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Meat quality of raw and processed guinea fowl (Numeda meleagris)Tlhong, Tumelo Maud 12 1900 (has links)
Thesis (MSc (Consumer Science)--Stellenbosch University, 2008. / The purpose of this study was to investigate the chemical composition mineral and cholesterol
content of the different cuts (breast, drumstick and thigh) of raw guinea fowl meat. The study
also aimed at establishing the effect of cooking method on guinea fowl quality attributes by
investigating the effect of different cooking methods on the chemical composition and sensory
attributes of the different cuts. The effect of injecting a brine solution on the chemical
composition and sensory attributes were also investigated.
There were no differences in terms of moisture content of the various cuts raw guinea fowl meat
The breast had significantly higher protein content when compared to drumstick and thigh
(P<0.05). The fat content was similar for all the cuts (P>0.05). Whilst the drumstick had
significantly the lowest value for ash content when compared to the thigh. Saturated fatty acids
(SFAs) and total unsaturated fatty acids (TUFAs) were not different (P>0.05) in all the cuts.
Drumstick had significantly higher monounsaturated fatty acids compared to other cuts (P<0.05),
and it had the highest polyunsaturated fatty acids (P<0.05). The breast had the lowest (P<0.05)
n-6 fatty acid value (44.25) and had relatively the lowest Polyunsaturated:Saturated (P:S) fatty
acid ratio of 1.74 when compared to the other cuts. High n-6:n-3 ratios, ranging from 7.05 to
16.58, were also found in all the cuts. Cholesterol was lowest (P<0.05) in the breast. Seventeen
amino acids were found, including the eight of the nine essential amino acids. Significant
differences were found in amino acid values for the different cuts. Values of iron were
significantly higher in the drumstick and thigh cuts (P<0.05), whilst drumstick had the highest
zinc content of all the cuts (P<0.05).
On investigating the effect of three cooking methods (baking-bag, foil-wrap, open-roasting at
140ºC for 65 minutes) on the chemical composition, the open-roasting method produced higher
moisture content (P<0.05) consistently for all cuts, with the breast having the highest and the
drumstick the lowest (P<0.05). The moisture content of the baking-bag method on the other
hand was consistently the lowest (P>0.05). This effect was significant for the breast, which had
lost the most moisture (P<0.05). The baking-bag method consistently resulted in a higher protein
content, which is attributed to the higher moisture loss (P<0.05) in comparison with the other
methods, resulting in a more concentrated product. With regard to the fat content no effect
resulting from the cooking methods could be observed (P>0.05), but the cuts’ natural fat content
was reflected especially in the open–roasting method (P<0.05) giving further support to the understanding that the open-roasting method indeed made the least inroads on the chemical
composition of guinea fowl meat under these restraints: controlled for cooking time and
temperature, internal temperature not controlled.
All the cuts cooked according to all the methods, had the favourable >0.4
Polyunsaturated:Saturated fatty acids (P:S) ratio, ranging from 0.91 to 1.42 between cuts and
treatments. The n-6:n-3 ratio was below the recommended beneficial value, namely <4:1, in all
the cuts irrespective of all the cooking methods, ranging from 2.47 to 3.08.
The study of the effect of the three cooking methods (baking-bag, foil-wrap and open-roast) on
the sensory attributes of the breast meat revealed that aroma-intensity of the three cooking
treatments did not differ significantly (P>0.05). Foil-wrap produced a more tender and juicier
product (P<0.05), while, when using the baking-bag method, values for flavour decreased
(P<0.05). It is proposed that a higher internal temperature (which was not controlled) was
attained when using the baking-bag method (temperature and time controlled) resulting in loss
of volatile flavour components.
The effect of the three cooking methods (baking-bag, foil-wrap and open-roast) on the proximate
composition (moisture, protein, fat and ash) of raw and cooked breast meat was investigated. As
anticipated raw breast meat had higher moisture content (74.55%, P<0.05) than the cooked
cuts, with open-roasting showing the highest (68.55%) value and foil-wrap close second
(68.12%). These values differed significantly from the baking-bag method (66.06%, P<0.05).
