Showing papers by "Per B. Brockhoff published in 2013"

Evaluation of Web-based Dietary Assessment Software for Children: comparing reported fruit, juice and vegetable intakes with plasma carotenoid concentration and school lunch observations.

Abstract: 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 children's 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.

Analysis of sensory ratings data with cumulative link models

Abstract: Examples of categorical rating scales include discrete preference, liking and hedonic rating scales. Data obtained on these scales are often analyzed with normal linear regression methods or with omnibus Pearson chi2 tests. In this paper we propose to use cumulative link models that allow for regression methods similar to linear models while respecting the categorical nature of the observations. We describe how cumulative link models are related to the omnibus chi2 tests and how they can lead to more powerful tests in the non-replicated setting. For replicated categorical ratings data we present a quasi-likelihood approach and a mixed effects approach both being extensions of cumulative link models. We contrast population-average and subject-specific interpretations based on these models and discuss how different approaches lead to different tests. In replicated settings, naive tests that ignore replications are often expected to be too liberal because of over-dispersion.We describe how this depends on whether the experimental design is fully randomized or blocked. For the latter situation we describe how naive tests can be stronger than over-dispersion adjusting approaches, and that mixed effects models can provide even stronger tests than naive tests. Examples will be given throughout the paper and the methodology is implemented in the authors’ free R-package ordinal.

Comparison of estimated energy intake using Web-based Dietary Assessment Software with accelerometer-determined energy expenditure in children.

Abstract: 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 811 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 811 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 WebDASC’s 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. WebDASC’s 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 811, 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. Keywords : children; reporting accuracy; under-reporting; over-reporting; food diary (Published: 17 December 2013) Citation: Food & Nutrition Research 2013. 57 : 21434 - http://dx.doi.org/10.3402/fnr.v57i0.21434

Dietary patterns on weekdays and weekend days in 4-14-year-old Danish children.

Abstract: Little is known about dietary patterns on weekdays and weekend days in children, and the aim of the present study was to investigate 4–14-year-old children's dietary patterns specifically on weekdays (Monday–Thursday) and weekend days (Saturday–Sunday). Dietary data were derived from the Danish National Survey of Dietary Habits and Physical Activity 2003–8, where a total of 784 children aged 4–14 years completed a 7 d pre-coded food record. Principal component analysis was used to identify dietary patterns in the age groups 4–6, 7–10 and 11–14 years. Consistently, two dietary patterns, labelled ‘processed’ and ‘health conscious’, emerged on both weekdays and weekend days. Factor scores from corresponding dietary patterns were significantly correlated between weekdays and weekend days with the exception of the ‘health conscious’ pattern in the 7–10-year-olds. Within each age group, children with high agreement for the ‘processed’ pattern had a significantly higher dietary energy density, which was reflected in significantly higher intakes of sugar-sweetened beverages and lower intakes of fruit and vegetables, compared with children with high agreement for the ‘health conscious’ pattern (P< 0·05). Moreover, these variables indicated less healthy dietary intakes on weekend days than on weekdays for both patterns. In conclusion, two distinct dietary patterns, labelled ‘processed’ and ‘health conscious’, were identified on both weekdays and weekend days for each age group. While overall major dietary patterns may somewhat track between weekdays and weekends, the specific foods actually eaten became less healthy during weekends.

Danish consumers' sensitivity towards the boar taint compounds androstenone and skatole

Abstract: A future production of pork including meat from entire males is a realistic scenario for the major pig producing countries. To ensure that no boar tainted meat reaches the consumers, the only reliable preventive method is to detect and sort out the boar tainted carcasses at the slaughterhouse. One of the prerequisite for sorting at the slaughterhouse is reliable sorting limits based on consumer sensitivity. The aim of the work presented here was to describe the proportion of Danish consumers that are sensitive towards androstenon and the proportion highly sensitive towards skatole and further to investigate any age and gender effect on sensitivity. Consumers in the age interval of 15 - 99 years (n=1294) were tested using triangle tests with paper strips containing 20 ppm solution of androstenone and 0.15 ppm solution of skatole. The consumers were recruited in shopping malls, at schools and at companies in all major regions of Denmark. Sensitivity towards androstenone is age related. An increasing proportion of consumers are sensitive with increasing age up to 70 years, where after the sensitivity decreases. In total, between 19 and 38 % of the consumers are sensitive towards androstenone. More females than males are sensitive towards androstenone. Even though it is expected that most people can detect skatole, only 5-6% were classified as highly sensitive. This proportion was constant with age, and no difference between genders was seen.

Automatic scatter detection in fluorescence landscapes by means of spherical principal component analysis

Abstract: In this paper, we introduce a new method, based on spherical principal component analysis (S-PCA), for the identification of Rayleigh and Raman scatters in fluorescence excitation–emission data. These scatters should be found and eliminated as a prestep before fitting parallel factor analysis models to the data, in order to avoid model degeneracies. The work is inspired and based on a previous research, where scatter removal was automatic (based on a robust version of PCA called ROBPCA) and required no visual data inspection but appeared to be computationally intensive. To overcome this drawback, we implement the fast S-PCA in the scatter identification routine. Moreover, an additional pattern interpolation step that complements the method, based on robust regression, will be applied. In this way, substantial time savings are gained, and the user's engagement is restricted to a minimum, which might be beneficial for certain applications. We conclude that the subsequent parallel factor analysis models fitted to excitation–emission data after scatter identification based on either ROBPCA or S-PCA are comparable; however, the modified method based on S-PCA clearly outperforms the original approach in relation to computational time. Copyright © 2013 John Wiley & Sons, Ltd.