Bart Kemps

KU Leuven, Leuven, VLG, Belgium

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Publications (31)29.76 Total impact

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    ABSTRACT: Viscosity values of albumen reported in the literature are difficult to compare because different shear rates and different methods of sample preparation have been adopted. Therefore, we first investigated the effect of shear rate on the viscosity measurements of thick albumen. For intact albumen, a large intersample fluctuation in viscosity with increasing shear rate was observed. Furthermore, a large hysteresis effect was observed, indicating that the structural properties were substantially altered by the rotational behavior of the rotor. From this, we concluded that to obtain reliable measurements, the albumen needed to be mixed. After mixing, a smooth evolution in viscosity with increasing shear rate was observed. Compared with intact albumen, the hysteresis effect was smaller but still present. We next investigated the correlation between albumen viscosity and Haugh units. For this, we compared the viscosity of fresh eggs with the viscosity of eggs stored for 24 d at a temperature of 18°C. The Haugh units were first determined, and the viscosity was next determined on mixed albumen at a shear rate of 200 rad/s. Mean viscosity equaled 0.0304 and 0.0181 Pa/s for fresh eggs and eggs stored for 24 d, respectively. The decrease in viscosity during storage was significant (α = 0.05). Furthermore, we observed that the correlation between Haugh units and viscosity measured on the same egg was low. Fresh eggs having comparable Haugh units differed substantially in their measured viscosities, whereas for stored eggs, the Haugh units differed substantially but the viscosities were comparable. It is unlikely that the very large variation in rheological properties observed among fresh eggs reflects the natural variation in albumen freshness present after lay. Results suggest that these differences were partly due to the structural changes caused by albumen sampling and by the turning motion of the rotor. We conclude that determination of the rheological properties of albumen is practically infeasible and that albumen viscosity cannot be used as an index for albumen freshness.
    Poultry Science 12/2010; 89(12):2699-703. · 1.52 Impact Factor
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    ABSTRACT: Stress and diseases have the potential to influence the deposition of eggshell pigmentation during egg formation. Therefore, defining the shell color of eggs on a daily basis could be a representative method for monitoring stress or health status of a flock and maintaining good performance. A novel way of measuring eggshell color based on visible-near infrared transmission spectroscopy transmission spectra was defined: the transmission color value (TCV). The TCV was calculated as the ratio between the transmission at 643 nm (maximum absorbance of the pigmentation molecule protoporphyrin IX) and the transmission at 610 nm (a reference wavelength). Experiments were carried out to investigate the relevance of TCV for monitoring flock stress and health or even anticipating any factors unfavorable to performance. In 2 small experimental flocks, deliberate heat stress challenges were applied. A medium-scale experimental flock in an aviary was monitored on a daily basis during the whole productive period. From the deliberate heat stress challenges, it was seen that stress had a significant effect on eggshell pigmentation. This observation was confirmed in a daily monitored flock, in which, for example, an infectious bronchitis infection occurred. These stress situations were quickly reflected by an increased TCV value: more transmission due to less pigmentation and hence less absorbance at the pigmentation wavelength. Furthermore, for the observed problems in the daily monitoring, the TCV value signaled the problem earlier (4 d) than the average egg weight or even signaled when the other parameters did not signal anything. Measuring the TCV of all eggs produced on a daily basis provides relevant information on the stress or health status of a flock of brown layers. This could be used as an early detection of stress situations or emerging diseases, even before important quality and health damage can occur.
    Poultry Science 03/2010; 89(3):609-17. · 1.52 Impact Factor
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    ABSTRACT: During the ripening season, measurements were performed on 4 grape varieties (i.e. Cabernet Sauvignon, Merlot, Syrah and Carmenère). Spectral reflection measurements were performed on intact grapes using the Zeiss corona 45 VIS–NIR spectrophotometer. Thereafter, the concentration of extractable anthocyanins at pH equal to 1.0 (pH10) and 3.2 (pH32), the concentration of polyphenols (IPT), the concentration of sugars (OH) and the density were determined from the samples. Partial least squares analysis showed that prediction of PH10 and PH32 was possible for Syrah. For this variety, PH10 and PH32 increased during the season and changes in the spectral properties of the grapes could be linked to these parameters. For all other varieties, the parameters PH10 and PH32 remained fairly constant over time and the results showed that prediction was not possible. The prediction of IPT was not possible for all varieties. The prediction of OH and density was achieved accurately for all varieties. An important region for the prediction of OH and density was detected around 700 nm, corresponding to the red colour. The prediction of sugar is consequently, at least partially, feasible due to the co-occurring colour change from green to blue/red.
