This page has only limited features, please log in for full access.
Project Goal: We would like to announce that we have started the realization of a new project entitled “Research and Development of Ionic Bio Fluids”. The considered IoBioFluids are going to be agricultural biomass nanoparticles suspensions in ionic fluids as the base fluid. The most common biomass from Autonomous Province of Vojvodina would be taken into consideration: wheat straw, barley straw, corn cob, corn
Current Stage: running
This study aimed to determine the effects of osmotic dehydration on the kinetics of hot air drying of apricot halves under conditions that were similar to the industrial ones. The osmotic process was performed in a sucrose solution at 40 and 60 °C and concentrations of 50% and 65%. As expected increased temperatures and concentrations of the solution resulted in increased water loss, solid gain and shrinkage. The kinetics of osmotic dehydration were well described by the Peleg model. The effective diffusivity of water 5.50–7.387 × 10−9 m2/s and solute 8.315 × 10−10–1.113 × 10−9 m2/s was calculated for osmotic dehydration. Hot air drying was carried out at 40, 50, and 60 °C with air flow velocities of 1.0 m/s and 1.5 m/s. The drying time shortened with higher temperature and air velocity. The calculated effective diffusion of water was from 3.002 × 10−10 m2/s to 1.970 × 10−9 m2/s. The activation energy was sensitive to selected air temperatures, so greater air velocity resulted in greater activation energy: 46.379–51.514 kJ/mol, and with the osmotic pretreatment, it decreased to 35.216–46.469 kJ/mol. Osmotic dehydration reduced the effective diffusivity of water during the hot air drying process. It also resulted in smaller shrinkage of apricot halves in the hot air drying process.
Ivan Pavkov; Milivoj Radojčin; Zoran Stamenković; Krstan Kešelj; Urszula Tylewicz; Péter Sipos; Ondrej Ponjičan; Aleksandar Sedlar. Effects of Osmotic Dehydration on the Hot Air Drying of Apricot Halves: Drying Kinetics, Mass Transfer, and Shrinkage. Processes 2021, 9, 202 .
AMA StyleIvan Pavkov, Milivoj Radojčin, Zoran Stamenković, Krstan Kešelj, Urszula Tylewicz, Péter Sipos, Ondrej Ponjičan, Aleksandar Sedlar. Effects of Osmotic Dehydration on the Hot Air Drying of Apricot Halves: Drying Kinetics, Mass Transfer, and Shrinkage. Processes. 2021; 9 (2):202.
Chicago/Turabian StyleIvan Pavkov; Milivoj Radojčin; Zoran Stamenković; Krstan Kešelj; Urszula Tylewicz; Péter Sipos; Ondrej Ponjičan; Aleksandar Sedlar. 2021. "Effects of Osmotic Dehydration on the Hot Air Drying of Apricot Halves: Drying Kinetics, Mass Transfer, and Shrinkage." Processes 9, no. 2: 202.
Drying is one of the oldest methods for food preservation that removes the water from fruit and makes it available for consumption throughout the year. Dried fruits can be produced by small- and large-scale processors, which makes them a very popular food among consumers and food manufacturers. The most frequent uses of drying technology include osmotic dehydration, vacuum drying, freeze-drying and different combinations of other drying technologies. However, drying may provoke undesirable changes with respect to physiochemical, sensory, nutritional and microbiological quality. Drying process energy efficiency and the quality of dried fruits are crucial factors in fruit drying. Recently, innovative technologies such as ultrasound, pulsed electric field and high pressure may be used as a pretreatment or in combination with traditional drying technologies for process intensification. This could result in quality improvements of dried fruits and enhanced efficiency and capacity of the production process, with a positive impact on environmental and economic benefits.
Milivoj Radojčin; Ivan Pavkov; Danijela Bursać Kovačević; Predrag Putnik; Artur Wiktor; Zoran Stamenković; Krstan Kešelj; Attila Gere. Effect of Selected Drying Methods and Emerging Drying Intensification Technologies on the Quality of Dried Fruit: A Review. Processes 2021, 9, 132 .
