Films biodegradables a base de almidón de maíz y policaprolactona: efecto del ácido cítrico como agente de entrecruzamiento

[ES] El objetivo del presente trabajo es estudiar la influencia de la incorporación del ácido cítrico en las propiedades estructurales, térmicas y fisicoquímicas de films biodegradables a base de almidón de maíz y policaprolactona (PCL), obtenidas mediante el método de moldeo por compresión, para su posterior aplicación en el envasado de alimentos. Se prepararon once formulaciones con distinta relación almidón: PCL (100:0, 90:10, 80:20, 70:30, 60:40 y 0:100) con y sin ácido cítrico, la relación almidón: ácido cítrico fue de 1: 0.01. A cada una de estas formulaciones se le adicionó glicerol siendo un 30% del total del almidón presente. Se caracterizaron los films en base a sus propiedades nano- y micro-estructurales (AFM, rayos X y SEM), propiedades térmicas y propiedades físico-químicas (propiedades mecánicas, humedad, disolución en agua, ácido cítrico ligado, propiedades barrera y propiedades ópticas). Los resultados obtenidos del análisis de las propiedades nano- y micro-estructurales y propiedades térmicas parecen indicar que el ácido cítrico favorece la dispersión de un polímero en otro, aunque este efecto de miscibilidad es poco patente en las propiedades macroscópicas, salvo en las formulaciones con proporción 80 de almidón y, sobre todo con 90, donde sí parece que la miscibilidad parcial entre el almidón y la policaprolactona afecta a las propiedades de los films.[EN] The aim of this work was to study the influence of the addition of citric acid in the structural, thermal and physicochemical properties of corn starch and polycaprolactone (PCL) based biodegradable films and obtained by the compression molding method, for subsequent application in food packaging. Eleven formulations were prepared with different ratio starch: PCL (100:0, 90:10, 80:20, 70:30, 60:40 and 0:100) with or without citric acid, the ratio starch: citric acid was 1 0.01. To each of these formulations was added glycerol being 30% of the total starch present. Films were characterized based on their properties nano-and micro-structural (AFM, SEM and X-rays), thermal and chemical properties (mechanical properties, humidity, dissolution in water, bound citric acid, optical properties and barrier properties). The results of the analysis of the properties nano-and micro-structural and thermal properties suggest that citric acid promotes the dispersion of one polymer in another, although this effect is little miscibility patent macroscopic properties except in the formulations starch ratio and 80, especially 90, where it seems that partial miscibility between starch and polycaprolactone affects the properties of the films.[CA] L'objectiu del present treball és estudiar la influència de la incorporació de l'àcid cítric en les propietats estructurals, tèrmiques i fisicoquímiques de films biodegradables a base de midó de dacsa i policaprolactona (PCL), obtingudes per mitjà del mètode de modele per compressió, per a la seua posterior aplicació en l'envasament d'aliments. Es van preparar onze formulacions amb distinta relació midó: PCL (100:0, 90:10, 80:20, 70:30, 60:40 i 0:100) amb i sense àcid cítric, la relació midó: àcid cítric va ser d'1: 0.01. A cada una d'estes formulacions se li va addicionar glicerol sent un 30% del total del midó present. Es van caracteritzar els films basant-se en les seues propietats nano- i microestructurals (AFM, rajos X i SEM), propietats tèrmiques i propietats fisicoquímiques (propietats mecàniques, humitat, dissolució en aigua, àcid cítric lligat, propietats barrera i propietats òptiques). Els resultats obtinguts de l'anàlisi de les propietats nano- i microestructurals i propietats tèrmiques pareixen indicar que l'àcid cítric afavorix la dispersió d'un polímer en un altre, encara que este efecte de miscibilitat és poc patent en les propietats macroscòpiques, excepte en les formulacions amb proporció 80 de midó i, sobretot amb 90, on sí que pareix que la miscibilitat parcial entre el midó i la policaprolactona afecta les propietats dels films.Collazo Bigliardi, S. (2013). Films biodegradables a base de almidón de maíz y policaprolactona: efecto del ácido cítrico como agente de entrecruzamiento. http://hdl.handle.net/10251/33929.Archivo delegad

