Purification of Whole Brown Flaxseed Meal from Coloring Pigments by Treatment in Hydrogen Peroxide Solutions: Impact on Meal Color

The main objective of the present project was the purification of brown flaxseed meal from coloring pigments in order to improve its potential use as ingredient in food formulations. Thus, this work was aimed to study the bleaching of non-defatted brown flaxseed meal in dilute hydrogen peroxide solutions. Bleaching was evaluated according to the Hunter L, (a), and (b) color scale as function of the hydrogen peroxide concentration (1%, 2%, and 3% v/v), the meal concentration (2.5%, 5%, and 10% w/w), the bleaching time (10, 20, and 30?min), and the pH (3, 7, and 9). Effect of all the independent variables was significant. The L value was the most significantly affected parameter and increased as the concentration of hydrogen peroxide increased, but decreased as the concentration of flaxseed meal increased. The L value was observed to be higher at pH?9 than at pH?3 and 7. The b value, which represents the yellowness, was significantly increased from 18.70?±?0.01 (control sample) to 35.45?±?0.04 after the meal was treated with a 3% hydrogen peroxide solution at pH?9. Total phenolics content significantly decreased when the meal was treated with 3% (v/v) hydrogen peroxide solution. This concentration yielded the higher L color value (highly bleached meal).     

Dynamic testing of large AISI-316L steel specimens behaviour using LDTF

The paper presents the results of a series of dynamic experiments on AISI-316L steel specimens having a cross section of 2000 mm² and a gauge length of 350 mm subject to dynamic traction up to rupture. Results for dynamic tests at a nominal strain rate up to 50 s⁻¹ are compared to quasi-static ones, showing an important increase in both yield stress and flow stress. The experimental techniques are described, with special emphasis on full-field optical strain measurements based on Moiré interferometry. A 1-D numerical analysis of the experiments is presented.     

Moment curvature relationship of reinforced concrete sections under combined bending and normal force

The modelling of tension stiffening effects is important for the verification of serviceability limit states of reinforced or prestressed concrete structures or even for the computation of the stability limit state of particular classes of slender concrete structures (bridge piles, towers, masts, etc.). The case of pure bending has received extensive analytical and experimental consideration, but little attention has been paid, up to now, to the case of combined bending and normal force. A series of tests on rectangular reinforced concrete beams submitted to bending and constant compressive normal force is reported in this paper. The moment-curvature relationships are evaluated and compared with the prediction of two theoretical models. The first model is the CEB model proposed by Favre and Koprna. It is a simplified model which refers to the uncracked and fully cracked stiffnesses in pure bending only. The second model is a proposition made by the authors which takes into account the tension stiffening effects, the variation in position of the neutral axis as a function of the eccentricity of the normal force, and the non-linear behaviour of concrete in compression.     

Cryoconcentration technology in the bio-food industry: Principles and applications

Cryoconcentration is a natural phenomenon which occurs during the ice thawing. More concentrated phase is then separated from the initial solution. This phenomenon was exploited for scientific objectives and the results were impressive. The use of the cryoconcentration technology in the bio-food industry makes it possible to obtain products of high nutritive, biological and organoleptic value. The aim of this review was to trace a detailed synthesis of the basic principles of this concentration and extraction technique, to summarize in one document the potential and principal applications reported in the literature and to try to predict the future and the necessary conditions for the industrial success of this technology.     

Boundary feedback control in networks of open channels

This article deals with the regulation of water flow in open-channels modelled by Saint-Venant equations. By means of a Riemann invariants approach, we deduce stabilizing control laws for a single horizontal reach without friction. The stability condition is extended to a general class of hyperbolic systems which can describe canal networks with more general topologies. A control law design based on this condition is illustrated with a simple case study: two reaches in cascade. The proof of the main stability theorem is based on a previous result from Li Ta-tsien concerning the existence and decay of classical solutions of hyperbolic systems.     

Binary spatial partitioning of the central‐difference time integration scheme for explicit fast transient dynamics

This paper proposes a generalization of the explicit central‐difference time integration scheme, using a time step variable not only in time but also in space. The solution at each element/node is advanced in time following local rather than global stability limitations. This allows substantial saving of computer time in realistic applications with non‐uniform meshes, especially in multi‐field problems like fluid–structure interactions. A binary scheme in space is used: time steps are not completely arbitrary, but stay in a constant ratio of two when passing from one partition level to the next one. This choice greatly facilitates implementation (via an integer‐based logic), ensures inherent synchronization and avoids any interpolations, necessary in other partitioning schemes in the literature, but which may reduce numerical stability. The mesh partition is automatically built up and continuously updated by simple spatial adjacency considerations. The resulting algorithm deals automatically with large variations in time of stability limits. The paper introduces the core spatial partitioning technique in the Lagrangian formulation. Some academic numerical examples allow a detailed comparison with the standard, spatially uniform algorithm. A final more realistic example shows the application of partitioning in simulations with arbitrary Lagrangian Eulerian formulation and fully‐coupled boundary conditions (fluid–structure interaction). Copyright © 2008 John Wiley & Sons, Ltd.     

