Search

Due to its nutritional and nutraceutical qualities, wild garlic (Allium ursinum L.) has great potential for use in the food and pharmaceutical industries. The availability of this plant is limited to the spring season, and it is perishable immediately after harvest. Osmotic dehydration (OD) is verified as an effective pre-treatment to improve sustainability by reducing the water content of raw material with minimal negative effect on its nutritive and sensorial qualities. In this study, OD of wild garlic leaves in aqueous solution of sucrose and salt was analysed at three temperatures and after diverse immersion times. The effects of the processing time and temperature on the dry matter content, water loss, and solid gain were evaluated using response surface methodology and analysis of variance. Some components in the samples were determined before and after OD. The results showed that during OD, the dry matter content of wild garlic increased from 7.91 ± 1.08% to 51.51 ± 1.34%. The maximum achieved values for water loss (0.6189 ± 0.0146 g/g i.s.) and solid gain (0.2417 ± 0.0146 g/g i.s.) indicated a good dehydration level. In the osmotically dehydrated wild garlic, the amount of analysed minerals decreased, sodium and sugar increased, and the content of protein, cellulose, and fat did not change – compared to the fresh sample.

The highest-quality peaches [Prunus persica (L.) Batsch] are cultivated in areas with sunny summers, therefore the territory of the Autonomous Province of Vojvodina is a favourable region for their production. Peaches are usually consumed fresh, canned, or dried and represent a great source of the essential nutrients. Osmotic dehydration is a well-known preservation method that relies on mild temperatures and requires low energy. Research conducted at the Faculty of Technology Novi Sad has introduced sugar beet molasses as an efficient osmotic solution for drying various food samples. In this research, peach samples were osmotically treated in sugar beet molasses, and the goal was to investigate the impact of different solution concentrations, temperatures, and immersion time on the mass transfer rate and the efficiency of treatment. The results have shown that the mass transfer rate during the osmotic treatment of peach samples in sugar beet molasses was the most intensive at the beginning of the process, at the highest solution concertation, and at the highest temperature. In accordance with the results, diffusion occurred most rapidly during the first three hours of the process; therefore, processing time can be reduced.

Copyright of Kemija u Industriji is the property of Croatian Society of Chemical Engineers and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In order to deal with invasive crayfish (Faxonius limosus) impact on the native crayfish, as well as fish biodiversity in the Danube River, a possible solution would be to find and adopt mechanisms for its utilization for novel valuable product production. Apart from utilizing edible parts for novel food products, the shell waste can also be considered a source of valuable compounds. The complex structure of the shell mainly consists of three basic compounds: chitin, protein and minerals-mainly calcium carbonate. In this study, shell waste proteins were extracted using three extraction methods. The first method involved using naturally present enzymes (proteases and lipases) in crayfish wastes to recover proteins through an autolysis process. To accelerate the process, UV radiation was used. The remaining two extraction methods were alkaline extraction of proteins, wherein one method alkaline extraction was applied directly to the shell waste, and the other method, alkaline extraction followed an acidic demineralization step of the shell waste. The obtained protein concentrates were analysed for yield, crude protein content, DPPH radical scavenging ability, amino acid content, and structure. The results have shown that a similar percentage of protein content was obtained by all three methods: 67.20-68.03 %, but the extraction yield was considerably different. Alkaline deproteinization with or without the step of demineralization resulted in a 9.20-10.98 % yield, while UV radiation accelerated autolysis resulted in only a 3.41 % yield. Although protein extraction without using exogenous enzymes or chemicals is a very interesting approach, a drawback of this approach is the low process yield. FTIR spectroscopy revealed a secondary structure that was similar in all three concentrates, according to peak deconvolution, with the autolytic concentrate differing to a lesser extent, showing a slightly higher share of b-sheet structures. The DPPH assay revealed high antioxidant activity of the concentrates (72.00-88.06 %), probably originating from active peptides derived from proteins and residual carotenoids, mainly astaxanthin.