Isolation and characterisation of microcrystalline cellulose and cellulose nanocrystals from coffee husk and comparative study with rice husk

[EN] Cellulosic material from coffee husk has not been previously studied despite being a potential source of reinforcing agents for different applications. This material has been extracted and characterised from coffee husk, in parallel with previously studied rice husk. Samples have been analysed as to their ability to obtain cellulosic fibres and cellulose nanocrystals (CNC) by applying alkali and bleaching treatments and final sulphuric acid hydrolysis. Microstructural changes were analysed after treatments, and the size and aspect ratio of CNCs were determined. Crystallinity and thermal stability of both materials progressed in line with the enrichment in cellulosic compounds. The CNC aspect ratio was higher than 10, which confers good reinforcing properties. These were tested in thermoplastic starch films, whose elastic modulus increased by 186 and 121% when 1 wt% of CNCs from rice and coffee husks, respectively, was incorporated into the matrix. Coffee husk represents an interesting source of cellulosic reinforcing materials.The authors thank the Ministerio de Economia y Competitividad (Spain) for the financial support provided through Project AGL2016-76699-R. Authors also thank the Electron Microscopy Service of the UPV for their technical assistance.Collazo-Bigliardi, S.; Ortega-Toro, R.; Chiralt, A. (2018). Isolation and characterisation of microcrystalline cellulose and cellulose nanocrystals from coffee husk and comparative study with rice husk. Carbohydrate Polymers. 191:205-215. https://doi.org/10.1016/j.carbpol.2018.03.022S20521519

Influence of citric acid on the properties and stability of starch-polycaprolactone based films

[EN] The influence of citric acid (CA) on structural and physicochemical properties of blend films based on corn starch and polycaprolactone (PCL) was studied. Films were obtained by melt blending of starch and PCL and compression molding. Phase separation of polymers observed by scanning electron microscope and atomic force microscope was reduced by CA incorporation. CA affected both starch and PCL crystallization as deduced from the X-ray diffraction patterns and values of melting enthalpy. Glass transition of starch was reduced by PCL incorporation, while this occurred to a greater extent in films containing CA. Obtained results point to enhanced interactions between PCL and starch chains in films with CA, although this only quantitatively benefits the film properties at a low PCL ratio. Compounding starch with small amounts of PCL, using glycerol and CA, can supply films with better functional properties than net starch films.The authors acknowledge the financial support from the Spanish Ministerio de Educacion y Ciencia throughout the projects AGL2010-20694 and AGL2013-42989-R. Rodrigo Ortega-Toro thanks the Conselleria de Educacio de la Comunitat Valenciana for the Santiago Grisolia grant. Authors also thank the Electron Microscopy Service of the UPV for their technical assistance.Ortega Toro, R.; Collazo-Bigliardi, S.; Talens Oliag, P.; Chiralt, A. (2015). Influence of citric acid on the properties and stability of starch-polycaprolactone based films. Journal of Applied Polymer Science. 133(2):1-16. doi:10.1002/app.42220S1161332Flieger, M., Kantorová, M., Prell, A., Řezanka, T., & Votruba, J. (2003). Biodegradable plastics from renewable sources. Folia Microbiologica, 48(1), 27-44. doi:10.1007/bf02931273GARCIA, M., PINOTTI, A., MARTINO, M., & ZARITZKY, N. (2004). 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Physical properties of edible modified starch/carboxymethyl cellulose films. Innovative Food Science & Emerging Technologies, 11(4), 697-702. doi:10.1016/j.ifset.2010.06.001Ortega-Toro, R., Jiménez, A., Talens, P., & Chiralt, A. (2014). Properties of starch–hydroxypropyl methylcellulose based films obtained by compression molding. Carbohydrate Polymers, 109, 155-165. doi:10.1016/j.carbpol.2014.03.059Reddy, N., & Yang, Y. (2010). Citric acid cross-linking of starch films. Food Chemistry, 118(3), 702-711. doi:10.1016/j.foodchem.2009.05.050Thiebaud, S., Aburto, J., Alric, I., Borredon, E., Bikiaris, D., Prinos, J., & Panayiotou, C. (1997). Properties of fatty-acid esters of starch and their blends with LDPE. Journal of Applied Polymer Science, 65(4), 705-721. doi:10.1002/(sici)1097-4628(19970725)65:43.0.co;2-oShi, R., Zhang, Z., Liu, Q., Han, Y., Zhang, L., Chen, D., & Tian, W. (2007). Characterization of citric acid/glycerol co-plasticized thermoplastic starch prepared by melt blending. Carbohydrate Polymers, 69(4), 748-755. doi:10.1016/j.carbpol.2007.02.010Chabrat, E., Abdillahi, H., Rouilly, A., & Rigal, L. (2012). Influence of citric acid and water on thermoplastic wheat flour/poly(lactic acid) blends. I: Thermal, mechanical and morphological properties. Industrial Crops and Products, 37(1), 238-246. doi:10.1016/j.indcrop.2011.11.034Labet, M., & Thielemans, W. (2009). Synthesis of polycaprolactone: a review. Chemical Society Reviews, 38(12), 3484. doi:10.1039/b820162pOlivato, J. B., Grossmann, M. V. E., Yamashita, F., Eiras, D., & Pessan, L. A. (2012). Citric acid and maleic anhydride as compatibilizers in starch/poly(butylene adipate-co-terephthalate) blends by one-step reactive extrusion. Carbohydrate Polymers, 87(4), 2614-2618. doi:10.1016/j.carbpol.2011.11.035Wang, N., Yu, J., Chang, P. R., & Ma, X. (2007). Influence of Citric Acid on the Properties of Glycerol-plasticized dry Starch (DTPS) and DTPS/Poly(lactic acid) Blends. 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Antifungal starch-based edible films containing Aloe vera

