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关键词： Desorption   Hydrocarbons   Fluids   Aromatic compounds   Bioaccessibility  

摘要： A potential risk from human uptake of microplastics is the release of plastics-associated xenobiotics, but the key physicochemical properties of microplastics controlling this process are elusive. Here, we show that the gastrointestinal bioaccessibility, assessed using an in vitro digestive model, of two model xenobiotics (pyrene, at 391-624 mg/kg, and 4-nonylphenol, at 3054-8117 mg/kg) bound to 18 microplastics (including pristine polystyrene, polyvinyl chloride, polyethylene terephthalate, polypropylene, thermoplastic polyurethane, and polyethylene, and two artificially aged samples of each polymer) covered wide ranges: 16.1-77.4% and 26.4-83.8%, respectively. Sorption/desorption experiments conducted in simulated gastric fluid indicated that structural rigidity of polymers was an important factor controlling bioaccessibility of the nonpolar, nonionic pyrene, likely by inducing physical entrapment of pyrene in porous domains, whereas polarity of microplastics controlled bioaccessibility of 4-nonylphenol, by regulating polar interactions. The changes of bioaccessibility induced by microplastics aging corroborated the important roles of polymeric structures and surface polarity in dictating sorption affinity and degree of desorption hysteresis, and consequently, gastrointestinal bioaccessibility. Variance-based global sensitivity analysis using a deep learning neural network approach further revealed that micropore volume was the most important microplastics property controlling bioaccessibility of pyrene, whereas the O/C ratio played a key role in dictating the bioaccessibility of 4-nonylphenol in the gastric tract.

关键词： Nanostructured lipid carrier   Curcumin   Composition influence  

摘要： The use of (nanostructured lipid carries) NLC to disperse curcumin in aqueous media is widely found in literature. However, few studies systematically analyze the influence of the lipid matrix composition and the presence of curcumin on the physicochemical characteristics of NLC. Thus, the present work aimed to verify the influence of the NLC composition on its structure. Different solid lipid (SL) to liquid lipid (LL) ratios were evaluated, yielding NLC < 600 nm and < 400 nm with the use of MCT and castor oil, respectively. The addition of Tween 80 favored the formation of smaller structures. Thermal analysis data confirmed the formation of different structures due to their different composition and also after the incorporation of curcumin. The present study also describes a correlation between the rheology of the NLC dispersion and the degree of structural organization of the NLC, indicating the formation of structures with a differentiated degree of organization. Photomicrographs showed the formation of two different structures, multiple types and amorphous, with drug concentrated in nucleus. in vitro studies have not shown significant IC50 differences between the systems developed with curcumin;however, the time and effectiveness of internalization were different for the two developed systems. The interaction between SL and LL demonstrated to be an important parameter that should be considered before the development of NLC, also the molecular characteristics of each component must be verified in order to develop NLC on a desirable type.

关键词： Emulsion   Protein   Surface tension   Particle size   Rheology   Stability  

摘要： Emulsifying properties of four different proteins (soy, potato, pea and whey) were analyzed and related to their solubility, surface hydrophobicity, surface tension and their ability to modify aqueous phase viscosity. The influence of protein (emulsifier) type and concentration (1, 4 and 7 %), and pH value of the system (protein native pH and pH 9.0) on droplet size distribution parameters, rheological behavior and stability of fish oil-inwater emulsions (5, 15 and 30 % of dispersed phase) was determined. The examined proteins showed similar surface activity. The highest aqueous solution viscosity was exhibited by soy protein, while the viscosity of pea protein aqueous solution was the lowest. Droplet size measurements of emulsions showed that increase in protein concentration from 1 to 4% resulted in the formation of smaller droplets during the homogenization, while further increase in protein concentration up to 7 % did not maintain the trend of droplets size decrease. Increase in emulsions pH from protein native to pH 9.0 for almost all proteins led to decrease in average droplets diameters of emulsions and formation of smaller droplets (except for emulsions stabilized by whey protein where the decrease was not significant). All investigated emulsions showed shear-thinning flow behavior. The consistency indexes (K) of emulsions, which are indicators of the system viscose behavior, increased with the increase in protein concentration, oil content and pH of the system. Despite low solubility and surface hydrophobicity, the soy protein emulsifier was capable of producing the most stable emulsions with the smallest droplets compared to the other three proteins. The soy protein stabilized emulsions were also characterized with the highest emulsion consistency index and continuous phase viscosity in comparison to emulsions containing other proteins indicating the role of protein as thickening agent in stabilizing emulsion.

关键词： Pharmaceutical cocrystal   Amino acid   Zwitterionic coformer   Structural resemblance   Crystal structure  

摘要： Cocrystals can be formed with a pair of carefully selected organic molecules, which may present novel structures that are not available for individual molecule. Pharmaceutical cocrystals may offer synergetic physicochemical properties of the drugs. In this paper, we aimed to screen chlorothiazide(CTZ) cocrystals under the structural resemblance strategy to investigate the correlation between the structure of CTZ cocrystals and their physicochemical properties. Four new cocrystals of CTZ were synthesized and characterized, namely CTZ−Sarcosine (CTZ−SAR), CTZ−DL-proline (CTZ−DL-PRO), CTZ−L-proline hydrate (CTZ−L-PRO-H₂O) and CTZ−D-proline hydrate (CTZ−D-PRO-H₂O). Single crystal data indicate the CTZ molecule attractively interacts with the amino acids through the amine−carboxylate interactions. CTZ−SAR and CTZ−DL-PRO exhibit very similar crystal structures due to the structural similarity between SAR and PRO. In the two PRO hydrate cocrystals, PRO molecule is in favor to form the hydrogen bonding with the CTZ molecule but not with other neighboring PRO molecules while water is strongly hydrogen bonded to both the CTZ (Sulfonyl O) and the PRO (Amino N-H) as a bridge link. Thermal analysis of hydrate cocrystals shows high thermal stability (∼156 °C). Dissolution kinetic measurements reveal that CTZ−SAR and CTZ−DL-PRO cocrystals exhibit improved solubility in water.