An investigation on the effect of brine infusion on the sensory attributes and chemical
composition (proximate and fatty acid composition, and mineral content) of breast meat, baked
in foil-wrap, was carried out using descriptive sensory analysis with the injected breast and the
control as variable. There were no significant differences (P>0.05) between the injected and the
control samples for any of the sensory attributes of aroma, tenderness, initial juiciness,
sustained juiciness and flavour. Judge:treatment variations were observed for all the attributes,
and samples differed for all attributes except for aroma. It is proposed that the use of the hand
injector could not effectively distribute the brine solution, hence the recommendation to repeat
the experiment using an electronic multineedle-injector. No effect was observed for the
proximate composition (P>0.05). Further research pertaining to cooking methods of meat of
free-range guinea fowl is recommended to address certain issues that have been highlighted.
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The use of near infrared reflectance spectroscopy (NIRS) for the chemical analysis of meat and feedstuffsViljoen, Mariaan 12 1900 (has links)
Thesis (MScAgric)--University of Stellenbosch, 2003. / ENGLISH ABSTRACT: Near infrared reflectance spectroscopy (NIRS) was evaluated as a tool to predict the chemical
composition of ostrich meat, mutton and feedstuffs. Seventy-three calibrations were developed. NIRS
analyses were conducted on an InfraAlyzer 500 spectrophotometer between 1100 and 2500 nm wavelengths.
Near infrared reflectance calibrations were developed for (i) the proximate chemical composition of
ostrich meat; (ii) the proximate chemical and mineral composition of mutton; (iii) the chemical composition
and digestibility of lupins, full-fat canola and the determination of alkaloids in lupins; (iv) the chemical
composition and digestibility of winter grains and maize; (v) the chemical composition and digestibility of
cereal hay, cereal straw, wheat stubble and alfalfa-grass/hay mixtures. The chemical composition of
different types of winter grain produced in the Western Cape area of South Africa, as well as the chemical
composition and digestibility of winter grain hay and straw produced in a Mediterranean rainfall area were
also determined.
Near infrared reflectance spectrometry proved to be successful for the prediction of crude protein (CP)
and fat in both animal species, as well as for ash and dry matter (DM) in freeze-dried mutton. Accurate
calibrations were also developed for certain minerals (K, P, Na, Mg, Fe and Zn).
Calibrations proved to be accurate for all the relevant chemical constituents in lupins, as well as the
DM, CP and fat calibrations in full-fat canola. The alkaloid calibration showed potential although more
samples should be included for a more accurate calibration. Winter grain calibrations were accurate for fat,
acid detergent fibre (ADF), in vitro organic matter digestibility (IVOMD), lysine and methionine. All
chemical composition calibrations of maize, except for ash, were accurate for future prediction. Chemical
composition calibrations of wheat stubble and alfalfa-grass hay mixtures resulted in prediction with similar
or slightly higher accuracy than calibrations reported in the literature. The calibrations developed for cereal
hay and straw were not suitable for prediction purposes. Possible reasons were discussed to explain these
inaccurate calibrations. Variation shown between different types of cereal grain (2-row barley, 6-row barley, oats, wheat and
triticale) accentuated the need for the analysis of different batches of grain produced under different
conditions for use in animal feed. The chemical composition and digestibility of winter grain straw and hay
were also obtained. These values provide a database for calculation of inclusion levels of these feedstuffs in
animal diets.
These investigations showed the NIRS to be a successful and rapid tool for the prediction of the
chemical composition of ostrich and lamb meat and locally produced feedstuffs. / AFRIKAANSE OPSOMMING: Naby infrarooi refleksie spektroskopie (NIRS) is geëvalueer as 'n metode om die chemiese
samestelling van volstruis- en skaapvleis, asook voedingsgewasse te voorspel. Drie en sewentig kalibrasies
is ontwikkel. NIRS ontledings is gedoen met ‘n InfraAlyzer 500 spektrofotometer tussen die golflengtes
1100 en 2500 nm.
Naby infrarooi refleksie kalibrasies is ontwikkel vir (i) die basiese chemiese samestelling van
volstruisvleis; (ii) die basiese chemiese en minerale samestelling van lamsvleis; (iii) die chemiese
samestelling en verteerbaarheid van lupiene en volvet kanola en die bepaling van alkaloïede in lupiene; (iv)
die chemiese samestelling en verteerbaarheid van wintergrane en mielies; (v) die chemiese samestelling en
verteerbaarheid van graanhooie, graanstrooie, koringstoppels and lusern-gras/hooi mengsels. Die chemiese
samestelling van verskillende tipes wintergrane wat in die Wes-Kaap omgewing van Suid-Afrika
geproduseer word, sowel as die chemiese samestelling en verteerbaarheid van wintergraanhooi en –strooi
wat geproduseer word in ‘n Mediterreënse reënval omgewing, is ook bepaal.
