Understanding soft scald and bitter pit development in ‘Scifresh’ apples

Simple item page
dc.contributor.advisorCrouch, Elkeen_ZA
dc.contributor.advisorBotes, Anelen_ZA
dc.contributor.advisorJooste, Marianaen_ZA
dc.contributor.authorLadegourdie, Jasonen_ZA
dc.contributor.otherStellenbosch University. Faculty of Agrisciences. Dept. of Horticulture.en_ZA
dc.date.accessioned2024-03-04T13:19:10Z
dc.date.accessioned2024-04-26T20:38:16Z
dc.date.available2024-03-04T13:19:10Z
dc.date.available2024-04-26T20:38:16Z
dc.date.issued2024-03
dc.descriptionThesis (MScAgric)--Stellenbosch University, 2024. en_ZA
dc.description.abstractENGLISH ABSTRACT: The South African pome fruit industry annually contributes approximately R11.47 billion to the country's economy. Effective storage techniques are essential to maintain fruit quality and remain competitive. This study focused on two storage disorders, namely soft scald and bitter pit, both of which significantly impact the South African apple industry. Soft scald is becoming increasingly problematic. Although a great deal of research has been conducted on bitter pit, it remains a common issue. 'Scifresh', a relatively new apple cultivar, was used in this study and is particularly susceptible to soft scald and bitter pit. This study comprises of a literature review and four scientific papers, with a focus on soft scald and bitter pit development under South African conditions. The main aim of the study was to understand the factors that influence disorder susceptibility and propose strategies to minimize the risk. The first paper assessed the impact of various storage regimes on 'Scifresh' apple quality and investigates biochemical indicators such as reactive oxygen species, internal ethylene concentration, total phenolics, total antioxidant capacity, and apple volatiles. Harvest maturity and cooling rate after harvest were identified as factors in soft scald and bitter pit development. Stepwise cooling limited the incidence of soft scald but increased the risk of bitter pit. Ethylene reduction methods are suggested for further research to address bitter pit in regular atmosphere storage whilst stepwise cooling is used for soft scald reduction. The second paper evaluated the effects of regular and controlled atmosphere (CA) storage, storage times, and 1-methylcyclopropene (1-MCP) on post-storage quality. The results indicate that 1-MCP reduced bitter pit in fruit stored under regular atmosphere. Post-optimum harvested fruit treated with 1-MCP that was stepwise cooled and CA stored long-term (6-8 months), had an increased risk of bitter pit development. This was not a risk for 1-MCP treated fruit that was cooled immediately and CA stored long-term (6-8 months). The third paper investigated the effects of forced-air cooling (FAC) after packing on 'Scifresh' apple quality, with a special focus on potential chilling disorders during the re-cooling process. FAC after packaging did not affect fruit quality compared to passive cooling, when re-cooling remained below 10 °C. The fourth paper investigated the effect of different fruit harvest maturities on post-storage fruit quality. It was found that ‘Scifresh’ apples must be harvested at optimum maturity to mitigate the risks of soft scald and bitter pit. Blush colour cannot be used as a single harvest maturity index but rather in combination with other harvest maturity parameters. The recommended harvest maturity includes a narrower starch breakdown window of 30–40 %, TSS > 12 %, firmness > 8 kg with a 40 % blush colour and F4 colour intensity according to the ‘Scifresh’ colour swatch. In conclusion, the research provided valuable insights into the storage disorders, soft scald and bitter pit, offering recommendations for optimal storage protocols and harvest practices of ‘Scifresh’ apples.en_ZA
