Filmogenic Solution Research Articles

Preparation and characterization of soy protein films reinforced with cellulose nanofibers obtained from soybean by-products

In this paper, we report the preparation of nanofibers obtained from low-cost agro-industrial by-products (soybean hulls and pods) and their use as nano reinforcers of soy protein films. From hulls, we obtained white and stable in-time aqueous dispersions of cellulose nanofibers of about 20 nm wide and 500 nm long and a hydrodynamic diameter of 269 nm, with a marked increase in the crystalline index as compared to raw material. Filmogenic solutions of soy proteins were prepared using glycerol as a plasticizer and different amounts of cellulose nanofibers (0; 10; 20 and 40% in relation to the amount of soy protein). The rheological behavior of filmogenic solutions containing nanofibers suggests an interaction between matrix and reinforcements. Films were prepared by casting of filmogenic solutions. As a result, we obtained films with a homogeneous surface having a large number of nanofibers, showing increasing opacity in samples with larger amounts of cellulose nanofibers. The addition of nanofibers decreases the film's susceptibility to water, by which a significant decrease in the total soluble matter and swelling in water was observed with an increase in contact angle. In addition, mechanical properties were also improved, obtaining more rigid films as the number of nanofibers increased.

Physical, thermal, mechanical and barrier properties of pearl millet starch films as affected by levels of acetylation and hydroxypropylation

Starch-based films possess potential application in food packaging, due to their biodegradability, lower cost, stretchability and clarity. The aim of this work was to develop novel edible films from native, acetylated and hydroxypropylated pearl millet starches with improved flexibility, transparency and water barrier properties. Each film contained a fixed concentration of starch (3 g/100 g) and glycerol (30%, w/w based on starch weight). The effect of levels of acetylation (4% and 8%, w/w) and hydroxypropylation (10% and 30%, w/v) on the rheological, physical, thermal, mechanical and barrier properties of films was investigated. SEM results showed that modified starch films possessed smoother surface in comparison to native starch film (NF). Rheological evaluation depicted that filmogenic solution of 30% hydroxypropylated starch was more viscous than other solutions. Films containing 4% and 8% acetylated starches showed excellent moisture barrier property as depicted by their low water vapor permeability (WVP) and water solubility (WS). The extent of these improvements depended on the levels of acetylation. Elongation at break (%EAB) and transparency (%T) of 10% and 30% hydroxypropylated starch films were higher than NF and increased with increasing amount of propylene oxide. Glass transition temperature (Tg) was lowered by addition of modified starches in film formulation.

Okra mucilage and corn starch bio-based film to be applied in food

Okra mucilage/corn starch films to apply in food were developed by casting and then characterized to know its main requirements for packing material. The film was submitted to an acute toxicity analysis in rats by ingesting the filmogenic solution. An okra mucilage material obtained by precipitation was analyzed by thermal analysis, Fourier Transformed Infrared Spectroscopy and Scanning Electron Microscopy with Energy Dispersive Spectroscopy. Okra mucilage and corn starch films presented compact and uniform structure, low water vapor permeability (1.32–2.84 g/m s Pa), low solubility (around 15%), good thermal and mechanical properties, swelling capacity (about 95%), and no toxicological responses. The precipitated material presented similar characteristics to those of polysaccharides. Thus, okra mucilage differed in view of its improvement in film properties because of high quality intermolecular bonds. The film obtained with okra mucilage has excellent potential to be applied in food packaging.

Effect of chitosan addition on the properties of films prepared with corn and cassava starches.

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.

Chitosan/Cellulose Nanofibril Nanocomposite and Its Effect on Quality of Coated Strawberries

The aim of this study was to develop a chitosan/cellulose nanofibril (CNF) nanocomposite and evaluate its effect on strawberry’s postharvest quality after coating. From the results of color, thickness, and scanning electron microscopy (SEM) and permeability to water vapor analyses, the best film formulation for coating strawberries was determined. Three coating formulations were prepared: 1% chitosan, 1% chitosan + 3% CNF, and 1% chitosan + 5% CNF. The strawberries were immersed in the filmogenic solutions and kept under cold storage (1 ± 1°C). The color of the film was not affected by increased concentration of cellulose nanofibrils; however, the thickness and water vapor permeability were affected by the CNF addition. The coating with the highest CNF concentration performed better in reducing fruit mass and firmness loss. The color was positively influenced by the addition of the coating, regardless of formulation, as well as soluble solid content, PG enzymatic activity, and the fruit appearance. The pH and titratable acidity showed no significant difference among treatments. It was observed that the vitamin C, phenolic compounds, and anthocyanin content, as well as the PAL activity and the antioxidant activity (except for % protection), were affected by chitosan coating, however not by the addition of CNFs.

