Determination of the Concentration of Heavy Metals in Artisanal Cheeses Produced in the Mexican States of Tabasco and Chiapas.

Cheese consumption provides humans with minerals, proteins, carbohydrates, and vitamins. In Mexico, several cheese varieties are produced, each with its texture, scent, and flavor. The artisanal cheeses made in the states of Tabasco and Chiapas-including, among others, the varieties named crema (cream), doble crema (double cream), oaxaca, panela, fresco, bola, poro, cotija, and asadero-have a high demand in the domestic and foreign markets. The intensification of anthropic activity in these states causes an increased emission to the environment of contaminants like heavy metals, which could reach human foodstuffs through the food chains. In particular, heavy metal contents in cheeses consumed daily by these states' local populations might represent a public health risk. Because of that, our objectives in this work were to determine the concentrations of lead, cadmium, nickel, copper, zinc, and iron in artisanal cheeses produced in the states of Tabasco and Chiapas and to determine the values of the hazard quotient (HQ), total hazard quotient (THQ), and cancer risk total (CRT) for adult and young men and women. The results of our analyses of cheese samples from the states of Tabasco and Chiapas showed that the average concentrations (mg kg-1) of cadmium (0.0023 ± 0.002, 0.0023 ± 0.002 mg kg-1, respectively, for each state), lead (0.0047 ± 0.00, 0.0051 ± 0.002), nickel (0.0039 ± 0.0046, 0.0031 ± 0.0039), copper (0.0199 ± 0.021, 0.0202 ± 0.022), zinc (0.1611 ± 0.18, 0.194 ± 0.21), and iron (61.84 ± 4.23, 65.76 ± 6.61 mg kg-1), the first three values lower than the limits established by the FAO/WHO and Codex Alimentarius. The value of THQ that we obtained was less than one, and that of CRT was within the limits established by the US-EPA, which means that the consumption of artisanal cheeses from Tabasco and Chiapas by humans does not imply a risk of disease or cancer.

Biohydrogen production by Chlorella vulgaris and Scenedesmus obliquus immobilized cultivated in artificial wastewater under different light quality.

The algal biotechnology together with the wastewater treatment can contribute to the production of renewable energies such as bioethanol, biodiesel and biohydrogen and solve many of the challenges currently facing the shortage of fossil fuels and environmental impacts. Hydrogen as the cleanest source of energy is a promising alternative to conventional fossil fuels. Among different technologies for hydrogen production, photosynthetic microorganism, such as microalgae, has a great potential to produce hydrogen, by using only water and sunlight. One of the great opportunities is that microalgae can be cultivated in urban wastewater, which contains sources of carbon and nutrients, helping to reduce the cost of biomass and energy production. Microalgae C. vulgaris and S. obliquus immobilized grown in urban wastewater was proposed for the production of biohydrogen by sulfur deprivation and two light quality prior to anaerobic condition at pH 7.5 and 30 °C and 140 µE/m2/s of light intensity. The results indicate that blue light induces greater algal growth than under Purple light, while the maximum hydrogen production was for cultures under purple light of 128 mL H2/L (productivity 204.8 mL H2/L/day) and 60.4 mL H2/L (productivity 39.18 mL H2/L/day) for S. obliquus and C. vulgaris, respectively. An additional advantage is the high removal of organic carbon by S. obliquus cultures under purple incident light compared to C. vulgaris, being a double benefit; energy production and wastewater treatment.

Polycyclic Aromatic Hydrocarbons in Surface Sediments and Fish Tissues Collected from a Protected Lagoon Region.

Polycyclic aromatic hydrocarbons (PAHs) were detected and quantified in sediment and edible fish (Megalops atlanticus) from Caleta lagoon (Lagoon of Terminos, Mexico) in order to assess their potential health impact on consumers. Sum PAH concentrations in sediment and fish muscle tissues were dominated by high molecular weight PAH compound (46.4%-93.1%) relative to low molecular weight compounds (6.9%-42.9%). Contamination was associated with local industrial activities and urbanization. The effective range low (ERL: 4022 ng g-1) value were lower suggested adverse biological effect would be rarely observed. While the analysis of PAHs in muscle of M. atlanticus suggests a minimum impact to consumers according to the permitted limits of dibenzo (a, h) anthracene (10 ng g-1) and benzo [a] pyrene (0.1-1.2 µg kg-1). It is advisable to propose environmental strategies to mitigate future environmental damage in the ecosystem.

Biodiesel synthesis from Chlorella vulgaris under effect of nitrogen limitation, intensity and quality light: estimation on the based fatty acids profiles.

Cultures under nitrogen limitation for Chlorella vulgaris were kept under different light quality (white, blue, yellow and violet) at 70 and 140 µE m-2 s-1; to evaluate the effect on fatty acids profiles and biodiesel quality. The results showed a maximum biomass and cell density at 140 µE m-2 s-1 of: white light (0.69 g L-1 and 6.5 × 106 cells mL-1, respectively) and blue light (0.65 g L-1 and 8.0 × 106 cells mL-1, respectively); compared to violet and yellow light. The chlorophyll concentration (µg mg-1 biomass dry weight) at 70 µE m-2 s-1 were in the order of light: white (25.61) > violet (17.10) > yellow (11.68) > blue (11.40) and, at 140 µE m-2 s-1 were: violet (23.64) > white (10.20) > yellow (9.66) > blue (7.99), suggesting the violet light stimulates the increase of chlorophyll a at higher intensity. The maximum lipid content (% w/w) were present under blue light (43.11), yellow (70.92) and violet (83.87) at 140 µE m-2 s-1. The different wavelengths did not have a negative effect on the quality of the biodiesel, however; violet light presented greater productivity and the indicators such as CFPP were related to the oxidative stability value and low PUFA content, leading biodiesel to good oxidative stability.