The global demand for proteins is constantly increasing, resulting in the need for science and industry to explore novel raw materials for protein extraction. Plum oil cake, obtained after plum oil cold pressing, has great potential as a nutritious, low-cost material. The high protein content (up to 50%) of this by-product is ideal for valuable protein-rich ingredients extraction. Protein isolates from plum oil cake (PPI) were prepared using different drying methodsthermal drying (PPIT) and freeze-drying (PPIF). Obtained isolates were compared in terms of their antioxidative properties and techno-functional properties. Protein content and process yield were also examined, resulting in high protein content (over 96%) with no influence of the drying method. The light colour of PPIF would be more appealing to consumers and more suitable for incorporation into food systems. The functional properties of the protein isolates were not significantly affected by different drying methods except for protein solubility. Both PIs exhibited minimum protein solubility at pH 5.0 and maximum solubility at pH 10.0, while PPIF was much more soluble than PPIT. The freeze-drying method led to a much higher antioxidant activity of PPIF. Overall, protein isolates from plum cake obtained from different processing methods differed in appearance, solubility and antioxidant capacity, but yield, protein content and other functional properties were similar. This information will be useful in optimising the production of this protein isolate and benefitting its applications.

The aim of this work was the activation of biopolymer material based on wild flax cake (Camelina Sativa) with eucalyptus and rosemary essential oils added in different concentrations (0.5%, 1% and 2%). The wild flax cake, left over after the cold pressing of the oil, was used to obtain biopolymer films. To obtain active packaging, essential oils were added to this biopolymer material and the influence of the addition of essential oils on the physico-chemical, mechanical, barrier and biological properties of biopolymer films based on wild flax cake was examined. The obtained results showed the most significant influence on water vapor permeability. The control sample had a water vapor permeability value of 5.43 g/m 2 h, while in the sample with 2% added eucalyptus essential oil, this value was 3.14 g/m 2 h. Antioxidant activity was also confirmed in the control sample without added essential oils (60.10%), but with the addition of 2% eucalyptus essential oil, this value increased to 78.54%. Eucalyptus essential oil proved to be more effective than rosemary oil on the investigated properties of the films. The addition of essential oils to biopolymer films broadens the spectrum of functional properties, including the improvement of mechanical, barrier and biological properties.

The paper presents the analysis of the three-dimensional polymer network distribution inside the polymer-stabilized ferroelectric liquid-crystal layer based on the laser scanning fluorescence confocal microscopy and a fluorescent dye tagging of the polymer. The studies of polymer-stabilized ferroelectric liquid-crystal structures described in this paper are focused on the comparison of the influence of polymer network in case that the polymerization is initiated in the chevron as well as in the quasibookshelf liquid-crystal molecular orientation. In the case of the chevron structure the regular distribution of the polymer network within the layer leads to the monostability of the chevron state. On the other hand the specific distribution of the polymer in the polymer-stabilized quasibookshelf stripe textures leads to the perfect bistability, improved multiplex driving, and analog gray scale capability. [ABSTRACT FROM AUTHOR]

This study aimed at investigating the synthesis of biopolymer films based on the Camelina sativa cake, an agricultural waste which remains after cold pressing of the oil from seed. During the film synthesis, three different granulations of the camelina cake were used: the whole cake, fractions with a size of 180-250 µm and fractions smaller than 180 µm. Half of the samples were pre-treated with an ultrasonic bath in order to examine the influence of the native mucilage from the cake on the properties of the obtained films. The biopolymer film samples were tested for mechanical, barrier, physicochemical and structural properties. The obtained films were dark, firm and flexible. Application of mucilage removal pre-treatment contributed to lower tensile strength and higher elongation at break. Significantly lower water vapour permeability was recorded in the samples not pre-treated regarding mucilage removal. A foil with optimal physicochemical characteristics was produced using oilcake with a particle size less than 180 µm, regardless of the pre-treatment application. There were no structural differences or differences in thermal behaviour among the tested samples. Statistical analysis (Z-Score analysis) showed the sample CSoC˂180,wo was optimal due to good mechanical, barrier and physicochemical properties.

