The effects of osmotic dehydration parameterson the kinetics, functional and antioxidantcharacteristics of nettle leaf (Urtica dioica)

U ovoj disertaciji proučavana je osmotska dehidratacija lista koprive u dva različita osmotska rastvora: 1. vodenom rastvoru saharoze i natrijum hlorida i 2. melasi šećerne repe. Ispitivan je uticaj temperature procesa (20°C, 35°C i 50°C) i vremena imerzije (30, 60 i 90 min) na gubitak vode, priraštaj suve materije, sadržaj suve materije, vrednosti aktivnosti vode, mikrobiooške promene, promenu mineralnog sastava (Ca, Mg, Na, K, Fe, Cu, Zn, Mn, Co) i promenu antioksidativne aktivnosti, tokom osmotske dehidratacije lista koprive. Dokazano je da se povećanjem temperature i produženjem vremena trajanja procesa pospešuje prenos mase tj. migracija molekula vode iz tretiranog biljnog materijala u okolni rastvor, i prodiranje molekula rastvorene supstance iz osmotskog rastvora u tretirano biljno tkivo. Snižene aw vrednosti u svim ispitivanim uzorcima ukazuju na pozitivan uticaj osmotske dehidratacije na mikrobiološku stabilnost tretiranog lista koprive. Dobijeni rezultati su pokazali značajno poboljšanje mineralnog sastava lista koprive, dehidriranih u melasi šećerne repe, dok je kod uzoraka tretiranih u rastvoru saharoze i natrijumhlorida uočeno smanjenje sadržaja ispitivanih mineralnih materija. Nasuprot rastvoru saharoze i natrijum hlorida koji je uticao na opadanje ukupne antioksidativnosti osmotski dehidriranih uzoraka, melasa šećerne repe, kao bogat izvor prirodnih antioksidanasa, doprinosi povećanju antioksidativnosti i poboljšanju funkcionalnog kvaliteta dehidriranog produkta. Statističkom obradom rezultata, uočeno je da su optimalni procesni parametri u pogledu efikasnosti procesa, kao i mikrobiološkog, nutritivnog i funkcionalnog kvaliteta osmotski dehidriranog lista koprive, vreme trajanja procesa od 60 min, na temperaturi od 50°C, u melasi šećerne repe kao osmotskom rastvoru.The osmotic dehydration of the nettle leaf into two different osmotic media was studied in this dissertation: 1. Aqueous solution of sucrose and sodium chloride and 2. Sugar beet molasses. The effects of the process temperature (20 °C, 35 °C and 50 °C) and the immersion time (30, 60 and 90 min) on water loss, solid gain, dry matter content, water activity, microbial changes, mineral composition (Ca, Mg, Na, K, Fe, Cu, Zn, Mn, Co) and the change in the antioxidant activity during osmotic dehydration of the nettle leaf were studied in this investigation. It has been proved that the increase in temperature and the prolonging of process time, accelerate the mass transfer, i. e., the migration of the water molecules from the treated plant material to the surrounding osmotic solution, and also the penetration of the molecules from the osmotic solution into the treated plant tissue. The reduced aw values in all tested samples indicate the positive effect of osmotic dehydration on the microbiological stability of the treated nettle leaf. The obtained results showed a significant improvement in the mineral composition of the nettle leaf dehydrated in sugar beet molasses, while the decrease in the mineral content was observed in the samples treated with sucrose and sodium chloride solution. Contrary to the sucrose and sodium chloride solution, which negatively affected the overall antioxidative effect of osmotically dehydrated samples, sugar beet molasses contributed to an increase in antioxidantity, being a rich source of natural antioxidants, and it also improves the functional quality of the dehydrated product. Statistical analysis of the obtained experimental results showed that optimal process parameters in terms of process efficiency, as well as microbiological, nutritive and functional quality of the osmotically dehydrated leaf net, could be reached after 60 min of osmotic treatment, at a temperature of 50 °C, using sugar beet molasses as an osmotic solution

