Search

The aim of this study was to investigate effects of osmotic treatment on microbiological profile and water activity (aw) in celery leaves and root, in order to indicate the usefulness of this drying technique. Samples of celery leaves and root were dehydrated in sugar beet molasses and aqueous solution of sodium chloride and sucrose, at three different temperatures. aw values of processed celery leaves and root were determined and the change of the microbiological profile between the dehydrated celery leaves and root was examined. The process of osmotic treatment improve the initial microbiological profile due to increasing dry matter content and lowering aw value of the all processed celery samples. Better microbiological load reduction was observed in samples of leaves compared with samples of roots. Measuring results were fitted to mathematical models using Response Surface Methodology and statistically evaluated using analysis of variance.

The presented paper describes an investigation of nettle leaves kinetics during osmotic treatment in two different osmotic solutions (sugar beet molasses and ternary solution, was made from sucrose in quantity of 1,200 g/kg water, NaCl in quantity of 350 g/kg water and distilled water), at temperature of 20, 35 and 50ºC, during 90 min process. The main objective of this study was to examine the influence of type of different osmotic agents, process temperature and immersion time on the mass transfer phenomena during osmotic treatment, as well as the antioxidant activity. Water loss and solid gain were monitored. Antioxidant activity of osmotically treated nettle leaves was measured using a novel assay based on decrease of DC polarographic anodic current of hydroxo-perhydroxo mercury (II) complex [Hg(O2H)(OH)] (HPMC) formed in alkaline solution of H2O2 at potential of mercury oxidation. In order to get an insight into agreement between HPMC assay and common spectrophotometric assay, DPPH (2.2- diphenyl-1-picrylhydrazyl) analysis has been included in this study. Strict correlation between HPMC with commonly used DPPH assay was observed.

In sugar industry, there is a problem of the presence of undesirable macromolecules such as pectins in sugar beet juice. Separation of these compounds is done mostly by CaO. Calcium may cause undesirable process of alkalization of soil in the near environment of the sugar factory. The theoretical basis of new juice purificatin method based on the application of Al2(SO4)3, CaSO4 and their mixtures are presented. Two model solutions of pectin (0.1 % w/w) are investigated using a method of measuring zeta potential. Pure salts Al2(SO4)3 and CaSO4, showed better binding properties with the pectin than mixtures. Amount of all studied pure salts and mixtures of Al3+ and Ca2+ ions were significantly less (142 - 710 mg/gpectin) than the average amount of CaO used in classical process (about 9 g/gpectin). Mechanism of discharge of pectin macromolecules in the presence of mixtures of these ions using a model of double electric layer are suggested.

The presented paper describes an investigation of osmotic treatment of nettle leaves in two different osmotic solutions (sugar beet molasses and ternary solution), under atmospheric pressure, at room temperature. The main objective was to examine the influence of type of osmotic agents and immersion time on the mass transfer phenomena during osmotic treatment. Different kinetics parameters were monitored (water loss, solid gain, water loss to solid gain ratio, weight reduction, normalized solid content and normalized moisture content), after 30-90 min of process. Principal Component Analysis showed good discrimination capabilities for different samples, while Standard Score was used in optimal process parameters determination.

This research was conducted in order to examine the mass transfer kinetics, during osmotic dehydration of celery leaves (Apium graveolens) in two different osmotic solutions (sugar beet molasses and the mixed solution of sodium chloride and sucrose), under atmospheric pressure, at room temperature. The significance of used hypertonic solutions and immersion time on the various kinetics parameters (water loss, solid gain and dehydration efficiency index) were tested during the process, using Analysis of variance. Principal component analysis and Cluster analysis were used for characterization of different samples, and standard score analysis was applied in optimal process parameters determination.

