Desarrollo y caracterización de recubrimientos comestibles con base en quitosano funcionalizado enzimáticamente
Currently, there is a growing interest in sustainable polymers particularly in basic applications such as packaging, edible films and coatings which biodegrade under controlled conditions of storage in order to alleviate the growing global synthetic materials waste problem. In this regard, the chito...
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| Format: | doctoral thesis |
| Status: | Published version |
| Publication Date: | 2014 |
| Country: | México |
| Institution: | Universidad Autónoma Metropolitana |
| Repository: | Repositorio Institucional de la UAM Iztapalapa |
| Language: | Spanish |
| OAI Identifier: | oai:bindani.izt.uam.mx:kh04dp79j |
| Online Access: | https://doi.org/10.24275/uami.kh04dp79j |
| Access Level: | Open access |
| Keyword: | info:eu-repo/classification/LEM/Chitosan info:eu-repo/classification/LEM/Quitosano info:eu-repo/classification/LEM/Biopolímeros info:eu-repo/classification/LEM/Biotechnology info:eu-repo/classification/LEM/Enzymes info:eu-repo/classification/LEM/Enzimas info:eu-repo/classification/LEM/Biopolymers info:eu-repo/classification/LEM/Biotecnología info:eu-repo/classification/cti/6 |
| Summary: | Currently, there is a growing interest in sustainable polymers particularly in basic applications such as packaging, edible films and coatings which biodegrade under controlled conditions of storage in order to alleviate the growing global synthetic materials waste problem. In this regard, the chitosan and its derivatives have demonstrated great potential as biological packaging material due to its inherent antimicrobial power, non-toxic characteristics, filmforming material as well as their versatile physical and chemical properties as several researchers have highlighted in recent reviews. As a result of the interest in this biomacromolecule, a wide range of chitosan-based materials have been proposed by means of suitable chemical or enzymatic modifications onto the polymer backbone to improve its solubility in water, antimicrobial properties, flocculant capacity, absorbency and adhesiveness, while remaining biodegradable and biocompatible for potential applications in biomedicine, food or water treatment. Chemical modifications mainly consisted in the insertion of small functional groups such as alkyl, carboxymethyl, saccharides or oligosacharides for increasing the Ch solubility at neutral and alkaline pH without affecting its cationic character. Other compounds like cyclodextrins, and acids, such as p-aminobenzoic, lactobionic, sialic and polyacrylic have also been attached to confer removal capacity of textile dyes, drug delivery, wound healing, inhibition of microorganisms, antioxidant capacity and increasing hydrophilicity. Despite of the possibility to modify chitosan by chemical means, enzymatic modifications offer alternative routes, especially in products to be applied in foodstuffs due to minimized hazards associated with toxic reagents, in addition to mild and environmentally friendly reaction conditions. The enzyme grafting of hydrophobic alkyl side chains onto Chitosan has been successfully achieved in the present work using octyl gallate and horseradish peroxidase as biocatalyst. The chemical structures of the octyl gallate-grafted Ch were corroborated by ATR-FTIR, 1 HRMN, ζ potential, and amino group content, The properties of the resulting materials have been studied by rheology, Intrinsic viscosity, antioxidant capacity by electron paramagnetic resonance (EPR) spectroscopy and antimicrobial activity in order to envisage its potential applications. The antioxidant capacity of materials determined by EPR shows that in functionalized chitosans, the radical scavenging increases with grafting, which was related to the aromatic ring in the octyl gallate. The chitosan with the highest grafting exhibited an antioxidant capacity of 81%. The amino groups increased with the grafting degree, which is related to the antimicrobial activity. Solutions of the materials in acetic acid and lactic acid exhibited a shear-thinning flow behavior which also increased with the grafting. The viscoelastic properties of solutions were characterized by oscillatory shear measurement and the result showed fluid-like viscoelastic behavior. The elasticity of the solutions decreased with the plasticizer addition. The chitosan with a higher grafting degree in acetic acid solution displayed the best viscoelastic properties that offer structure and stability which are desirable for the development of films or coatings. The derivatives exhibited fungicidal activity in vitro against the phytopathogenic fungi Rhizopus stolonifer and Colletotrichum gloeosporioides. Additionally, edible films were prepared from chitosan-co-octyl gallate and characterized by gas barrier, mechanical and topological properties. Topologically edible films based on QOG2 and QOG2 glycerol has a slightly rough and porous structure, this was reflected in the increase of the mechanical and gas barrier properties, tensile strength, elongation percentage and water vapor permeability (10.33 ± 0.06 kPa, 4.11 ± 0.09 % y 6.35 ± 0.38 x 10⁻⁴ g mmh⁻¹ m⁻² kPa⁻¹ ). Regarding to the edible films it was found that the velocity of weight loss decreased compared to the control, the weight loss of the coated Anjou pears was 2%, while for the Ataulfo mangoes weight loss was 8%. |
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