Functional Properties of Bioplastics Made from Wheat Gliadins Modified with Cinnamaldehyde

[EN] Cinnamaldehyde is a naturally occurring alpha,beta-unsaturated aldehyde. Its potential as a natural cross-linker to improve the physical performance of cast wheat gliadin films was evaluated. The cross-linking reaction was found to be dependent on the pH of the reaction medium, with pH 2 as the optimum. The water resistance (weight loss after immersion), mechanical properties (Young's modulus, tensile strength and elongation at break), thermal properties (T-g and decomposition behavior), optical properties and morphology of films were evaluated. Cross-linked films showed high transparency, maintained their integrity after immersion, and displayed significant improvements in tensile strength and Young's modulus without impairment of their elongation properties. These effects, which were proportional to the amount of cinnamaldehyde added, highlight the possible formation of intermolecular covalent bonds between "monomeric" gliadins, leading to a polymerized network. Thus, this treatment could provide a new alternative to the toxic cross-linkers commonly employed and so extend the use of gliadin films.The authors would like to thank the Spanish Ministry of Science and Innovation for the financial support (Project AGL2006-02176, AGL2009-08776 and M. P. Balaguer FPI fellowship).Balaguer, MP.; Gomez-Estaca, J.; Gavara Clemente, R.; Hernandez-Munoz, P. (2011). Functional Properties of Bioplastics Made from Wheat Gliadins Modified with Cinnamaldehyde. Journal of Agricultural and Food Chemistry. 59(12):6689-6695. https://doi.org/10.1021/jf200477aS66896695591

Approaching raw material functionality in the Upper Magdalenian of Coimbre cave (Asturias, Spain) through geometric morphometrics

Coimbre cave (Periamellera Alta, Asturias) is an Upper Palaeolithic site in Northern Spain, spanning an occupation sequence from the Gravettian to the Magdalenian periods. The upper layers -layer I and II-, corresponding to the Upper Magdalenian, register the highest intensity of human activity. In this paper, we analyse raw material functionality at the site through the study of cut-marks found on bone remains. At Coimbre, we have documented mainly quartzite, followed by flint; other raw materials are found in very low frequencies. There are several types of local quartzite that appear mainly as flaking debitage and stone tools such as burins and scrappers. On the other hand, flint is mainly knapped to elaborate blades and bladelets, as well as specialised implements, such as different types of side scrappers. Retouched flakes on flint are relatively more abundant than those made on quartzite. In this paper we employ the use of photogrammetry, geometric morphometrics and statistics to analyse the cut-marks from the Upper Magdalenian assemblage of Coimbre cave. Our aim is to determine the lithic raw material preferentially used for carcass processing at the site