Browsing by Author "Lago, M.A."
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- Characterization of chitosan intended to develop antimicrobial films: Microscopical StudiesPublication . Lago, M.A.; Sendón, R.; Rodríguez-Bernaldo de Quirós, A.; Sanches-Silva, A.; Costa, H.S.; Sánchez-Machado, D.I.; Soto Valdez, H.; Angulo, I.; Aurrekoetxea, G.P.; López-Cervantes, J.; Paseiro, P.Accumulation of organic wastes in intensive crustaceans culture ponds and nearby coastal waters has become a serious environmental and economical problem. For this reason, new ecofriendly and economically feasible products from agricultural wastes or byproducts for shrimp farms have been developed. This biowaste could be used as an important source of the useful biopolymer chitin and others components such as proteins or carotenoids like asthaxanthin [1]. Chitin is the most abundant polysaccharide after cellulose and the main source is the shell of crustaceans. Chitosan, derived from chitin, has proven useful for a wide range of applications due to its biodegradability, biocompatibility, antimicrobial activity, non-toxicity and versatile physicochemical properties. These properties make the chitosan an excellent candidate to use in food packaging [2]. The development of active packaging with antimicrobial and antioxidant activity based on chitosan and asthaxanthin obtained from shrimp waste is the main goal of the project: “Preparation of active packaging with antioxidant and antimicrobial activity based on asthaxanthin and chitosan” funded by FONCYCIT. The characterization of chitosan in the development of active materials is a key issue since their properties play an important role in its effectiveness as an antimicrobial agent. These properties are mainly molecular weight (Mw), acetylation degree (DA) and polymerization degree (PA). In addition, in mediums of low pH, the antimicrobial activity of chitosan increases [3]. The objective of the present study was characterized three different samples of chitosan obtained from shrimp waste by using two microscopy techniques, Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). Additionally, the films developed after the chitosan incorporation in the polyamide matrix were also characterized. Shrimp waste (heads and cephalotorax) samples were collected from local shrimp processing factories in South Sonora, Mexico. The waste was minced, fermented and centrifuged. After the treatment, three fractions were obtained: chitin-rich fraction, protein rich liquor and lipid fraction. Scanning Electron Microscopy was used to investigate the structure properties relationships of chitosan. Samples were spread on a carbon conducting adhesive tape pasted on a metallic stub, subjected to gold covering and observed. The samples for TEM observation were embedded in EPON resin and polymerized at 60 ºC; then were cut at (-120 ºC) using a Leica Ultracut crio-ultramicrotome. The images obtained showed the particle of chitosan embedded into the polyamide matrix.
- Preparation and Characterization of Antimicrobial Films Based on Chitosan for Active Food Packaging ApplicationsPublication . Lago, M.A.; Sendón, R.; Rodríguez-Bernaldo de Quirós, A.; Sanches-Silva, A.; Costa, H.S.; Sánchez-Machado, D.I.; Soto Valdez, H.; Angulo, I.; Aurrekoetxea, G.P.; Torrieri, E.; López-Cervantes, J.; Paseiro, P.The aim of this paper was to characterize chitosan samples from the shrimp shells for the later development of antimicrobial active systems. These systems include 100 % chitosan-based films obtained by casting, polyamide films with 5 and 10 % of chitosan obtained by extrusion and polyethylene/polyethylene terephthalate films with a coating of 0.6 % of chitosan. For that purpose, several analytical techniques including IR, 1H NMR, GPC, and microscopic techniques (scanning electron microscopy and transmission electron microscopy) were used. Within the studied samples, C1 showed the lowest DA and MW and consequently presented the most suitable properties for the development of an active packaging. Additionally, mechanical properties were performed. The effectiveness of the developed systems was evaluated by means of microbiological assays. The tested films showed antimicrobial capacity against coliform enterobacteria, mesophilic aerobic microorganism, and yeast and moulds.
- Preparation, characterization and evaluation by FTIR and NMR of antimicrobial activity of chitosan active filmsPublication . Lago, M.A.; Sendón, R.; Rodríguez-Bernaldo de Quirós, A.; Bueno, C.; Sanches-Silva, A.; Costa, H.S.; Sánchez-Machado, D.I.; Soto Valdez, H.; Angulo, I.; Aurrekoetxea, G.P.; López-Cervantes, J.; Paseiro, P.One of the main causes of food spoilage is the development of microorganisms. In order to inhibit or retard the growth of microorganisms and consequently, improve food security and extend the shelf life of food products, in the past years, active packaging and particularly films with antimicrobial properties have attracted the attention of the scientists. One of the approaches used is to add chitosan to the film. Due to their excellent properties, non-toxic, biodegradable, biofunctional and biocompatible with others antimicrobials, chitosan is one of the antimicrobial agents most appropriate for the development of active materials [1]. Chitosan (CAS nº 9012-76-4) is a polysaccharide, with the structure of a linear polymer of (1-4)-linked 2-amino-deoxy-β-D-glucan, obtained by the partial deacetylation of chitin, one of the most abundant polysaccharides in nature, found in shells of crustaceans [2]. Shrimp waste (heads and cephalothorax) samples were collected from local shrimp processing factories in South Sonora, Mexico. The waste was minced, fermented and centrifuged. After the treatment, three fractions were obtained: chitin rich fraction, protein rich liquor and lipid fraction. In this work, Fourier Transformed Infrared Spectroscopy (FTIR) and Nuclear Magnetic Resonance (NMR) were used to characterize three different samples of chitosan. Moreover, 100% chitosan-based films and films of polyamide with chitosan incorporated were also evaluated. The degree of acetylation (DA) values obtained may change, depending on the nature and level of impurities, source and polymer morphologies [3]. To evaluate the DA, FTIR and NMR were used. The samples were prepared as a thin pellet made from a mixture of KBr and the chitosan powder. To evaluate the DA in films, Fourier Transform Total Reflection infrared Spectroscopy (FTIR-ATR) was used. All spectra were recorded in the range of 400-4000 cm-1. Nuclear Magnetic Resonance (NMR) was also employed to evaluate the DA. Two experiments were tentatively carried out: 1H NMR and 13C NMR. In both cases approximately 5 mg of each sample were diluted in 1 % (v/v) CD3COOD in D2O. All data were compared with three commercially available standards submitted to the same experiments as samples. The sample 1 corresponding to chitosan obtained from shrimp waste and with high viscosity presented the lowest DA, therefore had higher antimicrobial activity. Both techniques; FTIR and NMR, led to the same conclusion.