The effects of osmotic dehydration parameterson the kinetics, functional and antioxidantcharacteristics of nettle leaf (Urtica dioica)

U ovoj disertaciji proučavana je osmotska dehidratacija lista koprive u dva različita osmotska rastvora: 1. vodenom rastvoru saharoze i natrijum hlorida i 2. melasi šećerne repe. Ispitivan je uticaj temperature procesa (20°C, 35°C i 50°C) i vremena imerzije (30, 60 i 90 min) na gubitak vode, priraštaj suve materije, sadržaj suve materije, vrednosti aktivnosti vode, mikrobiooške promene, promenu mineralnog sastava (Ca, Mg, Na, K, Fe, Cu, Zn, Mn, Co) i promenu antioksidativne aktivnosti, tokom osmotske dehidratacije lista koprive. Dokazano je da se povećanjem temperature i produženjem vremena trajanja procesa pospešuje prenos mase tj. migracija molekula vode iz tretiranog biljnog materijala u okolni rastvor, i prodiranje molekula rastvorene supstance iz osmotskog rastvora u tretirano biljno tkivo. Snižene aw vrednosti u svim ispitivanim uzorcima ukazuju na pozitivan uticaj osmotske dehidratacije na mikrobiološku stabilnost tretiranog lista koprive. Dobijeni rezultati su pokazali značajno poboljšanje mineralnog sastava lista koprive, dehidriranih u melasi šećerne repe, dok je kod uzoraka tretiranih u rastvoru saharoze i natrijumhlorida uočeno smanjenje sadržaja ispitivanih mineralnih materija. Nasuprot rastvoru saharoze i natrijum hlorida koji je uticao na opadanje ukupne antioksidativnosti osmotski dehidriranih uzoraka, melasa šećerne repe, kao bogat izvor prirodnih antioksidanasa, doprinosi povećanju antioksidativnosti i poboljšanju funkcionalnog kvaliteta dehidriranog produkta. Statističkom obradom rezultata, uočeno je da su optimalni procesni parametri u pogledu efikasnosti procesa, kao i mikrobiološkog, nutritivnog i funkcionalnog kvaliteta osmotski dehidriranog lista koprive, vreme trajanja procesa od 60 min, na temperaturi od 50°C, u melasi šećerne repe kao osmotskom rastvoru.The osmotic dehydration of the nettle leaf into two different osmotic media was studied in this dissertation: 1. Aqueous solution of sucrose and sodium chloride and 2. Sugar beet molasses. The effects of the process temperature (20 °C, 35 °C and 50 °C) and the immersion time (30, 60 and 90 min) on water loss, solid gain, dry matter content, water activity, microbial changes, mineral composition (Ca, Mg, Na, K, Fe, Cu, Zn, Mn, Co) and the change in the antioxidant activity during osmotic dehydration of the nettle leaf were studied in this investigation. It has been proved that the increase in temperature and the prolonging of process time, accelerate the mass transfer, i. e., the migration of the water molecules from the treated plant material to the surrounding osmotic solution, and also the penetration of the molecules from the osmotic solution into the treated plant tissue. The reduced aw values in all tested samples indicate the positive effect of osmotic dehydration on the microbiological stability of the treated nettle leaf. The obtained results showed a significant improvement in the mineral composition of the nettle leaf dehydrated in sugar beet molasses, while the decrease in the mineral content was observed in the samples treated with sucrose and sodium chloride solution. Contrary to the sucrose and sodium chloride solution, which negatively affected the overall antioxidative effect of osmotically dehydrated samples, sugar beet molasses contributed to an increase in antioxidantity, being a rich source of natural antioxidants, and it also improves the functional quality of the dehydrated product. Statistical analysis of the obtained experimental results showed that optimal process parameters in terms of process efficiency, as well as microbiological, nutritive and functional quality of the osmotically dehydrated leaf net, could be reached after 60 min of osmotic treatment, at a temperature of 50 °C, using sugar beet molasses as an osmotic solution

