Search Results

You are looking at 1 - 7 of 7 items for

  • Author: Agnieszka Ciurzyńska x
Clear All Modify Search
Open access

Agnieszka Ciurzyńska and Andrzej Lenart

Freeze-Drying - Application in Food Processing and Biotechnology - A Review

Freeze-drying is a method of removing water by sublimation of ice crystals from frozen material. Suitable parameters of process application allow us to obtain best quality products compared to products dried with traditional methods. Very good physical and chemical properties of food and biotechnological products make this method the best for drying exclusive products. On the domestic market there is a large selection of different types of freeze-dried products, and there is still increasing interest of consumers in these products. A high cost of the freeze-drying still limits the wide-scale application in the food industry. Equipment innovation and pretreatment of raw material can reduce the time and energy needed for this process.

Open access

Agnieszka Ciurzyńska and Andrzej Lenart

Abstract

The ability to create diverse structures and studies on the effect of the aerated structure on selected properties with the use of freeze-dried gels may provide knowledge about the properties of dried foods. Such gels can be a basis for obtaining innovative food products. For the gel preparation, 3 types of hydrocolloids were used: low-methoxyl pectin, a mixture of xanthan gum and locust-bean gum, and a mixture of xanthan gum and guar gum. Gels were aerated for 3 and 7 min, frozen at a temperature of −45°C 2 h−1, and freeze-dried at a temperature of 30°C. For the samples obtained, structure, porosity, shrinkage, rehydration, and colour were investigated. It was shown that the type of the hydrocolloid and aeration time influence the structure of freeze-dried gels, which determines such properties of samples as porosity, shrinkage, density, rehydration, and colour. The bigger pores of low-methoxyl pectin gels undergo rehydration in the highest degree. The delicate and aerated structure of gels with the mixture of xanthan gum and locust-bean gum was damaged during freeze-drying and shrinkage exhibited the highest value. Small pores of samples with the mixture of xanthan gum and guar gum were responsible for the lower rehydration properties, but the highest porosity value contributed to the highest lightness value.

Open access

Agnieszka Ciurzyńska, Andrzej Lenart and Joanna Karwosińska

Abstract

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.

Open access

Agnieszka Ciurzyńska, Joanna Cichowska, Hanna Kowalska, Kinga Czajkowska and Andrzej Lenart

Abstract

The aim of this work was to investigate the effects of osmotic dehydration conditions on the properties of osmotically pre-treated dried apples. The scope of research included analysing the most important mass exchange coefficients, i.e. water loss, solid gain, reduced water content and water activity, as well as colour changes of the obtained dried product. In the study, apples were osmotically dehydrated in one of two 60% solutions: sucrose or sucrose with an addition of chokeberry juice concentrate, for 30 and 120 min, in temperatures of 40 and 60°C. Ultrasound was also used during the first 30 min of the dehydration process. After osmotic pre-treatment, apples were subjected to innovative convective drying with the puffing effect, and to freeze-drying. Temperature and dehydration time increased the effectiveness of mass exchange during osmotic dehydration. The addition of chokeberry juice concentrate to standard sucrose solution and the use of ultrasound did not change the value of solid gain and reduced water content. Water activity of the dried apple tissue was not significantly changed after osmotic dehydration, while changes in colour were significant.

Open access

Agnieszka Ciurzyńska, Agata Pisarska, Ignacy Olsiński, Anna Maria Panfiluk, Magdalena Sylwia Ostap and Andrzej Lenart

Abstract

This paper seeks to explain the structural effect on selected properties of freeze-dried gels with different compositions and aeration times. Herein, sugars and citric acid were added to gels with low-methoxyl pectin, mixtures of xanthan gum and locust bean gum, as well as xanthan gum and guar gum, in order to obtain a strawberry model. Strawberry pulp was also added to hydrocolloids to develop an innovative strawberry product. All samples were aerated for 3 and 7 min, and freeze-dried. Composition changes were found to modify the structure of the examined samples and properties. Freeze-dried gels with low-methoxyl pectin seemed to reflect the best approach towards obtaining an innovative strawberry product with a tailored structure, as they had the best water absorbent capacity, and the most attractive and delicate structure. Samples with a mixture of hydrocolloids were more compact. Aeration time did not significantly affect the examined parameters, while the addition of sugar and citric acid increased them. The strawberry pulp experiment confirmed the strawberry model (with low-methoxyl pectin gels, and sugar and citric acid), which had the finest structure and the best rehydration properties.

Open access

Hanna Kowalska, Agata Marzec, Jolanta Kowalska, Agnieszka Ciurzyńska, Kinga Samborska, Michał Bialik and Andrzej Lenart

Abstract

The aim of the study was to determine the impact of osmotic pre-dehydration and drying of fruit on the rehydration properties of dried fruit. Herein, the effect of fruit juice, applied as a natural enriching substance was very important. In addition, the properties of dried fruits obtained through combined air-drying and subsequent microwave-vacuum drying with ‘puffing’ effect were similar to the freeze-dried fruits, but showed other rehydration properties. As raw material, frozen strawberry (Honeoye variety) and fresh apples (Idared variety) were used in the study. The apples and partially defrosted strawberries were prior dehydrated in solutions of sucrose and a mixture of sucrose with chokeberry juice concentrate at 50°C for 2 h. Next, the fruit samples were dried by one of two ways: air-drying (50°C, 5 h) and microwavevacuum drying for about 360 s; and freeze-drying (30°C, 63 Pa, 24 h). The rehydration was carried out in distilled water (20°C, 5 h). The osmotic pre-dehydration hindered fruit drying process. The impact of drying method became particularly evident while examining the kinetics of rehydration. During the rehydration of the pre-dehydrated dried fruit a slower hydration could be observed. Freeze-dried strawberries absorbed 2-3 times more water than those dried by the ‘puffing’ effect.

Open access

Agnieszka Łukiewska, Jan Świerczek, Mariusz Hasiak, Jacek Olszewski, Józef Zbroszczyk, Piotr Gębara and Wanda Ciurzyńska

Abstract

Mössbauer spectra and thermomagnetic curves for the Fe86− xMxZr7Nb2Cu1B4 (M = Co, Ni, CoCr, and Cr, x = 0 or 6) alloys in the as-quenched state and after the accumulative annealing in the temperature range 600–800 K for 10 min are investigated. The parent Fe86Zr7Nb2Cu1B4 amorphous alloy is paramagnetic at room temperature, and substitution of 6 at.% of Fe by Co, Ni, and CoCr changes the magnetic structure – the alloys become ferromagnetic, whereas replacing 6 at.% of Fe with Cr preserves the paramagnetic state. After the heat treatment at 600 K, the decrease of the average hyperfine field induction, as compared to the as-quenched state, is observed due to the invar effect. After this annealing, the Curie temperature for all investigated alloys decreases. The accumulative annealing up to 800 K leads to the partial crystallization; α-Fe or α-FeCo grains with diameters in the range of 12–30 nm in the residual amorphous matrix appear.