The influence of temperature on rehydration and sorption properties of freeze-dried strawberries

The aim of this work was to investigate the influence of heating shelf temperature on selected physical properties of freeze-dried strawberries. Frozen strawberries were freeze-dried at heating shelf temperature of 10, 30, 50 and 70°C for 24 hours. Rehydration, adsorption rate and sorption isotherms were determined for freeze-dried strawberries. With increase the temperature of heating shelves in the range 10-50°C, rehydration capacity was increased. After 30 minutes of the rehydration process there was a decrease in water content, which is probably connected with changes in structure. Sorption isotherms were included to II isotherms type and have a sigmoidal shape characteristic for most food products. For the mathematical description Peleg’s model was used. For freeze-dried strawberries obtained in the range from 10 to 50°C isotherms have the same courses. Increase of temperature to 70°C resulted in obtaining the lowest water content in the water activity range from 0.113 to 0.648. There is a statistically significant influence of temperature of heating shelf on water vapour sorption for freeze-dried strawberries. For fruit freeze-dried in 30°C there was the highest water vapour sorption rate

Ordering of [alpha]-FeCo phase in the nanocrystalline Fe83-xCoxNb3B13Cu1 (x = 6, 25 or 41.5) alloys

The microstructure and ordering of α-FeCo phase of the nanocrystalline Fe83−xCoxNb3B13Cu1 (x = 6, 25 or 41.5) alloys were investigated. We have stated that α-FeCo phase is atomically ordered in the Fe83−xCoxNb3B13Cu1 (x = 25 or 41.5) samples crystallized by the heat treatment in a furnace. However, after flash annealing (by current or laser) that phase is disordered. Moreover, we have found that Co concentration in the crystalline α-FeCo phase strongly depends on Co content in the as-quenched ribbons. The annealing conditions influence also the grain diameter of the crystalline phase. In the nanocrystalline alloys obtained by a flash annealing of the amorphous ribbons finer grains are present

Nanocrystallization studies of rapidly quenched Fe85.4-xCoxZr6.8-yNbyB6.8Cu1 (x=0 or 42.7, y=0 or 1) alloys

The microstructure of amorphous and nanocrystalline Fe42.7Co42.7Zr6.8−xNbxB6.8Cu1 (x = 0 or 1) alloys was investigated. We have stated that the nanocrystalline samples consist of the crystalline α-FeCo grains about 8 nm in diameter embedded in an amorphous matrix which is rich in cobalt. From Mössbauer spectroscopy studies we have found that the crystalline α-FeCo phase in the nanocrystalline samples obtained by the conventional annealing is atomically ordered. Moreover, the order degree depends on the annealing time. As for the samples partially crystallized during rapid quenching, the crystalline α-FeCo phase is atomically disordered

Differentiation of polyvalent bacteriophages specific to uropathogenic Proteus mirabilis strains based on the host range pattern and RFLP

Artykuł opublikowany pod nazwiskiem Piątkowska (Grzejdziak)Urinary tract infections (UTIs) caused by P. mirabilis are difficult to cure because of the increasing antimicrobial resistance of these bacteria. Phage therapy is proposed as an alternative infection treatment. The aim of this study was to isolate and differentiate uropathogenic P. mirabilis strain specific polyvalent bacteriophages producing polysaccharide depolymerases (PDs). 51 specific phages were obtained. The plaques of 29 bacteriophages were surrounded by halos, which indicated that they produced PDs. The host range analysis showed that, except phages 58B and 58C, the phage host range profiles differed from each other. Phages 35 and 45 infected all P. mirabilis strains tested. Another 10 phages lysed more than 90% of isolates. Among these phages, 65A, 70, 66 and 66A caused a complete lysis of the bacterial lawn formed by 62% to 78% of strains. Additionally, phages 39A and 70 probably produced PDs. The phages' DNA restriction fragment length polymorphism (RFLP) analysis demonstrated that genomes of 51 isolated phages represented 34 different restriction profiles. DNA of phage 58A seemed to be resistant to selected EcoRV endonuclease. The 33 RFLP-EcoRV profiles showed a Dice similarity index of 38.8%. 22 RFLP patterns were obtained from single phage isolates. The remaining 12 restriction profiles consisted of 2 to 4 viruses. The results obtained from phage characterization based on the pattern of phage host range in combination with the RFLP method enabled effective differentiation of the studied phages and selection of PD producing polyvalent phages for further study