AMA StyleMilivoj Radojčin, Ivan Pavkov, Danijela Bursać Kovačević, Predrag Putnik, Artur Wiktor, Zoran Stamenković, Krstan Kešelj, Attila Gere. Effect of Selected Drying Methods and Emerging Drying Intensification Technologies on the Quality of Dried Fruit: A Review. Processes. 2021; 9 (1):132.
Chicago/Turabian StyleMilivoj Radojčin; Ivan Pavkov; Danijela Bursać Kovačević; Predrag Putnik; Artur Wiktor; Zoran Stamenković; Krstan Kešelj; Attila Gere. 2021. "Effect of Selected Drying Methods and Emerging Drying Intensification Technologies on the Quality of Dried Fruit: A Review." Processes 9, no. 1: 132.
Serbia is one of the leading producers and exporters of raspberry in the world, and considering the short shelf life of raspberry, the processing, storage, and transport are some of the main issues to be addressed. A comparative experiment was conducted in order to find the suitable process parameters for convective drying that may be considered as the alternatives to freeze‐drying, which is a widely used preservation method for raspberry even though it is a costly and energy‐consuming method. Twelve convective drying regimens were applied with a combination of three influencing factors: air temperature (60°C, 70°C, and 80°C), air rate (0.5 and 1.5 m·s−1), and stage of raspberry (fresh and frozen). The final product, a dried raspberry, was assessed for chemical, physical, and mechanical properties and rehydration capacity. Deep ranking analysis by power eigenvectors (DRAPE) and sum of ranking differences (SRD) were used to uncover the differences and similarities between the applied drying methods. SRD showed that convective drying of fresh raspberries proved to be more similar to freeze‐dried raspberries than convective drying of frozen ones. Fresh samples dried at 60 °C air temperature and 1.5 m·s−1 air flow proved to be the most similar to the reference freeze‐drying method. This convective regimen gives samples with the lowest color change, shrinkage, and shape deformation. With the mechanical and chemical properties of these samples being observed, statistical Duncan's test show that there is no significant difference (P < .05) in terms of hardness, shear force resistance, total phenolic, and total flavonoid preservation, compared with freeze‐dried samples. DRAPE gave similar results, but it added the variable importance in ranking as well, and total phenol reduction was defined as the most important variable. These results can help practitioners to develop cheaper and simpler drying methods that would replace the freeze‐drying but keep the same quality of the dried products.
Zoran Stamenković; Milivoj Radojčin; Ivan Pavkov; Siniša Bikić; Ondrej Ponjičan; Rajko Bugarin; Sándor Kovács; Attila Gere. Ranking and multicriteria decision making in optimization of raspberry convective drying processes. Journal of Chemometrics 2020, 34, e3224 .
AMA StyleZoran Stamenković, Milivoj Radojčin, Ivan Pavkov, Siniša Bikić, Ondrej Ponjičan, Rajko Bugarin, Sándor Kovács, Attila Gere. Ranking and multicriteria decision making in optimization of raspberry convective drying processes. Journal of Chemometrics. 2020; 34 (4):e3224.
Chicago/Turabian StyleZoran Stamenković; Milivoj Radojčin; Ivan Pavkov; Siniša Bikić; Ondrej Ponjičan; Rajko Bugarin; Sándor Kovács; Attila Gere. 2020. "Ranking and multicriteria decision making in optimization of raspberry convective drying processes." Journal of Chemometrics 34, no. 4: e3224.
Raspberries are one of Serbia’s best-known and most widely exported fruits. Due to market fluctuation, producers are looking for ways to preserve this fresh product. Drying is a widely accepted method for preserving berries, as is the case with freeze-drying. Hence, the aim was to evaluate convective drying as an alternative to freeze-drying due to better accessibility, simplicity, and cost-effectiveness of Polana raspberries and compare it to a freeze-drying. Three factors were in experimental design: air temperature (60, 70, and 80 °C), air velocity (0,5 and 1,5 m · s−1), and state of a product (fresh and frozen). Success of drying was evaluated with several quality criteria: shrinkage (change of volume), color change, shape, content of L-ascorbic acid, total phenolic content, flavonoid content, anthocyanin content, and antioxidant activity. A considerable influence of convective drying on color changes was not observed, as ΔE was low for all samples. It was obvious that fresh raspberries had less physical changes than frozen ones. On average, convective drying reduced L–ascorbic acid content by 80.00–99.99%, but less than 60% for other biologically active compounds as compared to fresh raspberries. Convective dried Polana raspberry may be considered as a viable replacement for freeze-dried raspberries.