Performance evaluation of cashew gum and gelatin blend for food packaging

In this study, a polysaccharide and a protein were combined to form a polyblend that can be used for food packaging. Cashew gum (CG) and gelatin (G) films were generated by the casting method with the help of the central composite rotational design. When filmogenic solutions of 2.5–7.5 g of G and CG were dissolved in 100 mL water with 10% glycerol, the resulting films were compact and homogeneous with no pores present. Different CG/G ratios were examined for water vapor permeability (WVP), thickness, solubility, mechanical and thermal properties, surface morphology, and biodegradability. The results showed that at around 1:1 CG/G weight ratio the solubility decreased, reaching the minimum value at the CG composition of 45%. The blend of 50/50 CG:G showed the best WVP (1.16 g mm k Pa−1 h−1 m−2). For elongation at break, the combination of 5 g CG and 2.5 g G provided the best results with over 100% elongation. The films were shown to be easily biodegradable, producing as much CO2 as starch during the 22 days of an aerobic biodegradability test.

Potential of pinhão Coat as Constituents of Starch Based Films Using Modification Techniques

The potential of lignocellulosic fibers obtained by dry grinding of pinhao coat as fillers in starch filmogenic solutions for packaging applications was evaluated in this work. To improve the incorporation of this waste into the starch solutions different physical and chemical treatments were conducted. Thereafter, morphology, chemical structure, crystallinity and water absorption of the pinhao coat powders were determined. The composites were also characterized regarding their morphology, chemical structure, crystallinity, mechanical properties, water vapor permeability and hydrophilicity. Poor fiber/matrix adhesion and high water absorption of the fibers were evidenced. Consequently, water vapor permeability of composites was increased by incorporating the fibers. Moreover, mechanical properties were improved and the morphological results were used to support the water absorption differences among the powders. Regarding the food packaging applications, starch/pinhao coat composites appeared as promising materials to reach the requirements of respiring food products.

Development of Multilayer Films Obtained From Epoxidized Methyl Esters, Polyhydroxyalkanoates and Their Combinations

The aim of this work was the production and characterization of films prepared from starch, gelatin and methyl esters of epoxidized macauba (Acrocomia aculeata), corn (Zea mays), pacu (Piaractus mesopotamicus), pintado (Pseudoplatystoma corruscans) and soybean (Glycine max) and also multilayer films of polyhydroxyalkanoates (PHA) conjugated with two of the epoxides that presented the best results in characterizations. The two types of films EEF (Epoxidized esters films) and EEFPHA (Epoxidized esters and PHA conjugated films) were both characterized for their visual aspects, solubility in water and acid, width, color, opacity, water vapor permeability, tensile strength and elongation. EEFPHA were also characterized by differential scanning calorimetry, scanning electron microscopy and X-ray diffraction analyses. The epoxidation reaction was successfully carried out; with the GC-MS analysis indicating the formation of epoxidized esters derived from linoleic and oleic acids. The addition of the epoxidized esters to the EEF films caused an increase in film thickness, opacity, solubility in water, tensile strength and elongation, while the solubility in acid presented the same value as compared to the blank sample. In the EEFPHA samples, addition of filmogenic solution of epoxidized esters from corn and macauba presented a value exceeding the standard in the thickness, opacity, water solubility, water vapor permeability and tensile strength analyses. In the analysis of solubility in acid these samples showed results below the standard, and the elongation test showed values very close. DSC, SEM and XRD results showed that there was a polymeric incorporation between the starch and the PHA.