    Biosystems Engineering. 01/2010;
  • Journal of Near Infrared Spectroscopy - J NEAR INFRARED SPECTROSC. 01/2010;
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    01/2010;
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    ABSTRACT: During this work, it was investigated whether spectral measurements can be used to monitor embryonic growth. An experiment was conducted in which both the transmission spectra and embryonic weight were determined on 240 eggs (Cobb, 37 weeks) between Day 5 and Day 10 of incubation. The spectral data were linked to embryonic weight by means of a partial least squares analysis. Different preprocessing procedures were compared during this work, that is, smoothing, multiplicative scatter correction (MSC), and first- and second-order derivative. Compared to the remainder of the preprocessing procedures, MSC leads to a considerable improvement of the prediction capability of the embryonic weight. The ratio of performance to deviation obtained for the MSC spectra equaled 4.5 indicating that a very accurate prediction of embryonic weight is feasible based on the VIS/NIR transmission measurements. Important regions for the prediction are situated around 685-740 nm. It is suggested that the spectral changes in these spectral regions result from the displacement of carotenoids from the yolk into the blood circuitry.
    Biotechnology Progress 11/2009; 26(2):512-6. · 1.85 Impact Factor
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    ABSTRACT: Monitoring livestock production processes by means of statistical control charts can provide an important support for management. The non-stationary and autocorrelated characteristics of most data originating from such processes impede the direct introduction of these data into control charts. To deal with these characteristics Engineering Process Control strategies can be applied. Stationarity was achieved by modelling and subtracting the time dependent trend using a non-linear model. Next, the autocorrelation structure in the residual data is modelled and corrected for by means of an ARMA model. The resulting corrected stationary and independent residuals are then inserted in the traditional cusum control scheme. This combined use of Engineering Process Control strategies for modelling the unconventional statistical characteristics and Statistical Process Control strategies for constructing the control chart based on the resulting pre-processed data, is referred to as a Synergistic Control strategy. The developed cusum control chart was tested on data of two layer flocks. In both cases the control chart provided alarms for important problems in production and furthermore signalled problems that remained unnoticed by the layer managers. The amount of false alarms was acceptable. With this control scheme and the scheme of the average egg weight, control procedures for two important output parameters of the production process of consumption eggs are available. Furthermore, this strategy could provide a possible solution for other process parameters that also display non-stationarity and autocorrelation.
    Computers and Electronics in Agriculture. 01/2009;
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    ABSTRACT: During the incubation of an avian egg, water vapour, oxygen and carbon dioxide are exchanged through the porous shell of the incubated egg. Due to the high variability of the eggshell conductance (G), large variation in exchange rates are present and hence a significant number of eggs are incubated in suboptimal conditions for humidity and partial pressures of carbon dioxide.Because there is no reliable technique to measure G in a non-destructive and fast way, the direct adaptation of the ambient conditions during incubation in relation to the G of the incubated eggs is not yet possible and this has repercussions on both the hatchability and chick quality.In the present research, two non-destructive and fast techniques, the Acoustic Resonance Technique (ART) and the measurement of light transmission through the egg, are used to estimate G. It was found that the dynamic stiffness of the egg (kdyn) and the optical transmission at 611nm are the parameters with the highest predictive power when estimating G. Although this model is highly significant (P
    Computers and Electronics in Agriculture - COMPUT ELECTRON AGRIC. 01/2008; 62(1):35-40.
