Effect of hot-deboning on the physical quality characteristics of ostrich meat

The effects of hot-deboning on the physical meat quality characteristics and shelf-life of ostrich m. gastrocnemius, pars interna (gastroc) and m. iliofibularis (iliof) were investigated during 42 days (d) of refrigeration. The hot-deboned gastroc was initially tougher than the cold-deboned muscles, while hot-deboning had no significant effect on the shear force of the iliof. After 14 d of refrigerated storage, there was no difference in tenderness between the hot- and the cold-deboned muscles. Hot-deboning caused significantly more purge (3.4 ± 2.33%) compared to cold-deboning (2.1 ± 2.06%) throughout the 42-day storage period. All muscle samples were acceptable in terms of Aerobic Plate Counts (APC < 104 cfu/g) and E. coli (E. coli < 101 cfu/g), based on the South African Standards for the microbiological monitoring of meat for refrigerated export. It was concluded that hot-deboning did not influence the shelf-life of ostrich muscles negatively. South African Journal of Animal Science Vol. 36(3) 2006: 197-20

Effects of post mortem temperature on rigor tension, shortening and pH in ostrich muscle

Fully developed rigor mortis in muscle is characterised by maximum loss of extensibility. The course of post mortem changes in ostrich muscle was studied by following isometric tension, shortening and change in pH during the first 24 h post mortem within muscle strips from the muscularis gastrocnemius, pars interna at constant temperatures of 7 °C and 37 °C. Maximum shortening was significantly higher at 37 °C (33.4 ± 3.57%) than at 7 °C (10.7 ± 2.63%). The rate of rigor development was temperature dependent, reaching a maximum tension at 4.08 ± 3.89 h post mortem in muscle strips at 37 °C; while at 7 °C maximum tension was reached at 10.5 ± 6.47 h post mortem. It was concluded that the completion of rigor occurred at the point of minimum pH. Keywords: Rigor mortis, rigor tension, muscle shortening, ostrich, rigor shortening, cold-shortening, hot-deboning, rate of pH declineSouth African Journal of Animal Science Vol. 38 (3) 2008: pp. 184-19

Fluctuations of indicator and index microbes as indication of pollution over three years in the Plankenburg and Eerste Rivers, Western Cape, South Africa

The Plankenburg and Eerste Rivers (Western Cape) have been reported to be contaminated with faecal coliforms. Water is drawn from both rivers for irrigation of fresh produce. The potential risk in the use of these rivers as irrigation sources was assessed by determining the fluctuations of ‘indicator’ and ‘index’ microbes over 3 years. Selected physico-chemical (water temperature, pH, COD, conductivity and alkalinity) and microbiological parameters, including coliforms, faecal coliforms, Escherichia coli and enterococci, as ‘indicators’ of faecal pollution, and Salmonella, Listeria and Staphylococcus, as ‘index’ of the presence of potential pathogens, were monitored.No correlation was found between water temperature and COD (r2 = 0.0003), whereas for temperature and pH a significant trend (p = 0.0004), but low correlation (r2 = 0.108), was observed. With the exception of the faecal coliforms (E. coli), no significant trends and no correlations between temperature and the dependent variables were found. For the faecal coliforms there was a significant trend (p = 0.0289) with temperature but not a good correlation (r2 = 0.0434), but the impact of temperature over time was significant (p = 0.0047). This is important, when the World Health Organisation (WHO) and South African Department of Water Affairs (DWA) guidelines for faecal coliforms are applied, as it indicates that temperaturedoes impact the faecal coliform numbers. The presence of indicator organisms did not only indicate unsanitary conditions, but also the presence of potential pathogens such as Staphylococcus, Klebsiella, Listeria and Salmonella. Based on these results the microbial quality of these rivers was found to be unacceptable and does not meet the WHO and DWA guidelines for safe irrigation. There was also a high risk of exposure to human pathogens when water from these rivers is used to irrigate produce that is consumed without further processing.Keywords: Irrigation water, faecal pollution, indicator and index organisms, Plankenburg and Eerste River

Optimisation of the conditions for stripping voltammetric analysis at liquid-liquid interfaces supported at micropore arrays: a computational simulation

Micropore membranes have been used to form arrays of micro interfaces between immiscible electroly tesolutions (μITIES) as a basis for the sensing of non-redoxactiveions. Implementation of stripping voltammetry as asensing method at these arrays of μITIES was applied recently to detect drugs and biomolecules at low concentrations. The present study uses computational simulation to investigate the optimum conditions for stripping voltammetricsensing at the μITIES array. In this scenario, thediffusion of ions in both the aqueous and the organic phasescontributes to the sensing response. The influence of the preconcentration time, the micropore aspect ratio, the location of the micro interface within the pore, the ratio of the diffusion coefficients of the analyte ion in the organic and aqueous phases, and the pore wall angle were investigated. The simulations reveal that the accessibility of the microinterfaces during the preconcentration period should not be hampered by a recessed interface and that diffusional transport in the phase where the analyte ions are preconcentrated should be minimized. This will ensure that the ions are accumulated within the micropores close to the interface and thus be readily available for back transferduring the stripping process. On the basis of the results, an optimal combination of the examined parameters is proposed,which together improve the stripping voltammetric signal and provide an improvement in the detection limit

