G. Osthoff

Comparison of the lipid properties of captive, healthy wild, and pansteatitis-affected wild Nile crocodiles (Crocodylus niloticus).

The results presented describe and compare the fatty acid composition and melting properties of captive, healthy wild, and pansteatitis-affected wild crocodiles (Crocodylus niloticus). Differences in fatty acid composition between intramuscular and adipose fat is noted in captive crocodiles, and the latter differs from wild crocodiles as a result of different diets. Adipose fat of healthy wild crocodiles differs minimally from diseased ones, respectively with 37.3+/-2.6% vs. 43.2+/-2.3% monounsaturated fatty acids, and 43.2+/-2.9% in dead crocodiles, while polyunsaturated fatty acids decrease from 27.3+/-1.9% to as low as 21.9+/-3.6% respectively. Of the unsaturated fatty acids 18:2n-6 decreased from 6.5+/-2.6% in unaffected crocodiles to 3.5+/-0.6% in highly affected and 3.2+/-0.4% in dead crocodiles, and 22:5n-3 from 2.8+/-0.6% to 1.8+/-0.3% and 2.2+/-0.3% respectively. The melting properties as determined by differential scanning calorimetry show that extracted adipose fat is a small degree softer in pansteatitis-affected tissue, specifically in the temperature range 7-36 degrees C, and does not contribute to the hard texture noted for adipose fat tissue of pansteatitis-affected animals. A high moisture content of 51.0+/-19.7% of the fat tissue of pansteatitis-affected animals vs.17.1+/-8.0% of healthy ones, suggests that physiological changes due to interstitial inflammation may contribute to the hard texture.

The Effect of Variety and Location on Cactus Pear (Opuntia ficus-indica) Fruit Quality

Little is known about the performance of South African cactus pear varieties in different agro-ecological regions. Effects of locality on internal quality parameters of available cactus pear varieties were examined. With only one exception, no significant differences among the mean replication values for the different parameters between the different locations were observed. The differences between mean values for most individual parameters at the three localities were highly significant. Highly significant differences between the mean values for the measured characteristics were observed, not only among the locations (except for the pulp glucose values), but also for the influences of genotype and interaction between locality and genotype. Significant variations existed between mean values of the different characteristics between localities. Genotype × environmental interactions were noted. It was concluded that Meyers is the most appropriate cultivar for economical purposes in South Africa.

Milk composition of captive vervet monkey (Chlorocebus pygerythrus) and rhesus macaque (Macaca mulatta) with observations on gorilla (Gorilla gorilla gorilla) and white handed gibbon (Hylobates lar)

The nutrient content and fatty acid composition of vervet monkey milk has been determined and is compared with rhesus macaque, and two hominoid apes, the white handed gibbon and gorilla. With 15.7+/-4.1 g protein, 33.1+/-9.4 g fat, and 85.1+/-7.5 g lactose per kg milk, vervet monkey milk does not differ from that of rhesus macaque, and is within the range of other primates. Small amounts (>1 g kg(-1)) of oligosaccharides, glucose, galactose and fucose were noted. In comparison, gorilla milk has a low fat content of 13.8 g kg(-1), but contains high levels of oligosaccharides at 7.0 g kg(-1) milk. The hominoid partner, the white handed gibbon, contains no oligosaccharides and a milk fat content similar to other hominoid species. Differences between vervet monkey and rhesus macaque milks were observed in the electrophoretic pattern of the milk proteins, mainly amongst the kappa- and gamma-caseins, which also differ from that of the hominids. The fatty acid contents of these milks differ from studies where a natural diet of leafy material was available in that a low content of alpha-linolenic acid (18:3n-3) was noted. A phylogenetic effect is observed for the content of 8:0, 10:0 fatty acids between the Cercopithecidae and Hominoidea, and a further phylogenetic effect suggested between the Hylobatidae and Hominidae.

