Per B. Brockhoff
Technical University of Denmark
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Featured researches published by Per B. Brockhoff.
Biology of Reproduction | 2000
Dorthe Viuff; T. Greve; B. Avery; Poul Hyttel; Per B. Brockhoff; Preben D. Thomsen
Abstract Availability of embryos of high quality is required to obtain satisfactory embryonic developmental rates and normal calves following transfer of in vitro-produced (IVP) bovine embryos. One relevant quality parameter is the frequency of chromosome aberrations, which can be evaluated using multicolor fluorescent in situ hybridization (FISH) with chromosome 6- and chromosome 7-specific probes in cattle. In this study, interphase nuclei (n = 3805) were analyzed from 426 bovine IVP embryos. We found that 73%, 72%, 81%, and 58% of the embryos from Days 2, 3, 4, and 5 post-insemination (pi), respectively, displayed a normal diploid chromosome number in all cells. When looking at the types of chromosome aberrations, the percentages of mixoploidy at Days 2, 3, 4, and 5 pi were 22%, 15%, 16%, and 42%, respectively, whereas the percentages of polyploidy (i.e., all nuclei in an embryo were analyzed and were polyploid) were 5%, 13%, 3%, and 0%, respectively. In conclusion, numerical chromosome aberrations were detected as early as Day 2 pi. The development of polyploid embryos is slow and is apparently arrested during the third cell cycle, whereas the mixoploid embryos seem to continue development.
British Journal of Dermatology | 2000
F. Grønhøj Larsen; B. Steinkjer; P. Jakobsen; A. Hjorter; Per B. Brockhoff; F. Nielsen-Kudsk
Background Acitretin has replaced etretinate in the treatment of various disorders of keratinization due to a considerably shorter terminal half‐life. Possible esterification of acitretin to etretinate in the presence of ethanol has been reported.
European Food Research and Technology | 1996
Helle Lindberg Madsen; Lotte Andersen; Luise Christiansen; Per B. Brockhoff; Grete Bertelsen
The sensory intensity measured as theabsolute threshold value of spice andrecognition of spice was evaluated for summer savory and rosemary in meat balls. The values forabsolute threshold value of spice were found to be significantly lower for rosemary than for summer savory. The antioxidative activity of the spices was analysed in two accelerated model systems and in a storage experiment. In one of the model systems, oxidation was accelerated by heat and by an elevated pressure of oxygen. Both spices significantly improved the oxidative stability of the meat balls in this model system. In the second model system metal catalyst oxidation in a meat slurry was used and a reduction in the oxidative processes in samples containing the spices was again shown. In both model systems a slightly higher antioxidative activity was seen for rosemary compared to summer savory. In the storage experiment, the spices were added at a sensorially acceptable level and the heat-treated meat balls were stored at 5°C. A significant reduction in the development of warmed-over flavour (WOF) caused by the addition of spices was measured by a reduction in 2-thiobarbituricacid-reactivesubstances (TBARS) and in hexanal. A reduction in TBARS of approximately 30% in meat balls containing added spices was seen independently of packaging in 1% oxygen or in atmospheric air and the reduction (30%) was constant throughout the storage period.
British Journal of Nutrition | 2013
Anja Pia Biltoft-Jensen; Anette Bysted; Ellen Trolle; Tue Christensen; Pia Knuthsen; Camilla T. Damsgaard; Lene Frost Andersen; Per B. Brockhoff; Inge Tetens
Web-based Dietary Assessment Software for Children (WebDASC) was developed to estimate dietary intake in a school meal intervention study among 8- to 11-year-old Danish children. The present study validates self-reported fruit, juice and vegetable (FJV) intakes in 8- to 11-year-old children by comparing intake with plasma carotenoid concentration, and by comparing the reported FJV intake to actually eaten FJV, as observed by a photographic method. A total of eighty-one children, assisted by parents, reported their diet for seven consecutive days. For the same five schooldays as they reported their diet, the childrens school lunch was photographed and weighed before and after eating. In the week after the diet reporting, fasting blood samples were taken. Self-reported intake of FJV and estimated intake of carotenoids were compared with plasma carotenoid concentration. Accuracy of self-reported food and FJV consumption at school lunch was measured in terms of matches, intrusion, omission and faults, when compared with images and weights of lunch intake. Self-reported intake of FJV was significantly correlated with the total carotenoid concentration (0·58) (P< 0·01). Fruit and juice consumption showed higher correlations than vegetables with plasma carotenoid concentration (0·38 and 0·42 v. 0·33) (P< 0·01). A total of 82 % of the participants fell into the same or adjacent quartiles when cross-classified by FJV intake and carotenoids biomarkers. WebDASC attained 82 % reporting matches overall and a higher percentage match for reporting fruits compared with beverages. The present study indicated that WebDASC can be used to rank 8- to 11-year-old Danish children according to their intake of FJV overall and at school meals.