Preparation and evaluation of hemicellulose films and their blends

Cell wall hemicelluloses are useful in various industries due to their ability to form edible and biodegradable films with plasticizers such as glycerol. The objective of this research was to extract hemicelluloses from Caesalpina pulcherrima and Tamarindus indica, produce film blends from them, and evaluate their properties and their product development potential. The extraction process provided yields of 25% galactomannan (GalCp) from C. pulcherrima and 20% xyloglucan (XilTi) from T. indica. The apparent Mw obtained by GPC were 4.35 × 106 g/mol and 2.03 × 106 g/mol for GalCp and XilTi respectively. The ratio of mannose/galactose in GalCp determined by 13C NMR was (2: 1), while the ratio of glucose/xylose/galactose in XilTi obtained by 13C NMR was (1.0: 1.2: 1.0). All filmogenic solutions from these hemicelluloses showed non-Newtonian rheological behavior at 25 °C. The IR spectra were consistent with the presence of GalCp and XilTi and were fully assigned. Galactomannan film exhibited a higher permeability to moisture than xyloglucan and the blends. All films showed less than 20% opacity; thus, they were relatively transparent. Thermogravimetric analysis indicated that the blend films had good thermal stability. The use of these blends permits a wider range of properties to be obtained than the hemicelluloses alone. Thus, these materials may serve as useful biodegradable and environmentally friendly materials for food packaging applications.

Effect of the Incorporation of Lysozyme on the Properties of Jackfruit Starch Films

Jackfruit starch based biodegradable films containing lysozyme were characterized for their antimicrobial activity, thickness, solubility, water vapor permeability and mechanical properties. The biodegradable films had good appearance and antimicrobial activity against Micrococcus lysodeikticus. The thickness of the biodegradable films were not affected by the variation in pH, but the addition of lysozyme increased the thickness, the thickest films being those with the highest lysozyme concentrations. The variation in pH of the filmogenic solutions affected the solubility of the biodegradable films, water solubility being greatest at pH 7.0 and with the highest lysozyme concentration. The permeability of the biodegradable films was increased by incorporating lysozyme. The lysozyme concentration and pH variation caused changes in the mechanical properties. The addition of 8% lysozyme increased the tensile strength and Young’s modulus for all the pH values studied. With respect to the release of antimicrobial activity, the diffusion of lysozyme was shown to follow Fickian transport mechanism.

Structural, Thermal, Physical, Mechanical, and Barrier Properties of Chitosan Films with the Addition of Xanthan Gum.

Films based on chitosan and xanthan gum were prepared using casting technique aiming to investigate the potential of these polymers as packaging materials. Six formulations of films were studied varying the proportion of chitosan and xanthan gum: 100:0 (chitosan:xanthan gum, w/w, C100XG0 film); 90:10 (chitosan:xanthan gum, w/w, C90XG10 film); 80:20 (chitosan:xanthan gum, w/w, C80XG20 film); 70:30 (chitosan:xanthan gum, w/w, C70XG30 film); 60:40 (chitosan:xanthan gum, w/w, C60XG40 film); and 50:50 (chitosan:xanthan gum, w/w, C50XG50 film). The total quantity of solids (chitosan and xanthan gum) in the filmogenic solution was 1.5 g per 100 mL of aqueous solution for all treatments, according to the proportion of each polymer. The films were evaluated by their functional groups, structural, thermal, morphological, physical, mechanical, and barrier properties. All films have presented endothermic peaks in the range of 122 to 175 °C and broad exothermic peaks above 200 °C, which were assigned to the melting temperature and thermal decomposition, respectively. These results demonstrated that films with xanthan gum have the highest Tm and Δm H. The films containing higher content of xanthan gum show also the highest tensile strength and the lowest elongation. Xanthan gum addition did not affect the water vapor permeability, solubility, and moisture of films. This set of data suggests the formation of chitosan-xanthan complexes in the films.

Gelatin and pregelatinized starch orally disintegrating films: Properties and stability of vitamin C

ABSTRACTThe administration of active compounds by the oral mucosa is an efficient method for the delivery of drugs and nutrients. This work aimed to develop and characterize orally disintegrating films (ODFs) based on starch and gelatin as carriers of vitamin C. The ODFs were produced using a casting technique by varying the concentrations of starch and gelatin (0, 20, 40, 60, 80, and 100 g of starch/100 g of polymer) and were characterized in relation to contact angle, opacity, surface pH, infrared spectroscopy, mechanical properties, morphology, and disintegration time (in vitro and in vivo). Additionally, the stability of vitamin C in the ODFs was evaluated by the incorporation of the dry extract of acerola (4 g/100 g of filmogenic solution). Generally, the ODFs presented hydrophilic characteristics with a neutral surface pH near the mouth, and films with higher starch concentrations showed greater rigidity. In vitro and in vivo tests indicated that ODFs may be classified as rapidly disintegrating. The ODFs produced with higher concentrations of starch showed a higher stability of the active compound, in addition to a shorter disintegration time. Starch‐ and gelatin‐based ODFs can be considered a new system for administering active ingredients via the oral mucosa. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44841.