Zoran Stamenković; Ivan Pavkov; Milivoj Radojčin; Aleksandra Tepić Horecki; Krstan Kešelj; Danijela Bursać Kovačević; Predrag Putnik. Convective Drying of Fresh and Frozen Raspberries and Change of Their Physical and Nutritive Properties. Foods 2019, 8, 251 .
AMA StyleZoran Stamenković, Ivan Pavkov, Milivoj Radojčin, Aleksandra Tepić Horecki, Krstan Kešelj, Danijela Bursać Kovačević, Predrag Putnik. Convective Drying of Fresh and Frozen Raspberries and Change of Their Physical and Nutritive Properties. Foods. 2019; 8 (7):251.
Chicago/Turabian StyleZoran Stamenković; Ivan Pavkov; Milivoj Radojčin; Aleksandra Tepić Horecki; Krstan Kešelj; Danijela Bursać Kovačević; Predrag Putnik. 2019. "Convective Drying of Fresh and Frozen Raspberries and Change of Their Physical and Nutritive Properties." Foods 8, no. 7: 251.
Rolnice od sušene voćne kaše su proizvod koji se sve više može naći na tržištu. Sirovina za njihovu proizvodnju je voće koje ne odgovora tehnološkim procesima proizvodnje sušenog voća (zrelije voće). Postupak proizvodnje predstavlja konvektivno sušenje kaše od jagode nanesene na lesu sušare u sloju debljine do 5 mm. Prilikom pripreme voćne kaše i tokom konvektivnog sušenja dolazi do oksidacije voćnog tkiva. Kako bi se smanjio uticaj oksidacije u kašu se dodaju antioksidansi, poput L-askorbinske kiseline. Ispitan je uticaj temperature vazduha za sušenje (45°C i 65°C) i dodatak L - askorbinske kiseline (0,5% i 1,5%, od mase pripremljene kaše) na promenu boje krajnjeg poizvoda. Boja kaše od jagode merena je odmah nakon pripreme i nakon konvektivnog sušenja kaše, kolorimetrom Konika Minolta CR400. Najniža promena boje ΔE= 12,57, ostvarena je pri temperaturi vazduha za sušenje od 65°C i 1% dodatku L - askorbinske kiseline. Najviša promena boje ΔE = 14,66, ostvarena je pri temperaturi vazduha za sušenje od 45°C i dodatku askorbinske kiseline u vrednosti od 0,5%. Kontrolni uzorak konvektivno je osušen bez dodatka askorbinske kiseline. Ukupna promena boje kontrolnog uzorka osušenog vazduhom temperature 45°C je ΔE=22,95, odnosno ΔE=25,71 pri temperaturi vazduha od 65°C. Za aproksimaciju eksperimentalnih rezultata kinetkie konvektivnog susenja korišćeni su pet matematickih modela koji se mogu naci u referentnoj literaturi iz ove oblasti (Newton, Page, Modified Page, Henderson and Pabis and Logarithmic), proširenih bezdimenzionalnim koeficijentom koji predstavlja temperaturu vazduha za sušenje. Na osnovu vrednosti statističkih pokazatelja R, X2 i RMSE može se zaključiti da Prošireni Modifikovani Page model najbolje aproksimuje kinetiku konvektivnog sušenja kaše od kruške. jagoda; kinetika konvektivnog sušenja; matematičko modelovanje; promena boje; voćne rolnice
Zoran Stamenković; Ivan Pavkov; Milivoj Radojčin; Krstan Kešelj; Anita Vakula; Tihomir Novaković. Mathematical modeling of the kinetics of strawberry pulp convective drying and the effect of ascorbic acid on strawberry pulp color preservation. Journal on Processing and Energy in Agriculture 2019, 23, 170 -175.
AMA StyleZoran Stamenković, Ivan Pavkov, Milivoj Radojčin, Krstan Kešelj, Anita Vakula, Tihomir Novaković. Mathematical modeling of the kinetics of strawberry pulp convective drying and the effect of ascorbic acid on strawberry pulp color preservation. Journal on Processing and Energy in Agriculture. 2019; 23 (4):170-175.
