Application of compression test in analysis of mechanical and color changes in grapefruit juice powder as related to glass transition and water activity

Physicochemical and structural properties of grapefruit juice powder were studied as affected by water activity. Powdered juice was obtained by freeze-drying and equilibrated at different water vapor pressure atmospheres in order to give samples with water activity in the range of 0-084 The mechanical properties of the powder were measured by confined compression tests and the compressed samples, which presented uniform surface and thickness, were subjected to color analysis The maximum force attained during the compression tests and the color coordinates could be quantified with good reproducibility. The results were related to water activity and to glass transition temperature The occurrence of mechanical changes in the powder was shown to precede significant color changes with increasing water activity. Considering the susceptibility to stickiness, the stability limit was observed at T-T(g) approximate to 2 degrees C, with a high degree of mechanical changes being detected at T-Tg 16 degrees C, whereas for significant color changes this critical temperature difference was around 32 degrees CAuthors thank the Ministerio de Educacion y Ciencia and the Fondo Europeo de Desarrollo Regional (FEDER) for the financial support throughout the projects AGL2002-01793 and AGL 200505994. Vania R. N. Tells acknowledges the support of the Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES) as an external grant (Proc. BEX 4452/06-2).Telis, VRN.; Martínez Navarrete, N. (2010). Application of compression test in analysis of mechanical and color changes in grapefruit juice powder as related to glass transition and water activity. Food Science and Technology. 43(5):744-751. https://doi.org/10.1016/j.lwt.2009.12.007S74475143

Specific Appetite for Carotenoids in a Colorful Bird

Background: Since carotenoids have physiological functions necessary for maintaining health, individuals should be selected to actively seek and develop a specific appetite for these compounds. Methodology/Principal Findings: Great tits Parus major in a diet choice experiment, both in captivity and the field, preferred carotenoid-enriched diets to control diets. The food items did not differ in any other aspects measured besides carotenoid content. Conclusions/Significance: Specific appetite for carotenoids is here demonstrated for the first time, placing these compounds on a par with essential nutrients as sodium or calcium

Ganhos genéticos para caracteres de raiz em populações de cenoura nos sistemas orgânico e convencional de produção

O objetivo deste trabalho foi verificar os ganhos genéticos para caracteres de raiz em populações de cenoura cultivadas nos sistemas orgânico e convencional. Os experimentos foram conduzidos na Embrapa Hortaliças, Brasília (DF). Duas populações de cenoura derivadas da cultivar Brasília e de origem comum até 2002, foram subdivididas em duas populações, avaliadas e selecionadas, por oito gerações consecutivas, nos verões de 2000 a 2007. Em 2008, amostras de sementes das populações, provenientes de cada ciclo de seleção, foram semeadas em campo e conduzidas sob manejo orgânico e convencional de produção, em delineamento de blocos casualizados com nove tratamentos, quatro repetições e parcelas de 1 m². Aos 90 dias após a semeadura, 20 raízes por parcela foram colhidas para a avaliação dos caracteres comprimento, diâmetro do xilema e do floema; comprimento da extensão do ombro verde; massa fresca; presença de halo; formato de ponta e de ombro e coloração do xilema e floema. Foi realizada análise de variância com determinação da interação entre tratamentos e sistemas de produção, agrupamento de médias entre os tratamentos, e calculados os ganhos reais com a seleção. Pôde-se verificar que nos oito anos de seleção não houve ganhos significativos para os caracteres estudados nas duas populações. Com isso, conclui-se que os caracteres avaliados já se encontram fixados nas duas populações estudadas. Verificou-se que a seleção não precisa ser realizada nos dois sistemas de cultivo, orgânico e convencional, possibilitando diminuição de recursos financeiros e de mão-de-obra empregados no melhoramento.The objective of this work was to evaluate the genetic gain with the selection of root characters of carrot populations cultivated in organic and conventional production systems. The experiments were carried out at Embrapa Hortaliças, Brasília, Brazil. Two carrot populations derived from Brasília cultivar and with common origin until 2002, were separate in two populations and evaluated for eight generations during 2000 to 2007. In 2008, seed samples of the population in each cycle of selection were sowed in the field in both organic and conventional production systems, in a randomized blocks design with four replications of nine treatments and plots of 1 m². After 90 days of sowing, 20 roots per plot were harvested for the evaluation of the length, xylem and phloem diameter, green shoulder length, fresh mass, presence of halo, tip and shoulder format, and the color parameters of xylem and phloem. Variance analysis was carried out to determine the interaction between treatments and production systems, grouping of means among treatments, and the real gain with the selection was estimated. In the last eight years of selection, a significant gain was not observed on the studied characters in the two populations. So we concluded that those traits are already quite developed and stabilized in both populations. The selection doesn't need to be accomplished in both areas of organic and conventional cultivation, making possible the decrease of financial and labor resources utilized in the breeding