Caracterização reológica das diferentes fases de extrato de inulina de raízes de chicória, obtidas por abaixamento de temperatura

Inulin is a functional food ingredient, generally employed as sugar or fat substitute in food systems. This ingredient can be found in several vegetal products, including chicory roots. As the solubility of inulin is susceptible to temperature changes, the product suffers a fractionalization resulting in two phases when cooled, originating a precipitated phase, more viscose, and a liquid phase, of lesser viscosity. The study of rheological properties of different phases of inulin extract is important for equipment designing, such as mixer and bombs. In this work, rheological behavior at three different temperatures (25; 40 and 50 ºC) was determined for liquid and precipitated phases of inulin liquid extract, extracted from chicory roots by hot water diffusion and cooled at two different temperatures (8 and -10 ºC), suffering phases separation. The precipitated phase was analyzed in two conditions: pure and with the addition of microencapsulating agents (maltodextrin and hydrolized starch). All of them presented a linear behavior, similar to that of the Plastics of Bingham. Some of them, however, were not an adequate fit to this model.

Evaluation of the performance of different plastics used to seal nylon cDNA arrays

cDNA arrays are a powerful tool for discovering gene expression patterns. Nylon arrays have the advantage that they can be re-used several times. A key issue in high throughput gene expression analysis is sensitivity. In the case of nylon arrays, signal detection can be affected by the plastic bags used to keep membranes humid. In this study, we evaluated the effect of five types of plastics on the radioactive transmittance, number of genes with a signal above the background, and data variability. A polyethylene plastic bag 69 μm thick had a strong shielding effect that blocked 68.7% of the radioactive signal. The shielding effect on transmittance decreased the number of detected genes and increased the data variability. Other plastics which were thinner gave better results. Although plastics made from polyvinylidene chloride, polyvinyl chloride (both 13 μm thick) and polyethylene (29 and 7 μm thick) showed different levels of transmittance, they all gave similarly good performances. Polyvinylidene chloride and polyethylene 29 mm thick were the plastics of choice because of their easy handling. For other types of plastics, it is advisable to run a simple check on their performance in order to obtain the maximum information from nylon cDNA arrays.