[EN] Aloe vera gel, analysed as to its antifungal properties against six fungi causing plant diseases, was found to be most effective against Fusarium oxysporum. It was included in different ratios in starch based films plastiziced with glycerol to obtain antifungal films. These were characterized as to their physical (barrier and optical) and structural properties. Films containing the highest ratio of Aloe vera solids (1:1, with respect to starch) and different glycerol mass ratios with respect to starch (0.15 and 0.25) were analysed as to the water sorption and water plasticization effects, in order to discover the water sensitivity of the films in different RH ambients. Films with 0.15 g glycerol/g starch were more homogenous, with a lower degree of starch crystallization, reduced water vapour permeability and higher gloss and transparency. These films with the highest Aloe vera ratio were effective at controlling fungal decay and weight loss in cherry tomatoes. (C) 2017 Elsevier Ltd. All rights reserved.The authors acknowledge the financial support from the Spanish Ministerio de Economia y Competitividad throughout the project AGL2013-42989-R and AGL2016-76699-R. Rodrigo Ortega-Toro thanks Universidad Nacional Abierta y a Distancia from Colombia for their support through project PIE-01 2016. Authors also thank the Electron Microscopy Service of the Universitat Politecnica de Valencia for their technical assistance.Ortega-Toro, R.; Collazo-Bigliardi, S.; Rosello Caselles, J.; Santamarina Siurana, MP.; Chiralt, A. (2017). Antifungal starch-based edible films containing Aloe vera. Food Hydrocolloids. 72:1-10. https://doi.org/10.1016/j.foodhyd.2017.05.023S1107

Lignocellulosic fractions from rice and coffee husks to improve functionality of biodegradable films based on starch and poly-lactic acid

