Juan Pedro Pérez Trujillo

The current study was focused on the impact of accelerated ageing (heating step) on the amino acid and biogenic amine profiles of fortified wines. In this sense, three Madeira wines from two commonly used grape varieties (one red and the other white) were analysed during the heating, at standard (45°C, 3 months) and overheating (70°C, 1 month) conditions, following a precolumn derivatization procedure using iodoacetic acid, o ‐phthaldialdehyde, and 2‐mercaptoethanol, carried out in the injection loop prior to RP‐HPLC‐FLD detection. Eighteen amino acids were identified, with arginine being the most abundant. An important decrease of the amino acid levels was detected during the standard heating (up to 30%), enhanced up to 61% by the temperature increase. Cysteine, histidine, and asparagine revealed the greatest decreases at 45°C. Conversely, some amino acids, such as asparagine, slightly increased. Four biogenic amines were identified but always in trace amounts. Finally, it was observed that the accelerated ageing did not favour the biogenic amine development. The results also indicate that the heating process promotes the amino acid transformation into new ageing products.

Metals and metalloids are usually bound in the fine-grained (−1) in some cases. Principal component and correlation analysis were developed and the results obtained indicated that there are two principal sources of anthropogenic pollution, with a large number of elements related to them. The amounts of 13 elements found in the sediments of the sampling point of Santa Cruz of Tenerife, principal city of the island, were higher than those found in the other locations. Modifications in the sea bed were also detected due to industrial wastes; concentrations of metals related to metallurgic activities have increased in the industrial area while the proportion of original igneous sediments decreased. The mobility of the pollutants, according to the sea currents, was also evaluated. For some of the analyzed metals, differences between sampling points in agreement with the direction of the marine currents in the area were obtained. The large number of elements analyzed allowed the development of a geochemical characterization of the three slopes of the island. Significant differences were observed for some elements.

The influence of short‐range ordered minerals, especially allophane or ferrihydrite, in the total amount, resilience and molecular structure of the soil organic matter (SOM) was determined in a series of volcanic ash soils from Tenerife Island (Spain), with a range of amorphous minerals, organic carbon (C) and clay minerals. Up to 120 main analytical descriptors of the SOM were processed by uni‐ and multivariate statistical analyses. Short‐range ordered minerals were estimated from the (Al _o + ½ Fe _o ) index, organo‐metallic complexes were calculated from the Al _p :Al _o ratio and crystalline minerals were determined by X‐ray diffraction. The humic acids (HAs) were isolated, purified and analysed by visible, infrared and ¹³ C nuclear magnetic resonance spectroscopy and analytical pyrolysis. In addition, CO ₂ release curves from whole soil samples were used to obtain indices of SOM resilience. The results revealed that the amount and resilience of the SOM depended on the presence of short‐range ordered minerals: the greater the content of non‐crystalline minerals, the greater the C stabilization. However, no significant relationships were found between these amorphous minerals and aromatic compounds, which are indicators of resilience in HAs. Conversely, certain molecular characteristics of the HAs, such as the optical density at 465 nm, the concentration of quinone‐type fungal pigments, the yields of carbohydrate‐derivatives and N‐compounds, highlighted the role of allophane‐sized nanoparticles in the protection of microbial metabolites produced during the decomposition, and are also likely to provide active sites for soil C stabilization at the colloidal scale.