The interactions of pectin with TiO2 nanoparticles measured by FT-IR are confirmed in a model of the gastrointestinal tract.

The presence of nanoparticle fractions (<100 nm, NPs) in the food additive TiO2 (E171) rises concerns about its potential harmful impact on human health. The knowledge about the interaction of TiO2 NPs with food components is limited to proteins or polyphenols. The present paper is the first to report on interactions between TiO2 NPs and high molecular pectins that form gels in boluses and are remain nearly intact during digestion until they reach the colon. Direct interactions were studied using Fourier Transform Infrared Spectroscopy while indirect ones were monitored by measuring the "absorption" of TiO2 using a 0.2 microfiltration membrane, during in vitro digestion in a model of the gastro-intestinal tract. The FT-IR spectra registered for pectin-TiO2 NPs solutions confirmed changes in band intensities at 1020, 1100, 1610, and 1740 cm-1, suggesting interactions taking place mainly via the COO- groups. Furthermore, the I(1020)/I(1100) ratio was decreased (C-O stretching vibrations), suggesting partial blocking of the skeletal vibrations caused by interactions between pectin and TiO2. The modelled in vitro digestions confirmed that the "availability" of Ti was reduced when TiO2 NPs were combined with pectin, as compared to TiO2 NPs "digested" alone.

Concentration of metals and metalloids in livers of birds of various foraging guilds collected during the autumn migration period in Poland.

During migration, birds explore various habitats at stopover sites that differ in food resources and contamination levels. In this study, hepatic concentrations of 21 elements (metals and metalloids) in 11 species of birds, representing various foraging habitats (such as aquatic, aquatic/terrestrial, and terrestrial) and migration modes (migratory and sedentary) representing various foraging guilds (omnivores, piscivores, and molluscivores), were analyzed. The samples (N = 84) were collected during the autumn migration period in Poland. The concentrations of elements determined in this study exhibited high inter-species variability, reflecting the diversity in contamination levels depending on food resources used by specific bird groups. Many of the investigated individuals from different species showed exceeded levels of subclinical toxicity and moderate clinical poisoning due to Cd and Hg. Higher concentrations of As, Hg, and Ba and lower V concentrations were found in migratory birds as compared to sedentary birds. Species foraging in terrestrial habitat had different concentrations of some elements compared to aquatic and aquatic/terrestrial species. Some specific inter-species differences in hepatic elemental concentrations were found. Differences in elemental concentrations among various groups can primarily be attributed to their foraging guilds, with certain elements, particularly As, V, and Hg, playing a significant role in the dissimilarity of elemental concentrations between foraging habitat groups and migratory mode groups. The data collected confirmed the limited ability of As to enter ecosystem pathways. The results of this study contribute to understanding the year-round exposure of migratory birds to environmental contamination, which can have carry-over effects on their performance in wintering and breeding grounds.