Chicago/Turabian StyleZoran Stamenković; Ivan Pavkov; Milivoj Radojčin; Krstan Kešelj; Anita Vakula; Tihomir Novaković. 2019. "Mathematical modeling of the kinetics of strawberry pulp convective drying and the effect of ascorbic acid on strawberry pulp color preservation." Journal on Processing and Energy in Agriculture 23, no. 4: 170-175.
The hot air convective drying of blueberries (Vaccinium corymbosum) in a thin layer was performed using a laboratory-scale dryer. The experiments were carried out at drying air temperatures of 60, 70 and 80 o C, and drying air velocities of 0.5 and 1.5 m/s. At higher values of the drying air temperature and the drying air velocity, less time was required for the convective drying of blueberries, i.e. the drying time of blueberries decreased with increasing drying air temperatures and velocities. The experimental data obtained during the drying process were fitted to ten different mathematical models. The Midilli et al. model was found to be the most appropriate model for explaining the drying behavior of blueberries during convective drying. Effective moisture diffusion coefficients were calculated using the Fick's diffusion model, ranging from 9.66 x 10-12 m2 /s to 9.67 x 10-11 m2 /s. These values were found to increase proportionally with the increase in drying air temperatures and velocities. The lowest total color change and shrinkage of dried blueberries were recorded during freeze drying. A water activity less than 0.6 was measured at a blueberry moisture content of 0.235 kgw/kgd.m, a drying air temperature of 26 o C and a relative air humidity of 60 %.
Ivan Pavkov; Zoran Stamenković; Milivoj Radojčin; Kešelj Krstan; Siniša Bikić; Monika Lutovska; Ondrej Ponjičan. Air drying of blueberry fruits: Drying kinetics, mathematical modeling and physical properties. Journal on Processing and Energy in Agriculture 2019, 23, 151 -157.
AMA StyleIvan Pavkov, Zoran Stamenković, Milivoj Radojčin, Kešelj Krstan, Siniša Bikić, Monika Lutovska, Ondrej Ponjičan. Air drying of blueberry fruits: Drying kinetics, mathematical modeling and physical properties. Journal on Processing and Energy in Agriculture. 2019; 23 (4):151-157.
Chicago/Turabian StyleIvan Pavkov; Zoran Stamenković; Milivoj Radojčin; Kešelj Krstan; Siniša Bikić; Monika Lutovska; Ondrej Ponjičan. 2019. "Air drying of blueberry fruits: Drying kinetics, mathematical modeling and physical properties." Journal on Processing and Energy in Agriculture 23, no. 4: 151-157.
The purpose of this paper is to examine the effects of storage and treatment with sulfur dioxide of different concentration on the overall change in the color of dried apricots. Upon sulfurization of the prepared apricot samples, they were dried using the combined osmotic-convective drying technology, and subsequently kept either in a storage unit at t ≈ 25 o C or in a cooled environment at t ≈ 3 o C over a period of six months. The sample color was measured on the inside and the outside of the dried apricot fruits. Statistical analysis was performed using the Dependent Samples T-test so as to determine changes in the color of dried apricots after 3 and 6 months of storage. After six months of storage, the smallest color change of ∆E = 6.56 was measured in the apricot samples stored in a cooled environment. After six months, the greatest color change of ∆E = 49.38 was measured in the apricot samples stored at an air temperature of 25 o C.
Krstan Kešelj; Mirko Babić; Ivan Pavkov; Milivoj Radojčin; Zoran Stamenković; Dragana Tekić; Mladen Ivanišević. Effects of storage and sulfurization with sulfur dioxide of different concentration on changes in the color of dried apricots. Journal on Processing and Energy in Agriculture 2019, 23, 190 -194.
AMA StyleKrstan Kešelj, Mirko Babić, Ivan Pavkov, Milivoj Radojčin, Zoran Stamenković, Dragana Tekić, Mladen Ivanišević. Effects of storage and sulfurization with sulfur dioxide of different concentration on changes in the color of dried apricots. Journal on Processing and Energy in Agriculture. 2019; 23 (4):190-194.