In this paper, zein-based films with the addition of shellac were synthesized by lamination on the existing dry zein film (L samples) and by adding shellac alcohol solution during the synthesis of zein film in a ratio of 50-50 by casting process (M samples). Zein films without the addition of shellac were designated as control samples. Physico-chemical (thickness, moisture content and solubility), mechanical (tensile strength and elongation at break) and barrier characteristics (water vapor permeability) were examined for all samples. The resulting films were transparent, glossy, light yellow (control) to ocher (samples with shellac), flexible, and non-sticky. The results showed significantly higher values of elongation at the break of the samples with shellac (11.49% for M and 18.99% for L) compared to the control (7.14%). Significantly lower water vapor permeability values were found, 10.04 g/(m²ꞏh) for L, and 18.41 g/(m²ꞏ h) for M, compared to the control pure zein film (40.33 g/(m² ꞏh)).

Among many important requirements for packaging materials, environmental friendliness is a property that has become necessary for any material that needs to be competitive in the market. Life Cycle Analysis (LCA) is an analytical instrument that provides a framework for analyzing the impact of products and services on the environment, i.e. provides an understanding and the possibility of comparing different products. LCA studies the use of resources and the consequent emissions of pollutants on the environment during the entire life of a product from raw materials exploitation, through production, use and treatment at the end of the life cycle - recycling and final disposal. This paper will provide an overview of the LCA results of various commercial polymer packaging materials, as well as the results of LCAs of biopolymer materials. Although LCA faces the problem of data heterogeneity, since some studies focused on individual segments of the analysis, while some related to all aspects of the process, as well with the problem of interpreting heterogeneous results, because the output parameters were arbitrarily selected by the researcher, still it could be concluded that the available LCA studies and environmental assessments support further development of biobased polymers. When comparing biopolymer materials with commercial synthetic polymers, they have advantages - lower consumption of fossil fuels and lower emission rate of greenhouse gases from the whole life cycle.

The main aim of this research was to apply biopolymer coatings on osmotically dehydrated mushrooms and monitor their quality during storage. Mushrooms were osmotically dehydrated in sugar beet molasses (80% dry matter) under optimized conditions (45 °C for 5 hours), as previously reported elsewhere. Two different biopolymers were chosen: chitosan, a polysaccharide polymer, and zein, a protein polymer. A non-treated mushroom sample was chosen as a control sample. The mushroom samples were analysed for sugar and protein content, as well as water loss and microbiological profile. An increase in sugar content was the most noticeable in the osmotically dehydrated mushrooms compared to the control sample due to the use of molasses as a hypertonic solution. The contribution of used biopolymer coatings to the sugar and protein content of the coated and osmotically treated mushrooms was negligible. Chitosan coating contributed to better storage stability of treated mushrooms by lowering the moisture loss and microbial count. For this reason, chitosan treated sample was chosen for further examination related to the evaluation of its baking potential as a filling in a traditional stuffed pie-like layered bakery product - burek. Burek was stuffed with fresh mushrooms, osmotically treated mushrooms or osmotically treated mushrooms coated with chitosan. The sensorial assessment proved that control burek and burek samples with osmotically dehydrated mushrooms coated with chitosan were the most preferred groups based on odour and overall impression.

Lipid oxidation is a major cause of off-flavors and the loss of nutrients in fat-containing foods and oils. The prevention or retardation of those deteriorative reactions of oil during processing and storage is required. Commercially available synthetic packaging materials are causing serious environmental problems due to their non-degradability. To reduce environmental impacts associated with synthetic plastics, biopolymer materials have a great potential to be used instead. Further, biopolymers play an important role in food preservation because of their antioxidant and antimicrobial activities. The packing system is comprised of natural active materials that can improve the shelf life of oil-packed, minimize oxidation and improve mechanical, barrier and biological properties of biopolymer films. This paper aims to review currently available literature in the field of biopolymer materials application for packaging different types of edible oils.

