Finite element analysis of heat conduction in lasagna during thermal processing

Conductive heat transfer in lasagna during heating was computed by means of the finite element method. the thermophysical properties of the pasta and tomato sauce layers were derived from their chemical composition. Simulation results obtained with an axisymmetric 2D finite element mesh without the typical layer structure differed only slightly from results obtained with a 1D mesh in which the typical layer structure was incorporated. the predicted temperatures at various locations in the lasagna agreed well with experimentally determined temperatures during heating in a commercial medium scale oven under various operating conditions. It is shown that the temperature dependency of the thermophysical parameters has only a minor influence on the temperature near the centre of the lasagna. However, when the lasagna surface is subjected to temperatures above its boiling temperature, incorporation of the water/vapour phase change in the specific heat capacity can avoid over-estimation of the volume averaged temperature and process value.     

Predictive Analysis of Cocoa Procyanidins Using Near-Infrared Spectroscopy Techniques

ABSTRACT A near-infrared reflectance (NIR) spectroscopy technique for the prediction of procyanidins in cocoa beans ( Theobroma cacao ) has been developed. A select group of cocoa liquors from different origins used for the manufacture of chocolate were analyzed to determine quantitative levels of procyanidin oligomers (monomer to decamer) using normal-phase high-performance liquid chromatography. The calibration set included seasonal, environmental, and fermentation variations to cover the concentration range of procyanidins found at naturally occurring levels. The sample set was analyzed on FOSS NIR System II 6500 spectrophotometers and partial least-squares algorithms developed. Very good calibration statistics were obtained for the prediction of the total procyanidin oligomers ( r 2 = 0.983) with standard deviation/standard error of cross validation ratio (SD/SECV) of 5.68. A global version of this calibration, involving 20 Foss instruments produced a calibration r 2 = 0.98 with a SD/ SECV = 6.20. Procyanidins have attracted increasing attention because of the rapidly growing body of evidence associating these compounds with a wide range of potential health benefits. A rapid method for the analysis of procyanidins in cocoa liquors would be beneficial in quality-control environments and would provide cost benefits to manufacturing operations.     

Optimization of a FIB/SEM slice-and-view study of the 3D distribution of Ni4Ti3 precipitates in Ni–Ti

The 3D morphology and distribution of lenticular Ni₄Ti₃ precipitates in the austenitic B2 matrix of a binary Ni₅₁Ti₄₉ alloy has been investigated by a slice-and-view procedure in a dual-beam focused ion beam/scanning electron microscope system. Due to the weak contrast of the precipitates, proper imaging conditions need to be selected first to allow for semi-automated image treatment. Knowledgeable imaging is further needed to ensure that all variants of the precipitates are observed with equal probability, regardless of sample orientation. Finally, a volume ratio of 10.2% for the Ni₄Ti₃ precipitates could be calculated, summed over all variants, which yields a net composition of Ni_50.27Ti_49.73 for the matrix, leading to an increase of 125 degrees for the martensitic start temperature. Also, the expected relative orientation of the different variants of the precipitates could be confirmed.