Thesis (MScAgric (Horticulture))--University of Stellenbosch, 2009. / ENGLISH ABSTRACT: In order to develop a novel pink- or red-fleshed apple for the fresh consumer market,the red-fleshed genotype, ‘KAZ 91’ (Malus niedzwetzkyana Dieck.), was crossed with
‘Meran’ (M. domestica Borkh) at the Agricultural Research Council (ARC) apple breeding programme in South Africa. The objective of this study was to evaluate and quantify colour variability in the flesh and peel of this progeny (Family 1), to assess quality traits (i.e., acidity and total soluble solids) and phenolic levels in fruit peel and flesh, and to investigate consumer preference for the taste and appearance of redfleshed
apples. All data, except for consumer preference, were also collected on two
white-fleshed M. domestica Borkh families, i.e., ‘Reinette Burchardt’ x ‘Treco Red
Gala’ (Family 2) and ‘Meran’ x ‘Treco Red Gala’ (Family 3). Fruit of Family 1 seedlings were on average darker red with greater blush coverage
and higher anthocyanin and phenolic levels compared to fruits of Family 2 and 3. The
proportion of bearing trees with red-fleshed fruits in Family 1 increased from 25% in
2007 to 35% in 2008. The intensity and distribution of red pigmentation in the flesh
varied considerably between seedlings and even between individual apples from the
same tree. A high intraclass correlation coefficient was found for red-flesh coverage
within Family 1, indicating a high level of genetic determination that can be used in
breeding. When only red-fleshed seedlings were considered, an intermediate
repeatability coefficient (0.54) for red-flesh coverage indicates that the extent of red
flesh coverage varies to some extent between seasons. The effect of environmental
factors on red flesh colour needs to be assessed and breeders need to take care to
select for genotypes with stable flesh colour intensity and coverage. Small intraclass
correlations were found between families for other traits. No correlation was found for
anthocyanin and total phenolics in both peel and flesh or between anthocyanin levels
in the peel and flesh of Family 1 fruit. This suggests that red-fleshed fruit will not
necessarily be high in antioxidants – since phenolics is by far the greatest contributor
to fruit antioxidant capacity. The lack of a correlation between peel and flesh
anthocyanin levels also suggest that fruit with dark red flesh will not necessarily have
a dark red skin colour. Family 1 fruit were more prone to flesh browning and were
more acidic compared to fruit of Families 2 and 3. With regard to consumer preference for flesh colour, 74% of South African
consumers preferred white flesh while 64% preferred an attractive “floral” pattern
created by the combination of a red cortex and white core. Consumers indicated a
much lower liking for other distribution patterns and lower intensities of red flesh
colour. Consumers preferred the taste of apples that were crisp, crunchy and high in
apple flavour irrespective of flesh colour. Red-fleshed fruit were generally acidic or
had poor texture, and some were also astringent. However, despite a general dislike in
acidic fruit, consumers showed a preference for acidic fruit if that fruit also had high
red-flesh coverage. / AFRIKAANSE OPSOMMING: Appeltelers van die Suid-Afrikaanse Landbounavorsingsraad (LNR) Infruitec-
Nietvoorbij poog om unieke appelkultivars met ‘n pienk of rooi vleiskleur te
ontwikkel. Vir hierdie doel het hulle die rooivleis genotipe, ‘KAZ 91’ (Malus
niedzwetzkyana Dieck), gekruis met ‘Meran’ (M. domestica Borkh). Hierdie studie is
uitgevoer ten einde kleurvariasie, interne kwaliteitseienskappe (i.e., suurheid en totale
oplosbare vastestowwe) en vlakke van fenole in die vleis en skil van bogenoemde
kruisingkombinasie se nageslag (Familie 1) te evalueer en te kwantifiseer asook om
verbruikersvoorkeure vir die smaak en voorkoms van rooivleis appels te bestudeer.
Buiten vir verbruikersvoorkeure, is alle data ook ingesamel vir twee witvleis M.
domestica families, naamlik ‘Reinette Burchardt’ x ‘Treco Red Gala’ (Familie 2) en
‘Meran’ x ‘Treco Red Gala’ (Familie 3).
Familie 1 saailinge se vrugte was gemiddeld donkerder rooi met ‘n groter rooi blos en
hoër antosianien- en fenoolvlakke in vergeleke met vrugte van Families 2 en 3. Van
die Familie 1 saailinge wat wel vrugte gedra het, het 25% en 35% in onderskeidelik
2007 en 2008 vrugte met rooi vleis gehad. Die intensiteit en verspreiding van rooi
pigmentasie in die vleis het aansienlik varieer tussen saailinge en selfs tussen
individuele appels van dieselfde boom. ‘n Hoë intraklas korrelasie koëffisiënt is
gevind vir die proporsie van die vleis met rooi pigmentasie in Familie 1 nageslag. Dit
dui op ‘n hoë vlak van genetiese determinasie en vinnige vordering met teling vir
hierdie eienskap. Indien net rooi-vleis saailinge egter oorweeg word, word ‘n
intermediêre herhaalbaarheid koëffisiënt (0.54) vir die proporsie van die vleis wat rooi
is verkry, wat dui op aansienlike variasie tussen seisoene in die omvang van rooi
pigmentasie. Die effek van omgewingsfaktore op rooi vleiskleur behoort dus
bestudeer te word en telers moet let daarop om te selekteer vir genotipes met stabiele
vleiskleur intensiteit en bedekking. Die intraklas korrelasies tussen families vir ander
vrugeienskappe was klein. Antosianienvlakke en totale fenole in die skil en vleis van
Familie 1 vrugte het nie gekorreleer nie. Dit dui daarop dat rooivleis appels nie
noodwendig ‘n hoër antioksidantkapasiteit het nie – fenole maak by verre die grootste
bydrae tot die antioksidantkapisiteit van vrugte. Antosianienvlakke in die skil en vleis
van Familie 1 vrugte het ook nie gekorreleer nie wat daarop dui dat vrugte met ‘n
donker rooi vleis nie noodwendig ook ‘n donker skilkleur sal hê nie. Familie 1 vrugte was gemiddeld suurder as vrugte van Families 2 en 3 en Familie 1 vrugte se vleis het
gemiddeld ook meer verbruining ondergaan.
Ten opsigte van verbruikersvoorkeur vir vleiskleur is gevind dat 74% van verbruikers
‘n wit vleiskleur verkies het terwyl 64% gehou het van die aantreklike “blom” patroon
gevorm deur ‘n rooi korteks en wit kern. Verbruikers het aansienlik minder gehou
van enige ander verspreiding van rooi pigment in die vleis of van ‘n laer intensiteit
rooi kleur. In terme van smaak is geurige appels met ‘n bros tekstuur verkies ongeag
hul vleiskleur. Rooivleisappels was oor die algemeen suur met ‘n swak tekstuur.
Sommige rooivleisappels was ook frank. Tog, ten spyte van ‘n algemene afkeur in
suur appels, het verbruikers ‘n voorkeur getoon vir vrugte met ‘n kombinasie van hoë
suur en ‘n hoë proporsie vleis met rooi pigmentasie.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/2987 |
| Date | 12 1900 |
| Creators | Thovhogi, Fhatuwani |
| Contributors | Steyn, W. J., Labuschagne, I., Muller, M., University of Stellenbosch. Faculty of Agrisciences. Dept. of Horticulture. |
| Publisher | Stellenbosch : University of Stellenbosch |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | Unknown |
| Type | Thesis |
| Rights | University of Stellenbosch |
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