Očuvanje vitamina C, likopena i ugljenih hidrata u plodovima paradajza sušenim u tunelskom tipu sušara

The aim of this study was to find an optimal way of tomato drying in a tunnel type dryer, in order to achieve the lowest possible losses in nutritive value of dried tomato products. Domestic variety of tomato (SP-109) was used in this research. Drying was performed in three ways, applying five temperature regimes, as follows: cocurrent system (variant 1 at 70-80 oC; variant 2 at 90-75 oC), countercurrent system (variant 1 at 55-65 oC, variant 2 at 65-75 oC) and combined system (85-55 oC and 55-65 oC). In these systems, the kinetic of changes in nutritive value of tomato fruits was monitored by measuring the content of carbohydrates, lycopene and vitamin C. Different influences of temperature regimes on nutritive value of dried tomato were observed at the level of statistical difference (LSD 0.05; 0.01) in the researched systems. Cocurrent system was statistically significant for differences in temperature modes (variant 1 and variant 2). Monitoring of the tomato drying kinetics showed that, in all variants, period of constant drying rate lasted about 3.5 h and that the total drying was the fastest in parallel cocurrent flow of non-saturated hot air and material. The content of total carbohydrates in tomato was dependent on the temperature regime of the tested drying systems. The carbohydrate content obtained in tomato samples dried at lower temperatures was higher compared to the values observed in the samples dried at higher drying temperatures. Significant losses of vitamin C were determined in all drying systems. The lycopene content under all experimental conditions generally showed a tendency to decrease slightly. Comparing its content in dry and fresh tomato fruits, the loss ranged from 4.94% to 19.98% but did not reach the significant level as the occurrence remained below 95% of cases.Cilj ove studije bio je pronalaženje optimalnog načina sušenja paradajza u tunelskom tipu sušara kako bi se smanjili gubici vrednosti nutritijenata kod sušenog proizvoda paradajza. U ovom istraživanju korišćena je domaća sorta paradajza (SP-109). Istraživanje je izvedeno u tunelskom tipu sušara na tri načina u pet temperaturnih režima. Sušenje je izvedeno u sistemu paralelnog (varijanta 1 na 70-80 oC, varijanta 2 na 90-75 oC), suprotnosmernom (varijanta 1 na 55-65 oC, varijanta 2 na 65-75 oC) i kombinovanog sistema strujanja vazduha (85-55 oC i 55- 65 oC). U ovim sistemima sušenja praćena je kinetika promena nutritivnih vrednosti ploda paradajza: sadržaj ugljenih hidrata (%), likopena i askorbinske kiseline (vitamin C). Utvrđeni su različiti uticaji temperaturnih režima na nivou statističke razlike (LSD 0.05; 0.01) ispitivanih sistema za nutritivnu vrednost sušenog paradajza. Paralelni sistem je bio statistički značajan za razlike u varijanti temperature 1 i varijanti 2. Prateći kinetiku sušenja paradajza utvrđeno je da u svim varijantama period konstantnog sušenja traje oko 3,5 časa i da je za ukupno sušenje najbrži paralelni protok toplog vazduha i materijala. Sadržaj ugljenih hidrata u uzorcima paradajza koji su sušeni na nižim temperaturama bio je veći u poređenju sa sadržajem ugljenih hidrata koji je utvpđen u uzorcima osušenim na višim temperaturama sušenja. Na nižim temperaturama njihov sadržaj je bio veći nego kod viših temperatura sušenja. Značajni gubici vitamina C određeni su u svim sistemima sušenja. Vrednost likopena u svim eksperimentalnim uslovima sušenja pokazuje tendenciju blagog smanjenja. Poredeći sadržaj u suvim i svežim plodovima paradajza, gubitak je bio od 4,94% do 19,98%, ali ne na značajnom nivou

Preservation of vitamin C, lycopene and carbohydrate content in tomato dried in a tunnel type dryer

The aim of this study was to find an optimal way of tomato drying in a tunnel type dryer, in order to achieve the lowest possible losses in nutritive value of dried tomato products. Domestic variety of tomato (SP-109) was used in this research. Drying was performed in three ways, applying five temperature regimes, as follows: cocurrent system (variant 1 at 70-80 oC; variant 2 at 90-75 oC), countercurrent system (variant 1 at 55-65 oC, variant 2 at 65-75 oC) and combined system (85-55 oC and 55-65 oC). In these systems, the kinetic of changes in nutritive value of tomato fruits was monitored by measuring the content of carbohydrates, lycopene and vitamin C. Different influences of temperature regimes on nutritive value of dried tomato were observed at the level of statistical difference (LSD 0.05; 0.01) in the researched systems. Cocurrent system was statistically significant for differences in temperature modes (variant 1 and variant 2). Monitoring of the tomato drying kinetics showed that, in all variants, period of constant drying rate lasted about 3.5 h and that the total drying was the fastest in parallel cocurrent flow of non-saturated hot air and material. The content of total carbohydrates in tomato was dependent on the temperature regime of the tested drying systems. The carbohydrate content obtained in tomato samples dried at lower temperatures was higher compared to the values observed in the samples dried at higher drying temperatures. Significant losses of vitamin C were determined in all drying systems. The lycopene content under all experimental conditions generally showed a tendency to decrease slightly. Comparing its content in dry and fresh tomato fruits, the loss ranged from 4.94% to 19.98% but did not reach the significant level as the occurrence remained below 95% of cases

