This study aimed to evaluate the potential of the bacterium Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Listeria monocytogenes to adhere to stainless steel discs with ...differing degrees of surface roughness (Ra = 25.20-961.90 nm). Stainless steel is a material commonly used in the food industry for processing equipment, which is regularly exposed to cleaning procedures. The investigation included the commercial disinfectants hydrogen peroxide/peracetic acid and sodium hypochlorite which were evaluated for their antibacterial and anti-adhesion activity. The adhesion was assessed by the standard plate count method, while the broth microdilution method CLSI M07-A10 was used to determine the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of the disinfectants. Based on the MIC values, both disinfectants exerted significant inhibitory effects with MIC values for hydrogen peroxide/peracetic acid and sodium hypochlorite of 250 µg ml
−1
and 500 µg ml
−1
, respectively. Whereas the MBC values were equal to the MIC for all bacteria except for E. coli with values 2-fold higher than the MIC. Obtained results also revealed that all tested bacteria were able to adhere to stainless steel surfaces, although differences were found for strains and surface roughness. The lowest adhesion rate of each strain was recorded on the roughest stainless steel disc at a Ra of 961.90 nm. Further, at a concentration of 1 MIC, the disinfectant sodium hypochlorite reduced initial bacterial adhesion to stainless steel surfaces to a significantly greater extent than the disinfectant hydrogen peroxide/peracetic acid. These findings are consistent with the results obtained by Scanning Electron Microscopy (SEM) analysis, which indicates the great applicability of the tested disinfectants for the control of bacterial adhesion in the food industry.
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).
nema
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.
nema
In sugar industry, separation of undesirable compounds in sugar beet juice is done mostly by CaO and carbon dioxide. In order to reduce the amount of lime, a new method of pectin separation based on ...the application CaSO4 with the addition of various types of anionic polyacrylamides (PAMs) is presented. The effects of molecular weight (MW) and the surface charge type of anionic polyacrylamides on the pectin precipitation were investigated. These compounds cause the process of charge neutralization of pectin macromolecules, followed by two mechanisms of polymeric bridging effect: Ca2+ bridges between anionic polymer molecules and pectin particles that promote the coagulation of pectin and Ca2+ bridges between anionic polymers that hinder coagulation of pectin. The aim of this paper was to examine the effect of CaSO4 mixture and anionic PAMs of different molecular weights and degree of ionizaton to increase the efficiency of removal of pectin from sugar beet juice. Two pectin preparations were isolated from sugar beet pulp. CaSO4 was added to 100 cm3 (0.1 % wt) pectin solution. Studies were performed with 10 different concentrations of CaSO4 solution (50-500 mg/dm3) with the addition of anionic PAM with two ionization degree and three molecular weight, concentrations of 3 mg/dm3. The efficiency of pectin precipitation was monitored by measuring the zeta potential. The bridging effect of Ca2+ ions between anionic PAMs and pectin has increased with an increase in the MW of the anionic PAMs. Using anionic PAM of the largest MW (1500 · 106g/mol) and a lower degree of ionization (30%), the optimal amounts of CaSO4 were measured: 340-355 mg/dm3. These optimal concentrations were achieved at the zero value of the potential zeta when the pectin particles were discharged.
Three pectin preparations were isolated from fresh sugar beet pulp during the
150 minutes of extraction, at pH values of 1, 3.5 and 8.5. CaSO4 precipitant
was added to 100 cm3 of 0.1% (wt) solution ...of pectin. Studies were performed
with 9 different concentrations of CaSO4 solution (50-450 mg dm-3) with the
addition of a cationic polyelectrolyte (cationic PAM) in concentrations of 3
and 5 mg dm-3. The efficiency of pectin precipitation was monitored by
measuring the zeta potential of pectin preparations. Optimal amounts of
precipitant CaSO4, without the use of a cationic polyelectrolyte, were as
follows: 490-678 mg CaSO4/g pectin. After the use of a cationic
polyelectrolyte, the optimal amounts of CaSO4 were smaller (353-512 mg/g
pectin). These quantities are significantly lower than the average amount of
CaO used in the conventional clarification process of sugar beet juice (about
9 g/g pectin of sugar beet juice).