Influence of osmotic dehydratation on colour of freeze-dried strawberries

Celem pracy było zbadanie wpływu odwadniania osmotycznego i substancji osmotyeznej na barwę liofilizowanych truskawek. Analizę wpływu odwadniania osmotycznego, substancji osmotyeznej i suszenia wykonano na podstawie, zmian współczynnika jasności (L*), współczynnika barwy czerwonej (a*) oraz wskaźnika nasycenia barwy (S/) i kąta tonu (H).The aim of this work was to investigate the effect of osmotic dehydration and osmotic solution on colour of freeze-dried strawberries. Analysis of the influence of osmotic dehydration, osmotic solution and drying was made on the basis of changes in lightness coefficient (L*), red colour coefficient (a*), saturation index (SI) and hue angle (H)

Magnetic Susceptibility Disaccommodation and Mössbauer Effect in Microcrystalline Fe-Si Ribbons

The magnetic susceptibility disaccommodation of the microcrystalline Fe-xSi (x=3, 5, 6.5, and 7.2 wt%) ribbons in the as-quenched state and after annealing at 1370 K for 1 h was investigated in the temperature range from 220 to 410 K. Simultaneously, the microstructure of those samples was studied using the Mössbauer spectroscopy. It is found that the isochronal disaccommodation curves may be decomposed into five elementary processes. Taking into account the results obtained from the Mössbauer spectra analysis, the relaxational process with activation energy equal to 0.84 eV may be considered as the Snoek relaxation. However, the relaxational processes of higher activation energy seem to be connected with jumps of C atoms in the vicinity of Fe atoms surrounded by 1, 2, 3, and 4 silicon atoms

The development of technological process of obtaining freeze-dried green tea®

Według licznych sondaży herbata jest jednym z najbardziej popularnych napojów na świecie. Na polskim rynku można ją spotkać w różnych formach, ale nie w formie liofilizowanego naparu, który ze względu na zalety procesu liofilizacji byłby nadal bogaty w cenne dla zdrowia składniki bioaktywne, które uległyby zniszczeniu w dużo większym stopniu przy zastosowaniu tradycyjnych metod suszenia, takich jak np. suszenie konwekcyjne, z wykorzystywaniem gorącego powietrza. Biorąc pod uwagę popularność liofilizowanej kawy i wygodę jej przyrządzania, bardzo prawdopodobne jest, że liofilizowana zielona herbata także zdobyłaby wielu zwolenników.Key words: green tea, freeze-drying, infusion. According to numerous polls, tea is one of the most popular beverage in the world. It can be found on the polish market in different forms, but not in the form of a freeze-dried infusion, which due to the benefits of freeze-drying process would still be rich in bioactive compounds valuable for human health, which would be destroyed in greater extent in the case of traditional drying methods such as for example convective drying, in which hot air is used. Given the popularity of freeze -dried coffee and convenience of its preparation it is highly probable, that freeze-dried green tea would also get many supporters

The influence of osmotic substance type on adsorption of steam by the lyophilizated strawberry

