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Global concerns over environmental damage caused by non-biodegradable single-use packaging have sparked interest in developing biomaterials. The food packaging industry is a major contributor to non-degradable plastic waste. This study investigates the impact of incorporating different concentrations of polyvinyl alcohol (PVA) and yerba mate extract as a natural antioxidant into carboxymethyl cassava starch films to possibly use as active degradable packaging to enhance food shelf life. Films with starch and PVA blends (SP) at different ratios (SP radios of 100:0, 90:10, 80:20 and 70:30) with and without yerba mate extract (Y) were successfully produced through extrusion and thermoforming. The incorporation of up to 20â¯wt% PVA improved starch extrusion processing and enhanced film transparency. PVA played a crucial role in improving the hydrophobicity, tensile strength and flexibility of the starch films but led to a slight deceleration in their degradation in compost. In contrast, yerba mate extract contributed to better compost degradation of the blend films. Additionally, it provided antioxidant activity, particularly in hydrophilic and lipophilic food simulants, suggesting its potential to extend the shelf life of food products. Starch-PVA blend films with yerba mate extract emerged as a promising alternative for mechanically resistant and active food packaging.
Assuntos
Antioxidantes , Embalagem de Alimentos , Manihot , Extratos Vegetais , Álcool de Polivinil , Amido , Embalagem de Alimentos/métodos , Álcool de Polivinil/química , Amido/química , Amido/análogos & derivados , Antioxidantes/química , Manihot/química , Extratos Vegetais/química , Ilex paraguariensis/química , Resistência à Tração , Interações Hidrofóbicas e Hidrofílicas , Fenômenos MecânicosRESUMO
This work aimed to evaluate the properties of butylene adipate-co-terephthalate (PBAT) degraded after 1800 days of storage (DPBAT) by preparing blends (films) with crosslinked starch (Cm) through extrusion and thermocompression. Different ratios of DPBAT:Cm (70:30, 60:40, and 50:50 m/m) were prepared. The incorporation of Cm into DPBAT significantly changed the properties of the films by making them stiffer (increasing Young's modulus by up to 50%) and increasing the thermal resistance of DPBAT. The presence of crosslinked starch in the films made them less hydrophobic (with decreased contact angle and increased moisture content), but these parameters did not vary linearly with changes in the content of crosslinked starch in the blend (DPBAT:Cm). The microscopic images show an inhomogeneous distribution of Cm granules in the DPBAT matrix. Thus, the films prepared with PBAT show a significant decrease in their mechanical parameters and heat resistance after long-term storage. However, the preparation of blends of degraded DPBAT with crosslinked starch promoted changes in the properties of the films prepared by thermocompression, which could be useful for disposable packaging.
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The efficiency in the capabilities to store and release antioxidants depends on the film morphology and its manufacturing process, as well as on the type and methodology used to obtain the polyphenol extracts. Here, hydroalcoholic extracts of black tea polyphenols (BT) were obtained and dropped onto different polyvinyl alcohol (PVA) aqueous solutions (water or BT aqueous extract with and without citric acid, CA) to obtain three unusual PVA electrospun mats containing polyphenol nanoparticles within their nanofibers. It was shown that the mat obtained through the nanoparticles precipitated in BT aqueous extract PVA solution presented the highest total polyphenol content and antioxidant activity, and that the addition of CA as an esterifier or PVA crosslinker interfered with the polyphenols. The release kinetics in different food simulants (hydrophilic, lipophilic and acidic) were fitted using Fick's diffusion law and Peppas' and Weibull's models, showing that polymer chain relaxation is the main mechanism in all food simulants except for the acidic, which presented an abrupt release by Fick's diffusion mechanism of about 60% before being controlled. This research provides a strategy for the development of promising controlled-release materials for active food packaging, mainly for hydrophilic and acidic food products.
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Biodegradable polymers have been strongly recognized as an alternative to replace traditional petrochemical plastics, which have become a global problem due to their long persistence in the environment. In this work, the effect of the addition of titanium dioxide nanoparticles (TiO2NP) on the morphology, physicochemical properties and biodegradation under industrial composting conditions of cassava starch-based nanocomposites obtained by extrusion at different screw speeds (80 and 120 rpm) were investigated. Films performed at 120 rpm (S120 and S120-TiO2NP) showed completely processed starch and homogeneously distributed nanoparticles, leading to much more flexible nanocomposites than those obtained at 80 rpm. The incorporation of TiO2NP led to an increase in storage modulus of all films and, in the case of S120-TiO2NP, to higher strain at break values. From the Kohlrausch-Williams-Watts theoretical model (KWW), an increase in the relaxation time of the nanocomposites was observed due to a decrease in the number of polymer chains involved in the relaxation process. Additionally, S120-TiO2NP showed effective protection against UV light, greater hydrophobicity and faster biodegradation in compost, resulting in a promising material for food packaging applications.
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Starch films often present high water sensitivity, affecting their barrier and mechanical properties. The effects of processing technique, extrusion/thermo-compression and casting, and lentil protein concentration (0, 0.75 wt.% and 1.5 wt.%) on biodegradable starch films were investigated. Extrusion/thermo-compression process increased in 90% the mechanical resistance of starch films produced following the casting methodology and decreased their moisture content, water solubility and water vapor permeability in 35%, 23%, and 50%, respectively. In the presence of the protein, the mechanical properties (Young modulus and stress at break) and the water tolerance improved due to the crosslinking phenomenon prompted between the protein and the polymeric backbone, being these effects more pronounced on the extruded formulations. All samples resulted thermal stable until 240 °C and biodegraded in compost in 5 weeks. This work revealed that extrusion/thermo-compression process and proteins as crosslinking of starch are two alternatives to improve the drawbacks of starch-based materials.
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Interest in biodegradable edible films as packaging or coating has increased because their beneficial effects on foods. In particular, food products are highly dependents on thermal stability, integrity and transition process temperatures of the packaging. The present work describes a complete data of the thermal degradation and dynamic mechanical properties of starch-glycerol based films with citric acid (CA) as crosslinking agent described in the article titled: "Biodegradable and non-retrogradable eco-films based on starch-glycerol with citric acid as crosslinking agent" González Seligra et al. (2016) [1]. Data describes thermogravimetric and dynamical mechanical experiences and provides the figures of weight loss and loss tangent of the films as a function of the temperature.
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Biodegradable and non-retrogradable starch-glycerol based films were obtained using citric acid (CA) as crosslinking agent at 75°C. This material allowed decreasing water vapor permeability (WVP) more than 35%, remained amorphous for at least 45 days as a result of the network formed by the CA that avoided starch retrogradation and maintained the degradability in compost, occurring only six days after the films without citric acid. A simulation of the gelatinization process of starch-glycerol with and without CA, using a differential thermal analysis device, showed that the system with CA completed the gelatinization 5°C before than the other and, CA first reacted with glycerol and then starch-glycerol-CA reaction occurred. The temperature at which the gelatinization process was carried out was critical to obtain the best results. An increase of gelatinization process temperature at 85°C in system with CA, led to a worsening on WVP and its integrity after a swelling process with dimethylsulphoxide (DMSO), compared to the films processed at 75°C.