dc.description.abstractAFRIKAANSE OPSOMMING: Die Suid-Afrikaanse kernvrugtebedryf dra jaarliks ongeveer R11,47 miljard tot die land se ekonomie by. Doeltreffende bergingstegnieke is noodsaaklik om vrugkwaliteit te handhaaf en mededingend te bly. Hierdie studie het op twee opbergingsdefekte gefokus, naamlik sagte brandvlek en bitterpit. Beide het ’n betekenisvolle impak op die Suid-Afrikaanse appelbedryf, veral sagte brandvlek word toenemend ’n probleem. Hoewel heelwat navorsing al op bitterpit gedoen is, bly dit ’n algemene probleem. 'Scifresh', 'n relatief nuwe appelkultivar, is in hierdie studie gebruik en is veral vatbaar vir sagte brandvlek en bitterpit. Hierdie studie bestaan uit ’n literatuurstudie en vier navorsingshoofstukke met ’n spesifieke fokus op die ontwikkeling van sagte brandvlek en bitterpit onder Suid-Afrikaanse toestande. Die hoofdoel van die studie was om die faktore wat vatbaarheid vir defekontwikkeling beïnvloed, beter te verstaan en om strategieë voor te stel om die risko te verminder. Die eerste navorsingshoofstuk het die impak van verskillende opbergingsregimes op ‘Scifresh’ appelkwaliteit ondersoek en het biochemiese aanwysers soos reaktiewe suurstofspesies, interne etileenkonsentrasie, totale fenole, totale antioksidantkapasiteit en vlugtige verbindings gemeet. Oesrypheid en afkoeltempo na oes is geïdentifiseer as faktore wat die ontwikkeling van sagte brandvlek- en bitterpitontwikkeling beïnvloed. Trapsgewyse verkoeling het die voorkoms van sagte brandwonde beperk, maar het die risiko van bitterpit verhoog. Etileenreduksiemetodes word voorgestel vir verdere navorsing om bitter pit in gewone atmosfeer-berging aan te spreek, terwyl trapsgewyse verkoeling gebruik word om sagte brandvlek te verminder. Die tweede navorsingshoofstuk het die effek van gewone en beheerde atmosfeer (BA), opbergingstyd en 1-metielsiklopropeen (1-MCP) op die na-opberings kwaliteit van ‘Scifresh’ appels ondersoek. Die resultate dui daarop dat 1-MCP bitterpit verminder het in vrugte wat onder gewone atmosfeer gestoor is. Vrugte wat post-optimum geoes is, met 1-MCP behandel, trapsgewys afgekoel en langtermyn (6-8 maande) onder BA gestoor is, het 'n verhoogde risiko van bitterpit ontwikkeling getoon. Hierdie risiko is nie waargeneem by vrugte van post-optimum pluk rypheid wat onmiddellik afgekoel, met 1-MCP behandel en langtermyn onder BA gestoor (6-8 maande) is nie. Die derde navorsingshoofstuk het die effek van geforseerde lugverkoeling (GLV) ná verpakking op ‘Scifresh’ appel kwaliteit ondersoek met ’n spesifieke fokus op potensiële koueskade defekte wat tydens herverkoeling kan ontwikkel. Die resultate het getoon dat wanneer herverkoeling onder 10 °C gebly het, GLV nie vrugkwaliteit beduidend beïnvloed het in vergelyking met passiewe verkoeling in hierdie studie nie. Die vierde navorsingsprojek het die effek van verskillende oesryphede op na-oes vrug kwaliteit ondersoek. Daar is gevind dat ‘Scifresh’ appels by optimum rypheid geoes moet word om die risiko van sagte brandvlek en bitterpit ontwikkeling te verminder. Bloskleur kan nie as die enigste oesrypheidsindeks gebruik word nie, maar eerder inkombinasie met ander rypheidsindekse. Die aanbevole oesrypheid sluit in 'n nouer styselafbraakvenster van 30-40 %, TSS > 12 % en fermheid > 8 kg, 'n 40 % bloskleur en F4-kleurintensiteit volgens die ‘Scifresh’-kleurkaart. Ter afsluiting het die navorsing van hierdie studie waardevolle insigte navore gebring ten opsigte van die opbergingsdefekte sagte brandvlek en bitterpit asook optimale opbergingsprotokolle en oespraktyke vir ‘Scifresh’ appels voorgestel.af_ZA
dc.description.versionMastersen_ZA
dc.format.extent244 pages : illustrations (some color)en_ZA
dc.identifier.urihttps://scholar.sun.ac.za/handle/10019.1/130521
dc.language.isoen_ZAen_ZA
dc.language.isoen_ZAen_ZA
dc.publisherStellenbosch : Stellenbosch Universityen_ZA
dc.rights.holderStellenbosch Universityen_ZA
dc.subject.lcshPome fruit industry -- South Africaen_ZA
dc.subject.lcshFruit -- Quality -- South Africaen_ZA
dc.subject.lcshApples -- Effect of temperature on -- South Africaen_ZA
dc.subject.lcshFruit -- Postharvest technologyen_ZA
dc.subject.lcshScifresh apples -- Storageen_ZA
dc.subject.lcshProtective atmospheres -- Storageen_ZA
dc.subject.lcshApples -- Storage -- Diseases and injuries -- Preventionen_ZA
dc.subject.lcshApple scald -- Controlen_ZA
dc.subject.lcshBitter pit -- Controlen_ZA
dc.subject.nameUCTDen_ZA
dc.titleUnderstanding soft scald and bitter pit development in ‘Scifresh’ applesen_ZA
dc.typeThesisen_ZA
Files
Original bundle
Now showing 1 - 1 of 1
Thumbnail Image
Name:
ladegourdie_scald_2024.pdf
Size:
4.87 MB
Format:
Adobe Portable Document Format
Description:
Download
Collections
Masters Degrees (Horticulture)