Jednym ze sposobów utrwalania żywności jest obniżenie zawartości wody poprzez suszenie sublimacyjne. Proces ten zapewnia usunięcie wody z żywności i prawie idealne zachowanie właściwości chemicznych, fizycznych i biologicznych naturalnego surowca. Liofilizowane owoce charakteryzują się kruchą i otwartą strukturą, dlatego istnieje potrzeba modyfikacji tego sposobu suszenia dla ograniczenia niekorzystnych zmian. Jednym ze sposobów wzmocnienia struktury suszonych owoców jest odwadnianie osmotyczne, polegające na usuwaniu wody z tkanki roślinnej przy jednoczesnym wnikaniu do jej wnętrza substancji rozpuszczalnych. Dla zoptymalizowania warunków suszenia i osiągnięcia najwyższej jakości i stabilności produktu końcowego bardzo ważne jest poznanie właściwości sorpcyjnych liofilizatu. Celem pracy było zbadanie wpływu rodzaju substancji osmotycznej na właściwości sorpcyjne liofilizowanych truskawek. Zamrożone truskawki odmiany Senga Sengana odwadniano w roztworach o aktywności wody około 0,9: 61,5% sacharozy, 67,5% syropu skrobiowego i 49,2% glukozy w temperaturze 30°C przez 3 godziny pod ciśnieniem atmosferycznym w warunkach dynamicznych. Odwodnione owoce zamrożono i liofilizowano w temperaturze półek grzejnych 30°C przez 24 godziny. Dla otrzymanych suszy wyznaczono krzywe adsorpcji i izotermy adsorpcji pary wodnej. Wykazano, że odwadnianie osmotyczne w roztworze sacharozy i syropu skrobiowego poprzedzające proces suszenia sublimacyjnego powoduje zmniejszenie stopnia adsorpcji pary wodnej o około 30% w stosunku do truskawek nieodwadnianych i odwadnianych w roztworze glukozy. Susze te charakteryzuje także obniżenie szybkości adsorpcji pary wodnej.One way of food stabilization is reduction of water content by freeze drying. This process ensures removal of water from food while keeping chemical, physical and biological properties of natural raw product almost unchanged. The lyophilizated fruit is characterized by fragile and opened structure, therefore this drying method needs modification in order to limit adverse changes. One way of strengthening the structure of fruit put to drying is osmotic dehydration, which involves water removal from plant tissue with simultaneous penetration of soluble substances inside the tissue. In order to optimize drying conditions and ensure the highest quality and stability of the final product, it is very important to discover the sorptive properties of the lyophilizer. The purpose of the work was testing the influence of the osmotic substance type on the sorptive properties of the lyophilizated strawberry. Frozen strawberries of Senga Sengana variety were dehydrated in solutions with water activity of approx. 0,9: 61.5% of sucrose, 67.5% of starch syrup and 49.2% of glucose at 30°C for a period of 3 hours at the atmospheric pressure under dynamic conditions. Dehydrated fruits were frozen and lyophilizated at a temperature of heating shelves of 30°C for 24 hours. For obtained dried material, adsorption curves and adsorption isotherms of steam were set. It was demonstrated that osmotic dehydration in sucrose and starch syrup solution preceding the sublimation drying process resulted in decreasing of the degree of steam adsorption by approx. 30% in relation to nondehydrated and dehydrated in glucose solution strawberries. These dried materials are also characterized by reduced rate of steam adsorption

The influence of osmotic dehydration on chemical composition of freeze-dried strawberries

Celem badań zaprezentowanych w artykule było zbadanie wpływu odwadniania osmotycznego na zawartość i aktywność wody oraz na zawartość cukrów w liofilizowanych truskawkach. Do badań użyto truskawek odmiany Senga Sengana, odwadnianych osmotycznie w roztworach sacharozy, glukozy i syropu skrobiowego, a następnie liofilizowanych. Truskawki zostały równomiernie wysycone cukrem, o czym świadczy tylko nieznaczne obniżenie zawartości cukrów ogółem, cukrów bezpośrednio redukujących i sacharozy w powierzchniowej warstwie liofilizowanych truskawek w stosunku do całego owocu. Odwadnianie osmotyczne w roztworze sacharozy i glukozy spowodowało niewielki wzrost zawartości wody w liofilizowanych truskawkach w stosunku do owoców nieodwadnianych.The aim of the research presented in this paper was to investigate the influence of osmotic dehydration on water content and water activity and sugar content of freeze - dried strawberries. Senga Sengana strawberries were osmotically dehydrated in sucrose, glucose solution and starch syrup and freeze-dried. Strawberries were uniformly saturated by sugars, what provide insignificant decrease in total sugar content, directly reduced sugars and sucrose in surface layer for freeze-dried strawberries in comparison to whole fruit. Osmotic dehydration in sucrose and glucose solution caused small increase in water content in freeze-dried strawberries in comparison to fruit without osmotic dehydration

Effect of Quantity of Low–Methoxyl Pectin on Physical Properties of Freeze–Dried Strawberry Jellies

The development of fruit-based products with a high proportion of fruit and good nutritional, sensory and functional properties may help to diversify market supply. These products ought to be attractive, especially to young people, easy to consume and have a reasonably long shelf life. Three recipes of freeze-dried strawberry jelly with low-methoxyl pectin (LMP) (2.0, 2.5, 3.5% LMP) with the use of strawberry pulp were obtained and physical properties were investigated to choose the sample with the best quality factors. The quantity of added low-methoxyl pectin influences the physical properties of freeze-dried strawberry jellies. The recipe with 2.5% addition of low-methoxyl pectin was chosen based on the results obtained. Despite the relatively high friability and low hardness, and higher shrinkage, it has a fast rate of rehydration. It is also characterised by high porosity and the parameters of the colour most similar to the raw material and low water content and activity