The nutritional composition of South African eggs

Satnples of hens' eggs produced throughout South Africa during the winter and summer of 1990 were analysed for nutrient content to obtain representative values for inclusion in food tables intended for local use. Proximate analyses and vitamin, mineral, fatty acid and amino acid determinations were carried out on all the samples. When the analysed values obtained for whole eggs, egg yolks and egg whites were compared with values listed in the Research Institute for Nutritional Diseases food tables, a number of differences were found. With regard to the inclusion of eggs in diets in general, the cholesterol content of whole eggs was found to be 23,5% lower and the total fat and saturated fatty acid contents 9% and 10% lower, respectively, than the listed values.The eggs were found to be rich sources of protein of animal origin, all the essential amino acids, thiamine, riboflavin, pantothenic and folic acids, vitamin B12 , biotin, vitamin D1, vitamin E and phosphorus. Eggs are readily available and inexpensive and should be included in the diets of young children, adolescents, pregnant and breastfeeding women, adults, the elderly and particularly those ofall ages who are undernourished

Growth-suppressing and related effects on rats of unextracted and ethanol-extracted grains of certain sorghum cultivars

Samples of the grains of 6 different sorghum cultivars, whole as well as ethanol-extracted to reduce tannin content, were fed in balanced diets to young male rats (12 per sample) in an experiment aimed at assessment of the effect of sorghum grain feeding on growth rate and liver lipid content, as well as determination of the digestibility of the sorghum protein. The possible involvement of tannins in the biological utilisation of the sorghum grains was also considered. The results revealed statistically significant differences among cultivars, mainly in respect of effect on growth rate and protein digestibility. With regard to the possible cause(s) of such differences it was found that there were significant correlations between (i) growth rate and protein digestibility; (ii) protein digestibility and dietary tannin content; and (iii) growth rate and dietary tannin content. The degree of correlation observed varied in descending order from (i) to (iii). It was concluded that differences among cultivars in respect of effect on growth were essentially due to differences in protein digestibility, and that the digestibility figure provides the most convenient basis for selectionof cultivars for breeding purposes. Observed sample-to-sample variations in protein digestibility and effects on growth were only partially explicable in terms of variations in dietary tannin content. The data obtained on liver lipid content could not be explained on the basis of the reaction involving detoxification of gallic acid through O-methylation and the consequent reduction of available supplies of the methyl donors, methionine and choline.S. Afr. Med. J., 48, 1691 (1974

Suicidal ideation and attempt among South African medical students

International data reveal that medical students are at higher risk of attempting suicide than the general population. We aimed to determine the prevalence of suicidal ideation and attempt among South African medical students from three universities and identify key predisposing risk factors. Data were collected via a questionnaire to medical students on demographics, mental health history, depressive symptoms, suicidal ideation and attempt. A total of 874 medical students from three universities were enrolled. We found a high prevalence of suicidal ideation (32.3%) and suicidal attempt (6.9%), which is three times higher than the general age-appropriate South African population. Simple screening questionnaires can identify such students, enabling universities to provide targeted and improved support for at-risk students.http://www.samj.org.z

HRSBallast : a high-resolution dataset featuring scanned angular, semi-angular and rounded railway ballast

A high-resolution dataset of digitally scanned railway ballast (HRSBallast) is presented, consisting of 108 individual, digitised samples. The ballast samples were sourced from both a railway test track section located on a heavy haul coal export line in South Africa and a local quarry. The sampled ballast from the field installation represent angular, semi-angular and rounded geometric features depending on the sampled location. The fresh ballast sourced from the quarry was iteratively tested using a hydraulic actuator in a small-scale box test which forms part of a separate research project. The ballast samples were scanned before and after every test to ascertain the changes in geometry, in addition to the loss of material due to attrition. The field and laboratory samples were digitised using a high-resolution, commercial (Visual Simultaneous Localization and Mapping) VSLAM-based scanner with a 40-micrometre accuracy. Samples which were fractured by the hydraulic actuator are also included in the dataset. HRSBallast serves as a reference dataset for granular media (GM) simulations utilizing DEM (discrete element method), degradation or wear modelling, digital assets for the creation of synthetic datasets for deep learning applications, embedded railway instrumentation and video games requiring high-resolution geometry.http://www.elsevier.com/locate/dibpm2021Civil Engineerin

Removal of hard COD, nitrogenous compounds and phenols from a high-strength coal gasification wastewater stream

The objective of this study was to identify the factors affecting the suspended and fixed biomass in the removal of hard COD, nitrogenous compounds and phenols from a coal gasification wastewater (CGWW) stream using a hybrid fixed-film bioreactor (H-FFBR) process under real-time plant operational conditions and actual wastewater composition. The composition of the influent and effluent was studied to determine which compounds were not removed by hydrolysis (bacterial activity) and how this correlated to the suspended and fixed biomass activity, COD and phenol removal. A H-FFBR with 12 g∙m−3 attached biomass and 440 mg∙ℓ−1 suspended biomass achieved 78% phenol removal and 49% COD removal but insignificant removal of nitrogenous compounds. During the operation period, fixed biomass concentration was higher than the suspended biomass. Parameters such as pH, phenols, alkalinity, metal ions, conductivity, total dissolved solids and aeration rate affected the fixed biofilm properties such as adhesion, thickness and structure. It can be concluded that the composition of the effluent had a direct effect on the fixed biomass properties and thus a direct effect on the removal of phenols, COD and nitrogenous compounds in the wastewater.The authors would like to thank Buckman Africa for funding the chemical, EDX, GC-MS and SEM analyses and Sasol Technology (Pty) Ltd for the use and operation of the pilot plant.http://www.wrc.org.zaam201