Tesis por compendio[ES] La presente Tesis Doctoral se ha centrado en el aislamiento y caracterización de materiales celulósicos y extractos activos, procedentes de las cascarillas de arroz y café, y su incorporación a películas de almidón y mezclas compatibilizadas de almidón-PLA, para mejorar sus propiedades funcionales como materiales para el envasado de alimentos. Las fibras de celulosa (CF) se obtuvieron mediante tratamiento alcalino y de blanqueo, con un rendimiento de 41 y 53 g fibras/100 g cascarilla, respectivamente para cascarilla de arroz y café. Los nanocristales de celulosa (CNC) se aislaron de las fibras mediante hidrólisis ácida, con un rendimiento del 5% respecto a las fibras y con alta cristalinidad (90-92%), resistencia térmica y relación de aspecto (L/d: 20-40). Los compuestos activos se obtuvieron mediante extracción hidrotérmica (180 ºC; 9,5 bares), con un rendimiento de 17-18 g/ 100 g de cascarilla. Dichos extractos exhibieron capacidad antioxidante (EC50: 5,37-5,29 mg sólidos extraídos/ mg DPPH) y antimicrobiana (cuantificada en términos de concentración mínima inhibitoria: MIC) frente a L. innocua (MIC: 48-52 mg polvo/mL) y E. coli (MIC: 50-66 mg polvo/mL). Los materiales celulósicos procedentes de cascarilla de arroz y café se incorporaron a películas de almidón termoplástico (TPS), obtenidas mediante mezclado en fundido y moldeo por compresión. El módulo elástico aumentó un 186 y 121% cuando se incorporó a la matriz un 1% (p/p) de CNC de cascarilla de arroz y café, respectivamente. Del mismo modo, las CF se añadieron a las películas de TPS al 1, 5 y 10 pt%. Ambas CF aumentaron la rigidez y redujeron la extensibilidad de los films, aunque las CF de cascarilla de café mantuvieron mejor la ductilidad al 1 y 5% (p/p). La permeabilidad al vapor de agua de las películas de TPS no se redujo en los materiales compuestos, aunque la permeabilidad al oxígeno se redujo en aproximadamente un 17%. Al incorporar extractos activos a los films de almidón, mejoraron sus propiedades de tracción; el módulo elástico aumentó un 350%, a la vez que se hicieron menos extensibles. Las fibras de celulosa de ambos residuos fueron más efectivas como agentes de refuerzo en los films con extractos sólidos que en los de almidón solo. Se estudiaron también mezclas de almidón-PLA utilizando como compatibilizador policaprolactona funcionalizada con anhídrido maléico y/o glicidil metacrilato (PCLMG o PCLG). Se analizó el efecto de la proporción de PLA en la mezcla (20 y 40% respecto al almidón), y la de ambos compatibilizadores (2,5 y 5%), en las propiedades de los films. Los análisis de la microestructura, el comportamiento térmico y las propiedades funcionales (mecánicas, ópticas y de barrera) de los films, demostraron que sustituir el 20% del almidón por PLA e incorporar el 5% de PCLG podría ser una buena estrategia para obtener materiales adecuados para envasado de alimentos. Además, se estudió el efecto de la adición de rellenos celulósicos (CF y CNC) y del extracto antioxidante de cascarilla de café en la mezcla de almidón-PLA compatibilizada seleccionada. Las propiedades antioxidantes de los films se probaron a través de su eficacia para preservar al aceite de girasol de la oxidación. Se observaron diferencias significativas en las propiedades funcionales de los films cuando los CNC se incorporaron mediante dos métodos diferentes. El efecto de refuerzo de los materiales celulósicos en mezclas de S-PLA fue menos notable que en las películas de almidón, probablemente debido a la superposición del efecto de refuerzo de PLA. El extracto antioxidante no mejoró el comportamiento mecánico en la mezcla, pero le confirió capacidad antioxidante, adecuada para aplicaciones en el envasado de alimentos.[CA] La present Tesi Doctoral s'ha centrat en l'aïllament i caracteritzaciò de materials cel.lulòsics i extractes actius, procedents de pellorfa d'arròs i café, i la seua incorporació a pel·lícules de midó i mescles compatibilitzades de midò-PLA, per a millorar les seues propietats funcionals com materials per al envasat d'aliments. Les fibres de cel.lulosa (CF) s'obtingueren mitjançant tractament alcalí i de blanqueig, amb un rendiment de 41 i 53 g fibres/100g pellorfa, respectivament per a pellorfa d'arròs i cafè. Els nanocristalls de cel·lulosa (CNC) es van aïllar de les fibres de cel·lulosa per mig d'hidròlosi àcida, amb un rendiment del 5% respecte a les fibres; en tots dos casos, amb alta cristal·línitat (90-92%), resistència tèrmica i relaciò d'aspecte (L/d: 20-40). Els composts actius s'obtingueren mitjançant l'extracció hidrotèrmica (180 ºC; 9,5 bars), amb un rendiment del 17-18 g/100 g de pellorfa. Aquests composts exhibiren capacitat antioxidant (EC50: 5,37-5,29 mg extracte solit/ mg DPPH) i antimicrobiana, (quantificada en termes de concentració mínima inhibitòria: CMC) enfront a L. innocua (MIC: 48-52 mg pols/mL) i E. coli (MIC: 50-66 mg pols/ mL). Els materials cel·lulòsics procedents de pellorfa d'arròs i cafè es van incorporar a pel·lícules de midó termoplàstic (TPS), obtingudes mitjançant mesclat en fos i modelatge per compressió. El mòdul elàstic va augmentar un 186 i 121% quan es va incorporar a la matriu un 1 pt% CNC de pellorfa d'arròs i café, respectivament. De la mateixa manera, les CF es van afegir a les pel·lícules de TPS al 1, 5 i 10 pt%. Ambdues CF va augmentar la rigidesa de les pel·lícules i es va reduir la seua capacitat d'estirament. No obstant, les CF de pellorfa de cafè mantingueren millor la ductilitat al 1 i 5%. La permeabilitat al vapor d'aigua de les pel·lícules de TPS no es va reduir en els materials