Thesis (MScVoedselwet)--University of Stellenbosch, 2003. / ENGLISH ABSTRACT: Two experiments were conducted in order to manipulate the physical and chemical
properties and shelf life of ostrich meat.
Experiment 1: The effect of dietary fish oil rich in n-3 fatty acids on the organoleptic,
fatty acid and physicochemical characteristics of ostrich meat.
The diet of four ostrich groups (15 birds per group), approximately 3 months of age (ca. 41
kg live weight) grazing a predominantly oats pasture, was supplemented with a diet
containing 6.7% fish oil. The birds received a supplement of either 0 (diet 1), 800 (diet 2),
1600 (diet 3) or 2400 g (diet 4) DM/day resulting in the consumption of 0 (diet 1), 14.5 (diet
2), 29 (diet 3) and 43.5 (diet 4) g fish oil per day. The ostriches were slaughtered at 10
months of age (ca. 70 kg live weight).
An increase in the amount of fish oil consumed was found to have had statistically no
significant effect on the sensory characteristics of the M. iliofibularis, although there was a
tendency towards an increase in ‘fishiness’, for both aroma and flavour. However,
increased concentrations of fish oil had a significant effect on the aroma and flavour of the
abdominal fat pads. The muscle pHf and muscle lightness (L*) reflected a significant
reduction with increased fish oil levels. The increased feed intake, on the other hand, had
no effect on the chemical composition (moisture, protein, fat and ash content) of the meat.
The fatty acid profile of both fat and meat was affected by the consumption of fish oil. The
SFA concentration increased, while the PUFA concentration decreased, with an increase
in feed intake. The MUFA concentration remained constant for all four groups.
Experiment 2: The effect of dietary vitamin E and the type of packaging on the
sensory quality, physicochemical composition and shelf life of ostrich meat.
Two groups of ostriches (35 birds per group; ca. 3 months old) were fed diets containing
either 40 mg/kg feed vitamin E (control) or 150 mg/kg feed Vitamin E for nine months. The
birds were slaughtered at 12 months of age.
The effect of different the levels of vitamin E and heat shrink treatment of vacuum
packaging material on the shelf life of refrigerated (0°C) ostrich M. flexor cruris lateralis,
was evaluated over 81 days. Vitamin E and heat shrink treatments were found to have
had no significant effect on the sensory characteristics; off-meat aroma, sourness,
juiciness and mealiness. Rancidity was found to be slightly more pronounced (although not statistical significant) in the vitamin E and heat shrink groups than in the feed control
and vacuum-packed groups. A significant decrease in the organoleptic quality of the
meat, over a 40 day shelf life period, was observed. The pH and muscle tenderness
showed a significant reduction with increased storage time. The purge loss in the package
increased over time with no change in muscle drip loss. The colour, conjugated dienoic
acid and fatty acid content showed no significant changes over time or with regards to
treatment. The total viable counts and coliform numbers in the muscle increased over
time, with the coliforms being slightly suppressed by the inclusion of vitamin E in the diet.
A microbiological safe shelf life of 40 days at 0°C was obtained. / AFRIKAANSE OPSOMMING: Twee eksperimente is uitgevoer om die fisiese en chemiese eienskappe, asook die
rakleeftyd van volstruisvleis, te manipuleer.
Eksperiment 1: Die effek van visolie, ryk aan n-3 vetsure, op die organoleptiese,
vetsuur- en fisies-chemiese eienskappe van volstruisvleis.
Die dieet van vier groepe volstruise (15 voëls per groep), ongeveer 3 maande oud (ca. 41
kg lewende massa) wat ‘n hawer weiding bewei het, is aangevul met ‘n
byvoedingsmengsel wat 6.7% visolie bevat en in toenemende hoeveelhede vir die groepe
volstruise gevoer is. Die voëls het ‘n aanvulling van 0 (dieet 1), 800 (dieet 2), 1600 (dieet
3) of 2400 g (dieet 4) DM/dag ontvang wat gelei het tot ‘n inname van 0 (dieet 1), 14.5
(dieet 2), 29 (dieet 3) en 43.5 (dieet 4) g visolie per dag. Die volstruise is op ‘n ouderdom
van 10 maande geslag (ca. 70 kg lewende massa).