Multihormonal control of ob gene expression and leptin secretion from cultured human visceral adipose tissue: increased responsiveness to glucocorticoids in obesity

The direct role of hormones on leptin synthesis has not yet been studied in cultured adipose cells or tissue from lean and obese subjects. Moreover, this hormonal regulation has never been addressed in human visceral fat, although this site plays a determinant role in obesity-linked disorders. In this study, we investigated the hormonal control of ob expression and leptin production in cultured visceral adipose tissue from lean and obese subjects. We more particularly focused on the interactions between glucocorticoids and insulin. We also briefly tackled the role of cAMP, which is still unknown in man. Visceral (and subcutaneous) adipose tissues from eight obese (body mass index, 41 +/- 2 kg/m2) and nine nonobese (24 +/- 1 kg/m2) subjects were sampled during elective abdominal surgery, and explants were cultured for up to 48 h in MEM. The addition of dexamethasone to the medium increased ob gene expression and leptin secretion in a time-dependent manner. Forty-eight hours after dexamethasone (50 nmol/L) addition, the cumulative integrated ob messenger ribonucleic acid (mRNA) and leptin responses were, respectively, approximately 5- and 4-fold higher in obese than in lean subjects. These responses closely correlated with the body mass index. The stimulatory effect of the glucocorticoid was also concentration dependent (EC50 = approximately 10 nmol/L). Although the maximal response was higher in obese than in lean subjects, the EC50 values were roughly similar in both groups. Unlike dexamethasone, insulin had no direct stimulatory effect on ob gene expression and leptin secretion. Singularly, insulin even inhibited the dexamethasone-induced rise in ob mRNA and leptin release. This inhibition was observed in both lean and obese subjects, whereas the expected stimulation of insulin on glucose metabolism and the accumulation of mRNA species for the insulin-sensitive transporter GLUT4 and glyceraldehyde-3-phosphate dehydrogenase occurred in lean patients only. This inhibitory effect was already detectable at 10 nmol/L insulin and was also observed in subcutaneous fat. Although a lowering of intracellular cAMP concentrations is involved in some of the effects of insulin on adipose tissue, this cannot account for the present finding, because the addition of cAMP to the medium also decreased ob mRNA and leptin secretion (regardless of whether dexamethasone was present). In conclusion, glucocorticoids, at physiological concentrations, stimulated leptin secretion by enhancing the pretranslational machinery in human visceral fat. This effect was more pronounced in obese subjects due to a greater responsiveness of the ob gene and could contribute to the metabolic abnormalities associated with central obesity by para/endocrine actions of hyperleptinemia on adipocytes and liver. Unlike dexamethasone, insulin had no direct stimulatory effect on ob gene expression and leptin secretion, and even prevented the positive response to dexamethasone by a cAMP-independent mechanism that remained functional despite insulin resistance.     

Gravitational and microwave-assisted thawing during milk whey cryoconcentration

Cryoconcentration technology was successfully used to produce milk whey concentrates. Effect of cryoconcentration stage and thawing mode on process efficiency and physico-chemical characteristics of the concentrated and ice fractions were studied. It was found that the effect of the cryoconcentration stage was significant, whereas the thawing mode had no effect. Microwave-assisted thawing mode was an efficient procedure and was faster than gravitational mode. Whey concentrate with 37.72 ± 0.69% of total dry matter was obtained. Proteins were concentrated up to 6.49 ± 0.31% (w/v). The concentrated fraction was rich in potassium ions. To achieve high process efficiency, the whey should be completely frozen and thawed in three cryoconcentration stages because the process efficiency drastically decreased at the fourth cryoconcentration stage, because of high dry matter content of the frozen solution obtained in the preceding stage.     

Skim acidic milk whey cryoconcentration and assessment of its functional properties: Impact of processing conditions

In the present research two objectives were studied. The first was aimed to optimize whey cryoconcentration process by minimizing the amount of the dry matter entrapped in the ice fraction. This was possible by recycling the ice fraction. It was possible to concentrate acidic whey from 5.71 ± 0.01% (w/w) up to 24.68 ±0.03% (w/w) total dry matter using three cryoconcentration cycles and one recycling ice cycle. The second objective was to study the emulsifying and foaming properties of the concentrated whey as function of the cryoconcentration cycle. Results showed that emulsion stability index (ESI) of the cryoconcentrated whey increased by increasing the cryoconcentration cycle whereas the emulsion activity index (EAI) decreased. Foaming ability expressed as nitrogen volume needed to get foam volume three times higher than the initial volume increased by increasing cryoconcentration cycle and foam stability decreased by increasing the cryoconcentration cycle.Industrial relevanceSeveral efforts and studies have been made to increase the use of milk whey, a valuable by-product of cheese processing, especially for human nutrition. In the present work, cryoconcentration technology was used for whey recovery and valorisation as promising ingredient in the food industry.     

Ohmic Cooking of Processed Meats and its Effects on Product Quality

ABSTRACT: A basic bologna emulsion (lean and fatty pork meat, sodium chloride, sodium erythorbate, and sodium nitrite) was cooked in 1-kg portions, either in a smokehouse (180-min cycle; to 70 °C at core) or by ohmic heating (64 to 103 V; 3.9 °C/min to 10.3 °C/min; to 70 °C to 80 °C), and the finished products were compared for color, texture, pH, drip, Eh, and rancidity. Heating rates, final temperatures, and a 20-min holding time had little influence on the quality of ohmic sausages. In addition, ohmic sausages were always found to be similar to smokehouse products except for texture, which was significantly softer (P > 0.05) in ohmic products but could be hardened by use of binders.