José Venegas González

Enzymatic production of high fructose syrup from Agave tequilana fructans and its physicochemical characterization

®). Both syrups behave as Newtonian fluids and showed no significant differences (p < 0.05) in density, moisture, water activity, total solids, total reducing sugars and direct reducing sugars. It takes 4.4 kg of fresh agave head to obtain 1 kg of syrup with 70°Brix and 87.92 ± 1.28% fructose. As a result of its highest fructose-glucose ratio, agave syrup has lower viscosity and surface tension than the corn syrup. Due to its high content of fructans, the head of the A. tequilana Weber var. blue is a promising raw material for the industrial production of high fructose syrups.

Influence of starch source in the required hydrolysis time for the production of maltodextrins with different dextrose equivalent

The starches were statistically different (p < 0.05) in their protein, ash, fat, phosphorus, amylose and amylopectin content. The amylose/amylopectin ratios in corn, potato and rice starches were 0.389, 0.282 and 0.220, respectively. The phosphorus content in the same order of starches was: 0.15 ± 0.01; 0.80 ± 0.02 and 0.95 ± 0.02 g/kg, respectively. The chemical composition of the different starches, and specifically its amylose and amylopectin content, its phosphorus content and the way it is bound to the starch molecule, affect the functional properties like the viscosity of gels and the enzymatic hydrolysis rate of these molecules. The rice starch is easily hydrolyzed by the a-amylase enzyme from Aspergillus oryzae and therefore, it required less time to obtain maltodextrin by enzymatic hydrolysis from rice starch compared with those from corn or potato starch. Under saturation conditions of the enzyme, the dextrose equivalent content was proportional to the hydrolysis time, regardless of the starting starch source. Key words : Starch, maltodextrins, dextrose equivalent, amylose, amylopectin.

HIDROQUÍMICA Y CONTAMINANTES EMERGENTES EN AGUAS RESIDUALES URBANO INDUSTRIALES DE MORELIA, MICHOACÁN, MÉXICO

In Mexico, 54 % of the wastewater generated is not treated and it is discharged into the water bodies, soils and irrigation canals, leading to a severe pollution problem. This represents a high risk to human health and aquatic biota. In recent decades, emerging contaminants have been detected in surface water in contact with raw and treated sewage. These compounds and their reactive metabolites cause severe toxicological effects on aquatic organisms and soil microorganisms even at low concentrations. The objective of this work was to analyze the physical and chemical properties: pH, electrical conductivity (EC), total dissolved solids (TDS), Ca 2+ , Mg 2+ , Na + , boron (B), total phosphorus (P) and trace metals (Mn, Zn, Fe and Cu), and to identify and quantify emerging contaminants (pharmaceuticals and drugs of abuse) in the influent and effluent of Wastewater Treatment Plant (WWTP) of Morelia, using standardized methodologies, such as infrared spectroscopy FT-IR and mass spectrometry ESI-TOFMS. The values of pH, EC, TDS, sodium adsorption ratio (SAR), B, P and trace metals were within the limits set by Mexican standards and international guidelines for wastewater reuse in agriculture. Emerging contaminants identified by ESI-TOF-MS were tetracycline, cefaclor, cefadroxil, ampicillin, clonazepam, lormetazepam, secobarbital, maprotiline, levothyroxine, cis-androsterone, paracetamol, lidocaine, brompheniramine, fexofenadine, amphetamine, morphine, benzoylecgonine, 11-nor-Δ9-THC-9-COOH, dimetilamfetamina, phencyclidine, methadone y polyethyleneglycol. The removal efficiency of these pollutants in the effluent was 25.8 %, with extremes of 0 and 74.5 % for polyethyleneglycol and methadone, respectively.