compostos, encara que la permeabilitat a l'oxigen es va reduir en aproximadament un 17%. A l'incorporar extractes actius a les pel·lícules de midó, milloraren les propietats de tracció de les pel·lícules ; el mòdul elàstic va augmentar un 350%, mentre que les pel·lícules es feren menys extensibles. Les CF dels dos residus foren més efectives com agents de reforç en pel·lícules que contenien extractes actius, que en pel·lícules de midó pur. També es van estudiar mescles de midò-PLA utilitzant com a compatibilitzador policaprolactona funcionalitzada amb anhídrid maleic i/o glicidil metacrilat (PCLMG o PCLG). Es va analitzar l'efecte de la proporció de PLA en la mescla (20 i 40% respecte al midó), i de la tots dues compatibilitzadors (2,5 i 5%), en les propietats de les pel·lícules. Els anàlisis de la microestructura, el comportament tèrmic i les propietats funcionals (mecàniques, óptiques i de barrera) de les pel·lícules, demostraren que substituir el 20% del midó per PLA i incorporar el 5% de PCLG podria ser una bona estratègia per a obtindré pel·lícules adequades per a l'envasat d'aliments. A demés, es va estudiar l'efecte de l'addició de reforçaments cel·lulòsics (CF i CNC) i extracte antioxidant de pellorfa de cafè, en mescles de midó-PLA compatibilitzades. Les propietats antioxidants de les pel·lícules s'analitzaren a través de la seua eficàcia per a preservar de l'oxidació l'oli de gira-sol. S'observaren diferències significatives en les propietats funcionals de les pel·lícules quan els CNC s'incorporaren mitjançant dos mètodes diferents. L'efecte de reforç dels materials cel·lulòsics en mescles de S-PLA va ser menys notable que en les pel·lícules de midó, provablement degut a la superposició de l'efecte de reforç del PLA. L'extracte antioxidant no va millorar el comportament mecànic en les mescles, però li va conferir la capacitat antioxidant adequada per a aplicacions a l'envasat d'aliments.[EN] This Doctoral Thesis has focused on the isolation and characterisation of cellulosic materials and active extracts from coffee and rice husks, and their incorporation into starch films and starch-PLA compatibilised blend films in order to improve their functional properties as food packaging materials. Cellulose fibres were obtained through alkali and bleaching treatment with a final yield of 41 and 53 g fibres/100 g husk, respectively for rice and coffee husks. Cellulose nanocrystals were isolated from the bleached fibres by acid hydrolysis, with a yield of 5% with respect to bleached fibres, in both cases, with high crystallinity (90-92%), thermal resistance and aspect ratio (L/d: 20-40). The active compounds were obtained by hydrothermal extraction (180 ºC, 9.5 bar) with yields of 17 -18 g/100 g husks. They exhibited antioxidant properties (EC50: 5.37-5.29 mg extract solids/mg DPPH) and antibacterial activity against L. innocua (MIC: 48-52 mg powder/mL) and E. coli (MIC: 50-66 mg powder/mL), which were quantified in terms of the minimal inhibitory concentration. Cellulosic material from rice and coffee husks were incorporated into thermoplastic starch films (TPS) by melt blending and compression moulding. The elastic modulus increased by 186 and 121% when 1 wt% of cellulose nanocrystals (CNC) from rice and coffee husks, respectively, was incorporated into the matrix. Likewise, cellulose fibres (CF) were incorporated into TPS films at 1, 5 and 10 wt%. Both CF increased the film stiffness while reducing its stretchability. However, CF from coffee husk better maintained the film ductility at 1 and 5 wt%. The water vapour permeability of TPS films was not reduced in composites, although oxygen permeability was lowered by about 17%. When active extracts were incorporated into starch films, they improved the tensile properties; the elastic modulus increased by about 350%, while films became less stretchable. The cellulosic fibres from both residues were more effective as reinforcing agents in films containing extract solids than in net starch films. Starch-PLA blend films were also studied using grafted polycaprolactone with maleic anhydride and/or glycidyl methacrylate (PCLMG or PCLG) as compatibilisers. The effect of both the PLA ratio in the blend (20 and 40% with respect to starch) and the amount of both compatibilisers (2.5 and 5%) on the film properties was analysed. The analyses of microstructure, thermal behaviour and functional properties (mechanical, optical and barrier) of the films led to the conclusion that substituting 20% of the starch by PLA, and incorporating 5% of PCLG would be a good strategy to obtain films suitable for food packaging. The effect of the addition of cellulosic fillers (CF and CNC) and antioxidant aqueous extract from coffee husk to compatibilised starch-PLA blends was also studied. The antioxidant properties of the films were tested through their efficacy at preserving sunflower oil from oxidation. Significant differences were observed in the functional properties of the films when CNC was incorporated by two different methods. The reinforcing effect of cellulosic materials in S-PLA blends was less noticeable than in starch films, probably due to the overlapping of the PLA reinforcing effect. The antioxidant extract did not improve the mechanical performance in the blends, but conferred antioxidant capacity suitable for food packaging applications.Collazo Bigliardi, S. (2019). Lignocellulosic fractions from rice and coffee husks to improve functionality of biodegradable films based on starch and poly-lactic acid [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/123055TESISCompendi