The chemical composition of milk from free-ranging African buffalo (Syncerus caffer)

Milk was obtained from five African buffalo (Syncerus caffer) cows located In the Pilanesberg Nature Reserve and the Phalaborwa district, South Africa. The average nutrient content was 62.9 ± 24.9 g protein, 133.9 ± 80.9 g fat and 51.6 ± 21.0 g lactose per kg milk. The protein fraction respectively consisted of 4.7 ± 3.2 g whey per kg milk and 58.9 ± 21.4 g casein proteins per kg milk. Electrophoresis and subsequent Identification of protein bands showed a migrating sequence of proteins similar to that observed In cattle (Bos taurus) milk. The lipid fraction contained 587.1 ± 50.1 g saturated fatty acids per kg milk fat, and 313.1 ± 35.6 and 27.2 ± 5.8 g/kg mono- and poly-unsaturated fatty acids respectively. Compared to domesticated bovine species, a low content of short and Intermediary chain length fatty acids were observed, while stearic and oleic acid concentrations were higher. Substantial concentrations of uneven carbon chain fatty acids were also observed.

Characterization of a spray-dried soymilk powder and changes observed during storage.

Physical characterization of a soymilk powder was carried out by electron microscopy. Chemical characterization was analyzed by proximate analysis, mineral composition by atomic absorption spectrometry, fatty acid composition by gas chromatography and protein composition by electrophoresis. The powder consists of large granules of 60—80 μm, which may be hollow, with smaller granules of 10—20 μm attached to them. Powder particles are covered by a layer of fat. During storage at 25 °C fat is spreading over the surface, while at —12 °C the fat is contracting. This change affected chemical stability, resulting in high level of fat oxidation when stored at 4 °C or 25 °C as well as a decrease in unsaturated fatty acids. Storage also affected the chemical properties of the re-constituted soymilk; the pH of a 12% soy powder suspension increased from 6.68±0.05 to 7.06±0.08 after 12 months of storage. Storage temperature did not affect the pH of the suspension and this change could also not be ascribed to protein aggregation.

Physical and chemical properties associated with food quality in sorghum

Samples of 13 genetically diverse sorghum [Sorghum bicolor (L.) Moench] accessions were analysed for physical properties and chemical composition. The food (injera) quality and the phenolic (condensed tannins) content of six sorghum samples were also determined. The accessions showed a wide variation in protein (7.99 to 17.8%), lipids (2.52 to 4.76%), starch (51.88 to 85%), and amylose (12.30 to 28.38%) content. Grain weight varied in a wide range, and endosperm texture varied from intermediate to completely starchy. Linoleic acid (18:2) and oleic acid (18:1) were the major fatty acid constituents of sorghum lipids. Only a few significant correlations were observed among the physical and chemical properties. Three of the six accessions used for sensory analysis, namely Ambajeettee, AL-70 and ETS 2752 were chosen for their desirable properties in injera making. The chemical and physical properties of the selected accessions were characterised by high protein content, low tannins, intermediate endosperm texture, and white seed colours. Red seeded sorghum and white seeded sorghum with pigmented testa were found to be less desired.

Comparison of the milk composition of free-ranging blesbok, black wildebeest and blue wildebeest of the subfamily Alcelaphinae (family: Bovidae)

The proximate composition of milk from free ranging blesbok, black wildebeest and blue wildebeest is reported, with detailed analysis of fatty acid composition and protein identification by electrophoresis. The milk of the blesbok, black- and blue wildebeest contain respectively 5.6 +/- 0.3, 4.3 +/- 0.7 and 4.1 +/- 0.9 g/100 g protein, 8.6 +/- 1.1, 5.5 +/- 1.5 and 7.5 +/- 2.1 g/100 g fat, and 4.9 +/- 0.4, 4.1 +/- 0.6 and 5.3 +/- 1.6 g/100 g lactose, and are comparable with ovine milk. The milk contains high levels of saturated fatty acids, respectively, 82.5 +/- 1.7 g/100 g, 75.2 +/- 1.5 g/100 g and 88.2 +/- 1.8 g/100 g milk fat. The medium carbon chain length saturated fatty acids 8:0, 10:0 and 12:0 occur in the highest amounts recorded so far in ruminant milk, and the 14:0 content is the highest recorded in any milk. This suggests a genetic characteristic of the Alcelaphinae that reflects on the specificity and activity of the thioesterase involved in the fatty acid synthesis. By electrophoresis the kappa- and gamma-caseins are separated into multiple bands and the alpha-caseins of the wildebeest into two bands.

