Electric double layer and electrokinetic potential of pectic macromolecules in sugar beet

Electrokinetic potential is an important property of colloidal particles and, regarding the fact that it is a well defined and easily measurable property, it is considered to be a permanent characteristic of a particular colloidal system. In fact, it is a measure of electrokinetic charge that surrounds the colloidal particle in a solution and is in direct proportion with the mobility of particles in an electric field. Gouy-Chapman-Stern-Graham's model of electric double layer was adopted and it was proven experimentally that the addition of Cu++ ions to sugar beet pectin caused a reduction in the negative electrokinetic potential proportional to the increase of Cu++ concentration. Higher Cu++ concentrations increased the proportion of cation specific adsorption (Cu++ and H+) with regard to electrostatic Coulombic forces. Consequently, there is a shift in the shear plane between the fixed and diffuse layers directed towards the diffuse layer, i.e. towards its compression and decrease in the electrokinetic potential or even charge inversion of pectin macromolecules

Effects of temperature and immersion time on rehydration of osmotically dehydrated pork meat

The aim of this work was to study the changes in osmotically dehydrated (OD) pork meat during rehydration. Meat samples (lxlxlcm cubes) were osmotically treated in two solutions: (1) solution with 350g of NaCI and 1200g of sucrose diluted in I I of distilled water and (2) sugar beet molasses (80 °Brix) solution at 23±2°C for 1, 2, 3 and 4 hours. In both cases, the solution to sample mass ratio was 10:1 to avoid significant dilution of the medium by water removal. After being osmotically dehydrated, meat samples were rehydrated by immersing meat cubes in water bath at constant temperature (20, 40 and 60 °C). The samples were removed after different immersion periods (15, 30, 45 and 60 min) and examined for mass and volume gain and rehydration percentage was calculated. After relatively short time (15 min), significant weight and volume gains were observed for both treatments. Process temperature was the most significant variable affecting final dry matter content and rehydration kinetics. At the end of rehydration process, conducted at 20 °C and 40 °C, a significant recovery in mass was observed, although the values were lower than for fresh meat. Ruptured and shrunken meat tissue produced as the result of OD had reduced its ability to absorb water. Rehydration percentage at 20 °C for molasses solution was 24.11%, and for sucrose-salt solution was 26.19%. However, rehydration at 40° C brings higher mass gain in case of molasses as a solution (11.33%) compared with sucrose-salt solution (7.88%). Results obtained at 60 °C were negative which means that rehydration didn't take place. The best conditions for meat rehydration were obtained using a temperature of 20 °C and time of 60 min. Volume of samples increased almost linearly with weight increment

Osmotic dehydration of carrot in sugar beet molasses: Mass transfer kinetics

The osmotic dehydration process of carrot in sugar beet molasses solutions (40, 60 and 80%), at three temperatures (45, 55 and 65°C) and atmospheric pressure, was studied. The main aim was to investigate the effects of immersion time, working temperature and molasses concentration on mass transfer kinetics during osmotic dehydration. The most important kinetic parameters were determined after 20, 40, 60, 90, 120, 180, 240 and 300 min of dehydration. Diffusion of water and solute was the most intensive during the first hour of the process and the maximal effect was observed during the first 3 hours of immersion. During the next two hours of dehydration, the process stagnated, which implied that the dehydration time can be limited to 3 hours

Osmotic dehydration of red cabbage in sugar beet molasses: Mass transfer kinetics

The paper describes a study of osmotic dehydration of red cabbage in sugar beet molasses of different concentrations (40, 60 and 80%) at 50°C and under atmospheric pressure. The best results were obtained at the sugar beet molasses of 80% as an osmotic medium. The most important kinetic parameters of the process were determined: water loss, solid uptake, weight reduction, normalized solid content and normalized moisture content. The kinetic parameters were determined after 1, 3 and 5 hours. Mass transfer coefficients were calculated using Hawkes and Flink's model and the results indicate that the diffusion of water and solids was the most intensive during the first three hours of dehydration

Reduction of cyanogenic glycosides by extrusion - influence of temperature and moisture content of the processed material

Тhe paper presents results of the investigation of the influence of extrusion temperature and moisture content of treated material on the reduction of cyanogenic glycosides (CGs) in linseed-based co-extrudate. CGs are the major limitation of the effective usage of linseed in animal nutrition. Hence, some technological process must be applied for detoxification of linseed before its application as a nutrient. Extrusion process has demonstrated several advantages in reducing the present CGs, since it combines the influences of heating, shearing, high pressure, mixing, etc. According to obtained results, the increase in both temperature and moisture content of the starting mixture decreased the content of CGs in the processed material. HCN content, as a measurement of GCs presence, ranged from 25.42 mg/kg, recorded at the moisture content of 11.5%, to 126 mg/kg, detected at the lowest moisture content of 7%. It seems that moisture content and temperature had the impact on HCN content of equal importance. However, the influence of extrusion parameters other than temperature and moisture content could not be neglected. Therefore, the impact of individual factors has to be tested together. [Projekat Ministarstva nauke Republike Srbije, br. III 46012

Optimization of the osmotic dehydration of carrot cubes in sugar beet molasses

A Response Surface Methodology approach (RSM) was used to determine optimum conditions for the osmotic dehydration of carrot cubes in sugar beet molasses. Treatment times were set to 1, 3 and 5 h, at temperatures of 45, 55 and 65°C and molasses concentrations were 40, 60 and 80% (w/w). The used responses variables were: final dry matter content (DM), water loss (WL), solid gain (Sg), and water activity (aw). A Box and Behnken’s fractional factorial design (2 level-3 parameter) with 15 runs (1 block) was used for design of the experiment. DM, WL, Sg were significantly affected by all process variables (at 90-95% confidence level). The optimum conditions were determined by superimposing the contour plots, with the following response limiting values: DM 50-60%, WL 0.7- 0.8, Sg 0.08-0.09, and aw 0.84-0.86. The optimum conditions generated were: treatment time of 4h, temperature of 60°C, sugar concentration of 66% (w/w)

Osmotic dehydration of fish: principal component analysis

Osmotic treatment of the fish Carassius gibelio was studied in two osmotic solutions: ternary aqueous solution - S1, and sugar beet molasses - S2, at three solution temperatures of 10, 20 and 30oC, at atmospheric pressure. The aim was to examine the influence of type and concentration of the used hypertonic agent, temperature and immersion time on the water loss, solid gain, dry mater content, aw and content of minerals (Na, K, Ca and Mg). S2 solution has proven to be the best option according to all output variables.[ Projekat Ministarstva nauke Republike Srbije, br. TR 31055