Osmotic dehydration in molasses and successive lyophilization of peaches are investigated, in effort of obtaining new and improved product. Prepared samples were subjected to the osmotic dehydration ...in molasses of different time, concentration, and temperature, and then to the 5‐hr lyophilization process. The results showed that all three osmodehydration parameters statistically significantly affected dry matter content and aw of successively dehydrated samples, reaching peak values of 83.63% and 0.433 of dry matter content and aw, respectively. Osmodehydration process contributed to upgrading overall dehydration effectiveness, while aw values reduction in lyophilization stage contributed to the increased samples’ microbiological stability. Mineral matter content was highly increased, up to 8.63, 248.30, 64.05, and 101.56 times higher, for K, Ca, Mg, and Fe, respectively, as a consequence of molasses application. Developed mathematical models of 12 responses of osmotic dehydration and lyophilization processes were statistically significant, well‐describing synergetic performance of two successive dehydration methods.
Novelty impact statement
Osmotic dehydration, as a simple, low energy‐demanding process, especially with molasses used as an osmotic solution, was applied in effort to reduce the extent of further dehydration phase. The osmotic dehydration phase also supplemented mineral matter content of the dehydrating peach samples with its high value nutritional content. Lyophilization, as energy demanding, yet high quality‐producing technique, as a successive dehydration phase, provided peach samples of very high dry matter content and very low aw values in reduced duration of application.
Peach dehydrated by a combined method of osmodehydration and lyophilization is characterized by upgraded dehydration effectiveness and enhanced chemical and mineral matter content, and as such, is an ...interesting material to be applied to the cookies' formulation. Incorporation of this material requires testing and optimization of the addition level from the aspect of overall technological quality in order to obtain a new cookie product. Obtained cookie samples with different levels of dehydrated peach addition were subjected to the nutritive and technology quality parameters testing. Cookies' chemical, mineral matter, and phenolic compounds content, the antioxidative activity of nutritive parameters, and the physical, technological, textural, colour, and sensory characteristics of technological parameters were investigated. Obtained results showed that the addition of especially higher levels of dehydrated peach enhanced all nutritive, while simultaneously decreased most of the technological quality parameters. The statistical method of Z-score analysis was used to calculate the optimal level of dehydrated peach addition to the cookie formulation for obtaining the highest nutritive enrichment without excessive technological quality deterioration. The optimal addition of osmodehydrated and lyophilized peach to the cookie formulation was determined to be 15%.
The effects of the osmodehydration pretreatment parameters on successive lyophilization mass transfer kinetics of the peaches, dehydrated in the combined dehydration process, were investigated and ...mathematically modelled. The obtained results showed the statistically significant effect of osmotic dehydration pretreatment and its parameters on the final dry matter content and water activity values of the dehydrated peaches. The maximum dry matter content and minimal water activity values of dehydrated peach samples were 84.60 % and 0.423, respectively, produced in osmodehydration pretreatment in molasses of 80 % concentration, at 50 °C, during a 5-hour process and subsequent 6-hour lyophilization. With the increase of all osmodehydration pretreatment parameters it is possible to reduce the duration of the lyophilization process, reducing the high energy demand of the dehydration method (lyophilization) and substituting it with low energy demanding dehydration method (osmodehydration) without compromising the quality of the final product, regarding the dry matter content and water activity values. Mathematical models describing the effect of the duration of the lyophilization on the dry matter content and water activity values of the fresh and dehydrated peaches were developed. They showed a good correlation between calculated and experimental values, allowing a good prediction of the investigated responses. In the combined method, protein, sugar, K and Fe content of the dehydrated peach samples were enriched and further enhanced in prolonged lyophilization stages.
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
This article has been retracted. Link to the retraction 10.2298/APT1647105E
nema
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 (20-50?C),
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.
nema
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