Octavio Cota-Arriola

Controlled release matrices and micro/nanoparticles of chitosan with antimicrobial potential: development of new strategies for microbial control in agriculture

The control of micro-organisms responsible for pre- and postharvest diseases of agricultural products, mainly viruses and fungi, is a problem that remains unresolved, together with the environmental impact of the excessive use of chemicals to tackle this problem. Current efforts are focused on the search for efficient alternatives for microbial control that will not result in damage to the environment or an imbalance in the existing biota. One alternative is the use of natural antimicrobial compounds such as chitosan, a linear cationic biopolymer, which is biodegradable, biocompatible and non-toxic, has filmogenic properties and is capable of forming matrices for the transport of active substances. The study of chitosan has attracted great interest owing to its ability to form complexes or matrices for the controlled release of active compounds such as micro- and nanoparticles, which, together with the biological properties of chitosan, has allowed a major breakthrough in the pharmaceutical and biomedical industries. Another important field of study is the development of chitosan-based matrices for the controlled release of active compounds in areas such as agriculture and food for the control of viruses, bacteria and fungi, which is one of the least exploited areas and holds much promise for future research.

Preparation of chitosan matrices with ferulic acid: physicochemical characterization and relationship on the growth of Aspergillus parasiticus

ABSTRACT Antioxidant, anticarcinogenic, and antimicrobial properties have been reported for ferulic acid (FA), therefore, its application interests both food and agriculture research. FA was immobilized in different chitosan (CS) matrices, physicochemicaly characterized and the effect on Aspergillus parasiticus ecological parameters evaluated. Nanoparticles (Nparticles), microparticles (Mparticles) and microcapsules (Mcapsules) of 35–40 nm, 30–40 μm, and 20 μm, respectively were obtained; FA incorporation in matrices affected their morphology, physicochemical properties, and their fungistatic effect. The effect of the particles was dependent on the matrix exposed. Nparticles and Mparticles showed high FA immobilization efficiency as well as a good fungistatic effect against A. parasiticus: Radial growth at 168 h was 28.46 ± 1.01 and 28.84 ± 1.36 and the inhibition of spore germination at 30 h was 57.44 ± 0.22 and 55.74 ± 2.19, for Nparticles and Mparticles, respectively compared with control cultures. Abnormalities in mycelium, hyphae, and spores morphology were observed, as well as low sporulation due particle interaction with the fungus.

Chymotrypsin isolation from jumbo squid (Dosidicus gigas) hepatopancreas: Partial characterization and effect on muscle collagen

Chymotrypsin was purified from jumbo squid hepatopancreas (HP) with 2.4-fold and yield 1.9%, and characterized with a molecular weight of 31 kDa, as estimated by sodium dodecyl sulfatepolyacrylamide gel electrophoresis (SDS-PAGE). Chymotrypsin effect over collagen extracted from the mantle, fins and arms of the jumbo squid was evaluated. The enzyme exhibited the maximum activity at pH 7 and 65°C using Suc-Ala-Ala-Pro-Phe-p-nitroanilide (SAAPNA) as a substrate and it was identified using the specific inhibitors N-tosyl-L-phenylalaninechloromethyl ketone (TPCK) and phenyl methyl sulfonyl fluoride (PMSF), showing residual activities of 6% and 0%, respectively. Furthermore, high activity was observed in the pH range of 4.0 to 8.0. Purified enzyme showed a moderate in vitro activity using muscle collagen as a substrate. Although further research is needed, the results suggest that the enzyme has a potential application where acidic or slightly alkaline conditions are needed.

Physicochemical changes of pepsin-solubilized and insoluble collagen in jumbo squid (Dosidicus gigas) muscle after cooking process

ABSTRACT Collagen is the major connective tissue (CT) protein and one of the main constituents of the jumbo squid (Dosidicus gigas). Therefore, physicochemical changes of pepsin-solubilized collagen (PSC) and insoluble collagen (IC) were studied after cooking (100°C/30 min) of muscle (mantle, fins, and arms). Different pyridinoline (Pyr) contents (the major cross-linking molecule in collagen fibers) were found in the fresh muscle of the three anatomical regions. After the cooking process, a decrease from 10 to 30% in the thermal resistance of collagen was observed, depending on the anatomical region and fraction evaluated. Furthermore, the electrophoretic profile, Fourier transform infrared (FTIR) spectroscopy, and the amino-acid profile revealed that structural changes occurred in the two different collagen fractions caused by the thermal process, and the changes were greater in the mantle. Under the conditions applied in this study, collagen fractions from the squid arms showed more stability during the cooking process due to the high cross-linking degree of their fibers.