There are many biodegradable and recyclable packaging materials available, alternatives for plastics: paper and cardboard; biodegradable polyethene (degradable due to additives incorporated during production, whose role is to lead to the polyethylene breakdown into CO2, H2O, biomass and minerals when in landfill) and biodegradable plastic (made from renewable biomass-biopolymers in a relatively energy-efficient process). The decomposition routes of degradable materials are reflected in the degradation for which realization a physico-chemical stimulus is required and biodegradation for which microorganisms are responsible. The global biodegradable plastic market was valued at $1.6 billion in 2019 and it is expected to reach $4.2 billion by 2027. The largest segment by application of biodegradable materials is in packaging with a market share of more than 60%. Some examples of degradable packaging existing on the market will be presented in the paper.

Biopolymer-based materials present good alternatives for synthetic materials. However, their high water sensitivity may limit their usage for food products packaging. Addition of hydrophobic components into the material formulation could improve this property. In this work 3, 4 and 5 % (v/v) of Satureja montana or Ocimum basilicum essential oil was incorporated into biopolymer films based on pumpkin oil cake. The obtained materials were analyzed regarding mechanical, physicochemical, barrier and structural properties. Incorporation of the essential oils increased the thickness of the pumpkin oil cake film. Significant reductions in moisture sensitivity, related to physicochemical properties and water vapor transmission rate (almost for 30 %), were observed (p < 0.05). Improvement of light barrier properties was also observed so that the visible light transmission was decreased for around 50 % while the UV light transmission was lower than 1 %. The obtained FTIR spectra confirmed the presence of added essential oils in pumpkin oil cake films, as well as their influence on the reduction in the film surface hydrophilicity. However, mechanical properties, tensile strength and elongation at break, decreased significantly (p < 0.05). These results suggest that incorporation of Satureja montana or Ocimum basilicum essential oil improved barrier properties of pumpkin oil cake-based films and reduced the film affinity toward water.

Mushrooms (Agaricus bisphorus) were osmotically dehydrated in sugar beet molasses solutions at concentrations of 60%, 70% and 80%d.m., at operating temperatures of 25 °C, 35 °C and 45 °C during 0.5h, 1h, 1.5h, 2h, 3h, and 5 hours. Moisture content, water activity (aw), microbiological parameters (total plate counts, Enterobacteriaceae, total yeasts and moulds count) and content of mineral elements (potassium, magnesium, iron and calcium) were determined in the osmodehydrated mushroom samples. Response surface methodology and analysis of variance were selected to estimate the main effects of the process variables (temperature, time, concentration) on process performance and selected mushroom attributes (microbiological counts, chemical composition and mineral content). Increase in the values of applied osmotic process parameters led to the significant increase in the content of minerals (for example, an increase in K and Ca content by 269.42% and 939.03%, respectively) and a decrease in aw values (from 0.941 to 0.811), decrease in microbiological load and relative protein content (decrease by 33.07%), indicating a possibility for prolonged shelf life and suitability for further processing. The osmodehydrated mushrooms could be considered as ingredients for new functional (semi)products due to improved nutritive profile.

This paper examines the effect of starch coating and the osmotic dehydration in sugar beet molasses on the microbiological stability of apples. One-half of the osmotically treated/untreated apples were protected by starch coating, resulting in four sample groups (namely the K, P, OD and OD+P sample groups). E. coli, Salmonella spp. and Listeria monocytogenes were not detected in any of the samples. Enterobacteria were present in the K and P samples in the first four days (indicating a downward trend), but were not subsequently detectable. The total number of microorganisms (TVC) was found to be uniform in each sample group. However, the TVC values were significantly higher in the K and P sample groups than those of the OD and OD + P samples. Yeasts and molds were detected in the K and P samples, whereas the presence of yeasts and molds in the OD and OD+P samples was confirmed only after four days of storage. The results obtained indicate that osmotic dehydration is a suitable method for maintaining microbial stability, whereas starch coating did not justify its purpose.