关键词： Processing factors   cereal bran   biscuits   baking   pesticides   physicochemical properties  

摘要： Agricultural commodities are generally consumed as processed food. Therefore, it is indispensable to assess pesticide residues in processed products rather than only in the raw agricultural commodity, in order to approach a more realistic scenario of dietary exposure. Processing factors are important tools for dietary exposure risk assessments. In this study, processing factors for the baking process were derived for 41 pesticides in cereal bran-based biscuits. The raw materials used consisted of wheat, rye, oat, and barley grains with incurred pesticides, which originally was produced for test material for European Union Proficiency Tests. Information on physicochemical properties of pesticides was collected for understanding the fate of pesticides during the baking process. Average processing factors varied between 0.67 and 1.6. Most pesticide residues exhibited a reduction of pesticide residues of less than 24%, which correspond to a processing factor (PF) range between 1 and 0.76, showing resistance to the baking process. However, for polar compounds such as carbendazim and volatile compounds (chlorpyrifos-methyl, malathion, and pirimiphos-methyl) larger reduction rates were observed, up to 33% (PF: 0.67). In general, a prolonged baking time did not significantly affect the PF, because the main degradation process takes place within the first 6 min. However, this was not the case for the highly volatile compounds, highly polar compounds, and compounds of low degradation temperature. These latter were significantly reduced with prolonged baking time, resulting in a reduction rate of up to 95%, which means an almost complete elimination.

关键词： Biofuels standards   castor varieties   homogeneous alkaline transesterification   Soxhlet extraction method  

摘要： Biodiesel is an alternative fuel that has been used to replace petroleum diesel and to generate a positive impact on the economy and the environment. The aim of this paper was at identifying the variety of castor oil plant that could be cultivated and harnessed as bioenergy crops in Tlaltenango (Zacatecas, Mexico). Different varieties of wild castor (Ricinus communis L.) were studied, obtaining oil from its seeds and producing biodiesel from the variety with higher oil content by transesterification reaction at laboratory scale. Both oil and biodiesel were characterized physicochemically, and biodiesel quality was evaluated and compared with biofuels standards ASTM-D6751 (USA) and EN-14214 (European Union). Three varieties were identified;the denominated "green stem with wax, ashen fruit" showed the highest oil content (51.7 +/- 5.6%), presenting a yield of the transesterification reaction of 61.44 +/- 0.44%. The produced biodiesel complies with recommended value by both standards, except for the viscosity and the moisture, so its use is only suggested in blends with petroleum diesel. In conclusion, the variety "green stem with wax, ashen fruit" has the basic physicochemical characteristics for being considered an option in the industrial production of biodiesel in this city, being safe to use it in diesel engines.

关键词： Organic acids   Mixtures   Amides   Organic compounds   Solutions  

摘要： A series of all 12 cis- and trans-cyclopropanecarboxylic acids and cyclopropylamines bearing CH2F, CHF2, and CF3 substituents were synthesized by different methods on a multigram scale. Dissociation constants (pK(a)) and log P values were measured for the obtained compounds or their derivatives to evaluate the influence of the type and relative position of fluoroalkyl substituents on the acidity and lipophilicity of monofunctionalized cyclopropanes. An analysis of the selected products by X-ray crystallography was carried out to obtain a better insight into the observed differences in physicochemical properties.

关键词： Fructans   Acylation   Esterification   Modified carbohydrates   Surface tension  

摘要： Native agave fructans were modified by an acylation reaction with lauric acid. Native and modified fructans were characterized using NMR, FTIR and various physicochemical and functional properties at different pHs were evaluated. NMR and FTIR spectra demonstrated the incorporation of lauric acid in the molecular structure of fructans. Modified agave fructans exhibited a color, moisture and water activity similar to native fructans, but properties such as solubility, swelling capacity, emulsifying activity and foam capacity were significantly modified by the acylation reaction mainly when the samples were analyzed at different pHs. The thermogram of the acylated fructans evidenced significant changes in thermal properties when compared with native fructans and acylated fructans were able to form micellar aggregates. In general, modified fructans showed improved functional properties in comparison with native fructans representing an important opportunity to improve the functionality of the foods in which it is incorporated.

关键词： Pyroconversion   Chain-length distribution   Physicochemical property   Native starch  

摘要： Pyrodextrins are widely applied in industry as adhesives, coatings, binders, and in food as dietary fiber. In this study, the dynamic changes of structure and physicochemical property during pyroconversion of native maize starch are investigated. By quantifying the variations of chain-length distribution (CLD) between native starch and pyrodextrins, it is found that 1) the long starch chains with degree of polymerization (DP) about 500-20000 are degraded while its content is not significantly varied between pyrodextrins;2) the content of intermediate -long chains with DP 20-500 increases with temperature, indicating more pyrodextrin molecules with the equivalent Rh similar to 1.5-9.4 nm are newly formed;3) the content of A and B1 chains are not largely varied between pyrodextrins with temperature <= 190 degrees C, suggesting that the repolymerization might be more likely occur in the amorphous lamellae. This study improves the understanding of structural and physicochemical property changes during the pyroconversion process of native maize starch.