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

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

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

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

Effect of Osmotic Pretreatment Combined with Vacuum Impregnation or High Pressure on the Water Diffusion Coefficients of Convection Drying: Case Study on Apples

The paper presents water diffusion coefficients as providing a significant contribution to the creation of a comprehensive database and knowledge of weight variation during the drying process of raw plant materials that is used for modelling the technological process and designing innovative products. Dehydration is one of the most widely used methods for improving the stability and durability of fruit and vegetables because it reduces water activity and microbial activity, and minimises the physical and chemical changes during storage. The considerable impact of pressure on heat exchange and weight during the convection drying process of osmotically pretreated apples is demonstrated. The course of the drying curves and the drying rate is determined by the use of pressures of 0.02 and 500 MPa. Varied pressure applied during osmotic impregnation significantly influences the value of the diffusion coefficient: the average determined for the entire course of the drying curve and the average determined in the intervals of the reduced water content. The lowest values of the average water diffusion coefficient are obtained for apples preboiled under overpressure conditions and, at the same time, the determined diffusion coefficients in the water content are characterised on the drying curve by a clearly decreasing course until the reduced water content reaches approximately 0.2

Próba wytworzenia folii jadalnych na bazie wysortu warzywnego®

The article presents the results of research on the method of recycling the vegetable outgrades of cauliflower, broccoli, yellow and green beans in the form of edible packaging films. The prepared vegetable purees after drying in the form of thin layers did not show a continuous structure, therefore an attempt was made to use dried apple pomace, also a waste material, as a film-forming agent. Studies have shown that they do not fulfill their function due to the low gelling efficiency and a film-forming solution of apple pectin was used, which showed very good gelling capacity in combination with vegetable purées. The tests concerned the determination of appropriate concentrations of the film-forming substance, preparation and addition of vegetables, and drying parameters. It was found that vegetable films with acceptable functional properties were obtained with the use of a film-forming solution based on apple pectin at a concentration of 2.5% in combination with vegetable purees in the ratio of 50:50 and drying at a temperature of 60˚C for 4 hours.W artykule przedstawiono wyniki badań dotyczących sposobu zagospodarowania wysortu warzywnego z kalafiora, brokułu, żółtej i zielonej fasolki szparagowej w postaci opakowań jadalnych. Przygotowane purée warzywne po wysuszeniu w postaci cienkich warstw nie wykazywało struktury ciągłej, dlatego podjęto próbę zastosowania suszonych wytłoków jabłkowych, materiału odpadowego, jako substancji żelującej. Badania wykazały, że badane puree warzywne nie spełniło swojej funkcji z uwagi na niską efektywność żelowania i zastosowano foliotwórczy roztwór pektyny jabłkowej, która wykazała bardzo dobre właściwości żelujące w połączeniu z purée warzywnym. Próby dotyczyły określenia odpowiednich stężeń substancji powłokotwórczej, przygotowania i dodatku warzyw oraz parametrów suszenia. Na podstawie przeprowadzonych badań stwierdzono, że folie warzywne o akceptowalnych właściwościach użytkowych otrzymano z zastosowaniem roztworu powłokotwórczego na bazie pektyny jabłkowej o stężeniu 2% w połączeniu z warzywami w stosunku 50:50 oraz suszeniu w temperaturze 60˚C przez 4 godziny

Innovative Freeze-Dried Snacks with Sodium Alginate and Fruit Pomace (Only Apple or Only Chokeberry) Obtained within the Framework of Sustainable Production

The aim of the work has been to develop freeze-dried fruit snacks in the form of bars with the use of by-products derived from fruit processing. In effect 14 product designs of fruit gels based on: apple pulp, apple juice, water, sodium alginate and only apple or only chokeberry pomace were prepared. The snacks were freeze-dried. The dry matter content, water activity, structure, colour, mechanical properties, as well as organoleptic evaluation were determined. Freeze-dried bares were obtained according to sustainability production which in this case was relied on application of fruit pomace. The freeze-drying process ensures the microbiological safety of the product without the need to use chemical preservatives. Freeze-dried samples obtained low water activity in the range of 0.099–0.159. The increase in pomace concentration (3–9%) boosted the dry matter content to above 98%, and decreased the brightness of the freeze-dried bars about 6 to 10 units. Mechanical properties varied depending on the product design. With the increase in the amount of pomace, the shear force increased at 23% to 41%. Based on the results, the best variant, that has the most delicate structure and the best organoleptic properties, has proven to contain 1% sodium alginate and 2% pomace

Sustainable Development in the Agri-Food Sector in Terms of the Carbon Footprint: A Review

The concept of sustainable development is increasingly important in the agri-food sector and global economy. International activities are undertaken to improve the efficiency of industry by reducing its negative impact on the environment. To help determine harmful human activity, the environmental footprints of products and services are calculated using the LCA (life cycle assessment) method. The purpose of this article was to explain topics of sustainable development and environmental footprints, especially the carbon footprint in the agri-food sector, based on the latest literature. The agri-food industry consumes around 30% of global energy demand. It is also a source of emissions of a significant part of greenhouse gases released into the environment. The carbon footprint of food products is determined by many factors associated with their production. Food of animal origin is more harmful and has higher carbon footprints than plant-based products. GHG emission reduction is possible due to the use of renewable energy sources and the abandonment of the use of artificial fertilizers and plant protection products

Whey Protein Isolate-Based Edible Coatings Incorporated with Jojoba Oil as a Novel Approach for Improving the Quality of Fresh-Cut Root Parsley during Refrigerated Storage

In this paper, the effect of whey-protein-isolate-based edible coatings with the addition of jojoba oil at concentrations of 1 and 2% on the qualitative characteristics of fresh-cut root parsley was evaluated. Changes in hardness, color parameters, and the contents of polyphenols and flavonoids over 28 days of refrigerated storage, as well as changes in structure, were examined. It was observed that fresh-cut parsley, uncoated and coated with a protein solution, was characterized by a decrease in hardness, from 59.32 and 59.88 to 50.98 and 48.33 N, respectively, while parsley coated with whey protein isolate with the addition of jojoba oil showed an increase in hardness during storage, from 56.28 to 66.23 N and from 52.17 to 60.49 for 1% and 2% of jojoba-oil-containing formulations, respectively. The L*, a*, and b* color parameters and hue angle mostly remained at similar levels, which indicate the maintenance of the desired color, but changes in the values were observed during storage. Parameter L* was between 79.56 and 85.33 in the control samples and between 72.54 and 84.19 in the coated samples. It was shown that the use of whey protein coatings and storage time had a positive impact on the contents of polyphenols and flavonoids in the fresh-cut parsley. The highest changes in polyphenols, from 3.13 to 9.82 mg GAE/g d.m., were observed for the samples coated with the formulation containing 1% of jojoba oil. The highest increase in flavonoid content, from 23.65 to 40.60 mg QE/g d.m., was observed for the samples coated with the film-forming solution with 2% of jojoba oil. Scanning electron microscopy showed a smaller number of pores in the vegetable tissue as a result of the coatings, and this was the most noticeable for the samples without the jojoba oil. Storage deteriorated the quality of the fresh-cut parsley surface, and the drying effect was visible. The use of protein coatings incorporated with jojoba oil modifies the quality characteristics of fresh-cut parsley, and this can find application in reducing the waste of minimally processed vegetables during storage