Interest in maintaining food quality while reducing packaging waste has encouraged the exploration of the edible films. The present study investigates different composition and thickness effect of edible films of corn starch-based edible films on structural, barrier and mechanical properties. Films were obtained from solutions containing gelatinized starch, polyol, guar-xantan gum modified mixture and water by casting it on a Petri dish and evaporating water at room temperature for 72h. Sorbitol was used in three different concentrations (counted on dry starch basis) as polyol because it is compatible with starch improving film flexibility, facilitating its handling and preventing cracks. Two sample groups were obtained: 100 μm and 200 μm thick films. Within every group there were three additional subgroups regarding three different sorbitol concentrations used, which means that six film samples were obtained. Physical, mechanical, structural and barrier properties are determined: thickness, tensile strength and elongation at break, film structure (FT-IR) and water vapour and gas permeability. Films proved to be strong, moderately flexible with good barrier properties to oxygen and water vapour. Film thickness proved to be directly related to all tested film properties. The incorporation of plasticizers resulted in more flexible and manageable films. Mechanical strength of films depends on plasticizer addition resulting in increased tensile strength and elongation at break. Gas permeability decreases while water vapour permeability increases as plasticizer content of the film increases. [ABSTRACT FROM AUTHOR]

Packaging is inseparable retainer of almost all food products. However, most of produced packaging ends as packaging waste after consumption of the product. Increasing amounts of packaging waste that should be managed represents serious challenge of every modern society. There are many different approaches to address this subject, amongst which biodegradable, natural biopolymer-based or even edible packaging holds considerable potential. In this paper, a by-product of edible oil industry, left after completed extraction by cold pressing of oil from hulls of pumpkin seeds, was used to produce biopolymer packaging films. Pumpkin oil cake was used to produce composite bio-based films. Different filtration of film forming suspension was applied in order to test composite film production using different filtration fractions, leading to higher process yield and minimizing waste. In addition, films were casted on surface, about ten times larger comparing to the cast surface typically reported for these types of films in the literature, in order to test the possibility for commercial production and scale up process. Also, casted mass of film forming suspension was varied in order to define minimal casting mass per unit area. Presented results showed that biopolymer films based on the pumpkin oil cake can be successfully produced in sheets (50x35 cm), compared to films earlier produced in the form of discs with diameter 12 cm. Different filtration fractions from initial film forming suspension can be used for film formation, leading to increased production yield. Different filtration fractions lead to different film properties that should be adjusted according to selected application. Casted mass of film forming suspension was successfully decreased (comparing to earlier literature data) without compromising film functional properties and minimal casting mass was defined as 26 g/m2.

Biopolymer films can be used as packaging materials in the food industry, when they contribute to a better mechanical integrity of packaged foods and act as barrier to various environmental agents. The greatest disadvantage regarding biopolymer films application are poor barrier characteristic, which is a consequence of their high hydrophilicity; their mechanical and physico-chemical properties are considered to be a moderate disadvantage. This paper presents the effects of chemical modifications, such as the addition of hydrophobic components (essential oils), to the properties of biopolymer films. Except that the addition of essential oils significantly affects the mechanical, barrier and physico-chemical properties of biopolymer films, in this way, biopolymer films become active and exhibit antimicrobial and antioxidant action. Changes in the mechanical and barrier properties of various biopolymer films have been observed in particular, with and without the addition of oil in different concentrations.

Active films based on pumpkin oil cake, with 1 % and 2 % of winter savory and basil essential oil, were synthesized in the paper, and the antioxidant activity of the films obtained was subsequently examined. A biopolymer film based on pumpkin oil cake without the addition of essential oils was used as a control. The following methods were used for determining the antioxidant activity of the films: the DPPH radical scavenging activity, the hydroxyl radical scavenging activity and the reducing power assay. The control film showed some antioxidant activity (DPPH radical scavenging activity = 61 %, hydroxyl radical scavenging activity = 33 %, reducing power = 0.534). However, the addition of essential oils increased the antioxidant activity of the films, especially their reducing power, where as the film with 2 % of winter savory essential oil exhibited the highest activity. A slight increase in the DPPH radical and the hydroxyl radical scavenging activities was also observed with the incorporation of essential oils into the experimental films.