In the sugar industry, calcium ions (in the form of CaO) that are commonly used to eliminate the pectin from beet juice have a relatively low binding affinity. The quantities of used lime are very large (15 g/100 g juice). The precipitation of pectin could be achieved by the charge neutralization. Compounds with bi- and trivalent cations such as CaSO4 and Al2(SO4)3 could be used to extract pectin from colloidal systems. Application of polyelectrolyte previously referred to the improvement of flocculation in water treatment and sugar cane juice. Model - pectin solutions (50 cm3 and 0.1 % wt.) were treated with different concentration of CaSO4 and Al2(SO4). Optimal amounts of applied coagulants, determined using measurements of zeta potential were: 410 mg/dm3 for CaSO4 and 110 mg/dm3 for Al2(SO4)3. By adding a cationic polyelectrolyte (1, 3 and 5 mg/dm3), the most efficient separation of pectin was achieved with polyelectrolyte concentration 3 mg/dm3. Adding this type polyelectrolyte, amounts of applied coagulants required for charge neutralization (zero zeta potential) were reduced. These amounts were 460 mg CaSO4 and 128 mg Al2( SO4)3/gpectin and significantly less than the amount of CaO used in the conventional process of sugar beet juice clarification (9 g/gpectin).

In this work instrumental analysis of color and texture of fresh and osmotically dehydrated samples of pork meat (in three different osmotic solutions solutions R1: NaCl+sucrose+water, R2: R1+ molasses, 1:1, R3: molasses) was carried out. Results obtained for fresh and dehydrated meat in three different solutions were compared. The results obtained in the analysis of instrumental colors, showed a statistically significant difference between the samples of raw meat and dehydrated samples. From the comparative results, there are statistically significant difference between the R1 dehydrated meat and meat dehydrated in R2 and R3. The values of texture parameters that were monitored showed that the same trends were statistically significant, i.e. process of osmotic dehydration led to increase of these values for the dehydrated meat samples in all investigated osmotic solutions. The results obtained by instrumental analysis are in accordance with the results obtained by descriptive sensory analysis.

The aim of the sugar beet processing is to achieve the highest sugar quality and yield with the lowest energy consumption together with the most effective use of equipment and time. After product crystallization is the most important stage. Optimization of crystal size during evaporating and cooling crystallization result in reduction of sucrose loss in molasses and improvement of plant operation. Sucrose loss in molasses is the largest loss in sugar beet factory. In this study measurement of sucrose crystal size distribution was applied as a tool for control and conducting after product crystallization. The main task of this process is growth uniform crystal with correct size in the aim to provide maximum growth rate and molasses exhaustion. The content and size of crystal present micro kinetic elements for control and management after product crystallization.

In sugar industry molasses represents a syrup obtained in final stage of crystallization. In production of sugar from sugar beet, for cause of higher rentability, phase of crystallization needed to be conducted so that the less quantity of molasses is obtained in which, under optimal conditions, remains around 12 % of total beet sugar quantity. On forming molasses affect present nonsucrose compounds forming with sucrose complex easily soluble additive compounds, which have higher solubility than sucrose, due to which saturation coefficient increases. Depending on technological quality of sugar beet, from sucrose introduced in processing, 88 - 92 % of white sugar can be obtained. Sugar in molasses is the highest loss of sugar in sugar beet processing. High visosity is one of the reasons for which significant quantities of sucrose can not be crystallized on the final stage of crystallization by the usual technological procedure. Test include determination of the parameters of molasses saturation and viscosity as a function of nonsucrose compounds.

Processing of raw sugar beet juice and molasses are important operations which are used to remove pectin and protein substances in order to obtain the final product - white sugar. Separation of these compounds in our country is mostly done by compounds with calcium ion. Quantities of used limestone are very high (1 – 3 % w/w, calculated on the beet). The aim of study is application of coagulants with divalent and trivalent cations which cause the process of charge neutralization of pectin and protein macromolecules, thus create conditions for their coagulation and sedimentation. Different concentrations of CuSO4 and Al2(SO4)3 (30 - 210 mg/dm3) were added to the model solutions (0.1 % w/w) of pectin and protein preparations. The pH of solutions were regulated at 7. pH of solutions with Al2(SO4)3 were regulated using equivalent amount Na2CO3). In order to monitor coagulation and sedimentation process of solution, a method of measuring the residual turbidity of solution was used. Residual turbidity of the solution was determined by spectrophotometry. The amount of coagulants needed to achieve the minimum solution turbidity and charge neutralization of macromolecules (zero zeta potential) were measured and compared. The optimal quantities CuSO4 and Al2(SO4)3 obtained by the both methods are 84 - 140 mg/gp. Amount of studied compounds were significantly less than the average amount of CaO used in classical process ( ~ 9 gCaO/gp).

