On-farm instruments for assessing colostrum quality are needed in order to ensure that the calf i... more On-farm instruments for assessing colostrum quality are needed in order to ensure that the calf is supplied with enough IgG to avoid failure of passive transfer. The aim of this study was to evaluate methods for estimating the IgG concentration in cows' colostrum. This research included 126 colostrum samples from 21 Danish farms with different breeds, ensuring a broad variation pattern in IgG, total protein and fat concentration. Approximately one third of the samples did not fulfil the recommendation of >50 g IgG/l colostrum, and the IgG concentration decreased with time from calving to milking. The ratio of IgG to total protein varied from 6 to 61%, however IgG and total protein were correlated with r 2 = 0·70. The variation in fat was independent of variations in protein and IgG. The IgG concentration was measured by ELISA and compared to fast measurements by specific gravity by colostrometer, Brix by refractometer and prediction from infrared spectroscopy. The three fast ...
ABSTRACT New strategies for changing children's liking in a more healthy direction are ne... more ABSTRACT New strategies for changing children's liking in a more healthy direction are needed. Modulating food products by masking techniques have shown to convert dislikes into likes. In this study, children's (n = 204, 9–14 years) perception of sourness, preferences, liking and wanting for acidified milk products (AMP) with variation in fat (0.5% versus 3.5%) and fruit content (5–20%) were investigated. Multiple ranking and PARAllel FACtor analysis were used to evaluate ranking and rating data, respectively. The results show that high-fat AMP is preferred at low fruit content, whereas fat content has no influence on liking at high fruit contents. Children like and want AMPs with 15–20% fruit more than AMPs with 5–10% fruit. Segments of children rank and rate the AMPs significantly different. Finally, a high correlation between liking and wanting is observed.These results give the food industry an option to produce new healthy food products to children without loss in children's liking.PRACTICAL APPLICATIONSFrom a health perspective, the effects of increasing fruit content in acidified milk product on children's hedonic perceptions are very important. There is a serious need for shaping children's dietary habits in a more healthy direction to decrease the negative development in childhood obesity. These results provide knowledge about some of the main factors driving children's food choice in both the eating and the purchase situations. Knowledge about children's drivers toward healthy foods provides important information in product development of high fruit products. Moreover, the results are useful for researchers, producers, manufacturers and health professionals as a first step to design public health policies and consumer education strategies. The various methodologies presented in the paper can also be implemented in the study of children's liking and wanting for other foods.
The impact of temperature and gas composition on respiration rates of postharvest produce is well... more The impact of temperature and gas composition on respiration rates of postharvest produce is well understood, but only a few studies have documented variation in respiration rates of different varieties and at different harvest times of the growing season. Most studies rely on discrete determinations of respiration rates and do not depict the dynamic nature of respiration. The aim of this study was to determine the respiration rates in broccoli florets and wild rocket salad at different harvest times during the season, and of different varieties. Storage temperature and respiration rates were determined using a novel wireless sensor for continuous and non-invasive measurements of O2 concentrations and temperature in close proximity to the plant material. Respiration rates differed between broccoli varieties. Seasonal differences in respiration rate were found for broccoli and wild rocket salad. The response of respiration rate to storage temperature was distinct and differed between...
ABSTRACT The impact of temperature and gas composition on respiration rates of postharvest produc... more ABSTRACT The impact of temperature and gas composition on respiration rates of postharvest produce is well understood, but only a few studies have documented variation in respiration rates of different varieties and at different harvest times of the growing season. Most studies rely on discrete determinations of respiration rates and do not depict the dynamic nature of respiration. The aim of this study was to determine the respiration rates in broccoli florets and wild rocket salad at different harvest times during the season, and of different varieties. Storage temperature and respiration rates were determined using a novel wireless sensor for continuous and non-invasive measurements of O2 concentrations and temperature in close proximity to the plant material. Respiration rates differed between broccoli varieties. Seasonal differences in respiration rate were found for broccoli and wild rocket salad. The response of respiration rate to storage temperature was distinct and differed between harvest times. These differences could be related to differences in dry matter content. Biological differences in respiration rates prompt empirical determinations when used in models for product-designed MAP.
