Recent studies have shown that handcrafted glass-clay containers are a health risk because they can be contaminated by heavy metals, which can be transferred to food, thus reaching the human body to potentially cause illness. Therefore, in the present work, we evaluate the leaching of lead, cadmium, and cobalt from glass-clay containers into two types of food: tomato sauce (salsa), and chickpea puree. The containers were obtained from four regions in the Mexican state of Hidalgo. Repetitive extractions from the containers were carried out to quantify the leaching of the heavy metals into the salsa, the chickpea puree, and acetic acid using the technique proposed by the USFDA. The results show that greater use of the containers leads to more leaching of heavy metals into both types of food and into the acetic acid, with the greatest metal extraction recorded for the Ixmiquilpan vessels. These results indicate that the metals present in the glass-clay containers leach into the food and that increased reuse increases the risk to the people who use them in food preparation.

This study demonstrates that using beeswax hydrolyzates (Hw), short-or mediumchain-length polyhydroxyalkanoates (scl-mcl-PHA) can be obtained by a three stages fed-batch fermentation system. The fed batch fermentations were conducted with a strain of Cupriavidus necator. Glucose and ammonium sulphate as carbon and nitrogen sources, respectively, were used in a first and second culture stages. In the third stage (production of scl-mcl-PHA) a fresh medium was fed with Hw as a carbon source at a concentration of 5 g/L, obtaining 8.91 g/L of intracellular scl-mcl-PHA and 13.64 g/L of biomass, which resulted in 65.3 % w/w of scl-mcl-PHA. Using nuclear magnetic resonance, the presence of scl and mcl monomers, 3-hydroxybutyrate (3HB) and 3-hydroxydecanoate (3HD) was determined. The percentage of comonomer incorporation different to 3HB was 4.6 mol %. A glass transition temperature (Tg) of -50 ºC and a melting temperature (Tm) of 79.8 ºC were determined for the scl-mcl-PHA (3HB-co-3HDD).Palabras clave: biopolímeros, DSC, mcl-PHA, RMN, fermentación lote alimentado RESUMEN Este estudio demuestra que mediante el uso de hidrolizados de cera de abejas (Hw) pueden obtenerse polihidroxialcanoatos de cadena corta o media (scl-mcl-PHA), mediante un sistema de fermentación por lote alimentado de tres etapas. Las fermentaciones por lote alimentado se llevaron a cabo con una cepa de Cupriavidus necator. Se usaron glucosa y sulfato de amonio como fuentes de carbono y nitrógeno, respectivamente, en una primera y segunda etapas de cultivo. En la tercera etapa (producción de scl-mcl-PHA) se alimentó medio fresco con Hw como fuente de carbono a una concentración