Food Quality and Preference | 1998
Per B. Brockhoff; Pascal Schlich
We give in this paper an easy to use and statistically sound way of handling replications in discrimination tests based on a concept called overdispersion. The overdispersion is easily calculated by hand for any discrimination testing setup. And since the method simply amounts to correcting the total number of observations, and similarly the overall response, by the overdispersion, we can use any standard technique, table or software on the corrected numbers to perform a statistical test for difference, for similarity, power calculations, controlling risk I and risk II, etc. We also include a general discussion of the replicated discrimination testing situation, and some examples to illustrate how to use the method. The SAS® macro REPRISKS that handles all computations is available by e-mail: [email protected].
Public Health Nutrition | 2012
Berit Worm Rothausen; Jeppe Matthiessen; Camilla Hoppe; Per B. Brockhoff; Lene Frost Andersen; Inge Tetens
OBJECTIVE To compare differences in childrens diet quality on weekdays (Monday-Thursday), Fridays and weekend days. DESIGN A representative cross-sectional study in which participants completed a 7 d pre-coded food record. Mean intakes of energy, macronutrients and selected food items (g/10 MJ) as well as energy density were compared between weekdays, Fridays and weekend days for each gender in three age groups (4-6, 7-10 and 11-14 years) using Tobit analysis to account for zero intakes. SETTING The Danish National Survey of Dietary Habits and Physical Activity 2003-2008. SUBJECTS Children (n 784; 49·9 % boys) aged 4-14 years. RESULTS For both genders in all age groups (P < 0·05), energy intake was higher during weekends than on weekdays, and intakes of sugar-sweetened beverages and white bread were higher, whereas intake of rye bread was lower. This contributed to a higher percentage of energy from added sugars, a lower fibre content and a higher energy density on weekend days v. weekdays. In children aged 4-6 and 7-10 years, the diet on weekend days was also characterized by higher intakes of sweets and chocolate and lower intakes of fruit and vegetables. Overall, the diet on Fridays appeared as a mix of the diets on weekdays and weekend days. CONCLUSIONS Significant differences and distinct characteristic patterns were found in childrens diet quality during weekdays, Fridays and weekend days. The present study suggests that in prevention of childhood overweight and obesity, more attention should be paid to the higher energy intake, especially from sugar-rich foods and beverages, on Fridays and weekend days.
Food Quality and Preference | 2003
Per B. Brockhoff
Abstract A generalization of the approach of Brockhoff and Skovgaard [Food Quality & Preference, 5 (1994), 215] is given. The emphasis is on univariate assessor performance in sensory profiling. Statistical significance tests for difference between assessors of scaling, variability and sensitivity will be given. A test for disagreement effect is also presented. In addition the approach will provide individual scaling, variability, disagreement and sensitivity values, that can be used for subsequent tabulation, plotting and statistical analysis. The method of maximum likelihood is used throughout and all computations are implemented in a SAS® Macro PANMODEL that is available via the authors homepage: http://www.dina.kvl.dk/∼per .