The affinity of binding Al3+ and Cu2+ ions to non-sucrose compounds in sugar beet juice has been studied. The efficacy of ion binding was determined according to electrophoretic method by measuring Zeta potential. Model solutions of pectin and protein preparations (0.1% w.) were treated with solutions of CuSO4 and Al2(SO4)3 at seven different concentrations. The efficacy of Al3+ and Cu2+ ion binding was expressed as a minimal concentration of CuSO4 and Al2(SO4)3 needed for charge neutralization i.e. reaching zero Zeta potential. For pectin preparation, concentrations of these salts were 82 mg/dm3 CuSO4 and 105 mg/dm3 Al2(SO4)3. For protein preparation the concentrations were 115 mg/dm3 CuSO4 and 122 mg/dm3 Al2(SO4)3. Identical experiments were performed with the addition of cationic polyelectrolyte at 3 mg/dm3. Concentrations of CuSO4 and Al2(SO4)3 needed to change Zeta potential to zero decreased within interval from 7 to 20 mg/dm3. When the doses of tested ions were recalculated to industrial conditions, they were much lower in relation to consumption of Ca2+ ions in form of CaO (1 - 3% w.) which is commonly used in rafination of sugar juice.

This paper deals with the results on the connection between sugarbeet molasses quality, saturation coefficient and rheological properties. The saturation coefficient determined by the laboratory saturation test have been compared with the values predicted by means of the equations cited by Reinefeld et al. and Bohn et al. There is a statistically good relationship between the saturation values estimated by three methods. Sucrose solubility and viscosity of molasses present micro-kinetic elements for control and automatic management after-product massecuite cooling crystallization.

Composition of the molasses depends on the sugar beet composition and applied processing technology. Molasses, obtained under adequate conditions of sugar beet processing, has about 80% of dry matter content (about 50% is saccharose and about 30% non-saccharose matter). The molasses containes concentrated non-sugar components that have not been removed in the purification process, non-sugar components that are formed during the evaporation and crystallization, as well as the remains of the auxiliary materials used in the sugar beet processing. The non-sugar components of the molasses are divided into three major groups: inorganic (mineral) compounds, organic compounds with nitrogen and organic compounds without nitrogen. This paper examined the composition of organic nitrogen compounds in the molasses and the impact of sugar beet processing on the content of mentioned compounds. The research was comprehended within six local sugar factories by use of average campaign samples of molasses.

Faculty of Technology in Novi Sad developed a new method of osmotic dehydration of fruits and vegetables where the process of osmotic dehydration is followed by evaporation and the recirculation of osmotic solution. The process is carried out in several cycles and the osmotic solution is heated only in the first cycle. Moisture that exceeds the osmotic solution during osmotic dehydration of fruits and vegetables, in next stage is removed by evaporation. In order to prepare the energy-sustainable and economically effective production, an analysis of mass and energy balance of one complete cycle was performed. Energy model of evaporation of osmotic solution with the possibility of utilization of waste heat for heating other parts of the plant is shown. We used the solution of sugar beet molasses as an osmotic solution due it's favorable nutritional and microbiological properties.