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    ABSTRACT: Both animal dependent and non-dependent factors and their interactions have an effect on the quality of consumption eggs. With the recent development of fast, objective and non-destructive measurement methods for egg quality, extensive information on all input and output aspects of the production process of consumption eggs are available. This enables the application of the concepts of statistical process control (SPC), such as control charts, in order to detect anomalies. In this paper a quality control chart is presented for the daily monitoring of the average egg weight.In a first step for the design of the control chart, a non-linear model was developed to detect the natural increasing trend of the egg weight with the increasing hen age. This trend was then subtracted from the measured egg weight and the residual values were inserted into a cusum control chart.The data originating for two flocks of laying hens, a small flock (72 hens, deliberately subjected to challenges), and a large-scale experimental flock (500 hens) in an aviary housing, were used to evaluate the developed control charts.The results show that the quality control chart enables to quickly detect a decrease of the average egg weight. Similar algorithms for all variables on both input and output will make it possible to monitor the whole egg laying process to detect or to prevent a decreasing egg quality and hence increase profits for the poultry farmer.
    Computers and Electronics in Agriculture. 01/2008;
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    ABSTRACT: Recently, some nondestructive methods for the assessment of albumen freshness were developed. Among others, visible near-infrared transmission spectroscopy and low-resolution proton nuclear magnetic resonance (LR (1)H NMR) measurements were proposed. This study was performed to evaluate the potential of the combined measurement of visible near-infrared transmission spectroscopy and LR (1)H NMR measurements for the assessment of albumen freshness. Our results show that solely based on the transmission measurements, a good estimation of albumen freshness can be achieved. Based on LR (1)H NMR measurements, an estimation of albumen freshness can be achieved if larger egg collectives are used. However, when individual eggs are considered, only a moderate estimation is feasible. Finally, it was observed that combining both spectroscopic techniques did not improve the assessment of albumen freshness when compared solely to transmission measurements.
    Poultry Science 05/2007; 86(4):752-9. · 1.52 Impact Factor
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    ABSTRACT: Egg weight, shell thickness, number of pores, cuticle deposition, eggshell strength (dynamic stiffness and damping ratio), and the ability of Salmonella enterica serovar Enteritidis (SE) to penetrate the eggshell were determined. Penetration was assessed by filling the eggs with a selective medium that allowed viewing of Salmonella growth on the inside of the shell and membrane complex. After inoculation of each shell with on average 2.71 log CFU, the eggs were stored for up to 14 days at 20 degrees C and 60% relative humidity. Commercially available eggs were used. At 14 days of storage, only 6.0% of the eggs from free-range hens and 16.0% of the generic (i.e., eggs from hens in conventional battery cages that were given standard feed) white eggs were penetrated. The generic brown, organic, and omega-3-enriched eggs were penetrated at a frequency of 30 to 34%. In a second experiment it was shown that the layer strains of the hen (ISA-Brown Warren versus Bovans Goldline), which were kept in furnished cages, did not affect eggshell penetration by SE. For Bovans Goldline hens, the housing system (furnished cage versus aviary) did not affect penetration, while a trend was visible toward a higher fraction of penetrated eggshells when hens were fed corncob mix rather than standard feed. Eggshell penetration was observed more frequently in the absence of cuticle spots and for eggs having lower dynamic stiffness values. Shell contamination at the end of storage was highly correlated with SE penetration.
    Journal of food protection 04/2007; 70(3):623-8. · 1.83 Impact Factor
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    ABSTRACT: Based on an old paradigm that the extra-embryonic membranes develop semiautonomously from the embryo, it can also be postulated that subembryonic fluid (SEF) will be formed semiautonomously against embryonic growth, because the formation of SEF is mediated by the yolk sac membrane. In this study, we interfered in the development of SEF or the embryo. The acoustic resonance technique (which measures the resonant frequency of an excited egg) was used as a nondestructive tool to monitor the development of SEF. In the first experiment, in which the embryo was killed chemically with NaN3, it was proven that the formation of SEF continued, even when the embryo was killed after the initiation of the growth of the yolk sac membrane. In the second experiment, in which the development of SEF was inhibited chemically with amiloride, it was shown that the embryo developed further, although SEF formation was inhibited. In the last experiment, it was shown that the age of the flock affected the development of the embryo and the sudden decrease of the resonant frequency in a different way. However, some presetting conditions, such as storage, may affect both in a similar way. Our results further strengthen the idea that the formation of SEF develops semiautonomously against embryonic development by using the nondestructive acoustic resonance technique as an indirect method to monitor yolk sac membrane formation.