ABSTRACT Sensory descriptive analysis was used to evaluate visual and overall freshness and the u... more ABSTRACT Sensory descriptive analysis was used to evaluate visual and overall freshness and the underlying attributes of freshness of packaged wild rocket (Diplotaxis tenuifolia L.) quality. Variation was induced by differences in package atmosphere, temperature and storage time. The leaves were packaged in trays wrapped in film with a low oxygen transmission rate (OTR) (low OTR; 0.65 pmol s−1 m−2 kPa−1) or high OTR (high OTR; 17.4 pmol s−1 m−2 kPa−1). To create packages with variation in O2 and CO2 concentrations in the package atmosphere, and in the sensory quality, the packages were stored at 2 °C for 6 or 7 d or at elevated temperatures (10, and 20 °C) for various times (2, 3, 4, and 6 d). At low OTR, the O2 concentration decreased to ≤0.5 kPa, and the leaves developed a ‘smoked odor’, lost leaf integrity and texture, and turned olive-brown. At high OTR, the O2 concentrations inside the package remained at 10–18 kPa, and leaves showed signs of senescence, i.e. light-green to yellow leaves and a heterogeneous appearance of leaves in the tray. Freshness of the leaves was evaluated by sensory analysis without prior consensus. ‘Visual freshness’ was evaluated at first sight before opening the packages, while ‘overall freshness’ was evaluated after opening and careful inspection by looking, smelling and touching the product. ‘Visual freshness’ was highly correlated to green leaf color (r = 0.98), whereas ‘overall freshness’ was described by color, odor and texture as found by interval PLS. The high OTR packages had similar scores for ‘freshness’ before and after opening (P > 0.05), while the low OTR packages had significantly different scores (P ≤ 0.05). As appearance is an indication of freshness at purchase, wild rocket must be MAP packaged in an OTR film that permits sufficient levels of O2 for aerobic respiration when storage temperature cannot be controlled and kept low during distribution and retail.
ABSTRACT Green color and texture are important attributes for the perception of freshness of wild... more ABSTRACT Green color and texture are important attributes for the perception of freshness of wild rocket. Packaging of green leafy vegetables can postpone senescence and Yellowing, but a drawback is the risk of anaerobic respiration leading to loss of tissue integrity and development of an olive-brown color. The hypothesis underlying this paper is that color and textural quality of packaged wild rocket leaves can be predicted by multispectral imaging for faster evaluation of visual quality of leafy green vegetables in scientific experiments. Multispectral imaging was correlated to sensory evaluation of packaged wild rocket quality. CIELAB values derived from the multispectral images and from a spectrophotometer changed during storage, but the data were insufficient to describe variation in sensory perceived color and texture. CIELAB values from the multispectral images allowed for a more detailed determination of color compared to measurement with a spectrophotometer with an 8 mm aperture. Furthermore, the multispectral images enabled subtraction of background information of the sample and gave more accurate results on visual color of wild rocket leaves. The combination of wavelengths in the NIR range describing textural changes, and wavelengths in the VIS range describing color changes was optimal for quantification of sensory perceived color and textural quality of packaged wild rocket. (c) 2012 Elsevier B.V. All rights reserved
The changes in the VOC composition of industrially produced saveloy were measured with Proton-Tra... more The changes in the VOC composition of industrially produced saveloy were measured with Proton-Transfer-Reaction Mass-Spectrometry (PTR-MS) and HeadSpace Gas chromatography-mass spectrometry (HS-GC-MS) during a six weeks storage period. A decrease in the volatile organic compounds contributing to the fresh aroma of saveloy was the main change observed with both PTR-MS and HS-GC-MS. Samples of four other types of cooked and sliced meat product were measured with PTR-MS in the middle and at the end of the four week shelf-life period. These measurements showed an increase in m/z 69, 71, 87 and 89 for the pork loin and in m/z 61 for the herbal saveloy samples. These ions were assigned to the microbial spoilage markers: acetic acid, 2- and 3-methylbutanol, 2- and 3-methylbutanal, diacetyl and acetoin. Overall, this study shows that PTR-MS has potential for quality control of cooked and sliced meat products.
