The formation of oxo- and hydroxy-fatty acids in heated fats and oils

A fast-food fat (mostly tallow), olive oil and safflower oil were heated in air for 4 d and periodically analyzed for oxofatty acids (OFA), monohydroxy-fatty acids (HFA) and polyhydroxy-fatty acids (PHFA). After transmethylation, the OFA were estimated as 2,4-dinitrophenylhydrazones, and the HFA and PHFA were quantitated as pyruvic acid 2,6-dinitrophenylhydrazone esters. At least half of the maximum concentration attained for OFA, HFA and PHFA was generated between 16–24 h of heating of each oil. Safflower oil contained greater concentrations of HFA and PHFA than either olive oil or the fast-food fat. The fastfood fat sample contained a greater concentration of OFA than did the other oils. The sum of the concentrations of OFA, HFA and PHFA at the time of maximum formation in the oils was approximately 260 μmoles/g at 48–72 h for safflower, 200 μmoles/g at 48–72 h for olive and 170 μmoles/g at 72 h for the fast-food fat. Presented at the 79th Annual AOCS Meeting, Phoenix, Arizona, May 8–12, 1988.     

Distribution of the free and oil‐trapped air bubbles in simulated broths containing fungal biomass

The location of air bubbles (i.e. inside oil drops or free in the aqueous phase) was studied by image analysis as a function of the oil and biomass concentrations in a 2 L stirred tank using a simulated fermentation medium (aqueoussalt solution, castor oil, air and fungal biomass) agitated by a Rushton turbine. The solid (fungal) phase plays an important role in defining the location of bubbles, as the percentage (in bubble volume) of bubbles trapped in oil increases threefold when biomass is added to the medium. The bubbles located inside oil drops were found to occupy 60% of the total bubble volume and to be 40% smaller than those which were non‐oil associated. This phenomenon has important implications for oxygen mass transfer in multiphase fermentations.     

A combined measure for quantifying and qualifying the topology preservation of growing self-organizing maps

The Self-Organizing Map (SOM) is a neural network model that performs an ordered projection of a high dimensional input space in a low-dimensional topological structure. The process in which such mapping is formed is defined by the SOM algorithm, which is a competitive, unsupervised and nonparametric method, since it does not make any assumption about the input data distribution. The feature maps provided by this algorithm have been successfully applied for vector quantization, clustering and high dimensional data visualization processes. However, the initialization of the network topology and the selection of the SOM training parameters are two difficult tasks caused by the unknown distribution of the input signals. A misconfiguration of these parameters can generate a feature map of low-quality, so it is necessary to have some measure of the degree of adaptation of the SOM network to the input data model. The topology preservation is the most common concept used to implement this measure. Several qualitative and quantitative methods have been proposed for measuring the degree of SOM topology preservation, particularly using Kohonen's model. In this work, two methods for measuring the topology preservation of the Growing Cell Structures (GCSs) model are proposed: the topographic function and the topology preserving map.     

Analysis of volatile composition of toasted and non‐toasted commercial chips by GC‐MS after an accelerated solvent extraction method

The analysis of the volatile profile of different oak chips carried out by gas chromatography–mass spectrometry after their isolation by accelerated solvent extraction permitted faster and thorough extractions, while the appearance of artefacts was avoided. Statistical analysis revealed that toasting treatment is the main factor for the volatile compounds with a great sensorial impact. Indeed, toasting process overrode the differences between species. Furthermore, it was evidenced that the toasting treatment is not a homogeneity process. Concentrations of furaneol, 2,3‐dihydro‐3,5‐dihydroxy‐6‐methyl‐4H‐pyran‐4‐one and 5‐hydroxymethylfurfural could be used to monitor the intensity of the toasting process. Differences in the volatile composition with respect to species were also found, being the most remarkable the high concentration of trans and cis‐β‐methyl‐γ‐octanolactone in oak chips from Quercus alba and Quercus petraea species. The differences found in the volatile composition of different commercial oak chips evidenced the necessity to know their chemical composition previously to predict their aromatic potential.     

Analysis of cyclitols in different Quercus species by gas chromatography–mass spectrometry

BACKGROUND: The carbohydrate profile of some woods used for aging wines and spirits has been recently studied using a pressurized liquid extraction method, the main differences found being related to cyclitol content. The aim of this study was to perform a detailed study of these compounds in woods of different Quercus species in order to identify two unknown compounds which appeared in the extracts and to verify whether the obtained profile was homogeneous for other Quercus species. RESULTS: Besides the known monosaccharides and five cyclitols previously described, three deoxy‐inositols (epi‐, vibo‐ and scyllo‐quercitol) were identified. The presence of these eight cyclitols was confirmed in all subgenera and species of Quercus analyzed, allowing a characteristic cyclitol profile. CONCLUSIONS: Three deoxy‐inositols (quercitols) have been identified in the carbohydrate profile of oak wood. All examined Quercus species displayed a common profile consisting of four inositols and four quercitols, which represent a good dataset for characterization of this genus. Copyright © 2010 Society of Chemical Industry     