‘n Toename in die hoeveelheid visolie ingeneem, het geen statisties betekenisvolle
effek op die sensoriese eienskappe van die M. ilifibularis gehad nie, alhoewel daar ‘n
tendens was vir ‘n toename tot ‘n ‘visagtige’ aroma en smaak. ‘n Toename in die
konsentrasie visolie het egter ‘n betekenisvolle effek op die ‘visagtige’ aroma en smaak
van die abdominale vet neerslae gehad. Die spier pHf en spier ligtheid (L*) het ‘n
betekenisvolle afname met toename in voer inname getoon. Die verhoogde olie inname
het egter geen effek op die chemiese samestelling (vog-, proteïen-, vet- en asinhoud) van
die vleis gehad nie. Die vetsuurprofiel van beide die abdominale vet neerslae en die vleis
is deur die inname van visolie verander. Die versadigde vetsuurkonsentrasie het verhoog
terwyl die poli-onversadigde vetsuurkonsentrasie verlaag het met ‘n toename in
rantsoenvlakke. Die mono-onversadigde vetsuurkonsentrasie het egter konstant gebly vir
al vier groepe.
Eksperiment 2: Die effek van vitamien E en die tipe verpakking op die sensoriese
kwaliteit, fisies-chemiese samestelling en rakleeftyd van volstruisvleis.
Twee groepe volstruise (35 voëls per groep, ongeveer 3 maande oud) het voere oor ‘n
tydperk van nege maande ontvang wat 40 mg vitamien E/kg voer (kontrole) of 150 mg
vitamien E/kg voer bevat het. Die voëls is op 12 maande ouderdom geslag.
Die effek van die verskillende vlakke van vitamien E en hitte-behandeling van die
verpakkings materiaal op die rakleeftyd van verkoelde (0°C) volstruis M. flexor cruris lateralis, is oor 81 dae geëvalueer. Vitamien E en die hitte-behandeling het geen
betekenisvolle effek op die organoleptiese eienskappe (af-vleis aroma, suurheid,
sappigheid en melerigheid) gehad nie. Galsterigheid was ‘n bietjie meer gedefinieerd
(anie-betekenisvol) in die vitamien E en hitte behandelde groepe as in die rantsoen
kontrole en vakuum verpakte vleis. ‘n Betekenisvolle afname is waargeneem in die
organoleptiese kwaliteit van die vleis oor ‘n 40 dae rakleeftyd periode. Die pH en taaiheid
van die spier het betekenisvol afgeneem met ‘n toename in bergingsperiode. Die drup
verlies tydens verpakking het ook oor tyd toegeneem, terwyl geen verandering in die
analitiese drup verlies van die spier verkry is nie. Die kleur, gekonjugeerde dieensuur en
vetsuursamestelling het geen verandering oor tyd of ten opsigte van behandeling getoon
nie. Die Totale Lewendig Seltelling en coliforme het toegeneem oor tyd, terwyl die
coliforme deur die byvoeging van vitamien E tot ‘n mate onderdruk is. ‘n Mikrobiologies
veilige rakleeftyd van 40 dae is verkry.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/16341 |
| Date | 12 1900 |
| Creators | Joubert, Marisa |
| Contributors | Hoffman, L.C., Manley, M., Brand, T.S., University of Stellenbosch. Faculty of Agrisciences. Dept. of Food Science. |
| Publisher | Stellenbosch : University of Stellenbosch |
| Source Sets | South African National ETD Portal |
| Language | en_ZA |
| Detected Language | Unknown |
| Type | Thesis |
| Format | x, 71 leaves |
| Rights | University of Stellenbosch |
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