    Poultry Science 10/2006; 85(9):1626-31. · 1.52 Impact Factor
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    ABSTRACT: We first tried to monitor the critical points for eggshell breakage in different logistic chains. Second, we examined whether there was a difference in eggshell strength among eggs produced in different housing systems. Finally, we developed a model to investigate the relation between eggshell strength and the likelihood of an egg cracking during handling and grading. Four logistic chains with different housing systems (battery cages, furnished cages, aviary, and free-range), all housing Bovans Goldline chickens in their mid-lay (45 wk), were compared. In every chain, a randomized set of 1,500 eggs was sampled, and the strength was defined. At every critical point in every logistic chain, the eggs were reexamined for breakage. The classic and furnished cage systems showed the highest percentage of breakage directly at point of lay (6.73 and 10.72%), whereas the other systems showed lower breakage (1.94% in the aviary and 1.99% in the free-range system). Further, in the logistic chain, grading and packing of the eggs generated the second highest percentage of breakage (from 1.50 to 2.65%). Breakage due to transportation ranged from 0.16 to 2.65%. There was a significant difference among the eggshell strength (shell stiffness and damping ratio) of eggs from chickens in different housing systems, showing eggs from chickens in the aviary system to be stronger than cage eggs (classic and furnished) and free-range eggs to be weaker than the other eggs. A significant correlation was found between eggshell strength and the likelihood of breakage in the production chains. In conclusion, it was first shown that, besides the laying, packing of the eggs is a critical point in the logistic chain of consumption eggs; second, the strength of the eggs in the different housing systems differed, and, finally, the eggshell stiffness and damping ratio of consumption eggs are an acceptable measure for rapid eggshell quality assessment and could provide a good predictive value for eggshell breakage in all types of table egg production chains.
    Poultry Science 10/2006; 85(9):1670-7. · 1.52 Impact Factor
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    ABSTRACT: We investigated the correlations between different eggshell and membrane strength parameters and their changes over time. Eggshell and membrane characteristics were measured for 2 different lines of laying hens, Hisex Brown and Bovans Brown, from wk 33 up to wk 78. Several parameters were investigated: 2 parameters concerning total eggshell strength (static and dynamic stiffness), 1 structural parameter (i.e., eggshell thickness), 2 parameters describing the material characteristics of the shell [dynamic Young's modulus (EM) and nitrogen content], and 3 parameters to measure the membrane characteristics (attachment force breaking strength and nitrogen content). This study shows that the correlations among parameters change during the laying period and among lines. The EM of the eggshell increased during the laying period for the Hisex line. No difference was observed in case of the Bovans line. In general, a negative correlation was obtained between eggshell thickness and the EM. The correlation between static and dynamic stiffness increased during lay. Finally, the attachment force and breaking strength of the membranes declined during the laying period.
