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Cassava inner bark (CIB) and grape stalks (GS), residues from agro-industrial activities, were applied in the development of biodegradable foams by thermocompression. The samples produced with untreated stalks (sample GSWT) and with stalks only physically treated (sample GSP) presented good mechanical strength (2.1 MPa and 2.5 MPa, respectively) and low water absorption capacity (58% and 56% at 90 min, respectively). Therefore, these samples were selected for the storage of carrot cake and cherry tomatoes. Compared with the cakes stored in the supermarket packaging, there were no significant moisture content differences of the cakes stored in the biodegradable packaging developed by the formulation with the GSP sample (25% and 23%, respectively). The cakes' hardness increased up to 88% when stored in S + CIB + GSWT foam. More interesting, it was observed that the biodegradable packaging is more suitable for the storage of cherry tomatoes than the supermarket ones once the firmness of this product was maintained during storage (initial firmness of 5.4 N and final firmness of 5.3 N after 15 days in S + CIB packaging). Thus, biodegradable packaging developed from agro-industrial residues (CIB and GS) can be considered environmentally-friendly and promising materials to preserve the quality and freshness of carrot cake and cherry tomatoes.

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The starch-based film development has been extensively studied since, in general, it is possible to obtain transparent, non-toxic, odorless, good gas barrier, biodegradable, and tasteless samples. However, world hunger-related problems are a reality and the use of starches, a recognized carbohydrate source, in the packaging industry should be avoided. Thus, the use of different residual starchy can minimize the costs of production, promoting the development of innovative biomaterials, eliminating the competition with the food chain. The objective of the present work was to evaluate the impact of the cassava starch (CS) substitution by gelatinized starch (GS), a residue generated in the sieving step of starch processing, verifying possible changes in the final material characteristics. The raw materials characterization includes determination of amylose and moisture contents, centesimal composition, particle size distribution, and thermal analysis. After casting solution and drying processes, the samples were evaluated regarding the visual macroscopic and microscopic aspects showing continuous and homogeneous structure. The results were related to the physicochemical and mechanical properties. The GS addition promoted a decrease in the tensile strength (3.3 ± 0.1 MPa to 1.2 ± 0.3 MPa) and elastic modulus (52 ± 13 MPa to 10 ± 3 MPa) values, while the elongation percentage (160 ± 30% to 212 ± 14%) values seem to have not been so affected. It can be seen a high potential for the use of agro-industrial residues containing starch in bioplastic production.

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Biopolymers, as chitosan and alginate, have gained prominence in the biomedical area, mainly for application in wound dressings, as partial replacements for synthetic polymers. The present work aimed to compare the influence of the antimicrobial agent incorporation form on the properties of films prepared by casting. The chitosan/alginate-based films were manufactured containing oregano essential oil (OEO) or ground oregano leaves (OR). The OEO was chosen due to its excellent pharmacological properties, and the substitution by OR can represent an advantageous alternative for minimizing the final cost of the product, by removing the oil extraction step. The films, with different amounts of OEO and OR, were characterized in terms of their morphological, physicochemical, mechanical and antimicrobial properties. The films had properties according to desirable for wound dressing application: water vapor flux less than 35 g m-2 h-1, moderate liquid absorption capacity, and similar mechanical properties to human skin. All developed films showed antimicrobial activity against the bacteria Escherichia coli and Staphylococcus aureus. Formulations containing OEO presented the largest inhibition zones, although OR showed high potential for the proposed use. These results suggest that films developed, with both OEO and ground oregano leaves, are promising for use as dressings.

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Biopolymers have gained prominence in different areas, such as food packaging for single-use and biomedical applications, automotive field and electrostatic separation systems. The present work aims the development of films by casting based on chitosan and cornstarch incorporated with turmeric. Turmeric insertion is justified by its excellent antioxidant and pharmacological properties. All formulations containing chitosan presented inhibition halo for the microorganism Staphylococcus aureus justifying its addition. Regardless of the turmeric incorporation, the blended films containing the two biopolymers presented greater adhesiveness, remaining adhered to the swine mucosa used as a model surface for a longer time. In the migration tests after immersion in PBS buffer solutions, it was observed that the higher absorbance values occurred for films containing the bioactive agent. These results suggested that innovative materials could be used in several different applications.