In this work, pumpkin seed oil cake that remains after process of cold pressed oil extraction, was used for the production of composite biopolymer based packaging films. During the production of films, four degrees of filtration were applied. The obtained composite biopolymer films were analyzed for antioxidant activity using three different antioxidant activity assays: the ability to capture free radicals, including •DPPH radical and hydroxyl radical, •OH, as well as reduction power assay of the analyzed films. By comparing the antioxidant activity of the films obtained with different degrees of filtration, it can be concluded that the films obtained by finer filtration (smaller diameter of the filter pore) exhibit greater ability to capture •DPPH radicals, as well as higher reducing power, while the ability to capture hydroxyl radicals showed different trend. Films obtained from the coarser filtered fractions (higher diameter of the filtrate medium) showed greater •OH scavenging ability.

Fatty acid composition of Ricotta cheese filled bakery product was examined using a GC-MS method immediately after production and packaging in the case of a control sample, and after production, packaging under air atmosphere in a seven-layer packaging material consisting of PE/Ad/PA/Ad/PE/Ad/PET, and storing during a four weeks period at room temperature, in the case of the experimental samples. The statistical significance of the fatty acid profile change was examined using ANOVA method. The results of this research showed that there are no significant changes of fatty acids composition and content after defined storing period, with the exception of diunsaturated cis,cis-9,12-octadecadienoic (linoleic) acid, whose average content was reduced by 83.705%. However, a small amount of linoleic acid was converted to cis,trans-9,11-octadecadienoic (conjugated linoleic) acid. Therefore, it could be considered as appropriate to pack and storage Ricotta-filled pastry for the period of four weeks, considering the insignificant changes of fatty acid composition and content.

The purpose of this paper is the synthesis and characterization of biodegradable composite films based on whole sunflower oil cake, as well as the effect of process parameters (pH and temperature)on the film properties obtained. Films were synthesized at different temperatures (room temperature, 60 °C and 90 °C) and pH values (10 and 12). The film samples obtained were characterized by the mechanical, barrier and physicochemical properties determination. The experimental results showed that the tensile strength values increased with temperature and pH value increments, whereas the sample with the highest elongation at break value was 60 °C/pH12. The water vapour permeability values were uniform (8.62 g/m2h - 11.63 g/m2h), and lower values were recorded in samples synthesized at higher temperatures. The results obtained relative to light transmission were uniform, and the maximum transmission value was reached at 800 nm (24.1- 35.7 %). The values obtained for swelling and solubility parameters are characteristic of the nature of biopolymer films.

In this paper, the application of a biopolymer coating based on chitosan was tested. The optimized coating was formed as a two-layer coating, wherein the first layer (which is in contact with the product) was formed of chitosan with emulsified caraway essential oil as an active component, whereas the second layer was formed of chitosan with the addition of beeswax to optimize the moisture barrier of the coating. As a substrate, the traditional dry fermented sausage Petrovská klobása was selected. The coating was applied to the sausage after drying. During two months of storage under controlled conditions, the influence of the coating on the loss of moisture, the oxidative stability and the sensory characteristic of aroma of the control sausage (without the coating) and sausage with the coating was monitored. The results obtained indicate a significant contribution of the applied dual layer chitosan-based coating to the preservation of the sausage quality parameters analyzed.

Cardiac output is one of the important parameters used in evaluation of heart function. A turbine which works on mechanical principles was designed. It is also suitable for cardiac output measurements on isolated pig hearts in cases where some other equipment is not, like on doppler effect based transducers. The basic principle of measuring liquid flow through a turbine is based on measurement of the time that elapses when the rotor rotates by one degree. For this purpose, the rotor is fitted with transparent foil with a ring of 360 short black lines printed close to its circumference. Two infrared light-emitting diodes are mounted on one side of the foil and two photo-transistors, used as sensors of the transmitted infrared light, are mounted on the other. Voltage-regulated output ranging from 0 to +/- 2048 V at one revolution per second gives 500 mV at the output (changeable by programming), calculating time 2 ms, 1 mV resolution (11 bits), with an external power supply of 5 V. The turbine showed a linear response at a continuous saline flow up to 3000 ml min-1 at pressure loads of between 20 and 220 cm H2O. Pressure drop across the turbine depends on the volume flow and was 1 mm Hg at 100 ml min-1 and 3 mm Hg at 7000 ml min-1. A rotating movement 1.25 x 10(-4) kg m2 s-1 was calculated. The lowest volume change of a bolus of saline solution, detected by the turbine, was 1.6 ml. [ABSTRACT FROM AUTHOR]