Chicago/Turabian StyleKrstan Kešelj; Mirko Babić; Ivan Pavkov; Milivoj Radojčin; Zoran Stamenković; Dragana Tekić; Mladen Ivanišević. 2019. "Effects of storage and sulfurization with sulfur dioxide of different concentration on changes in the color of dried apricots." Journal on Processing and Energy in Agriculture 23, no. 4: 190-194.
U ovom radu definisan je postupak statističke verifikacije i validacije novogeneriranog modela izoterme sorpcije. Prikazan je osnovni pristup evaluacije uspeha modela za aproksimaciju eksperimentalnih sorpcionih podataka. Tačnost modela u okviru prihvatljivog opsega je osnova da bi se jedan model smatrao validnim za set eksperimentalnih uslova, potrebnih za njegovu namenu. Ispitivani su eksperimentalno dobijeni podaci sa izračunatim podacima. Korišćeno je nekoliko statističkih kriterijuma predloženih u naučnoj literaturi i više statističkih pokazatelja (koeficijent determinacije (R2), srednja kvadratna greška (RMSE) i srednja relativna devijacija (MRD), za kvantitativnu verifikaciju novogenerisanog modela izoterme sorpcije. Kvalitativna statistička analiza izvršena je proverom nekoliko statističkih pretpostavki u vezi sa rezidualima dobijenim iz regresione analize. Ovo je realizovano stvaranjem normalnog dijagrama quantile-quantile koji izražava normalnu raspodelu i Scatter plot dijagrama koji izražava slučajnu raspodelu ostataka. Validacija eksperimentalnih podataka izotermnih sorpcija kruške (određivanja na četiri temperature 15˚C, 30˚C, 45˚C i 60˚C, u opsegu aktivnosti vode od 0.110 do 0.920), aproksimirana novogeneriranim triparametarskim modelom izoterme sorpcije, poređena je sa rezultatima referentnog Andersonovog modela, poznatijeg u naučnoj literaturi pod imenom GAB (Guggenheim - Anderson - de Boer) model. Uspeh aproksimacije novoformiranog modela u odnosu na referentni model je potvrđen. verifikacija; validacija; model izoterme sorpcije
Monika Lutovska; Ivan Pavkov; Vladimir Mijakovski; Zoran Stamenković. A basic approach to the verification and validation of sorption isotherm models. Journal on Processing and Energy in Agriculture 2018, 22, 95 -100.
AMA StyleMonika Lutovska, Ivan Pavkov, Vladimir Mijakovski, Zoran Stamenković. A basic approach to the verification and validation of sorption isotherm models. Journal on Processing and Energy in Agriculture. 2018; 22 (2):95-100.
Chicago/Turabian StyleMonika Lutovska; Ivan Pavkov; Vladimir Mijakovski; Zoran Stamenković. 2018. "A basic approach to the verification and validation of sorption isotherm models." Journal on Processing and Energy in Agriculture 22, no. 2: 95-100.
Veljko Vukoje; Ivan Pavkov; Zoran Stamenković; Aleksandar Miljatović. Economic effects of dried blueberry production. Journal on Processing and Energy in Agriculture 2018, 22, 145 -149.
AMA StyleVeljko Vukoje, Ivan Pavkov, Zoran Stamenković, Aleksandar Miljatović. Economic effects of dried blueberry production. Journal on Processing and Energy in Agriculture. 2018; 22 (3):145-149.
Chicago/Turabian StyleVeljko Vukoje; Ivan Pavkov; Zoran Stamenković; Aleksandar Miljatović. 2018. "Economic effects of dried blueberry production." Journal on Processing and Energy in Agriculture 22, no. 3: 145-149.
Ivan Pavkov; Zoran Stamenković; Milivoj Radojčin; Kešelj Krstan; Vojislava Bursić; Sinisa Bikic; Vangelce Mitrevski. Osmotic and convective drying of strawberries: Effects of experimental parameters on the drying kinetics, color and rehidratation. Journal on Processing and Energy in Agriculture 2018, 22, 58 -64.
AMA StyleIvan Pavkov, Zoran Stamenković, Milivoj Radojčin, Kešelj Krstan, Vojislava Bursić, Sinisa Bikic, Vangelce Mitrevski. Osmotic and convective drying of strawberries: Effects of experimental parameters on the drying kinetics, color and rehidratation. Journal on Processing and Energy in Agriculture. 2018; 22 (2):58-64.
