The aim of the work was to study the feasibility of using aqueous extracts from rowanberry, blue-berried
honeysuckle, and chokeberry pomace for the formulation of fish gelatin films with antioxidant and antimicrobial
activity as well as improved mechanical and water barrier properties. The predominant phenolic components in
rowanberry and chokeberry extracts were hydroxycinnamates, and in blue-berried honeysuckle extract antho
Although the gelatin film itself showed antioxidative activity, addition of blue-berried honeysuckle
extract increased it 3-fold. Unlike the films containing 1.2 mL of extract, the films with increased extract volume
possessed strong antimicrobial properties against E. coli, P. fluorescens, S. aureus, L. innocua. Films plasticized
with glycerol at 15 and 17.5% did not increase the mechanical strength in the presence of all extracts tested, but
at 20%, a positive effect of each extract on mechanical strength was observed. None of the extracts affected the
water barrier properties of the films.
The aim of this work was to improve the mechanical and water barrier properties of composite ﬁlmsprepared from starch and clays, plasticized with glycerol at different concentrations. The effects ofhydrophilic Closite Naþand Nanomer PGV were compared with that exerted by organicallymodiﬁedmorehydrophobicNanoﬁl2 and NanoBent ZR-1. The antimicrobial activity of compositescontaining hydrophobic clays was also investigated. The hydrophilic Nanomer PGV atconcentrations of 5–10%increased the tensile strength (TS) of unplasticized composites, butstarch-Closite Naþcomposites were too brittle to measure their mechanical properties. Thehydrophobic clays did not improve the mechanical properties of the unplasticized composites. Inthe presence of glycerol at concentrations of 20–30%, TS of composites containing hydrophilic claysand even hydrophobic NanoBent ZR-1 increased in comparison to plasticized ﬁlmswithout clay.Noneof the claysimproved the waterbarrier propertiesof the unplasticized composites,while in theplasticized composites all the clays decreased the water vapor permeability to an extent dependenton the kind and concentration of clay and glycerol concentration. Starch-NanoBentZR-1 compositeshowed very high activity against gram-positive Staphylococcus aureus and Listeria innocua. Starch-Nanoﬁl2 composites were characterized by smaller activity. Neither composite showed anyantimicrobial activity, or their activity against gram-negative bacteria was low.
The aim of work was the improvement of the mechanical and water barrier properties of nanocomposites prepared from fish gelatin and nanoclays (5–15%), plasticized with glycerol at different concentrations. The effect of hydrophilic Cloisite Na1 and Nanomer®PGV was compared with that exerted by organically modified more hydrophobic Nanofil®2 and NanoBent ZR-1. Antimicrobial activity of nanocomposites containing hydrophobic nanoclays was also investigated. In a nanocomposite with 5% Cloisite Na1 and 15% glycerol, the Tensile strength (TS) was by 20% higher than that for plasticized films without nanoclay. The improvement of TS was also evidenced for plasticized nanocomposites containing 5% of hydrophobic NanoBent ZR-1 and Nanofil®2. Nanocomposites containing 5% of Cloisite Na1 with 15% glycerol, and these containing 5% Nanofil ®2 or NanoBent ZR-1 with 20% glycerol, showed 23% and about 15%, respectively, lower water vapor permeability than gelatin films. Gelatin-NanoBent ZR-1 nanocomposite caused complete inactivation of gram-positive bacteria S. aureus and L. innocua.
The antimicrobial properties of chitosan solutions and films against selected bacteria and the
effect of chitosan incorporation into gelatin films were studied. The bactericidal effect of chitosan solutions
increased with time and temperature of sample incubation. Two psychrotrophic strains Pseudomonas
fluorescens and Listeria innocua were more sensitive to chitosan than mesophilic strains Escherichia coli
and Staphylococcus aureus. The growth of bacteria under chitosan discs was inhibited. In the case of two
component gelatin-chitosan films strong antimicrobial effect was also observed.