Treatment of ventilation air from livestock production by biological airfiltration has emerged as... more Treatment of ventilation air from livestock production by biological airfiltration has emerged as a cost-effective technology for reduction of emissions of odorants and ammonia. Volatile sulfur compounds from livestock production include H2S and methanethiol, which have been identified as potentially important odorants that are not removed sufficiently by biological air filters. Light-expanded clay aggregates (Leca(®)) is a biotrickling filter material that contains iron oxides, which can oxidize H2S and methanethiol, and thus potentially may help to remove these two compounds in biological air filters. This study used on-line PTR-MS measurements to investigate the performances of two Leca(®) biotrickling filters (abraded Leca(®) filter and untreated Leca(®) filter) for removal of odorants and ammonia emitted from an experimental pig house. The results indicated that the abraded Leca(®) filter had a similar or slightly better capability for removing odorants than the untreated Leca(®) filter. This may be due to the enlargement of the surface area by the friction process. The volatile sulfur compounds, however, were not removed efficiently by either of the two Leca(®) filters. Kinetic analysis of a ventilation controlled experiment during the first period indicated that Grau second-order kinetics could be applied to analyze the removal of sulfur compounds and other odorants, whereas the Stover-Kincannon model could only be applied to analyze the removal of odorants other than sulfur compounds, partly due to the limitation of mass transfer of these compounds in the biotrickling filters. In the last measurement period, a production of dimethyl disulfide and dimethyltrisulfide coinciding with strongly enhanced removal of methanethiol was observed for the untreated filter. This was assumed to be enhanced by an incidence of low local air velocity in the filter and indicated involvement of iron-catalyzed reactions in the removal of sulfur compounds.
On-farm instruments for assessing colostrum quality are needed in order to ensure that the calf i... more On-farm instruments for assessing colostrum quality are needed in order to ensure that the calf is supplied with enough IgG to avoid failure of passive transfer. The aim of this study was to evaluate methods for estimating the IgG concentration in cows' colostrum. This research included 126 colostrum samples from 21 Danish farms with different breeds, ensuring a broad variation pattern in IgG, total protein and fat concentration. Approximately one third of the samples did not fulfil the recommendation of >50 g IgG/l colostrum, and the IgG concentration decreased with time from calving to milking. The ratio of IgG to total protein varied from 6 to 61%, however IgG and total protein were correlated with r 2 = 0·70. The variation in fat was independent of variations in protein and IgG. The IgG concentration was measured by ELISA and compared to fast measurements by specific gravity by colostrometer, Brix by refractometer and prediction from infrared spectroscopy. The three fast ...
ABSTRACT New strategies for changing children's liking in a more healthy direction are ne... more ABSTRACT New strategies for changing children's liking in a more healthy direction are needed. Modulating food products by masking techniques have shown to convert dislikes into likes. In this study, children's (n = 204, 9–14 years) perception of sourness, preferences, liking and wanting for acidified milk products (AMP) with variation in fat (0.5% versus 3.5%) and fruit content (5–20%) were investigated. Multiple ranking and PARAllel FACtor analysis were used to evaluate ranking and rating data, respectively. The results show that high-fat AMP is preferred at low fruit content, whereas fat content has no influence on liking at high fruit contents. Children like and want AMPs with 15–20% fruit more than AMPs with 5–10% fruit. Segments of children rank and rate the AMPs significantly different. Finally, a high correlation between liking and wanting is observed.These results give the food industry an option to produce new healthy food products to children without loss in children's liking.PRACTICAL APPLICATIONSFrom a health perspective, the effects of increasing fruit content in acidified milk product on children's hedonic perceptions are very important. There is a serious need for shaping children's dietary habits in a more healthy direction to decrease the negative development in childhood obesity. These results provide knowledge about some of the main factors driving children's food choice in both the eating and the purchase situations. Knowledge about children's drivers toward healthy foods provides important information in product development of high fruit products. Moreover, the results are useful for researchers, producers, manufacturers and health professionals as a first step to design public health policies and consumer education strategies. The various methodologies presented in the paper can also be implemented in the study of children's liking and wanting for other foods.