Pri proizvodnji kvalitetnog belog konzumnog šećera iz šećerne repe, srećemo se sa problemom prisustva makromolekularnih jedinjenja u soku šećerne repe koja su štetna pa ih je neophodno odstraniti. Uklanjanje ovih jedinjenja, koja čine oko 60 % od ukupno sadržanih nesaharoznih materija u soku šećerne repe, zasniva se na principu taloženja uz primenu različitih koagulanata (najčešće jedinjenja koja sadrže pozitivne jone kalcijuma). Međutim, afinitet vezivanja kalcijuma sa nepoželjnim makromolekulima iz soka šećerne repe je mali, pa su potrebne velike količine ovog jedinjenja u svakodnevnoj proizvodnji šećera.Cilj istraživanja obuhvaćenih ovom doktorskom disertacijom usmeren je ka primeni alternativnih koagulanata sa dvo- i trovalentnim katjonima, pre svega soli aluminijuma i bakra koja izlazivaju proces razelektrisavanja makromolekula soka šećerne repe. Merenjem elektrokinetičkih potencijala utvrđene su optimalne količine koagulanata potrebne za uspešnu koagulaciju makromolekularnih jedinjenja iz soka šećerne repe. Ispitivan je i uticaj drugih procesnih veličina kao što su pH, koncentracija makromolekula i uticaj brzine mešanja na efikasnost taloženja makromolekula. Predložen je mehanizam razelektrisavanja makromolekularnih jedinjenja kao i model dvojnogelektričnog sloja koji okružuje koloidne čestice u soku šećerne repe. Ispitivana su dva model-rastvora komercijalno raspoloživih pektina u koncentracijama koje odgovaraju koncentracijama u soku šećerne repe kao i jedan model-rastvor proteinskog preparata. Ispitivani sistemi su tretirani rastvorima CuSO4i Al2(SO4)3 i rastvorima njihovih smeša u različitim odnosima. Dokazano je, za sva tri ispitivana preparata, da su manje količine Cu+2 jona u odnosu na Al+3jone potrebne za sniženje vrednosti Zeta potencijala na nulu. Međutim, zbog mogućih nepoželjnih efekata CuSO4u obradi hrane, Al(SO4)3 bi se mogao upotrebiti umesto tradicionalnog koagulanta CaO, kako zbog manje potrošnje koagulanta, tako i zbog očuvanja životne sredine. Cilj eksperimenata sa smešama je ispitivanje mogućnosti poboljšanja koagulacionih karakteristika često korišćene soliAl2(SO4)3, dodavanjem malih količina Cu+2 jona. Međutim, čiste soli su pokazale bolja koagulaciona svojstva. Istraživanja sa flokulantima, odnose se na odabiranje najpogodnijeg tipa i optimalne količine flokulanata, uz primenu predloženih koagulanata. Najveća efikasnost čišćenja soka šećerne repe, uočena je nakon primene anjonskog flokulanta koncentracije 3 mg/dm3. Dokazano je da ovaj tip flokulanata dodatno smanjuje vrednost Zeta potencijala prisutnih makromolekula čime se smanjuje potrebna količina ispitivanih koagulanataCuSO4 iAl(SO4)3. &nbsp, During production of full quality consumed white sugar from sugar beet, there is a problem of the presenceof macrom olecular compounds in sugar beet juice, which are harmful and we have to be removed.Separation ofthese compounds, which make around 60% oflotal non-sucrose compounds in sugar beetjuice,is done by the principle of sedimentation with different types of coagulants (mostly compounds with calciumion). However, affinity of calcium binding with undesirable macromolecules fiom sugar beet juice is notsignificant and in that way it is necessary a lot of quantities of this compound throughout daily production ofsugar.The aim of this doctoral thesis is to consider the application of alternative coagulants with divalent andtrivalent cations, especially the salt of aluminum and cooper, which cause the process of dischargeablemacromolecules in sugar beet juice.Optimal quantities of coagulants needing for the efficient coagulation of macromolecules compounds fromsugar beet juice were determined by means of measuring of electrokinetic potentials. It was investigated theinfluence of other process variables such as pH, concentration of macromolecules and the impact of speedmixing on the efficiency of sedimentation of macromolecules.Mechanism of discharge of macromolecules compounds as well as the model of double electric layersurrounding colloidal particles in sugar beetjuice are suggested for sugar beetjuice clarification.Two model solutions of pectin are investigated together with one model solution of protein. Theirconcentration correspond to concentration of these macromolecules in sugar beet juice. All investigatedsystems were treated by using both solutions of CuSO4 as well as Al2(SO4)3 and slutions of their mixtures indifferent proportion.It was proven for all three investigated samples that fewer quantities of Cu+2 ions compared to the values ofAl+3 ions are needed to reach zero Zeta potential. However, due to possible undesirable effects of CuSO4 onfood processing, Al2(SO4)3 is proposed instead of traditional coagulant CaO, not only because of lowerconsumptions of coagulants but owing to protection of the environment.The objective in the experiments with mixtures was to investigate enhancement of coagulated characteristicswith commonly used salt Al2(SO4)3 by adding small quantities of Cu+2 ions. It was proven that pure saltsshowed better-coagulated properties.Further investigation was focused to selection of the most appropriate type and optimal quantity of chosenflocculants. The highest efficiency of clarification of sugar beet juice was noticed by applying anionflocculants of concentration 3 mg/dm3. It was shown that this type of flocculants additionally decreased thevalue of Zeta potential of present macromolecules which further reduce required quantity of investigatedcoagulants CuSO4 and Al2(SO4)3.