Reinforcement of Thermoplastic Starch Films with Cellulose Fibres Obtained from Rice and Coffee Husks

[EN] Cellulosic fibres from coffee (CF) and rice (RF) husks have been obtained applying chemical treatments and characterized as to their microstructure and thermal behaviour. These materials have been incorporated into glycerol plasticised thermoplastic starch (TPS) films obtained by melt blending and compression moulding at 1 wt%, 5 wt% and 10 wt%. Microstructure, thermal behaviour and optical, tensile and barrier properties of the composites were analysed. Both kinds of micro-fibres improve the film stiffness while reduced the film stretchability. However, CF better maintained the film ductility at 1 and 5 wt%. A network of fine oriented fibres was observed on the surface of the films, while internal fibres exhibited a good adherence to the polymer network. The water vapour permeability of TPS films was not reduced in composites, although oxygen permeability was lowered by about 17%. Film transparency decreased by fibre addition in the UVVIS range. Thermal stability of composites was slightly higher than net TPS films.The authors thank the Ministerio de Economía y Competitividad (Spain) for the financial support provided through Project AGL2016-76699-R. Authors also thank the Electron Microscopy Service of the UPV for their technical assistance.Collazo-Bigliardi, S.; Ortega-Toro, R.; Chiralt, A. (2018). Reinforcement of Thermoplastic Starch Films with Cellulose Fibres Obtained from Rice and Coffee Husks. Journal of Renewable Materials (Online). 6(6):599-610. https://doi.org/10.32604/JRM.2018.00127S5996106

Using grafted poly(epsilon-caprolactone) for the compatibilization of thermoplastic starch-polylactic acid blends