Removal of hard COD, nitrogenous compounds and phenols from a high-strength coal gasification wastewater stream

The objective of this study was to identify the factors affecting the suspended and fixed biomass in the removal of hard COD, nitrogenous compounds and phenols from a coal gasification wastewater (CGWW) stream using a hybrid fixed-film bioreactor (H-FFBR) process under real-time plant operational conditions and actual wastewater composition. The composition of the influent and effluent was studied to determine which compounds were not removed by hydrolysis (bacterial activity) and how this correlated to the suspended and fixed biomass activity, COD and phenol removal. A H-FFBR with 12 g∙m−3 attached biomass and 440 mg∙ℓ−1 suspended biomass achieved 78% phenol removal and 49% COD removal but insignificant removal of nitrogenous compounds. During the operation period, fixed biomass concentration was higher than the suspended biomass. Parameters such as pH, phenols, alkalinity, metal ions, conductivity, total dissolved solids and aeration rate affected the fixed biofilm properties such as adhesion, thickness and structure. It can be concluded that the composition of the effluent had a direct effect on the fixed biomass properties and thus a direct effect on the removal of phenols, COD and nitrogenous compounds in the wastewater.The authors would like to thank Buckman Africa for funding the chemical, EDX, GC-MS and SEM analyses and Sasol Technology (Pty) Ltd for the use and operation of the pilot plant.http://www.wrc.org.zaam201

In-vitro screening of Kalahari browse species for rumen methane mitigation

The nutritional value of browse foliage from the Thorny Kalahari Dune Bush veld of South Africa is not characterized. Most of this browse species is rich in tannin, but still palatable, and is consumed by ruminants during the dry season, as well as having a role to play in mitigating enteric methane emission from ruminants. In this study, the rumen methane mitigation potential of 19 browse species foliage collected from the Thorny Kalahari Dune Bush veld, was analyzed in terms of chemical composition, in vitro fermentation, digestibility and methane production. In vitro gas and methane production and organic matter digestibility (IVOMD) were determined by using rumen fluid collected, strained and anaerobically prepared. A semi-automated system was used to measure gas production (GP) from each browse species by incubating 400 mg samples in a shaking incubator at 39 °C with or without inclusion of 400 mg of polyethylene glycol (PEG). Data for all the parameters collected were statistically analyzed using the SAS (9.0) general linear model (GLM) procedure, and differences between foliage species were determined using Duncan’s multiple-range test. Acacia luederitziiand Monechma incanumshowed the best potential for decreasing methane production by up to 90 % after 48 h of incubation. The secondary components (mainly tannins) of the browse species appeared to have a significant effect on volatile fatty acids (VFA), methane and gas production as judged by the comparison of samples incubated with or without PEG inclusion. The substantial amount of crude protein (CP) content coupled with their anti-methanogenic effect during fermentation would make these browses a potential mitigation option for small scale farmers and pastoralists in sub-Sahara Africa. However, it is also very important that systematic and strategic supplementation in a mixed diet should be looked at as the way forward in terms of best utilization

An automated system for impedance measurements in milk

Measurement of milk quality is important for commercial food safety and in the dairy processing industry. Several techniques have been investigated before, and measurements range from impedance detection time [1] [2] (for shelf-life prediction just after pasteurization) and conductivity [3] [4] [5] (mostly for mastitis detection) to pH and capacitance [6]. Most techniques use invasive probes, for which a good reference in milk is not yet available. This article discusses the design and results of an automated measurement system used to characterize impedance probes for bacterial content measurement in milk. With a reliable, repeatable measurement system, probe characterization and calibration is improved, which leads to faster and more accurate measurements of bacterial content and remaining shelf-life. ©2007 IEEE.Conference Pape

Influence of species/cultivar and season on the quality of Atriplex grown at different sites in South Africa

Atriplex species/cultivars [Atriplex nummularia, A. canescens (Santa Rita) and A. canescens (Field Reserve 1)] were compared in terms of chemical composition and in vitro digestibility. The plant material was sampled at different seasons (autumn and winter) and from different sites (Hatfield in the Gauteng Province and Mier and Lovedale, both in the Northern Cape Province) and were analysed for crude protein (CP), neutral detergent fibre (NDF) and in vitro digestibility (IVOMD). The CP and IVOMD of the leaves were higher than the stem for the Atriplex species. Leaf percentage for the autumn samples was not affected by species at Hatfield and Mier, but A. canescens (Field Reserve 1) had lower leaf percentage at Lovedale as well as for winter samples at Hatfield. At Lovedale, however, A. nummularia had the highest leaf : stem ratio compared to A. canescens (Santa Rita) and A. canescens (Field Reserve 1). Atriplex nummularia had a higher CP concentration than A. canescens (Field Reserve 1) and A. canescens (Santa Rita) at both Mier and Lovedale, but species/cultivar had no effect on CP concentration at Hatfield. Autumn samples had a higher CP concentration than winter samples at both Mier and Lovedale, but season had no effect on the N concentration at Hatfield. Atriplex nummularia had a lower NDF and higher IVOMD concentration compared to A. canescens (Santa Rita) and A. canescens (Field Reserve 1). Autumn samples were less fibrous and more digestible than winter samples. Atriplex nummularia seems to be better in terms of its nutritive value compared to A. canescens (Santa Rita) and A. canescens (Field Reserve 1), with better quality forage in autumn than winter