Ana C. Soria

Prevention of diet-induced obesity by apple polyphenols in Wistar rats through regulation of adipocyte gene expression and DNA methylation patterns

This study was conducted to determine the mechanisms implicated in the beneficial effects of apple polyphenols (APs) against diet-induced obesity in Wistar rats, described in a previous study from our group. Supplementation of high-fat sucrose diet with AP prevented adiposity increase by inhibition of adipocyte hypertrophy. Rats supplemented with AP exhibited improved glucose tolerance while adipocytes isolated from these rats showed an enhanced lipolytic response to isoproterenol. AP intake led to reduced Lep, Plin, and sterol regulatory element binding transcription factor 1 (Srebf1) mRNA levels and increased aquaporin 7 (Aqp7), adipocyte enhancer binding protein 1 (Aebp1), and peroxisome proliferator-activated receptor gamma co-activator 1 alpha (Ppargc1a) mRNA levels in epididymal adipocytes. In addition, we found different methylation patterns of Aqp7, Lep, Ppargc1a, and Srebf1 promoters in adipocytes from apple-supplemented rats compared to high-fat sucrose fed rats. The administration of AP protects against body weight gain and fat deposition and improves glucose tolerance in rats. We propose that AP exerts the antiobesity effects through the regulation of genes involved in adipogenesis, lipolysis, and fatty acid oxidation, in a process that could be mediated in part by epigenetic mechanisms.

Evaluation of different operation modes of high performance liquid chromatography for the analysis of complex mixtures of neutral oligosaccharides

Chromatographic methods based on different HPLC operation modes, reverse phase (RP), high performance anion exchange chromatography (HPAEC), graphitized carbon chromatography (GCC) and hydrophilic interaction liquid chromatography (HILIC), have been developed and compared for the analysis of complex mixtures of neutral oligosaccharides with functional properties. Whereas GCC gave the best chromatographic separation of isomeric oligosaccharides with the same molecular weight (R(s) values in the range 1.0-4.0 and 2.4-5.6 for tetra- and pentasaccharides, respectively), HILIC provided the best results for mixtures including oligosaccharides of different degrees of polymerization (R(s) values of maltooligosaccharides between 3.4 and 6.2). Validation of the HILIC LC-MS method proved its utility for the analysis of oligosaccharide mixtures with functional properties: relative standard deviations lower than 10%, LODs and LOQs in the range 12.7-130.2 ng mL(-1) and 39.3-402.2 ng mL(-1), respectively, and linearity up to 10-20 μg mL(-1). Quantitative data for fructooligosaccharides, gentiooligosaccharides and dextransucrase cellobiose acceptor oligosaccharides were obtained by using this method.

Chemical and physicochemical quality parameters in carrots dehydrated by power ultrasound.

Preservation of the quality and bioactivity of carrots dehydrated by power ultrasound (US) under different experimental conditions including prior blanching has been evaluated for the first time by measuring the evolution of the Maillard reaction and the changes in soluble sugars, proteins, total polyphenols, antioxidant activity, and rehydration ability. This study also includes a comparison with a freeze-dried sample and data of commercial dehydrated carrots. The synergic effect of US and temperature (60 degrees C) increased the dehydration rate of carrots (90% moisture loss in only 75 min) while still providing carrots with a level of 2-furoylmethyl-amino acids significantly lower than that of dehydrated commercial samples. Whereas a decrease in the content of reducing soluble sugars was observed with processing temperature, minor carbohydrates (scyllo- and myo-inositol and sedoheptulose) were rather stable, irrespective of the US dehydration parameters. Blanching significantly improved the rehydration ability of US-dehydrated carrots without increasing the loss of soluble sugars by leaching. As supported by the similarity of most quality indicators studied in both US-treated and freeze-dried carrots, the mild processing conditions employed in US dehydration gave rise to premium quality dehydrated carrots.

Impact of power ultrasound on chemical and physicochemical quality indicators of strawberries dried by convection

A study on the quality parameters of strawberries dehydrated by convection assisted by power ultrasound (US) at 40-70°C and 30 and 60W has been carried out for the first time. In general, the quality of US-treated samples was higher than that of commercial samples. Even under the most severe conditions used (US at 70°C and 60W), high values of vitamin C retention (>65%) and scarce advance of Maillard reaction (2-furoylmethyl derivatives of Lys and Arg<90mg 100g(-1) protein) were observed. Rehydration ratio was not affected by the power applied and the obtained values were similar to those of convectively-treated samples. According to the results here presented, US is a suitable example of an emerging and environmentally friendly technology that accelerates convective drying, allowing the obtainment of dried strawberries with premium quality.

Determination of carbamate, phenylurea and phenoxy acid herbicide residues by gas chromatography after potassium tert-butoxide/dimethyl sulphoxide/ethyl iodide derivatization reaction.

The usefulness of the potassium tert-butoxide/dimethyl sulphoxide/ethyl iodide reaction with carbamate and phenylurea herbicides, and its application to phenoxy acids as a way to prevent hazards and toxicity of the sodium hydride/dimethyl sulphoxide/methyl iodide reaction was studied. Using factorial design optimization of this reaction was carried out. A solid-phase extraction method using dimethyl sulphoxide as eluent on-line with this reaction was developed to determine these herbicides in water samples by gas chromatography-mass spectrometry. Relative standard deviation values were lower than 10% for most of the herbicides in multicomponent trace determinations. Detection limits were in the 0.110-0.652 ng L(-1) concentration range. The validity of the method was confirmed by recovery studies from natural water samples.