[EN] Thermoplastic starch (S) and polylactic acid (PLA) blend films were obtained by melt blending and compression moulding using grafted polycaprolactone with maleic anhydride and/or glycidyl methacrylate (PCLMG or PCLG) as compatibilizers. The effect of both the PLA ratio in the blend (20 and 40% with respect to starch) and the amount of both compatibilizers (2.5 and 5%) on the film properties was analysed. Compatibilized blends presented a better dispersion of the PLA in the continuous starch phase, but the use of PCLG provoked a phase inversion in the matrix when 40% of the starch was substituted by PLA. The compatibilized blend films exhibited higher values of elastic modulus than pure starch films, but were less extensible. The use of compatibilizers did not affect the film's water vapour permeability, which was reduced by up to 33 or 50% for 20 and 40% PLA, respectively, although inverted films with 40% PLA and 5% PCLG exhibited marked reduction (67%). Compatibilizers decreased the oxygen permeability of the films by about 50%, regardless of the ratio of PLA and the kind and amount of compatibilizer. Therefore, substituting 20% of the starch by PLA and incorporating 5% of PCLG would be a good strategy to obtain films useful for food packaging.The authors thank the Ministerio de Economia y Competitividad (Spain) for the financial support provided through Project AGL2016-76699-R. The authors also wish to thank the Electron Microscopy Service of the UPV for their technical assistance.Collazo-Bigliardi, S.; Ortega-Toro, R.; Chiralt, A. (2019). Using grafted poly(epsilon-caprolactone) for the compatibilization of thermoplastic starch-polylactic acid blends. Reactive and Functional Polymers. 142:25-35. https://doi.org/10.1016/j.reactfunctpolym.2019.05.013S253514

Comparative study of active edible coatings based on Yam Starch and Cassava Starch

Objetivo. Comparar las propiedades de materiales comestibles activos a comestibles activos a base de almidón de ñame y de yuca con la incorporación de aceite esencial de orégano (Origanum vulgare) (OEO) para aplicación en recubrimiento de uvas. Materiales y métodos. Se obtuvieron las dispersiones formadoras de películas y se determinó el ángulo de contacto sobre diferentes cortezas de frutas y verduras y la estabilidad de las dispersiones. Posteriormente se obtuvieron las películas mediante casting se evaluaron sus propiedades fisicoquímicas como capacidad antioxidante, capacidad antimicrobiana, entre otras. Con los mejores tratamientos se procedió hacer un recubrimiento de uvas y se hizo seguimiento de pérdida de peso e inspección visual sobre su estado. Resultados. Se evidenciaron diferencias remarcables entre los materiales obtenidos a partir de estas dos fuentes de almidón. Las dispersiones de ñame mostraron ser más estables, adicionalmente, sus películas presentaron mayor contenido de humedad, menor capacidad de absorción de agua, mayor transmitancia interna y ligeramente mayor capacidad antimicrobiana y antioxidante. Conclusiones. En la aplicación como recubrimiento, se observó que las uvas recubiertas con dispersiones a base de ñame perdían peso a menor velocidad, conservándose en buen estado por mayor tiempo, evidenciando un mayor potencial en la conservación de frutas en comparación con el almidón de yuca.Aim. To compare the properties of active edible materials to active edible based on yam and cassava starch with the incorporation of essential oil of oregano (Origanum vulgare) (OEO) for application in grape coating. Materials and methods. The film-forming dispersions were obtained and the contact angle on different kinds of fruits and vegetables and the stability of the dispersions were determined. Subsequently, the films were obtained by casting, their physicochemical properties were evaluated, such as antioxidant capacity, antimicrobial capacity, among others. The grapes were covered with the best treatments and weight loss was traced and a visual inspection of their condition was carried out. Results. Remarkable differences were evident between the materials obtained from these two starch sources. The yam dispersions showed to be more stable, additionally, their films had higher moisture content, lower water absorption capacity, higher internal transmittance and slightly higher antimicrobial and antioxidant capacity. Conclusions. In the application as a coating, it was observed that the grapes coated with yam-based dispersions lost weight at a slower rate, maintaining them in good condition for a longer time, evidencing a greater potential in this type of applications compared to cassava starch