Hydrophilicity and physicochemical properties of chemically modified cassava starch films

The surface properties and microstructure of films composed of chemically modified cassava starches (cross-linked, acetylated and doubly modified) were evaluated in this study. The films were produced using a casting technique with fixed concentrations of starch and sorbitol (4.0 and 1.2g/100g in the filmogenic solution, respectively). The hydrophilicity and surface characteristics of the films were analyzed by determining the optical contact angle (θ). The films were also evaluated for surface properties (polarity and nonpolar and polar components), water solubility, and water vapor permeability. It was determined that films produced from cross-linked and acetylated cassava starch showed greater hydrophobicity and better mechanical properties than those prepared with native cassava starch. The films prepared with doubly modified and acetylated cassava starch had a lower surface energy than the film prepared with untreated and cross-linked starch. The results from scanning electron microscopy, infrared spectroscopy and X-ray diffraction demonstrated marked differences between the films, which were dependent on the type of starch. According to the results obtained in this study, the physicochemical properties of films are related to the chemical structure, microstructure and surface properties.

Development and characterization of multilayer films based on polyhydroxyalkanoates and hydrocolloids

ABSTRACTNew biodegradable polymeric materials have been developed in order to minimize the environmental impact caused by the traditional packaging found in the market. Polyhydroxyalkanoates (PHAs) are biopolymers with important features such as biodegradability and biocompatibility; however, the costs associated with PHAs production and the limited mechanical properties reduce their application. Whey is a residual product from dairy industry and gelatin is a biopolymer with good processing characteristics. In this context, a filmogenic solution based on these two biopolymers was incorporated into pure PHA films to improve their optical, mechanical, and structural properties. The filmogenic solution was prepared from gelatin, cheese whey and PHAs, using glycerol as plasticizer agent. The multilayers films (gelatin concentrations at 3 and 5%, w/v) showed higher values for all properties when compared with the PHA standard film. In this sense, the addition of this solution was responsible for the improvement of the film properties. The 5% gelatin multilayers films added of cheese whey and PHAs showed better results when compared with the multilayers films with gelatin at 3%. The film composed of gelatin 5% and cheese whey showed a water vapor permeability ranging from 0.45 g mm/m2/d/kPa, elongation of 2.18%, and opacity of 14.5%. However, the results of the morphological analysis showed that both films presented a homogeneous surface without cracks. Moreover, the results of the thermal analysis of both films indicate polymeric miscibility. Thus, the choice of the best film will depend on its applicability. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44458.

Impact of acid and oxidative modifications, single or dual, of sorghum starch on biodegradable films

The objective of this study was to evaluate the effects of acid and oxidation modifications on sorghum starch, as well as the effect of dual modification of starch on the physical, morphological, mechanical, and barrier properties of biodegradable films. The acid modification was performed with 3% lactic acid and the oxidation was performed with 1.5% active chlorine. For dual modification, the acid modification was performed first, followed by oxidation under the same conditions as above. Both films of the oxidized starches, single and dual, had increased stiffness, providing a higher tensile strength and lower elongation when compared to films based on native and single acid modified starches. However, the dual modification increased the water vapor permeability of the films without changing their solubility. The increase in sorghum starch concentration in the filmogenic solution increased the thickness, water vapor permeability, and elongation of the films.

Edible films based on cassava starch and fructooligosaccharides produced by Bacillus subtilis natto CCT 7712

The objectives of this work were to produce fructooligosaccharides (FOSs) by using the microorganism Bacillus subtilis natto CCT 7712 and to employ these FOSs as a functional ingredient in cassava starch edible films, which were characterized according to their microstructure, mechanical and barrier properties. The produced FOSs could be easily dissolved, resulting in homogeneous filmogenic solutions, which were easily manipulated to obtain films by casting. FOSs were added in different concentrations (0, 1, 5 and 10g/100g solids), and glycerol was used as a plasticizer (20g/100g solids). All formulations resulted in films that had a good appearance and were easily removable from the plates without bubbles or cracks. The FOSs exerted a plasticizing effect on the starch films and decreased their glass transition temperature. The addition of FOSs resulted in higher solubility and elongation and a decreased water vapor permeability of the films. FOSs were shown to be a promising ingredient for use in edible starch films.

Films based on protein isolated from croaker (Micropogonias furnieri) and palm oil.