Simultaneous determination of carbohydrates, carboxylic acids, alcohols, and metals in foods by high-performance liquid chromatography inductively coupled plasma atomic emission spectrometry

The applicability of the HPLC-ICP-AES coupling for the simultaneous determination of carbohydrates, carboxylic acids, alcohols, and metals in a single chromatographic run has been demonstrated in the present work. Five saccharides, glucose, fructose, sucrose, sorbitol, and lactose; five carboxylic acids, citric, tartaric, malic, lactic, and acetic; and three alcohols, glycerol, ethanol, and methanol, have been determined. A H+ cation exchange column has been used to separate these compounds. The chromatograms have been obtained by monitoring the carbon emission signal at 193.09 nm. The results obtained by HPLC-ICP-AES have been compared against those found with conventional detection systems (i.e., refractive index, UV, and photodyode array detectors). The HPLC-ICP-AES method has shown the following features: (i) organic compounds and metals can be simultaneously determined; (ii) the detection method is universal; (iii) for nonvolatile organic compounds, a complete calibration line can be obtained from a single injection; and (iv) it provides absolute limits of detection similar to or lower than those found with conventional detection systems (i.e., on the order of several tens of nanograms of organic compound). The methodology has been validated through the analysis of food samples such as juices, isotonic beverages, wines, and a certified nonfat milk powder sample.     

Development and characterization of Poly (vinyl alcohol) based hydrogels for potential use as an articular cartilage replacement

Hydroxyapatite (HA) reinforced Poly(vinyl alcohol) (PVA) hydrogel composites has been proposed as a promising biomaterial to replace diseased or damaged articular cartilage. Here, PVA/in-situ produced HA hydrogels with 0, 3 and 7.5 wt.% of HA content were obtained by freezing/thawing technique. Thermal, structural and mechanical characterizations were carried out. SEM micrographs revealed that HA was homogeneously distributed in PVA until 3 wt.% whereas partial agglomeration was observed for higher contents (7.5 wt.%). No significant changes were observed in the glass transition temperature (the average value was near to 78 °C ± 3 °C), the melting point and structural water content whereas the gel fraction slightly increased (from 0.72 to 0.78) with the increase the content of HA. The absorbed water decreased (from 85.7% to 80.5%) as a function of HA content The stress–strain curves were really different in hydrated and non-hydrated conditions, changing from non-linear, in presence of water, to linear behavior in a dried state, being in the first case consistent with the articular cartilage . The lowest friction coefficient was obtained for samples with 3 wt. % HA (0.067 ± 0.049), which is, together with a high resistance (721 ± 25 kPa), an important property for materials that will be used as articular replacement. The results indicate that this hydrogel could be used, after other studies, as articular cartilage replacement.     

Review of the different methods for the evaluation of the in vitro antioxidant activity of wine and study of in vivo effects

The aim of this paper is to evaluate the significance of these methods, as well as to correlate the antioxidant activity of wines with their phenolic profile, both in qualitative and quantitative terms. Red wines show higher antioxidant capacities than white ones and the magnitude of these differences depends on the method used. The antioxidant activity of wine can not be mainly ascribed to a particular phenolic compound, instead it is explained by the global interaction of all of them. To evaluate the influence of red wine consumption in the human organism, plasma antioxidant capacity has been frequently used as biomarker, and studies have shown that it increases after wine ingestion. We can conclude that it is necessary to use a battery of methods that provide different and complementary information to properly interpret the results. Phenolic compounds undergo metabolic transformations in the organism which modify their activities. In vivo assays do consider these changes. From the studies performed up to date we can conclude that acute ingestion of wine directly acts on plasma antioxidant capacity due to phenolic compounds and indirectly influences by means of changes on plasmatic concentration of endogenous antioxidants.     

Development of a new Fear of Hypoglycemia Scale: FH-15.

Hypoglycemia is the most common adverse event associated with insulin treatment in diabetes. The consequences of hypoglycemia can be quite aversive and potentially life threatening. The physical sequelae provide ample reason for patients to fear hypoglycemia and avoid episodes. For these reasons, our purpose in this study was to develop a new measure that explores specific fear of hypoglycemia (FH) in adult patients with type 1 diabetes and to examine its psychometric properties. The instrument developed to assess FH was initially made up of 20 items, of which 18 were negative and 2 were positive, assessed on a 5-point Likert scale (1–5). This scale was completed by 229 patients with type 1 diabetes. Additionally, a structured interview and a closed question called subjective fear of hypoglycemia were included as diagnostic criteria. A factor analysis employing the principal-components method and promax rotation was carried out, resulting in a new scale composed of 15 items. Three factors (fear, avoidance, and interference) were obtained and explained 58.27% of the variance. The scale showed good internal consistency (Cronbach's α = .891) and test–retest reliability (r = .908, p