Traveling EEG slow oscillation along the dorsal attention network initiates spontaneous perceptual switching

An ambiguous figure such as the Necker cube causes spontaneous perceptual switching (SPS). The mechanism of SPS in multistable perception has not yet been determined. Although early psychological studies suggested that SPS may be caused by fatigue or satiation of orientation, the neural mechanism of SPS is still unknown. Functional magnetic resonance imaging (fMRI) has shown that the dorsal attention network (DAN), which mainly controls voluntary attention, is involved in bistable perception of the Necker cube. To determine whether neural dynamics along the DAN cause SPS, we performed simultaneous electroencephalography (EEG) and fMRI during an SPS task with the Necker cube, with every SPS reported by pressing a button. This EEG–fMRI integrated analysis showed that (a) 3–4 Hz spectral EEG power modulation at fronto-central, parietal, and centro-parietal electrode sites sequentially appeared from 750 to 350 ms prior to the button press; and (b) activations correlating with the EEG modulation traveled along the DAN from the frontal to the parietal regions. These findings suggest that slow oscillation initiates SPS through global dynamics along the attentional system such as the DAN

Early members of ‘living fossil’ lineage imply later origin of modern ray-finned fishes

Modern ray-finned fishes (Actinopterygii) comprise half of extant vertebrate species and are widely thought to have originated before or near the end of the Middle Devonian epoch (around 385 million years ago). Polypterids (bichirs and ropefish) represent the earliest-diverging lineage of living actinopterygians, with almost all Palaeozoic taxa interpreted as more closely related to other extant actinopterygians than to polypterids. By contrast, the earliest material assigned to the polypterid lineage is mid-Cretaceous in age (around 100 million years old), implying a quarter-of-a-billion-year palaeontological gap. Here we show that scanilepiforms, a widely distributed radiation from the Triassic period (around 252–201 million years ago), are stem polypterids. Importantly, these fossils break the long polypterid branch and expose many supposedly primitive features of extant polypterids as reversals. This shifts numerous Palaeozoic ray-fins to the actinopterygian stem, reducing the minimum age for the crown lineage by roughly 45 million years. Recalibration of molecular clocks to exclude phylogenetically reassigned Palaeozoic taxa results in estimates that the actinopterygian crown lineage is about 20–40 million years younger than was indicated by previous molecular analyses. These new dates are broadly consistent with our revised palaeontological timescale and coincident with an interval of conspicuous morphological and taxonomic diversification among ray-fins centred on the Devonian–Carboniferous boundary. A shifting timescale, combined with ambiguity in the relationships of late Palaeozoic actinopterygians, highlights this part of the fossil record as a major frontier in understanding the evolutionary assembly of modern vertebrate diversity

EEG Microstate Analysis in Drug-Naive Patients with Panic Disorder

Patients with panic disorder (PD) have a bias to respond to normal stimuli in a fearful way. This may be due to the preactivation of fear-associated networks prior to stimulus perception. Based on EEG, we investigated the difference between patients with PD and normal controls in resting state activity using features of transiently stable brain states (microstates). EEGs from 18 drug-naive patients and 18 healthy controls were analyzed. Microstate analysis showed that one class of microstates (with a right-anterior to left-posterior orientation of the mapped field) displayed longer durations and covered more of the total time in the patients than controls. Another microstate class (with a symmetric, anterior-posterior orientation) was observed less frequently in the patients compared to controls. The observation that selected microstate classes differ between patients with PD and controls suggests that specific brain functions are altered already during resting condition. The altered resting state may be the starting point of the observed dysfunctional processing of phobic stimuli

The Brain Matures with Stronger Functional Connectivity and Decreased Randomness of Its Network

We investigated the development of the brain's functional connectivity throughout the life span (ages 5 through 71 years) by measuring EEG activity in a large population-based sample. Connectivity was established with Synchronization Likelihood. Relative randomness of the connectivity patterns was established with Watts and Strogatz' (1998) graph parameters C (local clustering) and L (global path length) for alpha (∼10 Hz), beta (∼20 Hz), and theta (∼4 Hz) oscillation networks. From childhood to adolescence large increases in connectivity in alpha, theta and beta frequency bands were found that continued at a slower pace into adulthood (peaking at ∼50 yrs). Connectivity changes were accompanied by increases in L and C reflecting decreases in network randomness or increased order (peak levels reached at ∼18 yrs). Older age (55+) was associated with weakened connectivity. Semi-automatically segmented T1 weighted MRI images of 104 young adults revealed that connectivity was significantly correlated to cerebral white matter volume (alpha oscillations: r = 33, p<01; theta: r = 22, p<05), while path length was related to both white matter (alpha: max. r = 38, p<001) and gray matter (alpha: max. r = 36, p<001; theta: max. r = 36, p<001) volumes. In conclusion, EEG connectivity and graph theoretical network analysis may be used to trace structural and functional development of the brain