Mass transfer of pork meat cubes (M. triceps brachii), shaped as 1x1x1 cm, during osmotic dehydration (OD) and under atmospheric pressure was investigated in this paper. The effects of different parameters, such as concentration of sugar beet molasses (60-80%, w/w), temperature (20-50ºC), and immersion time (1-5 h) in terms of water loss (WL), solid gain (SG), final dry matter content (DM), and water activity (aw), were investigated using experimental results. Five artificial neural network (ANN) models were developed for the prediction of WL, SG, DM, and aw in OD of pork meat cubes. These models were able to predict process outputs with coefficient of determination, r2, of 0.990 for SG, 0.985 for WL, 0.986 for aw, and 0.992 for DM compared to experimental measurements. The wide range of processing variables considered for the formulation of these models, and their easy implementation in a spreadsheet calculus make it very useful and practical for process design and control
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)
The main purpose of this paper is
to determine how the torrefaction
influences the pelletability of birch (hardwood) and spruce (softwood).
Woods were torrefied at two different temperatures (225 and 275 °C)
for 30 min. Energy loss (EL) and weight loss (WL), higher heating
value (HHV), moisture uptake, water activity (a
w), and particle size distribution of raw and torrefied woods
were determined to characterize the materials before pelleting and
to see how torrefaction affects physical properties of wood. The impact
of biomass type, temperature, and compacting pressure on pellet strength
and compressibility of raw and torrefied wood was investigated using
a single pellet press method. Pellets were produced at three different
temperatures (60, 120, and 180 °C) and eight different compacting
pressures (5, 10, 20, 40, 80, 160, 240, and 300 MPa). Torrefaction
at 275 °C significantly increased the HHV of both types of wood,
in contrast to torrefaction at 225 °C. Compressing pressure and
pelleting temperature had a significant positive impact on the material
compressibility and strength. The strongest pellets were produced
from raw spruce (68.62 ± 1.69 N/mm) and birch torrefied at 275
°C (86.34 ± 3.33 N/mm). Compression strength and density
of the pellets were strongly correlated following a power low trend
(R
2 > 0.98). Torrefied material required
higher force for pellet discharge because of the higher friction generated
on the pellet surface–die area.
The effects of osmotic dehydration on mass transfer properties and microbiological profile were investigated in order to determine the usefulness of this technique as pre-treatment for further treatment of meat. Process was studied in two solutions (sugar beet molasses, and aqueous solution of sodium chloride and sucrose), at two temperatures (4 and 22°C) at atmospheric pressure. The most significant parameters of mass transfer were determined after 300 minutes of the dehydration. The water activity (aw) values of the processed meat were determined, as well as the change of the microbiological profile between the fresh and dehydrated meat. At the temperature of 22°C the sugar beet molasses proved to be most suitable as an osmotic solution, despite the greater viscosity
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