    Poultry Science 08/2006; 85(7):1309-17. · 1.52 Impact Factor
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    ABSTRACT: The objective of this research was to investigate the feasibility of visible transmission spectroscopy for the non-destructive assessment of the freshness of an individual egg. A total of 600 intact white-shelled eggs of the same flock (Lohmann, 40 weeks of age) were measured. To obtain a considerable variation in freshness, groups consisting of 60 eggs were stored (18 °C, 55% RH) for 0, 2, 4, 6, 8, 10, 12, 14, 16 and 18 days. The non-destructive spectral measurements were compared with the two most widely used destructive freshness parameters, namely Haugh units and albumen pH. A partial least squares (PLS1) model was built in order to predict Haugh units and pH of the albumen based on the transmission spectra. The correlation coefficients between the predicted value and the measured value were 0.842 and 0.867 for Haugh unit and pH of the albumen, respectively. These results show that the light transmission spectrum of an egg provides quantitative information about egg freshness. Relevant information concerning egg freshness is restricted to the interval between 570 and 750 nm. Furthermore, the models obtained for both destructive parameters were strikingly similar, indicating that Haugh unit and pH have the same physico-chemical background. Copyright © 2006 Society of Chemical Industry
    Journal of the Science of Food and Agriculture 06/2006; 86(9):1399 - 1406. · 1.76 Impact Factor
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    ABSTRACT: The modern poultry industry is not satisfied with the traditional system of the handling and processing of eggs which is based on candling and visual inspection of the eggs. Currently, the operator of the conveyer does not have the opportunity to inspect 120 000 eggs per hour and to estimate the freshness, weight, bacterial infection, presence of technical spoilage, eggshell defects without elimination of subjectivity, fatigability and destruction. That is why the problem of automatization of egg quality control is rather difficult. In order to assure a high and consistent egg quality, an attractive and alternative strategy for determining the state of egg freshness can be achieved by sensors technologies. These techniques (e.g., near-infrared, mid-infrared, fluorescence spectroscopies, etc.) appear to be very promising for non-destructively determining egg freshness because they are relatively not expensive. Such methods cannot eliminate the need for more detailed physico-chemical analyses, but they may help to screen samples that require further examination.
    European Food Research and Technology 02/2006; 222(5):727-732. · 1.44 Impact Factor
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    ABSTRACT: This preliminary study is devoted to the application of front-face fluorescence spectroscopy to the study of egg yolks during storage. A total of 79 eggs stored for 1, 2, 3, 4, 5, 9, 10, 12, 16, 18, 23, 25 and 29 days at room temperature were analysed. The fluorescence emission spectra of tryptophan residues (excitation: 290nm; emission: 305–430nm) of proteins and the excitation spectra of vitamin A (emission: 410nm; excitation: 270–350nm) were recorded directly on egg yolk samples. Factorial discriminant analysis (FDA) was used to classify the eggs according to their date after they were laid. Using tryptophan fluorescence spectra, correct classification was observed for 57.1 and 51.9% for the calibration and the validation sets, respectively. Better classification (94.9 and 91.4% of the calibration and validation samples, respectively) was obtained from the vitamin A fluorescence spectra. The first five principal components (PCs) of the principal component analysis (PCA) extracted from each data set (tryptophan and vitamin A fluorescence spectra) were pooled (concatenated) into a single-matrix and analysed by FDA. Correct classifications were obtained for 97.5% of the calibration and 96.3.1% of the validation spectra. The discrimination of the investigated egg yolks according to their storage time was excellent. It was concluded that the concatenation of different fluorescence spectra might be considered as a promising indicator of shell egg freshness when they are used in egg products.
    European Food Research and Technology 01/2006; 223(2):180-188. · 1.44 Impact Factor
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    ABSTRACT: In this preliminary study, the intrinsic fluores-cence of thick and thin egg albumens was evaluated as a possible rapid method for the monitoring of egg freshness. The fluorescence emission spectra of tryptophan residues (excitation: 290 nm; emission: 305–430 nm) of proteins and fluorescent Maillard reaction products (excitation: 360; emission: 380–580 nm) were recorded directly on thick and thin albumen samples within 2–3, 4, 5, 9, 10, 12, 16, 18, 23, 25 and 29 days of storage. Principal component analy-sis (PCA) and factorial discriminant analysis (FDA) were applied to the spectra data sets. Considering tryptophan fluorescence spectra recorded on thick egg albumen, cor-rect classification was observed for 62.8 and 54.3% for the calibration and the validation sets, respectively. Better clas-sification was obtained from thin egg albumen since 67.3 and 69.1% of samples were correctly classified. Consid-ering fluorescent Maillard reaction products, the similarity map determined by the principal components (PCs) 1 and 2 showed a discrimination of eggs as a function of their storage time on both thick and thin albumens. The percent-age of samples correctly classified into four groups by the FDA was 97.4 and 91.4% for the calibration and validation thick albumen samples, respectively. It was concluded that fluorescent Maillard reaction products could be considered as fingerprints that may allow the discrimination between fresh and aged eggs.
    European Food Research and Technology 01/2006; 223:303-312. · 1.44 Impact Factor