U ovoj disertaciji proučavana je osmotskadehidratacija lista koprive u dva različitaosmotska rastvora: 1. vodenom rastvorusaharoze i natrijum hlorida i 2. melasi šećernerepe. Ispitivan je uticaj temperature procesa(20°C, 35°C i 50°C) i vremena imerzije (30, 60i 90 min) na gubitak vode, priraštaj suvematerije, sadržaj suve materije, vrednostiaktivnosti vode, mikrobiooške promene,promenu mineralnog sastava (Ca, Mg, Na, K,Fe, Cu, Zn, Mn, Co) i promenu antioksidativneaktivnosti, tokom osmotske dehidratacije lista koprive.Dokazano je da se povećanjem temperature iproduženjem vremena trajanja procesapospešuje prenos mase tj. migracija molekulavode iz tretiranog biljnog materijala u okolnirastvor, i prodiranje molekula rastvorenesupstance iz osmotskog rastvora u tretiranobiljno tkivo.Snižene aw vrednosti u svim ispitivanimuzorcima ukazuju na pozitivan uticaj osmotskedehidratacije na mikrobiološku stabilnosttretiranog lista koprive. Dobijeni rezultati supokazali značajno poboljšanje mineralnogsastava lista koprive, dehidriranih u melasišećerne repe, dok je kod uzoraka tretiranih urastvoru saharoze i natrijumhlorida uočenosmanjenje sadržaja ispitivanih mineralnihmaterija. Nasuprot rastvoru saharoze i natrijumhlorida koji je uticao na opadanje ukupneantioksidativnosti osmotski dehidriranihuzoraka, melasa šećerne repe, kao bogat izvorprirodnih antioksidanasa, doprinosi povećanjuantioksidativnosti i poboljšanju funkcionalnogkvaliteta dehidriranog produkta.Statističkom obradom rezultata, uočeno je dasu optimalni procesni parametri u pogleduefikasnosti procesa, kao i mikrobiološkog,nutritivnog i funkcionalnog kvaliteta osmotskidehidriranog lista koprive, vreme trajanjaprocesa od 60 min, na temperaturi od 50°C, umelasi šećerne repe kao osmotskom rastvoru., The osmotic dehydration of the nettle leaf intotwo different osmotic media was studied in thisdissertation: 1. Aqueous solution of sucrose andsodium 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, drymatter content, water activity, microbialchanges, mineral composition (Ca, Mg, Na, K,Fe, Cu, Zn, Mn, Co) and the change in the antioxidant activity during osmotic dehydrationof the nettle leaf were studied in thisinvestigation.It has been proved that the increase intemperature and the prolonging of process time,accelerate the mass transfer, i. e., the migrationof the water molecules from the treated plantmaterial to the surrounding osmotic solution,and also the penetration of the molecules fromthe osmotic solution into the treated plant tissue.The reduced aw values in all tested samplesindicate the positive effect of osmoticdehydration on the microbiological stability ofthe treated nettle leaf. The obtained resultsshowed a significant improvement in themineral composition of the nettle leafdehydrated in sugar beet molasses, while thedecrease in the mineral content was observed inthe samples treated with sucrose and sodiumchloride solution. Contrary to the sucrose andsodium chloride solution, which negativelyaffected the overall antioxidative effect ofosmotically dehydrated samples, sugar beetmolasses contributed to an increase inantioxidantity, being a rich source of naturalantioxidants, and it also improves the functionalquality of the dehydrated product.Statistical analysis of the obtained experimentalresults showed that optimal process parametersin terms of process efficiency, as well asmicrobiological, nutritive and functional qualityof the osmotically dehydrated leaf net, could bereached after 60 min of osmotic treatment, at atemperature of 50 °C, using sugar beet molassesas an osmotic solution.