Growing consumer demand for the food without chemical preservatives focused significant extent of research in the direction of finding natural compounds that can be used in food preservation. In this context, natural substances with strong antimicrobial and antioxidant properties, like essential oils, as well as natural biopolymers, particularly draw attention. Natural biopolymers can serve as carriers of the active components, such as essential oils in order of their sustained release to the food during storage, and may themselves exhibit activity in protecting foods from oxidation and/or microbial spoilage. Chitosan has been extensively studied as semi-natural polymer with expressed bioactive properties. While antimicrobial activity of chitosan solution in different acids has been confirmed towards different bacteria, yeasts and moulds, reports concerning intensity, underlying machanism and different factors afecting antioxidant activity of chitosan vary through the available literature. This paper presents a review in the field of antioxidative activity of chitosan with different properties, as well as chitosan based biopolymer films in order to clarify this aspect of chitosan bioactivity and confront different reports found in the literature.

Osmotic treatment of celery root was studied in two osmotic solutions (sugar beet molasses and a ternary solution of water, sucrose and salt), at three temperatures (20, 35 and 50°C), and three different immersion periods (1, 3 and 5 h), at atmospheric pressure. The aim was to examine the influence of the type of the used hypertonic agent, the temperature and the immersion time on the water loss, solid gain, water activity, dry matter content, antioxidant activity (expressed by DPPH) and colour attributes (described by CIELAB coordinates L*, a* and b*). During the experiments, the antioxidant activity of celery root was increased in sugar beet molasses, while the DPPH value tended to decrease in the ternary solution. The experimental data of osmotic dehydration was used for PCA modelling. The standard scores analysis revealed that the optimum process parameters were gained with an immersion time of 5 h and a temperature of 35°C. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. TR-31055]

The objective of this study was to examine influence of glycerol and guar-xanthan in different concentrations on bi-layer film based on pumpkin oil cake (PuOC) and corn zein, and to find optimal concentrations of these additives which result in film with optimal mechanical and barrier characteristics. Different concentrations of glycerol (30%, 40%, and 50%) as plasticizer and guar-xanthan (0.1%, 0.3%, and 0.5%) as a stabilizer were added in PuOC layer, while zein layer stayed unchanged in all film compositions. Obtained results showed that the optimal mechanical properties had film with the lowest concentration of glycerol (30%) and the highest concentration of guar-xanthan (0.5%). Films showed poor barrier for water vapour, typical for biopolymer-based films. However, all tested films were very good barrier to O2 (transmission rate lower than 50 ml/m2/day at 1 bar). On the other hand, with increase of concentration of added substances, transmission rate of CO2 increased.

Bilayer biodegradable films based on pumpkin oil cake (PuOC) and zein, as well as pouches made from these materials, were prepared, and the changes of their mechanical, physicochemical and barrier properties were analyzed during four weeks of storage. Heat seal quality of formed pouches and composition of the gas atmosphere in the pouches were also monitored. The results showed that the bilayer film had a thickness of 300 ± 10 (μm), and no its changes were observed during the storage time. The tensile strength of the tested film increased slightly in the third week, but the elongation at break showed a decreasing trend during the whole storage period. The decreases in the moisture content, total soluble matter and swelling of the obtained film, were also observed. After one month of storage, the O2 transmission rate of tested films, increased from 27 to 64 (ml/m2 24h 1 bar), and the CO2 gas transmission rate from 147 to 188 (ml/m2 24h 1 bar). The heat seal strength of the PuOC/Zein pouches decreased during the whole storage period. The percentage of O2 in PuOC/Zein pouches increased up to 7 times during the storage period; however, the percentage of CO2 decreased up to 18 times already after one week, and then remained stable in the rest of the storage period. These results are, to a smaller extent, due to the gas transmission rate through the material, especially for CO2 , and to a greater extent, due to the low heat seal strength, which decreased through the storage period, and probably influenced the content of the gases in the pouches.[Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. 46010]