The microstructure and the physical, mechanical, barrier and thermal properties of films based on different concentrations of protein isolated from croaker waste (CPI) and palm oil (PO) were analyzed. Films were elaborated by a casting technique using 2, 3 and 4 g CPI 100 g(-1) of a filmogenic solution and 0, 10 and 20 g of PO 100 g(-1) CPI. Microstructure of the film surfaces of CPI with PO showed no presence of lipid droplets dispersed in the filmogenic matrix, although a rough surface was present. Films with 3% and 4% CPI and 20% PO had the lowest rates of water vapor permeability. When there was an addition of PO to the reduced tensile strength of the films, regardless of the concentration of CPI, this addition reduced the elongation of films with 3% and 4% CPI; however, it did not influence films with 2% CPI, which did not differ from the control film (0% OP). Thermal analysis revealed that films with the highest PO percentage had a lower initial weight loss when compared with other films, due to higher hydrophobicity. The use of protein isolate obtained from fish residues of low commercial value and palm oil is viable for the production of biodegradable films because the latter constitute good barrier properties and thermal stability. © 2015 Society of Chemical Industry.

Chitosan molecular weight effect on starch-composite film properties

The aim of this work was to prepare and characterize composite films based on chitosan (CH) and corn starch (CS), analyzing the influence of the chitosan molecular weight (MW) on film structure and functional properties. Three chitosan products were characterized and classified as low (LMW), medium (MMW) and high (HMW) according to its MW. Rheological behavior of filmogenic solutions depend on CH-MW from Newtonian to pseudoplastic one. Chitosan based film physicochemical properties were strongly affected by its molecular weight: the lower the MW the higher the color differences and film solubility. SEM observations demonstrated that plasticized chitosan films exhibited homogeneous structures, the higher the MW the more compact is the structure and the lower is the water vapor permeability (WVP, 4.55 ± 0.6 × 10−11 g/m s Pa.). Likewise, CH and CS were compatible polymers which led to the development of homogeneous blend films. Polymer interactions were evidenced in FTIR spectra by the shifts observed within the region of 1500–1700 cm−1, which reduce the hydrophilic groups’ availability of chitosan matrices, leading to a reduction in WVP of composite films. Mechanical properties of the developed films were performed through different complementary tests. Chitosan MW affects both the type and number of interactions, which determine the matrix structure and characteristics. In HMW-CH matrix polymer–polymer interactions are favored, leading to strong and resistant matrices with high dynamic elastic modulus values. Meanwhile, in LMW-CH one, polymer-plasticizer and polymer–solvent interactions became important and the development of high extensible and soluble materials is privileged.

Crosslinked soy protein films and their application as ophthalmic drug delivery system

In this research, the potential of soy protein (SPI) based-films as drug delivery devices for ocular therapy was developed. Hence, crosslinked films with a natural and non-cytotoxic crosslinking agent, genipin (Gen), coated with poly(lactic acid) (PLA), were prepared. Filmogenic solutions were loaded with timolol maleate (TM) as a model drug, to be used as drug delivery devices, a novel application for this material. The mechanical properties of the films were studied, observing that with the presence of PLA coating, more rigid materials with improved properties were obtained. Furthermore, the release behavior of TM was evaluated in aqueous medium, it being influenced by the degree of film crosslinking. Furthermore, it was determined that PLA coating decreased TM release rate compared to that of uncoated films. Similarly, this behavior was observed via indirect estimation of the release by assessing the hypotensive effectiveness of the films by in-vivo assays. Through intraocular pressure (IOP) determination tests in rabbits, it was demonstrated that, through the use of high crosslinked and coated films, a significant decrease in IOP could be achieved for prolonged time periods. These results suggest that the use of soy protein-based films as drug delivery systems is highly suitable.

Synthesis and characterization of biofilms using native and modified pinhão starch

In the present work, native pinhão starch, modified pinhão starch (hydrolyzed with different concentrations of HCl), glycerol and xanthan gum were used to produce biofilms. The synthesis of filmogenic solutions was performed by casting. The biofilms were characterized by measurement of thickness, Environmental Scanning Electron Microscopy, Water Vapor Permeability, Differential Scanning Calorimetry and Water Solubility. The results showed that there was an increase in the water solubility of the biofilms and a reduction of the water vapor permeability due to the modification of the starch. According to the thermal analysis, the starch modification process did not promote changes in the glass transition temperature of the films. The biofilms also exhibited good resistance to high temperatures. Moreover, jaboticaba flour was added to the composition of the biofilm to test the use of the anthocyanins as an indicator due to its ability to change color at different pH values.