Food & Nutrition Research | 2013
Anja Pia Biltoft-Jensen; Mads F. Hjorth; Ellen Trolle; Tue Christensen; Per B. Brockhoff; Lene Frost Andersen; Inge Tetens; Jeppe Matthiessen
Background The OPUS (Optimal well-being, development and health for Danish children through a healthy New Nordic Diet) project carried out a school meal study to assess the impact of a New Nordic Diet (NND). The random controlled trial involved 834 children aged 8–11 in nine local authority schools in Denmark. Dietary assessment was carried out using a program known as WebDASC (Web-based Dietary Assessment Software for Children) to collect data from the children. Objective To compare the energy intake (EI) of schoolchildren aged 8–11 estimated using the WebDASC system against the total energy expenditure (TEE) as derived from accelerometers worn by the children during the same period. A second objective was to evaluate the WebDASCs usability. Design Eighty-one schoolchildren took part in what was the pilot study for the OPUS project, and they recorded their total diet using WebDASC and wore an accelerometer for two periods of seven consecutive days: at baseline, when they ate their usual packed lunches and at intervention when they were served the NND. EI was estimated using WebDASC, and TEE was calculated from accelerometer-derived activity energy expenditure, basal metabolic rate, and diet-induced thermogenesis. WebDASCs usability was assessed using a questionnaire. Parents could help their children record their diet and answer the questionnaire. Results Evaluated against TEE as derived from the accelerometers worn at the same time, the WebDASC performed just as well as other traditional methods of collecting dietary data and proved both effective and acceptable with children aged 8–11, even with perhaps less familiar foods of the NND. Conclusions WebDASC is a useful method that provided a reasonably accurate measure of EI at group level when compared to TEE derived from accelerometer-determined physical activity in children. WebDASC will benefit future research in this area.
Meat Science | 2009
Lene Meinert; Kaja Tikk; Meelis Tikk; Per B. Brockhoff; Wender L.P. Bredie; Charlotte Bjergegaard; Margit Dall Aaslyng
Flavour development and overall eating quality of pan-fried pork chops of longissimus dorsi from eight different raw meat qualities aged for 4 and 15 days were assessed by a trained sensory panel. The raw meat qualities were obtained through combinations of strategic feeding/fasting (control vs. low glycogen concentration), slaughter live-weight (84kg vs. 110kg), and gender (female vs. castrate). The flavour development was investigated for possible correlation with the concentrations of selected individual flavour precursors present in the raw meat: monosaccharides, IMP and degradation products, fatty acids, lactate and thiamine. Differences in precursor concentrations between the raw meat qualities were observed with feeding/fasting and ageing as the main factors with the largest influence of all experimental factors. However, the concentrations of the precursors could not explain the differences in sensory perception of the pan-fried pork chops. Overall, the differences were small.
Applied and Environmental Microbiology | 2006
Tina Hornbæk; Per B. Brockhoff; Henrik Siegumfeldt; Birgitte Bjørn Budde
ABSTRACT In situ analyses of single Listeria monocytogenes cells at subinhibitory concentrations of leucocin 4010 and nisin revealed two subpopulations when measured by fluorescence ratio imaging microscopy (FRIM) after staining with 5(6)-carboxyfluorescein diacetate succinimidyl ester. One subpopulation consisted of cells with a dissipated pH gradient (ΔpH), and the other consisted of cells that maintained ΔpH. The proportion of cells belonging to each subpopulation was estimated, and the concentrations of bacteriocins required to dissipate ΔpH for 90% of the cell population (ED90) was predicted. ED90 increased after the addition of sodium chloride (1 to 3% [wt/vol]) to the bacteriocin solutions, while ED90 decreased by the addition of sodium nitrite (60 and 100 ppm). Other meat additives, including sodium phosphate, sodium lactate, sodium citrate, and sodium acetate slightly increased ED90. The inhibitory effect of sodium chloride on the antilisterial activity of leucocin 4010 and nisin was confirmed on the surfaces of meat sausages. This study highlights the important practical implications of applying subinhibitory concentrations of bacteriocins, which results in unaffected target cells. In situ analyses by FRIM in combination with modeling of single-cell data can be applied to ensure that sufficient concentrations of bacteriocins are used in food preservation.