Characterization by the solvation parameter model of the retention properties of commercial ionic liquid columns for gas chromatography.

For the first time, four commercial ionic liquid columns (SLB-IL59, SLB-IL76, SLB-IL82 and SLB-IL100) for gas chromatography have been comprehensively evaluated in terms of efficiency, polarity and solvation properties. Grob tests and McReynolds constants showed that they were all high-efficiency columns of high polarity, but with low inertness to compounds with hydrogen bonding capabilities. The solvation parameter model was used to characterize the solvation interactions of the four columns in the 80-160°C temperature range. Results revealed that all the ionic liquids studied can be considered moderately hydrogen-bond acid and highly cohesive stationary phases, on which the dominant contributions to retention were the dipolar-type and hydrogen-bond base interactions, while π-π and n-π interactions were barely significant. The SLB-IL59 column provided the best separation of homologs, while the SLB-IL76 and SLB-IL100 columns had the most basic and the most acidic phases, respectively. A principal component analysis for the commonly used stationary phases in capillary GC showed that these commercial ionic liquid columns fill an empty area of the available selectivity space, which clearly enhances the separation capacity of this technique.

Survey of quality indicators in commercial dehydrated fruits

Physical and chemical quality parameters (dry matter, aw, protein, carbohydrates, vitamin C, 2-furoylmethyl amino acids, rehydration ratio and leaching loss) have been determined in 30 commercial dehydrated fruits (strawberry, blueberry, raspberry, cranberry, cherry, apple, grapefruit, mango, kiwifruit, pineapple, melon, coconut, banana and papaya). For comparison purposes, strawberry samples processed in the laboratory by freeze-drying and by convective drying were used as control samples. Overall quality of dehydrated fruits seemed to be greatly dependent on processing conditions and, in a cluster analysis, samples which were presumably subjected to osmotic dehydration were separated from the rest of fruits. These samples presented the lowest concentration of vitamin C and the highest evolution of Maillard reaction, as evidenced by its high concentration of 2-furoylmethyl amino acids. This is the first study on the usefulness of this combination of chemical and physical indicators to assess the overall quality of commercial dehydrated fruits.

Analysis of volatiles in dehydrated carrot samples by solid-phase microextraction followed by GC-MS

A solid-phase microextraction (SPME)-based method for the GC-MS analysis of volatiles in dehydrated carrot root samples has been developed and the effect of the most important factors (fibre coating, extraction temperature, equilibrium time and extraction time) on the fractionation of different volatiles has been studied. GC-MS chromatograms showed terpenoids relevant to carrot aroma such as alpha-pinene, sabinene, beta-myrcene, limonene, gamma-terpinene, terpinolene, trans-caryophyllene and beta-bisabolene, and several furan derivatives whose origin is discussed in this paper. As an example of application, this methodology has been used for the characterization of volatile composition of industrially dehydrated carrots. SPME followed by GC-MS is shown as an affordable, fast and solvent-free technique which can be performed with low sample amounts and be easily implemented at an industry for quality control purposes.

Characterization of O-trimethylsilyl oximes of trisaccharides by gas chromatography–mass spectrometry

Gas chromatography (GC) data (linear retention indices and relative areas) and mass spectra (most representative m/z fragments) of 12 reducing trisaccharides as trimethylsilyl oximes (TMSO) and four non-reducing as trimethylsilyl (TMS) ethers have been described for the first time and related to their structural features. Some trends have been observed: earlier elution of non-reducing compounds and fructotrioses; aldotrioses bearing the reducing end with link in position 6 showing the highest retention. Abundance of several fragment ions and their ratios were useful for trisaccharide characterization; some of these features seem to be useful for the characterization of new trisaccharides.

Effect of glycation on sodium caseinate-stabilized emulsions obtained by ultrasound.

This work explores the potential of high-intensity ultrasound to produce fine-dispersion, long-time-stable, oil-in-water emulsions prepared with native and glycated bovine sodium caseinate (SC). Regardless the ultrasound amplitude and time assayed, the sonicated emulsions of native SC at 0.5 mg/mL had much higher emulsifying activity indexes compared with those emulsions formed by Ultra-Turrax (IKA Werke GmbH & Co., Staufen, Germany) homogenization. Nevertheless, the native SC emulsions were very unstable despite the optimization of parameters such as protein concentration, amplitude of ultrasound wave, and sonication time by using a Box-Behnken design. Early glycation of SC with either galactose, lactose, or 10 kDa dextran substantially improved both emulsifying activity and the stability, whereas at advanced stages of glycation, SC emulsions showed notably reduced emulsifying properties, likely because extensive glycation of SC promoted its polymerization mainly through covalent cross-linking, as was demonstrated by particle size measurements. The increase in particle diameter of glycoconjugates likely affected the diffusion of SC from bulk to the oil-water interface and slowed the reorientation process of the protein at the interface. These findings show that the combined effect of early-stage glycation of SC and high-intensity ultrasound as an emergent technique to form emulsions has the potential to provide improved emulsions that could be used in several food applications.