Chicago/Turabian StyleIvan Pavkov; Zoran Stamenković; Milivoj Radojčin; Kešelj Krstan; Vojislava Bursić; Sinisa Bikic; Vangelce Mitrevski. 2018. "Osmotic and convective drying of strawberries: Effects of experimental parameters on the drying kinetics, color and rehidratation." Journal on Processing and Energy in Agriculture 22, no. 2: 58-64.
U centrima za sušenje često se prebiranjem javlja određeni udeo voća koje je 'prezrelo' za ovakav vid prerade. Jedan od novijih metoda prerade prezrelih voćnih plodova jeste proizvodnja rolnica od sušene voćne kaše. U radu je predstavljen uticaj konvektivnog sušenja kaše od kruške proizvedene po organskim principima sorte 'Kiferov sejanac'. Ekperiment je izveden kao dvofaktorski sa dva nivoa faktora. Prvi faktor je temperatura vazduha za sušenje od 45°C i 65°C, pri brzini vazduha za sušenje od 1,5 m/s, a drugi faktor ekperimenta je dodatak askorbinske kiseline u kaši od kruške u količini od 1% i 2%, od mase pripremljene kaše. Cilj rada je da se ispita uticaj konvektivnog sušenja, na promenu boje, sadržaj vitamina C i da se definišu matematički modeli kinetike konvektivnog sušenja kaše od kruške. Najniža promena boje ostvarena je kod kaše sa dodatkom askorbinske kiseline u vrednosti 2% od mase kaše i temperaturi vazduha za sušenje od 45°C (ΔE= 23,981). Najviša promena boje ostvarena je pri temperaturi vazduha za sušenje od 65°C i dodatkom askorbinske kiseline u vrednosti od 1% (ΔE= 30,039). Zabeležena je razgradnja vitamina C u svim uzorcima. Kod kontrolnih uzoraka razgradnja vitamina C je ≈ 77-80%. Kod uzoraka sa dodatkom askorbinske kiseline razgradnja vitamina C prelazi preko 99%, kod svih uzoraka. Page model najbolje prikazuje konvektivno sušenje kaše od kruške pri temperaturi vazduha od 65°C. Koeficijent korelacije izonosi R= 0,998, vrednost of the reduced X2= 0,000262 i RMSE= 0,02. Konvektivno sušenje kaše od kruške, vazduhom temperature 45°C, najbolje prikazuje Logarithmic model. Koeficijent korelacije iznosi R= 0,999660, vrednost of the reduced is X2= 0,000066 i RMSE= 0,01. organska kruška; kinetika konvektivnog sušenja; matematički modeli; sadržaj vitamina C; promena boje; voćne rolnice
Zoran Stamenković; Ana Dolovac; Ivan Pavkov; Vojislava Bursić; Milivoj Radojčin; Mirko Babić; Krstan Kešelj. Convective drying of organic pear pulp in a thin stagnant layer. Journal on Processing and Energy in Agriculture 2018, 22, 153 -156.
AMA StyleZoran Stamenković, Ana Dolovac, Ivan Pavkov, Vojislava Bursić, Milivoj Radojčin, Mirko Babić, Krstan Kešelj. Convective drying of organic pear pulp in a thin stagnant layer. Journal on Processing and Energy in Agriculture. 2018; 22 (4):153-156.
Chicago/Turabian StyleZoran Stamenković; Ana Dolovac; Ivan Pavkov; Vojislava Bursić; Milivoj Radojčin; Mirko Babić; Krstan Kešelj. 2018. "Convective drying of organic pear pulp in a thin stagnant layer." Journal on Processing and Energy in Agriculture 22, no. 4: 153-156.