The role of the tour guide profession in the Drava and Sava regions: communicating attractions in increasingly aestheticized tourism consumption

In the process of sustainable tourism development the role of tour guides is significant. They are not mere presenters of natural and cultural attractions, but ambassadors of cultures, sustainability and intercultural dialogue. It is thus essential that they are well educated, adequately trained and actively involved in the tourism planning processes. Especially important is their role when it comes to presenting attractions to tourists by employing their communication and professional skills. This article describes the experiment of presenting an object (attraction) without a tour guide on the one hand, and the experiments involving tour guides presenting an object (attraction) by using the method of description, and the experiements involving tour guides using a description o fan object (attraction) and an invitation to participants (tourists) to actively participate on the other. The experimental research was focused on the role of tour guides and on the experiencing the beautiful. The results showed that the participants (tourists) evaluated the object (attraction) as more beautiful when it was presented by a tour guide implicating the essential role of the tour guide in the process of presenting attractions, destinations, and cultures.Uloga zanimanja turističkog vodiča na području rijeka Save i Drave: komuniciranje atrakcija u rastućoj estetiziranoj turističkoj potrošnji U procesu razvoja održivog turizma uloga turističkog vodiča iznimno je značajna. Turistički vodiči nisu samo prezenteri prirodnih i kulturnih atrakcija, već ambasadori kulture, održivosti i interkulturalnog dijaloga. Iz tog je razloga od ključne važnosti da vodiči imaju dobro obrazovanje, da su dobro obučeni za svoj posao i da su aktivno uključeni u proces planiranja razvoja turizma. Njihova je uloga osobito značajna kada govorimo o prezentiranju atrakcija turistima pomoću komunikacijskih i stručnih vještina. Ovaj rad opisuje testiranje prezentiranja objekta (atrakcije) bez vodiča i testiranje gdje su objekt (atrakciju) prezentirali turistički vodiči, i to pomoću metode deskripcije, te testiranja gdje su turistički vodiči koristili opis objekta (atrakcije), i pozivali sudionike (turiste) na aktivno sudjelovanje. Eksperimentalno istraživanje bilo je fokusirano na ulogu turističkih vodiča i na doživljaj ljepote. Rezultati istraživanja ukazuju da su sudionici (turisti) ljepšim ocijenili onaj objekt (atrakciju) kojeg je prezentirao turistički vodič, čime se implicira ključna uloga turističkih vodiča u procesu prezentiranja atrakcija, destinacija i kultura

Modeling the Effects of Osmotic Dehydration Pretreatment Parameters and Lyophilization Kinetics on Mass Transfer and Selected Nutritive Parameters of Peaches

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

Re-use of Osmotic Solution

In this paper the re-use of osmotic solution after osmotic treatment has been studied. A large amount of used osmotic solution remaining after the process is one of the major unsolved problems of osmotic treatment process. This problem has both ecological and economic aspects that should be concerned.Pork meat cubes were treated in three different osmotic solutions diluted with distilled water (R1 -sugar beet molasses, R2 – solution of salt and sucrose and R3 - combination of R1 and R2 solutions in a 1:1 mass ratio). Osmotic process has been observed during 5 hours, at temperature of 35oC and atmospheric pressure. Osmotic treatment has been performed simultaneously in concentrated solutions and diluted solutions (dilutions were obtained by mixing the solution and water in the mass ratio of 7:1 and 3:1). Parameters monitored during osmotic treatment were: dry mater content (DMC), water loss (WL), solid gain (SG) and osmotic dehydration efficiency index (DEI).Maximum values of these parameters were obtained in the dehydration with concentrated solutions, while recorded values in diluted solutions were much lower.The results show that the least effect on the osmotic process efficiency, when the osmotic concentration is lowered, has been observed for solution R3. This conclusion indicates that molasses is good osmotic solution with the possibility of re-using in successive processes of osmotic dehydration, with minimal treatment of reconstitution to original values of concentration

