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

Efficacy of biocontrol agents and bactericides in control of pepper bacterial spot

Bacterial spot caused by Xanthomonas euvesicatoria is considered one of the most important diseases of pepper in Serbia. In order to control this disease, copper based compounds (copper hydroxide, copper oxychloride, copper hydroxide + mancozeb, copper oxychloride + mancozeb), antibiotics (streptomycin sulfate and kasugamycin), resistance inducer (acibenzolar-S-methyl), antagonistic bacteria Bacillus subtilis (strains QST 713 and AAac), bacteriophage (strain K Phi 1) and one commercial microbial fertilizer, were tested for efficacy and compared to untreated control. The experiments were carried out in a greenhouse and climatic chamber conditions. Plants were inoculated with X euvesicatoria strain KFB 13 (10(8) CFU mL(-1)) using hand-held sprayer. Results of three experiments showed that all treatments except microbiological fertilizer significantly reduced intensity of bacterial spot symptoms compared to the untreated control. The most efficient treatment was acibenzolar-S-methyl reducing disease severity 93-97%. There was no statistically significant difference in efficacy of this treatment and copper hydroxide, copper oxychloride, copper hydroxide + mancozeb, copper oxychloride + mancozeb, streptomycin sulfate, kasugamycin and antagonistic strain QST 713 treatments. Application of antagonistic strain AAac and bacteriophage K Phi 1 significantly reduced disease intensity but less than the first group of treatments. Bacteriophage K Phi 1 (78-85% rH) was more effective in the climatic chamber compared to the efficacy (38% rH) in the greenhouse experiments

PRIMENA ANTIBIOTIKA U ZAŠTITI BILJA – ZA I PROTIV

biljaka u vidu guste sadnje, korišćenja osetljivih podloga i novih, osetljivih sorti, doprinose češćoj i jačoj pojavi bolesti biljaka. U tom pogledu bakteriozna obolenja ne predstavljaju izuzetak. U uslovima pogodnim za razvoj i širenje bolesti, fitopatogene bakterije za kratko vreme mogu pričiniti ogromne štete. Ukrupnjavanje poseda i velike površine pod jednom biljnom vrstom, osim što stvaraju uslove za brzo širenje patogena, često smanjuju mogućnost i efekte primene preventivnih agrotehničkih, mehaničkih, fizičkih i bioloških mera zaštite. U takvoj situaciji proizvođači se uglavnom odlučuju za mere intervencije odnosno zaštitu hemijskim sredstvima. Jedan od načina kontrole bakterioznih oboljenja je primena preparata na bazi bakra. Međutim, ograničena primena tokom mirovanja ili do određene fenofaze razvoja biljaka, fitotoksičnost jona bakra usled niskih temperatura i pojava rezistentnosti fitopatogenih bakterija dovode u pitanje efikasnost bakarnih preparata. Stoga se u pojedinim državama za suzbijanje fitopatogenih bakterija koriste i antibiotici. To su proizvodi biološke sinteze aktinomiceta, bakterija i gljiva, ili hemijski sintetisane materije koji deluju inhibitorno na mikroorganizme. Ipak, upotrebu antibiotika u zaštiti bilja prate mnoge kontroverze, ali i zablude. Neke od osnovanih bojazni vezane za upotrebu antibiotika u zaštiti bilja su: razvoj rezistentnih sojeva bakterija, rizik od transfera gena rezistentnosti iz poljoprivredne sredine u humanu populaciju, uticaj na neciljane mikroorganizme i smanjenje genetičkog diverziteta, kao i pitanje ostataka antibiotika u biljnim proizvodima i posledice koje mogu nastati zbog toga. S druge strane, jedna od najvećih zabluda je da se antibiotici široko primenjuju u zaštiti bilja od bakterioznih obolenja. Iskustva iz SAD zapravo pokazuju da se antibiotici u zaštit bilja u najvećoj meri koriste u kontroli jednog obolenja: bakteriozne plamenjače jabučastih voćaka. Količina upotrebljenih antibiotika u zaštiti bilja u SAD su zanemarljivo male, svega 0,26%, dok se preostali deo upotrebi u uzgoju životinja. U našoj zemlji nije dozvoljena upotreba antibiotika u zaštiti bilja. Ipak, situacija na terenu ukazuje na njihovo nedozvoljeno korišćenje u pojedinim slučajevima. Dodatnu opasnost predstavlja aktivna materija koja se tom prilikom koristi, a to je streptomicin sulfat koji je zapravo registrovan za primenu u veterinarskoj medicini, a ne kao formulacija prilagođena zaštiti bilja. Takva praksa stvara uslove za ostvarenje navedenih bojazni, a takođe može ugroziti poverenje domaćih potrošača kao i plasman poljoprivrednih proizvoda na inostrano tržište. Pojedine evropske zemlje poput Austrije, Švajcarske i Nemačke regulisale su upotrebu antibiotika u zaštiti od bakteriozne plamenjače izdavanjem specijalnih dozvola od strane nadležnih institucija u godinama kada se proceni da postoji jak infekcioni pritisak i povoljni uslovi za razvoj bolesti. Možda je model strogo kontrolisane upotrebe onaj koji bi zadovoljio sve strane: proizvođače, potrošače i zakonodavca, a sve u cilju smanjenja neodgovorne upotrebe antibiotika u zaštiti bilja