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Biopolymers have received considerable attention in recent years given the environmental concern related to the incorrect disposal of materials based on synthetic plastics. Starch and chitosan are good examples of raw materials of interest, and its combination can exhibit some newsworthy barrier and mechanical properties. Therefore, this study aimed to determine the impact of the acid type, acetic and lactic solutions (1% v/v), used for chitosan solubilization and the starch:chitosan proportion on the properties of cornstarch/chitosan-based films. The films were prepared by casting and characterized by analyses of water vapor permeability, tensile strength, elongation, elastic modulus, antimicrobial activity, and biodegradability. Mechanical properties analyses showed that the films prepared by using acetic acid presented higher rigidity and lower deformation, giving higher values of Young's Modulus and a smaller percentage of elongation, in comparison to the films fabricated with lactic acid. Besides, starch/chitosan films containing acetic acid also exhibited better water vapor barrier properties, showing smaller water permeation values. Moreover, the antimicrobial activity of the cornstarch-based films containing chitosan was confirmed, obtaining better results for the blended films prepared with lactic acid, indicating a high potential for the development of active packaging. For the biodegradation tests, all samples started the degradation after 15 days.

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Starch and chitosan are biodegradable polymers from renewable sources that can be used to overcome the serious environmental problem caused by improper disposal of synthetic plastic materials, non-biodegradable, derived from petroleum sources. The starch-chitosan based films manufactured allow improving the better characteristics of each one, adding their good characteristics and compensating for some limitations. In this work, it was studied: two sources of starch (corn and cassava), two different modes of chitosan addition (chitosan blended in the starch filmogenic solution and chitosan as coating), and the effect of glutaraldehyde as crosslinking agent. All films were prepared by casting using glycerol as a plasticizer and were characterized by their physicochemical (water vapor permeability, water contact angle, and FTIR), mechanical, and antimicrobial properties. The properties analyzed were influenced by all variables tested. Moreover, the principal component analysis was also conducted in order to relate and describe the variables analyzed. The antimicrobial activity of the corn starch-based films containing chitosan was confirmed, and these films have potential for development of active packaging.

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Blueberry waste from juice processing was valorised to develop starch films by compression moulding. The compression process resulted in hydrophobic films with water contact angles even higher than 100° for the films prepared with the highest blueberry waste content. Additionally, the film solubility was reduced by the incorporation of blueberry waste, regardless of the solution pH. These films also exhibited good barrier properties against UV light due to the aromatic compounds present in the blueberry waste. Furthermore, films showed a homogenous surface, although some pores appeared in the cross-section for the films with the highest blueberry waste content. Results highlighted the use of thermo-mechanical processes such as compression to manufacture sustainable films with enhanced properties through waste valorisation by the techniques actually employed at industrial scale.

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This work is focused on the development of renewable and biodegradable films by the valorisation of wastes from food processing industries, with the aim of contributing to the development of more sustainable films. In this context, different contents of blueberry pomace (BP) were incorporated into cassava starch (CS) film forming solutions and the functional properties of the films prepared by solution casting were investigated, specifically, thermal, optical and physicochemical properties. BP-incorporated films showed good barrier properties against light, indicating their beneficial effect to prevent food deterioration caused by UV radiation when these films are used for food packaging applications. These results were related to the presence of aromatic compounds in BP, which can absorb light at wavelengths below 300nm. Furthermore, all films maintained their structural integrity after immersion in water (24h) and the maximum swelling displayed was lower than 300%. Additionally, the release of active compounds from BP into food simulants (after 10days) showed higher migration into the acetic acid medium in comparison with the ethanol medium. Therefore, the incorporation of BP into CS film forming solution resulted in the improvement of film performance, suggesting the potential application of these films as active packaging.

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Intelligent packaging is an emerging area of food technology that can provide better preservation and be of further convenience for consumers. It is recommended that biodegradable materials be used to develop low-impact designs for better packaging, which could benefit the environment by simply expanding their use to new areas. In this work, corn starch, glycerol and blueberry powder (with and without prior fruit bleaching) were used to produce films by casting. Blueberry powder, a co-product from juice processing, which is rich in anthocyanins, was added in the films to evaluate its potential as a colorimetric indicator, due to the ability of anthocyanin to change color when placed in an acidic or basic environment. After the films were immersed in different buffer solutions, visual color changes were observed, where the films became reddish at acidic pH and bluish at basic pH. The ΔE* values were greater than 3, suggesting a visually perceptible change to the human eye. The samples with fruit bleaching (CB) were visually darker (lower luminance values), while the samples without bleaching (SB) had a lighter color and higher brightness, represented by larger L* values. These results indicate the potential of blueberry powder as a pH indicator for intelligent food packaging or even for sensing food deterioration.

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