Harvest maturity, storage conditions and tree age influencing internal browning and fruit quality of Rosy Glow apple (Malus domestica Borkh)

Doe, James Wonder (2020-03)

Thesis (MScAgric)--Stellenbosch University, 2020.

Thesis

ENGLISH ABSTRACT: ‘Rosy Glow’ being a limb/bud sport variety of ‘Cripps’ Pink’ apple, is also regarded prone to internal flesh browning (IFB) similar to its parent cultivar. IFB in ‘Cripps’ Pink’ apples has been reported to be influenced by both pre-harvest and post-harvest factors, such as harvest maturity, tree age, mineral nutrition, storage temperature, and duration. The application of chemicals, such as 1-methylcyclopropene (1-MCP) and diphenylamine (DPA), also influences the development of IFB. This study investigated the effect of tree age, harvest maturity, storage temperature, 1-MCP treatment, and storage duration in controlled atmosphere (CA) on IFB development in ‘Rosy Glow’ apples over two seasons (2014/2015 and 2015/2016). Fruit were harvested at <40% and >50% starch breakdown (SB) for the harvest maturity trial (Trial 1) and <40% SB for the storage duration, temperature, 1-MCP (Trial 2), and tree age trial (Trial 3). Trial 1 and Trial 3 fruit were stored for 7 months in CA (1% CO2 and 1.5% O2) plus 6 weeks in regular atmosphere (RA) at -0.5 °C and 7 days at 20 °C and evaluated after each period. Trial 2 fruit, treated with or without 1-MCP, were stored at -0.5 °C or 2 °C and evaluated after 3, 5, and 7 months in CA plus 6 weeks in RA and a 7-day shelf-life period. Fruit were evaluated for IFB, SB, firmness, background colour, total soluble solids (TSS), titratable acidity (TA), greasiness, and blush colour at the end of each storage period. The results showed that diffuse browning (DB), radial browning (RB), combination browning (CB), and CO2 browning (CO2B) were the types of IFB observed in all three trials. Optimum harvested fruit exhibited a lower susceptibility to IFB in general in both seasons (2015 and 2016), comparative to fruit harvested post-optimum. 1-MCP treated fruit had a lower IFB incidence and no tree age effect was observed in this trail. DB and RB was first observed after 5 months in CA plus 6 weeks RA at -0.5 °C. DB was the main type of browning present. Harvest maturity (>50% SB) played a significant role in ‘Rosy Glow’ IFB development. Fruit quality was better retained at -0.5 °C than at 2 °C, while 1-MCP treated fruit quality was better maintained than control fruit over time. An orchard influence was observed on ‘Rosy Glow’ IFB and requires further investigation.

AFRIKAANSE OPSOMMING: ‘Rosy Glow’, wat 'n tak/knop sport variëteit is van ‘Cripps’ Pink’ appels, word ook beskou as geneig tot interne vlees verbruining (IVV), soortgelyk aan die ouerkultivar. Daar word beweer dat IVV in ‘Cripps’ Pink’ appels beïnvloed word deur beide voor-oes- en na-oes faktore, soos oesrypheid, boomouderdom, minerale voeding, opbergingstemperatuur en duur. Die toediening van chemikalieë, soos 1-metielsiklopropeen (1-MCP) en difenielamien (DPA), beïnvloed ook die ontwikkeling van IVV. Hierdie studie het die effek van boomouderdom, oes volwassenheid, opbergingstemperatuur, 1-MCP behandeling en opbergingsduur in beheerde atmosfeer (BA) op IVV-ontwikkeling in ‘Rosy Glow’ appels gedurende twee seisoene ondersoek (2014/2015 en 2015/2016). Vrugte is geoes teen <40% en> 50% styselafbraak (SA) vir die oesrypheidsproef (proef 1) en <40% SA vir die opbergingsduur, temperatuur, 1-MCP (proef 2) en die boomouderdomsproef (Proef 3). Proef 1 en Proef 3-vrugte is vir 7 maande in BA gestoor (1% CO2 en 1,5% O2) plus 6 weke in gewone atmosfeer (GA) by -0,5 °C en 7 dae by 20 °C, en na elke periode geëvalueer. Proef 2 vrugte, behandel met of sonder 1-MCP, is by -0,5 °C of 2 °C gestoor en na 3, 5 en 7 maande in BA plus 6 weke in GA en 'n 7-dae rakleeftydperk geëvalueer. Vrugte is geëvalueer vir IVV, SA, fermheid, agtergrondkleur, totale oplosbare vastestowwe (TOVS), titreerbare sure (TS), vetterigheid en bloskleur aan die einde van elke opbergtydperk. Die resultate het getoon dat diffuse verbruining (DB), radiale verbruining (RB), kombinasie-verbruining (CB) en CO2-verbruining (CO2B) die tipes interne IVV was wat in al drie die proewe waargeneem is. In beide seisoene (2015 en 2016) het die vroeg tot optimaal geoesde vrugte 'n laer vatbaarheid vir IVV in die algemeen gehad, vergelykend met vrugte wat na-optimum oesrypheid (>50% SA) geoes is. 1-MCP behandelde vrugte het 'n laer IVV-voorkoms gehad en geen boomouderdomseffek is in hierdie studie waargeneem nie. DB en RB is eers na 5 maande in BA plus 6 weke GA by -0.5 °C waargeneem. DB was die belangrikste tipe IVV teenwoordig. Oesrypheid (> 50% SA) het 'n belangrike rol gespeel in die ontwikkeling van ‘Rosy Glow’ IVV. Die vrugkwaliteit is beter behou by -0,5 °C as by 2 °C, terwyl 1-MCP behandelde vrugkwaliteit beter gehandhaaf is as kontrole-vrugte. Die invloed van die boord is op die 'Rosy Glow'-IVV waargeneem en vereis verdere ondersoek.

Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/108268
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