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Although a lot of research has been done into modelling microbial processes, the applicability of these concepts to problems specific for bioreactor design and optimization of process conditions is limited. This is partly due to the tendency to separate the two essential factors of bioreactor modelling, i.e. physical transport processes and microbial kinetics. The deficiencies of these models become especially evident in industrial production processes where O 2 supply is likely to become the limiting factor, e.g. production of gibberellic acid and other organic acids. Hydrodynamics, mass transfer and rheology of gibberellic acid production by Gibberella fujikuroi in an airlift bioreactor is presented in this work. Important hydrodynamic parameters such as gas holdup, liquid velocity in the riser and in the downcomer, and mixing time were determined and correlated with superficial gas velocity in the riser. Mass transfer was studied evaluating the volumetric mass transfer coefficient, which was determined as a function of superficial gas velocity in the riser and as a function of fermentation time. Culture medium rheology was studied through fermentation time and allowed to explain the volumetric mass transfer coefficient behaviour. Rheological behaviour was explained in terms of changes in the morphology of the fungus. Finally, rheological studies let us obtain correlations for gas holdup and volumetric mass transfer coefficient estimation using the superficial gas velocity in the riser and the culture medium apparent viscosity.

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In this study, total phenolics, total flavonoids, hesperidin and ascorbic acid contents in bagasse, juice and seed of mexican sweet lime (Citrus limetta) and mandarine (Citrus reticulata) were determined at two commercial maturity stages (maturation index), as well as their bactericidal effect on Escherichia coli and Staphylococcus aureus. The results showed that bagasses had the highest total phenolics, total flavonoids, and hesperidin content for both, C. limetta, and C. reticulata; highest ascorbic acid contents were found in C. limetta juice (3.36 ± 0.25 mg g -1 DW) and C. reticulata bagasse (3.83 ± 0.37 mg g -1 DW). All tested extracts showed bacterial growth inhibition at 50 and 800 lg mL -1 . Bagasse extracts of both fruits showed the highest inhibitions ([90%) on tested bacteria. Total phenolics, total flavonoids, and hesperidin contents, as well as bactericidal effect increased with maturity. Results indicated that both Mexican citric fruits (C. limetta and C. reticulata) were good sources of antioxidant and bactericidal agents.

Characterize the content of phytochemical compounds present in samples of extracts of strawberry (Fragaria sp.) and blackberry (Rubus sp.). The extraction of said compounds was carried out with solutions of polar solvents, such as acetone, ethanol and methanol, using an experimental design with three factors: state of maturity, resting time and temperature. The characterization of these fruits is the beginning of the utilization mainly of ellagitannins to produce ellagic acid. Total phytochemical content was determined by spectrophotometric techniques, for phenolic content it was used Folin-Ciocalteu, for flavonoids it was determined with aluminium chloride, the antioxidant activity was evaluated by the methods of DPPH and ABTS + , the bactericidal effect of the extracts was shown for strains of E. coli and S. aureus. The determination of ellagitannins was performed by spectrometry. The influence of the state of maturity on the response variable was evaluated; it was observed that concentration of phytochemicals increases proportionally to maturity stage. The antioxidant activity was evaluated, determining that extracts obtained exhibit 94%-95% inhibition. The determination of ellagitannins, finding that the highest concentration of ellagitannins was found in a state of green maturity, for strawberries as well as blackberries.

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Lignocellulosic residues are an important biomass source in Mexico, which can be considered as starting materials for obtaining carbon materials. In this work, carbon materials were produced by pyrolysis of agave fiber (AF). The results obtained revealed that the hydrothermal process was successfully used for the synthesis of carbon fibers and subsequently potentiate the production of graphite sheets and graphene oxide (GO), after determining and optimizing the reaction conditions. The formation of graphite and GO was indicated by XRD, Raman spectroscopy and TGA thermal analysis, the latter evaluated the carbon oxidation range. Scanning electron microscope showed the samples morphology and microstructure of the AF Tequilana Weber and the synthesized products (Graphite-600 °C, GO-800 °C and GO-1000 °C), being all of them carbon allotropes, they presented size and variable thickness, with potential surface characteristics useful in various industrial applications. The hydrothermal and thermal processes were considered an economic and environmental way of obtaining materials under inert conditions, especially to produce GO, which is a material that has many useful properties and a plethora of new applications, like a more affordable support for catalysts, absorbent, semiconductor.