Transparent bionanocomposites with improved properties prepared from acetylated bacterial cellulose and poly(lactic acid) through a simple approach

The preparation and characterization of biocomposite materials with improved properties based on poly(lactic acid) (PLA) and bacterial cellulose, and, for comparative purposes, vegetal cellulose fibers, both in their pristine form or after acetylation, is reported. The composite materials were obtained through the simple and green mechanical compounding of a PLA matrix and bacterial cellulose nanofibrils (or vegetable fibers), and were characterized by TGA, DSC, tensile assays, DMA, SEM and water uptake. The bionanocomposites obtained from PLA and acetylated bacterial cellulose were particularly interesting, given the considerable improvement in thermal and mechanical properties, as evidenced by the significant increase in both elastic and Young moduli, and in the tensile strength (increments of about 100, 40 and 25%, respectively) at very low nanofiller loadings (up to 6%). These nanocomposites also showed low hygroscopicity and considerable transparency, features reported here for the first time.FCT - PTDC/QUI/68472/2006FCT - SFRH/BPD/63250/2009FCT - L. C. T/ E. T.FCT-CAPES 2009FCT - National Program for Scientific Re-equipmentRede/1509/RME/2005REEQ/515/CTM/200

Physical and Antimicrobial Properties of Compression-Molded Cassava Starch-Chitosan Films for Meat Preservation

[EN] Cassava starch-chitosan films were obtained by melt bending and compression molding, using glycerol and polyethylene glycol as plasticizers. Both the starch/chitosan and the polymer/plasticizer ratios were varied in order to analyze their effect on the physical properties of the films. Additionally, the antimicrobial activity of 70:30 polymer:plasticizer films was tested in cold-stored pork meat slices as affected by chitosan content. All film components were thermally stable up to 200 A degrees C, which guaranteed their thermostability during film processing. Starch and chitosan had limited miscibility by melt blending, which resulted in heterogeneous film microstructure. Polyethylene glycol partially crystallized in the films, to a greater extent as the chitosan ratio increased, which limited its plasticizing effect. The films with the highest plasticizer ratio were more permeable to water vapor, less rigid, and less resistant to break. The variation in the chitosan content did not have a significant effect on water vapor permeability. As the chitosan proportion increased, the films became less stretchable, more rigid, and more resistant to break, with a more saturated yellowish color. The incorporation of the highest amount of chitosan in the films led to the reduction in coliforms and total aerobic counts of cold-stored pork meat slices, thus extending their shelf-life.The authors acknowledge the financial support provided by the Spanish Ministerio de Economia y Competividad (Projects AGL2013-42989-R and AGL2016-76699-R). Author Cristina Valencia-Sullca thanks the Peruvian Grant National Program (PRONABEC Grant).Valencia-Sullca, CE.; Atarés Huerta, LM.; Vargas, M.; Chiralt, A. (2018). Physical and Antimicrobial Properties of Compression-Molded Cassava Starch-Chitosan Films for Meat Preservation. Food and Bioprocess Technology. 11(7):1339-1349. https://doi.org/10.1007/s11947-018-2094-5S13391349117Alves, V. 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Thermoplastic cassava starch-chitosan bilayer films containing essential oils

[EN] Starch-chitosan bilayer films, containing or not essential oils in the casted chitosan layer were obtained by thermo-compression. Bilayer films exhibited a good interfacial adhesion and better mechanical resistance than starch monolayers, although they were less stretchable and less transparent. Starchchitosan films were effective at controlling the bacterial growth in pork meat, but the thermal treatment applied to obtain the bilayers reduced their antimicrobial properties as compared to chitosan monolayers. The addition of essential oils did not promote any antimicrobial action in chitosan mono and bilayer films applied to pork meat. The final amount of essential oils in the films was very limited probably due to the losses occurred during film processing method. Other strategies to incorporate the essential oils into chitosan-based films should be used to improve their final retention in the film matrix and their effective release into the coated food. (C) 2017 Elsevier Ltd. All rights reserved.The authors acknowledge the financial support provided by the Spanish Ministerio de Economia y Competividad (Projects AGL2013-42989-R and AGL2016-76699-R). Author Cristina Valencia-Sullca thanks the Peruvian Grant National Program (PRONABEC).Valencia-Sullca, CE.; Vargas, M.; Atarés Huerta, LM.; Chiralt, A. (2018). Thermoplastic cassava starch-chitosan bilayer films containing essential oils. Food Hydrocolloids. 75:107-115. https://doi.org/10.1016/j.foodhyd.2017.09.008S1071157