Material and heat transfer rate in the gas-lquid system

In this paper substance transfer rate in the multistage system was investigated. Substance transfer between liquid and gas phases in a distillation packed column with packing was examined. Substance and heat transfer rate were examined and substance transfer coefficients were determined. Efficiency of substance transfer were examined by height of transfer units and volumetric substance transfer coefficients. Based on derived mathematical model the total height of transfer units and individual height of transfer units for the liquid and gas phases were determined. The investigation was performed by computer simulation and experiments. Several correlation models for height of transfer units and substance transfer coefficients were studied

Effects of tomato processing on carotenoids antioxidant activity and stability during one-year storage

The degradation of carotenoids (lycopene and β-carotene) and total antioxidant activity was investigated after one- year storage of pasteurized tomato juice. Tomato juice, thermally treated for 7 min at 100°C, was subjected to one-year storage a) in the light at 20°C; b) in the dark at 20°C and c) in the dark at 4°C. β-Carotene had the fastest dynamics of degradation and was dissolved in the largest quantities, regardless of the storage conditions. For all investigated components the fastest decomposition was observed in the first two months, when the sample was stored in the light at 20°C. Lycopene was most stable in the sample stored in the dark at 40C. Partial regression coefficients for all researched traits proved a significant difference of ratio for storing in the light (20°C) compared to the variants stored in the dark at 20°C and 4°C, lycopene p=0.0041**, p=0.0304**; β-carotene, p=0.0009** and p=0.0183**; antioxidative activity p lt 0.0001** and p=0.009**

Modelling of the substance transfer in the gas-liquid system with chemical reaction

In this paper substance transfer phenomena in the multistage reactive system were investigated.Substance transfer between liquid and gas phases in a distillation packed column with reactionesterification was examined. Efficiency of substance transfer were examined by HTU-Height of transferunits and volumetric substance transfer coefficients. The esterification reaction of the ethanol andacetic acid was examined. Based on derived mathematical model the total height of transfer units andindividual height of transfer units for the liquid and gas phases were determined. The investigation wasperformed by computer simulation and experiments. Several correlation models for HTU/NTU andsubstance transfer coefficients were studied. The correlations for component transfer were derived inquaternary systems ethanol-ethyl acetate-acetic acid -water

A new kinetic model for the common juniper essenstial oil extraction by microwave hydrodistillation

The main objective of the present study was to model the kinetics of essential oil extraction from swelled ground juniper berries by classic hydrodistillation (HD) and microwave-assisted hydrodistillation (MAHD). A new phenomenological kinetic model was developed on the basis of the juniper essential oil extraction mechanism that assumed three mass transfer processes occurring simultaneously: washing, unhindered diffusion and hindered diffusion. The new model was compared to the existing kinetic models. Among the tested models, the new model had the smallest mean relative percentage deviation and the highest corrected Akaike information criterion value. In addition, that, the new model was verified for HD and MAHD of essential oils from some other plant materials. On the basis of the above-mentioned facts, the new model can be recommended for modeling the kinetics of essential oil extraction by both HD and MAHD.Peer-reviewed manuscript: [http://technorep.tmf.bg.ac.rs/handle/123456789/5031

Comparative Study of Batch and Fluidized Bed Bioreactors for Lipase-Catalyzed Ethyl Cinnamate Synthesis

Ethyl cinnamate, an ester known as flavor and fragrance compound, has been synthesized using two immobilized bioreactor systems, batch and fluidized bed bioreactors. The enzyme used for this synthesis is a commercial lipase B preparation, Novozyme 435. Initial kinetic studies were conducted in both employed bioreactor configurations, and kinetic constants were obtained. Several models were tried for fitting of experimental data, but the best fit, for both bioreactors, was obtained when the ping-pong bi-bi mechanism was used. Interestingly enough, ethanol inhibition occurred in batch bioreactor, but it did not exist in the fluidized bed bioreactor. Solid-liquid mass transfer coefficients were calculated for both bioreactors to determine whether mass transfer limitations existed in either of these systems. The calculation of Damkohler numbers and Thiele modulus confirmed that mass transfer limitations had no effect on the overall reaction in both bioreactors