The impact of temperature and gas composition on respiration rates of postharvest produce is well... more The impact of temperature and gas composition on respiration rates of postharvest produce is well understood, but only a few studies have documented variation in respiration rates of different varieties and at different harvest times of the growing season. Most studies rely on discrete determinations of respiration rates and do not depict the dynamic nature of respiration. The aim of this study was to determine the respiration rates in broccoli florets and wild rocket salad at different harvest times during the season, and of different varieties. Storage temperature and respiration rates were determined using a novel wireless sensor for continuous and non-invasive measurements of O2 concentrations and temperature in close proximity to the plant material. Respiration rates differed between broccoli varieties. Seasonal differences in respiration rate were found for broccoli and wild rocket salad. The response of respiration rate to storage temperature was distinct and differed between...
ABSTRACT The impact of temperature and gas composition on respiration rates of postharvest produc... more ABSTRACT The impact of temperature and gas composition on respiration rates of postharvest produce is well understood, but only a few studies have documented variation in respiration rates of different varieties and at different harvest times of the growing season. Most studies rely on discrete determinations of respiration rates and do not depict the dynamic nature of respiration. The aim of this study was to determine the respiration rates in broccoli florets and wild rocket salad at different harvest times during the season, and of different varieties. Storage temperature and respiration rates were determined using a novel wireless sensor for continuous and non-invasive measurements of O2 concentrations and temperature in close proximity to the plant material. Respiration rates differed between broccoli varieties. Seasonal differences in respiration rate were found for broccoli and wild rocket salad. The response of respiration rate to storage temperature was distinct and differed between harvest times. These differences could be related to differences in dry matter content. Biological differences in respiration rates prompt empirical determinations when used in models for product-designed MAP.
ABSTRACT Sensory descriptive analysis was used to evaluate visual and overall freshness and the u... more ABSTRACT Sensory descriptive analysis was used to evaluate visual and overall freshness and the underlying attributes of freshness of packaged wild rocket (Diplotaxis tenuifolia L.) quality. Variation was induced by differences in package atmosphere, temperature and storage time. The leaves were packaged in trays wrapped in film with a low oxygen transmission rate (OTR) (low OTR; 0.65 pmol s−1 m−2 kPa−1) or high OTR (high OTR; 17.4 pmol s−1 m−2 kPa−1). To create packages with variation in O2 and CO2 concentrations in the package atmosphere, and in the sensory quality, the packages were stored at 2 °C for 6 or 7 d or at elevated temperatures (10, and 20 °C) for various times (2, 3, 4, and 6 d). At low OTR, the O2 concentration decreased to ≤0.5 kPa, and the leaves developed a ‘smoked odor’, lost leaf integrity and texture, and turned olive-brown. At high OTR, the O2 concentrations inside the package remained at 10–18 kPa, and leaves showed signs of senescence, i.e. light-green to yellow leaves and a heterogeneous appearance of leaves in the tray. Freshness of the leaves was evaluated by sensory analysis without prior consensus. ‘Visual freshness’ was evaluated at first sight before opening the packages, while ‘overall freshness’ was evaluated after opening and careful inspection by looking, smelling and touching the product. ‘Visual freshness’ was highly correlated to green leaf color (r = 0.98), whereas ‘overall freshness’ was described by color, odor and texture as found by interval PLS. The high OTR packages had similar scores for ‘freshness’ before and after opening (P > 0.05), while the low OTR packages had significantly different scores (P ≤ 0.05). As appearance is an indication of freshness at purchase, wild rocket must be MAP packaged in an OTR film that permits sufficient levels of O2 for aerobic respiration when storage temperature cannot be controlled and kept low during distribution and retail.