The aim of the paper is to evaluate the level of profitability of dried fruit production by combined technology (osmotic and convective). In the focus of the research is small capacity dryer - 500 kg of fresh fruit per day, which is used on agricultural holding. The costs of fresh fruit are the most important item in the structure of the price of all types of fruit (67.1% on average), followed by labor costs (14.0%) and packaging (6.8%), while the share of energy is very modest (2.74%). Comparative analysis shows that, individually, the most cost-effective is dried pears production. For 120 days of effective operation of the dryer, profit of 9,815 € is realized, with an acceptable degree of coefficient of economic efficiency (1.21). Investment in construction of drier (31,900 €) is paid in 2.74 years. It is a profitable business, which can be a good source of income for agricultural holdings. dried fruit; combined technology; cost-effectiveness; economy
Veljko Vukoje; Ivan Pavkov; Aleksandar Miljatović. Economic aspects of dried fruit production by combined technology. Ekonomika poljoprivrede 2018, 65, 1031 -1044.
AMA StyleVeljko Vukoje, Ivan Pavkov, Aleksandar Miljatović. Economic aspects of dried fruit production by combined technology. Ekonomika poljoprivrede. 2018; 65 (3):1031-1044.
Chicago/Turabian StyleVeljko Vukoje; Ivan Pavkov; Aleksandar Miljatović. 2018. "Economic aspects of dried fruit production by combined technology." Ekonomika poljoprivrede 65, no. 3: 1031-1044.
Sušenje maline obavlja se sušenjem zamrzavanjem (liofilizacija). Dobijeni proizvod je kvalitetan. Liofilizacija je skup process. U radu upoređena je potrošnja energije i dužina trajanja procesa pri sušenju 100 kg maline postupkom sublimacionog sušenja i konvektivnog sušenja. Konvektivno sušenje obavljeno je u labaratorijskoj sušari 'IVA-2' na Poljoprivrednom fakultetu u Novom Sadu. Za sušenje zamrzavanjem korišćen je labaratojiski liofilizator 2-4 LD plus, švajcarskog proizvođača Marthin Christ. Obavio se proračun potrošnje energije za oba oblika sušenja kao i njihovo poređenje. Prilikom proračuna potrošnje energije obratila se pažnja na sve potrošače uključene u process sušenja (direktno i indirektno). Obavio se proračun potrošnje energije za svaki postupak sušenja pojedinačno. Kod svakog procesa izdvojili su se glavni potrošači i izračunata je njihova potrošnja. Kod sublimacionog sušenja glavni potrošačai su bili su: komora za zamrzavanje, liofilizator i vakum pumpa. Kod postupka konvektivnog sušenja ti potrošači bili su aksijalni ventilator i grejna tela tj. toplotna energija potrebna za isparavnje vlage iz maline. Takođe je utvrđena i dužina trajanja procesa sušenja. Dobijeni rezultati sušenja oba slučaja upoređeni su jedni sa drugima. Rezultati su pokazali da je potrošnja energije za process sušenja zamrzavanjem veća od procesa sušenja konvektivnom metodom. Dužina sušenja zamrzavanjem duže traje od sušenja konvektivnim postupkom. potrošnja energije; sušenje zamrzavanjem; liofilizacija; konvektivno sušenje; malina
Krstan Keselj; Ivan Pavkov; Milivoj Radojcin; Zoran Stamenkovic. Comparison of energy consumption in the convective and freeze drying of raspberries. Journal on Processing and Energy in Agriculture 2017, 21, 192 -196.
AMA StyleKrstan Keselj, Ivan Pavkov, Milivoj Radojcin, Zoran Stamenkovic. Comparison of energy consumption in the convective and freeze drying of raspberries. Journal on Processing and Energy in Agriculture. 2017; 21 (4):192-196.
Chicago/Turabian StyleKrstan Keselj; Ivan Pavkov; Milivoj Radojcin; Zoran Stamenkovic. 2017. "Comparison of energy consumption in the convective and freeze drying of raspberries." Journal on Processing and Energy in Agriculture 21, no. 4: 192-196.
In this study, a thin - layer drying of pear slices as a function of drying conditions were examined. The experimental data set of thin - layer drying kinetics at five drying air temperatures 30, 40, 50, 60 and 70?C, and three drying air velocities 1, 1.5 and 2 m s-1 were obtained on the experimental setup, designed to imitate industrial convective dryer. Five well known thin - layer drying models from scientific literature were used to approximate the experimental data in terms of moisture ratio. In order to find which model gives the best results, numerical experiments were made. For each model and data set, the statistical performance index, (?), and chi-squared, (?2), value were calculated and models were ranked afterwards. The performed statistical analysis shows that the model of Midilli gives the best statistical results. Because the effect of drying air temperature and drying air velocity on the empirical parameters was not included in the base Midilli model, in this study the generalized form of this model was developed. With this model, the drying kinetic data of pear slices can be approximated with high accuracy. The effective moisture diffusivity was determined by using Fick?s second laws. The obtained values of the effective moisture diffusivity, (Deff), during drying ranged between 6.49 x 10-9 and 3.29 x 10-8 m2 s-1, while the values of activation energy (E0) varied between 28.15 to 30.51 kJ mol-1.
