘Granny Smith’ apples were subjected to 12 treatments for 4(6), 8, and 16 weeks (short-term) as well as 24, and 33 weeks (long-term) cold storage followed by a simulated 6‑week RA shipment period at −0.5 °C plus a 10-d shelf-life at 20 °C, for three seasons. The fruit were stored under RA (−0.5 °C), with, or without diphenylamine (DPA) (9.6 mL L-1), or 1‑methylcyclopropene (1-MCP) (1 μL L- 1). Low-oxygen storage treatments included controlled atmosphere (CA; 1.5 % O2 and 1.0 % CO2 at 0 °C), dynamic controlled atmosphere ‑ chlorophyll fluorescence (DCA-CF; 0.5 % O2 and 0.7 % CO2 at 0 °C), and cycles of repeated low oxygen stress (RLOS; 0.5 % O2 for 10 d at 0 °C) + ultra-low oxygen storage (ULOS; 0.9 % O2 and 0.8 % CO2 for 21 days) and 0.5 % O2 for 7d at 0 °C. Subsamples of the 1-MCP+CA treated fruit were subjected to a secondary 1‑MCP or DCA‑CF (0.5 % O2 + 0.7 % CO2 for 7 d) or combination (1-MCP+DCA-CF) treatment after long‑term storage, prior to the simulated shipment period. Results indicated that the RA and RLOS+ULOS stored fruit, with or without 1-MCP or DPA, and untreated CA fruit posed a high superficial scald risk during short-term storage plus simulated shipment and shelf-life. Fruit accumulating even low levels of ethylene often posed a higher risk of developing the defect later in storage or shelf-life. DPA treatment did not reduce internal ethylene but reduced scald by preventing the oxidation of α-farnesene to MHO. CA, DCA-CF and RLOS+ULOS in combination with 1-MCP inhibited internal ethylene accumulation and reduced MHO concentrations during short- and long-term storage, however ethylene inhibition did not last during shelf-life after long-term storage. A 1-MCP treatment at harvest and after long-term storage resulted in complete control of superficial scald for these treatments (1-MCP+CA+1-MCP and 1‑MCP+CA+(1‑MCP+DCA‑CF)), even after shipment and shelf-life, and maintained fruit sensory quality. Only complete inhibition of internal ethylene resulted in the prevention of superficial scald incidence for all the storage treatments, except for RLOS+ULOS. Monitoring exogenous ethylene levels during storage and applying a second 1‑MCP treatment after long-term storage before shipping to overseas markets, is advised. This study provided unique insights into the modes of action of different storage techniques to prevent superficial scald in ‘Granny Smith’ apples during short- and long‑term storage. AFRIKAANSE OPSOMMING: Oppervlakkige brandvlek is ’n belangrike na-oesafwyking wat gedurende die eerste 7 dae na oes, tydens korttermynopberging of vervoer in gewone atmosfeer (GA) deur oksidatiewe stres veroorsaak word. Die induksieperiode word geassosieer met etileen-afhanklike prosesse en die akkumulasie van α-farneseen- oksidasieprodukte, byvoorbeeld 6-metiel-5-hepten-een (MHE). Die defeksimptome ontwikkel as brons vlekke op die vrugskil wanneer die vrugte vanaf GA‑ of lae-suurstofopbergingstoestande na verskepings- en raklewetoestande geskuif word. Wanneer meer as 1 % van die vrugte by aankoms in die oorsese mark die defek toon, lei dit to afkeurings en aansienlike ekonomiese verliese. Hierdie studie het die doeltreffendheid van die opbergingsmetodes, en hul kombinasies, soos deur die Suid-Afrikaanse uitvoerbedryf gebruik om oppervlakkige brandvlek te beheer, geëvalueer. ‘Granny Smith’ appels is oor drie seisoene aan 12 koelopbergingsbehandelings vir 4(6), 8 en 16 weke (korttermyn) en 24 en 33 weke (langtermyn) onderwerp. Elke behandeling is gevolg deur ’n gesimuleerde 6‑week GA‑verskepingsperiode teen -0.5 °C en ’n 10-dag rakleweperiode teen 20 °C. Die vrugte is met of sonder diphenylamien (DPA) (9.6 mL L⁻¹) of 1-metielsiklopropeen (1‑MCP) (1 µL L⁻¹) behandeling onder GA (‑0.5 °C) opgeberg. Lae-suurstof opbergingsbehandelings het beheerde atmosfeer (BA; 1.5 % O₂ en 1.0 % CO₂ by 0 °C), dinamiese beheerde atmosfeer-chlorofilfluoresensie (DBA-CF; 0.5 % O₂ en 0.7 % CO₂ by 0 °C), en siklusse van herhaalde lae-suurstofstres (HLSS; 0.5 % O₂ vir 10 d by 0 °C) + ultra‑lae-suurstofopberging (ULSO; 0.9 % O₂ en 0.8 % CO₂ vir 21 d) ingesluit. Monsters van die 1-MCP+BA-behandelde vrugte is na langtermynopberging, voor gesimuleerde verskeping, aan 'n sekondêre 1‑MCP- of DBA-CF-behandeling onderwerp . Resultate het getoon dat GA- en HLSS+ULSO-gebergde vrugte, met of sonder 1-MCP- of DPA‑behandeling, en onbehandelde BA-vrugte ’n hoë risiko vir oppervlakkige brandvlek tydens korttermynopberging plus gesimuleerde verskeping en raklewe ingehou het. Vrugte wat selfs net lae etileenvlakke getoon het, het dikwels 'n hoër oppervlakkige brandvlek risiko later tydens opberging of raklewe gehad. DPA het nie interne etileen verminder nie, maar het skade beperk deur oksidasie van α- farneseen na MHE te voorkom. BA, DBA-CF, en HLSS+ULSO in kombinasie met 1-MCP het interne etileen- en MHE‑konsentrasies tydens kort- en langtermynopberging verminder. ’n 1‑MCP‑behandeling by oes en na langtermynopberging het oppervlakkige brandvlekskade volledig beheer en sensoriese kwaliteit behou in die 1-MCP+BA+1-MCP- en 1-MCP+BA+(1-MCP+DBA-CF)-behandelings. Slegs totale onderdrukking van interne etileen het voorkoming van oppervlakkige brandvleksimptome in al die behandelings, behalwe die HLSS+ULSS-behandeling, verseker. Dit word dus aanbeveel om eksterne etileenvlakke tydens opberging te monitor en ’n tweede 1‑MCP‑behandeling na langtermynopberging, voor verskeping na oorsese markte, toe te dien. Hierdie studie bied unieke insigte betreffende die werking van verskillende opbergingsmetodes om oppervlakkige brandvlek in ‘Granny Smith’ appels tydens kort- en langtermynopberging te voorkom. Doctoral 2025-05-29T08:20:05Z 2025-05-29T08:20:05Z 2025-03 Thesis https://scholar.sun.ac.za/handle/10019.1/132187 en Stellenbosch University xxii, 331 pages : illustrations application/pdf Stellenbosch : Stellenbosch University |
| spellingShingle | Apple scald Apples -- Storage -- Diseases and injuries Apples -- Postharvest technology -- South Africa Apples -- Storage -- Quality control Oxidative stress Protective atmospheres UCTD Gerber, Monja Superficial scald on ‘Granny Smith’ – understanding commercial storage protocols and their limitations |
| title | Superficial scald on ‘Granny Smith’ – understanding commercial storage protocols and their limitations |
| title_full | Superficial scald on ‘Granny Smith’ – understanding commercial storage protocols and their limitations |
| title_fullStr | Superficial scald on ‘Granny Smith’ – understanding commercial storage protocols and their limitations |
| title_full_unstemmed | Superficial scald on ‘Granny Smith’ – understanding commercial storage protocols and their limitations |
| title_short | Superficial scald on ‘Granny Smith’ – understanding commercial storage protocols and their limitations |
| title_sort | superficial scald on granny smith understanding commercial storage protocols and their limitations |
| topic | Apple scald Apples -- Storage -- Diseases and injuries Apples -- Postharvest technology -- South Africa Apples -- Storage -- Quality control Oxidative stress Protective atmospheres UCTD |
| url | https://scholar.sun.ac.za/handle/10019.1/132187 |
| work_keys_str_mv | AT gerbermonja superficialscaldongrannysmithunderstandingcommercialstorageprotocolsandtheirlimitations |