In this paper, influence of increasing concentrations of beeswax on the antimicrobial activity of chitosan-caraway essential oil biofilm was investigated. Selected microorganisms for the test were Salmonella Typhimurium and Listeria monocytogenes. Reduction of S. Typhimurium and L. monocythogenes viable counts in bacterial suspension in the presence of chitosan films with or without added beeswax amounted over 80 % after 24 h contact time, and over 95 % after 3 h of contact time, respectively and influence of added beeswax on growth reduction was not detected. However, when number of S. Typhimurium viable cells was analyzed (log CFU/ml), it was shown that addition of beeswax led to increased activity of films, especially for the films with 36 kg/m3 and 54 kg/m3of beeswax. When films were transferred, after 24 h in bacterial suspension, onto Petri dishes with nutrient agar and incubated for 24 h on 37°C, results also showed beeswax contribution to growth inhibition of S. Typhimurium.

The purpose of this paper is to improve the properties of biopolymer protein monofilms and produce a novel bilayer biopolymer film on the basis of the monofilms analyzed. Biopolymer monolayer films, based on pumpkin oil cake (PuOC) and zein, and a bilayer film, based on PuOC and zein (PuOC/Zein), were produced as a result of the study. The visual, mechanical, physicochemical and structural properties of the films were evaluated. The results obtained showed that the PuOC film exhibited the highest elongation at break, followed by the bilayer film, whereas the zein film showed the lowest elongation at break. However, the zein film showed the highest tensile strength, followed by the PuOC film. The tensile strength of the bilayer PuOC/Zein film was almost 3 times lower than that of the PuOC film, and almost 4 times lower than that of the zein film. The physicochemical properties recorded indicate that the hydrophobic zein film is the least sensitive to moisture, affecting the moisture sensitivity of PuOC film by reducing the moisture content, swelling and total soluble mater of the bilayer PuOC/Zein film. Based on the FTIR spectra, it could be concluded that there are no significant differences between the two sides of the bilayer PuOC/Zein film. Both sides of the bilayer film examined indicated characteristic peaks for protein biopolymer films in the FTIR spectrum.

In this study, three biopolymer films were synthesized: zein (protein), gelatin (protein), and starch (polysaccharide) films and characterized by determining mechanical and physico-chemical properties. Gelatin films proved to be the strongest (tensile strength 84 N/15 mm), while the zein were most flexible (elongation at break 41.6 %). Moisture content was higher in starch films, which is a result of the hydrophilic nature of the polysaccharide films. Swelling degree was 22.5 % for zein, 90.9 % for gelatin, while the highest average value was recorded in starch film samples (840.6 %). Starch films had highest value of solubility degree (36.5 %), while zein film had 27.9 % and gelatin film had 11.85 %.Obtained characterization results are consequences of the different structure of the raw materials and synthesis routes. All undesirable characteristics could be improved by optimizing the composition of the film, as well as synthesis of composite/laminated films.

This study investigated properties of starch-based edible films with oregano and black cumin essential oil addition. Essential oils addition positively affected film swelling (decreased due to essential oil addition), mechanical properties (tensile strength decreased while elongation at break increased), and water vapor barrier properties (decreased along with essential oils addition). Control film did not have any biological activity, which proves the need for essential oils addition in order to obtain active packaging. Oregano oil was more effective in terms of biological activity. Endothermal peak, above 200°C, represents total thermal degradation of edible films. Diffraction pattern of control film showed significant destruction of A-type crystal structure. Addition of essential oils resulted in peak shape change: diffraction peaks became narrower. Principal Component Analysis has been used to assess the effect of essential oils addition on final starch-based edible films characteristics with the aim to reveal directions for the film characteristics improvement, since the next phase will be optimal film application for food packaging.