Monika Lutovska; Vangelce Mitrevski; Ivan Pavkov; Vladimir Mijakovski; Milivoj Radojcin. Mathematical modelling of thin layer drying of pear. Chemical Industry and Chemical Engineering Quarterly 2016, 22, 191 -199.
AMA StyleMonika Lutovska, Vangelce Mitrevski, Ivan Pavkov, Vladimir Mijakovski, Milivoj Radojcin. Mathematical modelling of thin layer drying of pear. Chemical Industry and Chemical Engineering Quarterly. 2016; 22 (2):191-199.
Chicago/Turabian StyleMonika Lutovska; Vangelce Mitrevski; Ivan Pavkov; Vladimir Mijakovski; Milivoj Radojcin. 2016. "Mathematical modelling of thin layer drying of pear." Chemical Industry and Chemical Engineering Quarterly 22, no. 2: 191-199.
This paper is focused on the mathematical model of the Air Torque Position dampers. The mathematical model establishes a link between the velocity of air in front of the damper, position of the damper blade and the moment acting on the blade caused by the air flow. This research aims to experimentally verify the mathematical model for the damper type with non-cascading blades. Four different types of dampers with non-cascading blades were considered: single blade dampers, dampers with two cross-blades, dampers with two parallel blades and dampers with two blades of which one is a fixed blade in the horizontal position. The case of a damper with a straight pipeline positioned in front of and behind the damper was taken in consideration. Calibration and verification of the mathematical model was conducted experimentally. The experiment was conducted on the laboratory facility for testing dampers used for regulation of the air flow rate in heating, ventilation and air conditioning systems. The design and setup of the laboratory facility, as well as construction, adjustment and calibration of the laboratory damper are presented in this paper. The mathematical model was calibrated by using one set of data, while the verification of the mathematical model was conducted by using the second set of data. The mathematical model was successfully validated and it can be used for accurate measurement of the air velocity on dampers with non-cascading blades under different operating conditions.
Ivan Pavkov; Dušan N. Uzelac; Maša Ž. Bukurov; Milivoj T. Radojčin; Ivan S. Pavkov. Experimental calibration of the mathematical model of Air Torque Position dampers with non-cascading blades. Thermal Science 2016, 20, 567 -578.
AMA StyleIvan Pavkov, Dušan N. Uzelac, Maša Ž. Bukurov, Milivoj T. Radojčin, Ivan S. Pavkov. Experimental calibration of the mathematical model of Air Torque Position dampers with non-cascading blades. Thermal Science. 2016; 20 (2):567-578.
Chicago/Turabian StyleIvan Pavkov; Dušan N. Uzelac; Maša Ž. Bukurov; Milivoj T. Radojčin; Ivan S. Pavkov. 2016. "Experimental calibration of the mathematical model of Air Torque Position dampers with non-cascading blades." Thermal Science 20, no. 2: 567-578.
Vangelce Mitrevski; Monika Lutovska; Ivan Pavkov; Vladimir Mijakovski; Filip Popovski. The Power Series as Water Sorption Isotherm Models. Journal of Food Process Engineering 2015, 39, 178 -185.
AMA StyleVangelce Mitrevski, Monika Lutovska, Ivan Pavkov, Vladimir Mijakovski, Filip Popovski. The Power Series as Water Sorption Isotherm Models. Journal of Food Process Engineering. 2015; 39 (2):178-185.
Chicago/Turabian StyleVangelce Mitrevski; Monika Lutovska; Ivan Pavkov; Vladimir Mijakovski; Filip Popovski. 2015. "The Power Series as Water Sorption Isotherm Models." Journal of Food Process Engineering 39, no. 2: 178-185.