Naby infrarooi refleksie spektrofotometrie was suksesvol in die voorspelling van ru-proteïen (RP) en
vet in beide dierspesies, sowel as vir die bepaling van as en droë materiaal (DM) in gevriesdroogde
lamsvleis. Akkurate kalibrasies is ook ontwikkel vir sekere minerale (K, P, Na, Mg, Fe en Zn).
Kalibrasies ontwikkel vir die chemiese samestellings komponente in lupiene is reg deur die bank
akkuraat, sowel as die DM, RP en vet kalibrasies vir volvet kanola. Die alkaloïed kalibrasie het goeie
potensiaal getoon, alhoewel meer alkaloïedmonsters benodig word vir ‘n akkurate kalibrasie. Wintergraan
kalibrasies was akkuraat vir vet, suurbestande vesels (SBV), in vitro organiese materiaal verteerbaarheid
(IVOMV), lisien en metionien. Al die chemiese komponent kalibrasies vir mielies, behalwe die een vir as,
was akkuraat vir toekomstige bepalings. Chemiese komponent kalibrasies vir koring stoppels en luserngras/
hooi mengsels het akkuraatheid getoon wat gelyk, of effe beter, is as kalibrasies wat in die literatuur
opgeteken is. Kalibrasies ontwikkel vir graanhooie en graanstrooie was nie geskik vir
voorspellingsdoeleindes nie. Moontlike redes vir die onakkurate kalibrasies is volledig bespreek. Variasie gevind tussen verskillende tipes wintergrane (2-ry gars, 6-ry gars, hawer, koring en korog)
het die behoefte beklemtoon vir ontledings van grane geproduseer onder verskillende omgewingstoestande
vir gebruik in dierevoeding. Die chemiese samestelling en verteerbaarheid van wintergraanstrooi en –hooi is
ook bepaal. Hierdie waardes verskaf ‘n databasis vir berekening by insluiting van hierdie voergewasse in
diererantsoene.
Hierdie ondersoek het bewys dat NIRS ‘n suksesvolle en vinnige metode is vir die voorspelling van
die chemiese samestelling van volstruis- en lamsvleis en plaaslik geproduseerde voergewasse.
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Development and application of dispersive liquid-liquid microextraction for the determination of tetracyclines in meat by liquid chromatography tandem mass spectrometryMookantsa, Sandy Oshi Squizer 02 1900 (has links)
An environmentally friendly, rapid and cost effective analytical procedure based on dispersive liquid-liquid microextraction was developed for the determination of six tetracyclines (TCs) in meat destined for human consumption. Meat extracts were analyzed for TCs using a sensitive and selective analytical technique, liquid chromatography tandem mass spectrometry. Various influencing factors on the extraction, separation and determination of TCs such as pH of mobile phases, type and volume of disperser solvent, type and volume of extraction solvent and sample pH were optimized. Validation parameters such as calibration function, limit of detection (LOD), limit of quantification (LOQ), detection capability (CCα), decision limit (CCβ), accuracy and precision were established according to EU commission decision 2002/657/EC. Linearity in the range of 25-200 μg kg-1 was obtained with regression coefficients ranging from 0.9991 to 0.9998. Recoveries of spiked blank muscle samples at three levels (i.e. 50, 100 and 150 μg kg-1) ranged from 80 to 101% and reproducibility was between 2 and 7%. The LODs and LOQs ranged from 2.22 to 3.59 μg kg-1 and from 7.38 to 11.49 μg kg-1 respectively. The CCα ranged from 105 to 111 μg kg-1 while CCβ ranged from 107 to 122 μg kg-1. The proposed method compared well with the dispersive solid phase extraction method and was successfully applied to the determination of TCs in meat samples. Some of the thirty bovine muscle samples obtained from local abattoirs and butcheries were found to contain two tetracycline antibiotics residues (chlortetracycline and oxytetracycline) with oxytetracycline being the most commonly detected. The concentration levels of the TC residues detected in the eleven bovine muscle samples were between 12.4 and 68.9 μg kg-1, levels that are lower than the European Union set maximum residue level (MRL) of 100 μg kg-1 hence the meat was fit for human consumption. / Chemistry / M. Sc. (Chemistry)
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