Comparison of the Milk Composition of Free-Ranging Eland, Kudu, Gemsbok and Scimitar Oryx, with Observations on Lechwe, Okapi and Southern Pudu

The proximate composition of milk from freefree-ranging-ranging kudu, eland, and oryx is reported with detailed analysis of fatty acid composition and protein identification by electrophoresis. The milk of the eland, kudu and gemsbok contained, respectively, 88.0 ± 13.3,67.5 ± 5.6 and 61.7 ± 12.3 g/kg protein, 67.9 ± 22.7,61.0 ± 18.0 and 71.9 ± 27.1 g/kg fat, and 50.0 ± 10.5,41.0 ± 2.5 and 41.9 ± 2.3 g/kg lactose, and are comparable with ovine milk. The gemsbok milk contained 4.4 ± 1.5 g/kg oligosaccharide, which is four times higher than that found in other ruminants. The milk of the eland and kudu contained significantly lower levels of saturated fatty acids than that of the gemsbok, the levels being respectively, 62.55 ± 3.61,69.70 ± 1.62 and 79.46 ± 0.84%, due to the saturated acids of 8–14 carbon chain lengths. When adding the milk composition of sable antelope from the literature, statistical analysis (PCA) showed a difference between the milk composition of the subfamilies Hippotraginae and Bovinae (tribe Tragelaphini), suggesting phylogenetic effects. Observations on the composition of milk from scimitar oryx, lechwe, okapi and southern pudu are also reported.

Comparison of the Lipid Composition of Three Adipose Tissue Types of Male and Female Wild Nile Crocodiles (Crocodylus niloticus)

Abstract We describe and compare the fatty acid composition of three different adipose tissue types, namely, abdominal, tail, and steatotheca (an abdominal fat body) tissues of healthy wild Nile Crocodiles (Crocodylus niloticus). No significant differences were observed in the fatty acid composition among the three fat tissues, apart from eicosapentaenoic acid, which occurs in small amounts of less than 1% in all the types of tissue. In individual animals, limited variation in the steatotheca may occur compared with the other two adipose fats. The total fat of the male crocodile is more saturated, with 44.4% ± 3.2% saturated fatty acids compared with the 42.0% ± 3.2% of the female. The greatest differences between the sexes were observed for pentadecylic, margaric, stearic, palmitoleic, vaccenic, and oleic acids. No interaction between gender and anatomical position of fatty acids was observed. This is a first comparative study of fat composition of different adipose tissues in a reptile. When the data are compared with similar data of fish, birds, and mammals, it may be concluded that differentiation of the composition of adipose fat is an evolutionary development of mammals.

Acceleration of yoghurt fermentation time by yeast extract and partial characterisation of the active components

Water soluble autolysate of yeast, usually utilised for microbial growth support, was used as additive in yoghurt fermentation. The yeast extract (YE) resulted in a decrease of fermentation time by 21% to reach a pH of 4·6. However, the YE resulted in unacceptable flavour and taste. By size exclusion chromatography, a fraction of the YE was obtained that could account for the observed 21% decrease in fermentation time. The fraction contained molecules of low molecular weight, consisting of minerals, free amino acids and peptides. The acceleration of the yoghurt fermentation was ascribed to the short peptides in the fraction. It is proposed that the application of this extract in industrial yoghurt manufacture would result in savings for both the industry and the consumer.