Application of natural polymers to forming edible films for food applications has been reviewed. Due to the hydrophilic nature of proteins and polysaccharides, films prepared from these polymers are too susceptible to moisture. Modification of them with critically selected a suitable compounds can result in their improved functional properties and making them useful for food packaging.
Starch is a natural polymer which, due to its renewability, biodegrability, availability and a relatively low cost, has a high potential for applications in biodegradable materials. However, because of its hydrophilic nature, the number of commercially available starch-based products is still limited. Recently, starch-based nanocomposites with the addition of clay minerals as nanofillers have given rise to large-scale improvements in physical, mechanical, and barrier properties. In our studies, potato starch-clay nanocomposite films were prepared using a solution casting technique. The effect of different types of clays as nanofillers of the hydrophilic Cloisite® Na+ and Nanomer® PGV, or of hydrophobic NanoBent ZR-1 and Nanofil® 2, on the structure as well as thermal, mechanical and barrier to water vapor properties of the obtained films was determined. It was observed that the starch-Cloisite® Na+ nanocomposite showed an intercalation of starch in the silicate layers due to interactions of the hydroxyl groups of the polymer with the sodium ion of the clay or with its edge hydroxyl groups, which, however, did not improve neither thermal, mechanical nor water barrier properties of starch-Cloisite® Na+ nanocomposite films as compared to the unmodified starch film. The latter showed melting temperature (Tm) of 176°C, tensile strength (σ) of 30.2 MPa, elongation (ε) of 3.8%, and water vapor permeability (WVP) of 0.43 g•mm•kPa-1•h-1•m-2. It was found that the addition of 5% hydrophilic nanofillers, in contrast to those of hydrophobic nature, decreased the film melting temperature, while the addition of 10 and 15% of the nanofillers resulted in an increase of Tm.
Artykuł jest przeglądem literatury, dotyczącym wykorzystania polimerów naturalnych do wytwarzania jadalnych powłok powierzchniowych lub opakowań do żywności. Omówione zostały właściwości folii z różnych białek i polisacharydów oraz sposoby poprawy ich właściwości użytkowych poprzez modyfikacje fizyczne, chemiczne i enzymatyczne. Przedstawiono również możliwości włączania w matryce polimerową nanonapełniaczy i scharakteryzowano właściwości otrzymanych nanokompozytów polimerowych. Ponadto wskazano możliwości poszerzenia właściwości użytkowych folii z naturalnych polimerów poprzez wprowadzenie dodatkowych substancji, przede wszystkim o aktywności przeciwdrobnoustrojowej.
This work is focused on study of the mechanical and barrier properties of films obtained from potato starch modified with sodium tetrahydroxozincate generated in situ. The results show that the chemical modification of starch improved the water vapor permeability by about 25%, unfortunately decreased the elongation at break by 60%, when compared with unmodified starch films. However, placitization of films with glycerol at a concentration of 20% (of the starch mass) significantly improved the elongation.
Przedstawiono możliwości kompleksowego zagospodarowania odpodów przemysłu rybnego.
In this paper production of a cold-active esterase EstA from the Antarctic bacterium Pseudoalteromonas sp. 643A in E. coli expression system was described. The purification and biochemical characteristic of EstA were performed in the presence of urea and then compared with results obtained for the esterase with no addition of urea and isolated from the native source. In both cases the cold-active enzyme displayed similar properties. However, the differences concerned the thermal activity were observed. The optimal temperature for recombinant esterase in the presence of urea (1M) was about 15°C lower in comparison with enzyme isolated from the native source. Furthermore, the EstA was found to be more thermolabile in denaturant conditions. The differences were presumably caused by slightly changed protein structure in the presence of urea. The preservation of activity of EstA dissolved in buffer containing 8M urea suggests that the protein structure is retained and it does not undergo dramatic changes due to high urea concentration. This thesis was confirmed with the FT-IR data.