Re-use of osmotic solution

In this paper the re-use of osmotic solution after osmotic treatment has been studied. A large amount of used osmotic solution remaining after the process is one of the major unsolved problems of osmotic treatment process. This problem has both ecological and economic aspects that should be concerned. Pork meat cubes were treated in three different osmotic solutions diluted with distilled water (R1 -sugar beet molasses, R2 – solution of salt and sucrose and R3 - combination of R1 and R2 solutions in a 1:1 mass ratio). Osmotic process has been observed during 5 hours, at temperature of 35oC and atmospheric pressure. Osmotic treatment has been performed simultaneously in concentrated solutions and diluted solutions (dilutions were obtained by mixing the solution and water in the mass ratio of 7:1 and 3:1). Parameters monitored during osmotic treatment were: dry mater content (DMC), water loss (WL), solid gain (SG) and osmotic dehydration efficiency index (DEI). Maximum values of these parameters were obtained in the dehydration with concentrated solutions, while recorded values in diluted solutions were much lower. The results show that the least effect on the osmotic process efficiency, when the osmotic concentration is lowered, has been observed for solution R3. This conclusion indicates that molasses is good osmotic solution with the possibility of re-using in successive processes of osmotic dehydration, with minimal treatment of reconstitution to original values of concentration

Antioxidant Capacity of Nettle Leaves During Osmotic Treatment

Osmotic treatment (OT) of nettle leaves was assessed in various osmotic solutions (sugar beet molasses – SBM and ternary aqueous solution – TAS), at temperatures of 20, 35 and 50 °C, under the atmospheric pressure. The influence of the kind of utilized osmotic solution, process temperature and osmotic time on the antioxidant activity (AOC), expressed with the spectrophotometric assays (ABTS, FRAP and DPPH), as well as two direct current polarographic assays, Hydroxo Perhydroxo Mercury (II) complex assay, based on the decrease of anodic current and assay based on the decrease of a cathodic current of Hg (II) reduction. For determination of the total phenolic content Folin-Ciocalteu assay was used. The Relative Antioxidant Capacity Index (RACI), obtained by setting equal weight for every involved assay was applied in order to get an extensive comparison among analyzed samples and between the used assays. Based on these results, after the OT of nettle leaves in TAS, the AOC decreased, while the OT in SBM increased AOC values. The phenolic antioxidant coefficients (PAC), calculated as the ratio between particular AO capacity and TPC, were used to achieve a more comprehensive comparison between analysed samples, as well as applied assays. The results of RACI evaluation revealed that the most favorable osmotic treatment is the one performed for 5h at 35 °C

Brain abscess: A rare complication of catheter: Associated infection in patients on hemodialysis

Introduction: Vascular approach is one of the main risk factors that causes infections in patients that are treated by hemodialyses. Brain abscess is one of the rarer metastatic complications of dialytic catheter sepsis. Metastatic infections contribute to the increase of morbidity and mortality rates in hemodialytic patients. Case report: A 38 year-old male patient with the case history of hypertension and a rapid progressive glomerulonephritis treated by hemodialyses who developed brain abscess caused by catheter related complication in the region where he had left-sided parenteral ischemic brain stroke. The admitted patient had no subjective symptoms and neurological deficiency, elevated inflammation parameters. No microorganisms were found after the necessary laboratory analyses, puncture point and catheter tip swab tests. Two weeks after hospital admission the patient's condition deteriorated in terms of an increased number of abscess lesions diagnosed by MRI of endocardium, without clinical impairment and increase of inflammation parameters, so the right choice and duration of parenteral antibiotic administration caused brain abscess regression. Conclusions: Albeit brain abscess is a rare complication of the septic state, physicians should have in mind previous brain lesions, especially in immunosuppressed patients