Study of Some Functional Properties of Casein: Effect of pH and Tryptic Hydrolysis

The trypsin was used to hydrolyze commercial casein at varied times and pH range. The functional properties studied were the emulsifying capacity (EC), the emulsifying activity index (EAI), and the emulsion stability (ES). The dispersed phase used was corn oil. The tryptic hydrolysis was beneficial to the solubility and EC of casein in practically all pH values and reaction times. In case of EAI, this same effect was less intense and was observed only in acid region (pH 3.0 to 5.0), while for ES the trypsin action was mainly deleterious in almost all pH range and reaction times.     

Ultra‐Performance Liquid Chromatographic Determination of L‐Ergothioneine in Commercially Available Classes of Cow Milk

A new efficient and sensitive precolumn hydrophilic interaction ultra‐performance liquid chromatography (HILIC‐UPLC) method was established for the quantitative determination of L‐ergothioneine (ERT) in milk. After derivatization of ERT with 7‐diethylamino‐3‐[4‐(iodoacetamido)phenyl]‐4‐methylcoumarin, chromatographic separation was achieved in a fairly short time, less than 5 min, on a 100 × 2.1 mm Waters Cortecs UPLC HILIC 1.6‐μm column, by using a mixture of 30 mmol/L ammonium acetate/acetonitrile (10:90, v/v) as a mobile phase flowing isocratically at 0.9 mL/min. Limit of detection and the limit of quantification were 0.03 and 0.10 μmol/L, respectively. The method exhibited linearity in a concentration range of 0.16 and 5.08 μmol/L. Mean recovery was 106.66%, whereas intra‐ and interassay precisions were determined to be within 6 RSD%. On average, ERT concentration in different commercially available classes of cow milk was found to be 0.442 ± 0.191 μmol/L, with the highest levels in the ultra‐high temperature milks and low values in the unprocessed and HTST whole milks. In this light, our experiments suggest that ERT could be used as a marker for the heat treatment of milk.     

Determination of aloe emodin in Aloe vera extracts and commercial formulations by HPLC with tandem UV absorption and fluorescence detection

Aloe emodin is an anthraquinone compound found in Aloe vera and other species of the Asphodelaceae and the Polygonaceae families, which has recently attracted much attention as a prospective antineoplastic agent. A HPLC method with tandem UV absorption and fluorimetric detection, was developed and validated for the analysis of aloe emodin in products obtained from Aloe leaves, such as capsules, tablets, dried extracts and mother tinctures. The stationary phase was a C18 reversed-phase column and the mobile phase was composed of water and methanol (30/70, v/v). Satisfactory linearity was obtained over the 10.0–1000.0 ng/mL range for photodiode array detection (limit of detection: 3 ng/mL) and over the 2.5–1000.0 ng/mL range for fluorimetric detection (limit of detection: 0.8 ng/mL). Aloe emodin levels were determined in A. vera extracts and commercial formulations by both detection means, with good precision (R.S.D. < 9%) and accuracy (recovery > 85%) and consistent results. Thus, the method seems to be suitable for the analysis of aloe emodin in different herbal and commercial products; it could also be useful for the identity confirmation of formulations and extracts.     

Formation of glucose and fructose acetates during maturation and ageing of balsamic vinegars

We report for the first time the detection of glucose acetates in balsamic vinegars. It is well known that during traditional balsamic vinegar (TBV) ageing several modifications occur. In this paper it was experimentally determined that some modifications take also place during the short maturation time of balsamic vinegar of Modena (BVM), with an increase of the esters content due to the reaction between acetic acid and sugars, in particular glucose. The formation of esters was observed both on reference solutions containing glucose and acetic acid, subjected to an accelerated ageing by heating at 50 °C, and on real balsamic vinegar samples. Glucose esters were mainly detected as α- and β-glucopyranose acetates. The formation of fructose acetates in reference solutions, was also studied, recording a more complex pattern of products. The structures of the esters were determined by GC/MS analyses and NMR spectroscopy.     