ABSTRACT Green color and texture are important attributes for the perception of freshness of wild... more ABSTRACT Green color and texture are important attributes for the perception of freshness of wild rocket. Packaging of green leafy vegetables can postpone senescence and Yellowing, but a drawback is the risk of anaerobic respiration leading to loss of tissue integrity and development of an olive-brown color. The hypothesis underlying this paper is that color and textural quality of packaged wild rocket leaves can be predicted by multispectral imaging for faster evaluation of visual quality of leafy green vegetables in scientific experiments. Multispectral imaging was correlated to sensory evaluation of packaged wild rocket quality. CIELAB values derived from the multispectral images and from a spectrophotometer changed during storage, but the data were insufficient to describe variation in sensory perceived color and texture. CIELAB values from the multispectral images allowed for a more detailed determination of color compared to measurement with a spectrophotometer with an 8 mm aperture. Furthermore, the multispectral images enabled subtraction of background information of the sample and gave more accurate results on visual color of wild rocket leaves. The combination of wavelengths in the NIR range describing textural changes, and wavelengths in the VIS range describing color changes was optimal for quantification of sensory perceived color and textural quality of packaged wild rocket. (c) 2012 Elsevier B.V. All rights reserved
The changes in the VOC composition of industrially produced saveloy were measured with Proton-Tra... more The changes in the VOC composition of industrially produced saveloy were measured with Proton-Transfer-Reaction Mass-Spectrometry (PTR-MS) and HeadSpace Gas chromatography-mass spectrometry (HS-GC-MS) during a six weeks storage period. A decrease in the volatile organic compounds contributing to the fresh aroma of saveloy was the main change observed with both PTR-MS and HS-GC-MS. Samples of four other types of cooked and sliced meat product were measured with PTR-MS in the middle and at the end of the four week shelf-life period. These measurements showed an increase in m/z 69, 71, 87 and 89 for the pork loin and in m/z 61 for the herbal saveloy samples. These ions were assigned to the microbial spoilage markers: acetic acid, 2- and 3-methylbutanol, 2- and 3-methylbutanal, diacetyl and acetoin. Overall, this study shows that PTR-MS has potential for quality control of cooked and sliced meat products.
Treatment of ventilation air from livestock production by biological airfiltration has emerged as... more Treatment of ventilation air from livestock production by biological airfiltration has emerged as a cost-effective technology for reduction of emissions of odorants and ammonia. Volatile sulfur compounds from livestock production include H2S and methanethiol, which have been identified as potentially important odorants that are not removed sufficiently by biological air filters. Light-expanded clay aggregates (Leca(®)) is a biotrickling filter material that contains iron oxides, which can oxidize H2S and methanethiol, and thus potentially may help to remove these two compounds in biological air filters. This study used on-line PTR-MS measurements to investigate the performances of two Leca(®) biotrickling filters (abraded Leca(®) filter and untreated Leca(®) filter) for removal of odorants and ammonia emitted from an experimental pig house. The results indicated that the abraded Leca(®) filter had a similar or slightly better capability for removing odorants than the untreated Leca(®) filter. This may be due to the enlargement of the surface area by the friction process. The volatile sulfur compounds, however, were not removed efficiently by either of the two Leca(®) filters. Kinetic analysis of a ventilation controlled experiment during the first period indicated that Grau second-order kinetics could be applied to analyze the removal of sulfur compounds and other odorants, whereas the Stover-Kincannon model could only be applied to analyze the removal of odorants other than sulfur compounds, partly due to the limitation of mass transfer of these compounds in the biotrickling filters. In the last measurement period, a production of dimethyl disulfide and dimethyltrisulfide coinciding with strongly enhanced removal of methanethiol was observed for the untreated filter. This was assumed to be enhanced by an incidence of low local air velocity in the filter and indicated involvement of iron-catalyzed reactions in the removal of sulfur compounds.
Uploads
Papers