The species-specific ratios of 2,3-butanediol and acetoin isomers as a tool to evaluate wine yeast performance

The isomers of 2,3-butanediol [R,R; S,S; R,S (meso-form)] and of acetoin (R,S) were determined in laboratory wine fermentations carried out by 50 yeast strains, 10 for each of the following species, Saccharomyces cerevisiae, Kloeckera apiculata, Candida stellata, Metschnikowia pulcherrima and Brettanomyces bruxellensis, in order to evaluate if such parameters might be used to differentiate wines obtained with different yeast species. According to analysis of variance (ANOVA), the strains of the same species behaved similarly, whereas the five yeast species behaved differently so that species-specific profiles were recognized. Moreover, the discriminant analysis grouped the wines into five groups, each including the 10 wines obtained by the 10 yeast strains of the same species. Trials were also included where musts partially fermented by non-Saccharomyces species were inoculated with a selected strain of S. cerevisiae to complete fermentation, and the content in 2,3-butanediol and acetoin isomers was again determined and statistical analysis was performed. Although the final values of these parameters resembled those obtained in pure fermentation with S. cerevisiae, statistical analysis discriminated wines according to the yeast species performing the first fermentation phase.     

Cellular Metabolism and Bioenergetic Function in Human Fibroblasts and Preadipocytes of Type 2 Familial Partial Lipodystrophy

LMNA mutation is associated with type-2 familial partial lipodystrophy (FPLD2). The disease causes a disorder characterized by anomalous accumulation of body fat in humans. The dysfunction at the molecular level is triggered by a lamin A/C mutation, impairing the cell metabolism. In human fibroblasts and preadipocytes, a trend for ATP production, mainly supported by mitochondrial oxidative metabolism, is detected. Moreover, primary cell lines with FPLD2 mutation decrease the mitochondrial ATP production if compared with the control, even if no differences are observed in the oxygen consumption rate of bioenergetic parameters (i.e., basal and maximal respiration, spare respiratory capacity, and ATP turnover). Conversely, glycolysis is only inhibited in FPLD2 fibroblast cell lines. We notice that the amount of ATP produced in the fibroblasts is higher than in the preadipocytes, and likewise in the control, with respect to FPLD2, due to a more active oxidative phosphorylation (OXPHOS) and glycolysis. Moreover, the proton leak parameter, which characterizes the transformation of white adipose tissue to brown/beige adipose tissue, is unaffected by FPLD2 mutation. The metabolic profile of fibroblasts and preadipocytes is confirmed by the ability of these cell lines to increase the metabolic potential of both OXPHOS and glycolysis under energy required independently by the FPLD2 mutation.     

Monitoring of less-common residual elements in scrap feeds for EAF steelmaking

The steel scrap quality is classified according to the amount of residual elements. However, there is a limited analysis of some of the less common residual elements such as antimony (Sb), tungsten (W), cobalt (Co), nickel (Ni) and molybdenum (Mo) mixed with steel scrap received by steel plants. This paper reports a historical analysis of these elements in the steel compositions from two steel plants, located in different regions, during 2011 to 2018, analysing around 21000 heats. The concentration of W and Sb dropped by 0.002%, due to the increasing recovery of non-ferrous metals from mixed scrap. It was found that the calibration and maintenance of the spectrometer used to analysis had a direct impact on the results. The presence of Sb, W and Co in the steel indicates contamination from other materials, since 80% of the use of these elements is in applications associated with non-ferrous materials. This is the first analysis of these elements in steel scrap reported the literature and the conclusion of the study is that more attention should be paid to monitor less common residuals elements, because analysis of these elements can provide information about the quality of the metal scrap.     

Distributed stabilisation of spatially invariant systems: positive polynomial approach

The paper gives a computationally feasible characterisation of spatially distributed controllers stabilising a linear spatially invariant system, that is, a system described by linear partial differential equations with coefficients independent on time and location. With one spatial and one temporal variable such a system can be modelled by a 2-D transfer function. Stabilising distributed feedback controllers are then parametrised as a solution to the Diophantine equation ax + by = c for a given stable bi-variate polynomial c. The paper is built on the relationship between stability of a 2-D polynomial and positiveness of a related polynomial matrix on the unit circle. Such matrices are usually bilinear in the coefficients of the original polynomials. For low-order discrete-time systems it is shown that a linearising factorisation of the polynomial Schur-Cohn matrix exists. For higher order plants and/or controllers such factorisation is not possible as the solution set is non-convex and one has to resort to some relaxation. For continuous-time systems, an analogue factorisation of the polynomial Hermite-Fujiwara matrix is not known. However, for low-order systems and/or controller, positivity conditions on the closed-loop polynomial coefficients can be invoked. Then the computational framework of linear matrix inequalities can be used to describe the stability regions in the parameter space using a convex constraint.