Aflatoxin M1 (AFM1) occurrence in human and animal milk, infant formula, powdered milk, cheese and yoghurt represents a risk for health. The last four years (2010–2014) of data, as well as the most frequently and updated analytical methods applied for AFM1 quantification, are evaluated. Aflatoxin B1, considered the most potent toxic aflatoxin, is metabolised to form the monohydroxy derivative AFM1. This metabolized, expressed in the milk, is relatively stable, and it is not eliminated by heat treatments or pasteurisation, and thus represents a serious health concern.

Pulsed electron−electron double-resonance (PELDOR) and CW-ESR spectroscopies were used to study the dipole−dipole interaction of spin labels in frozen glassy solutions of mono- and double-labeled analogues of the 22-residue, the head-to-tail covalent dimer of the peptaibol antibiotic trichogin GA IV. The [TOAC-1] and [TOAC-1,19] dimers were studied in methanol and in a chloroform−toluene mixture. It was shown these dimer molecules do not form aggregates in methanol. However, in chloroform−toluene, the PELDOR signal of the mono-labeled dimer shows oscillations, due to the dipole−dipole interaction of the nitroxide spin labels. From the signal decay, the number of molecules per aggregate was estimated to be ∼2−3, depending on the concentration used. The contributions of inter- and intra-aggregate interactions of spin labels to the PELDOR signal decay were separated. The distance distribution functions of the intra-aggregate interactions range from 3.0 to 4.5 nm. The maxima are observed at 3.4 nm. From the PELDOR data, we obtained the functions of distance distributions of labels for the monomeric double-labeled peptide in methanol as well as for the same peptide isolated within aggregates of nonlabeled peptide molecules in chloroform−toluene. In the latter case, the distribution function is the most narrow with a maximum at a distance between the nitroxide spin labels of 2.8 nm, which is in agreeement with the theoretical distance between labels at corresponding residue positions of an α-helical structure.

In the dipeptides Boc-Bip-L-Val-OMe and Boc-Bip-D-Val-OMe, an induced axial chirality in the biphenyl core of the Bip residue, a conformationally labile, proatropoisomeric C(alpha,alpha)-disubstituted glycine, was observed by electronic CD and (1)H NMR. Chiral induction is significantly higher when the Val residue is located at the C-terminal position of Bip. An outstanding phenomenon of propagation of chirality was demonstrated to occur in the related 3(10)-helical -(Bip)n-L-Val (n = 2-6) oligopeptides by CD and vibrational CD techniques.

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Anthocyanins are colored valuable biocompounds, of which extraction increases globally, although functional applications are restrained by their limited environmental stability. Temperature is a critical parameter of food industrial processing that impacts on the food matrix, particularly affecting heat-sensitive compounds such as anthocyanins. Due to the notable scientific progress in the field of thermal stability of anthocyanins, an analytical and synthetic integration of published data is required. This review focuses on the molecular mechanisms and the kinetic parameters of anthocyanin degradation during heating, both in extracts and real food matrices. Several kinetic models (Arrhenius, Eyring, Ball) of anthocyanin degradation were studied. Crude extracts deliver more thermally stable anthocyanins than purified ones. A different anthocyanin behavior pattern within real food products subjected to thermal processing has been observed due to interactions with some nutrients (proteins, polysaccharides). The most recent studies on the stabilization of anthocyanins by linkages to other molecules using classical and innovative methods are summarized. Ensuring appropriate thermal conditions for processing anthocyanin-rich food will allow a rational design for the future development of stable functional products, which retain these bioactive molecules and their functionalities to a great extent.

2,2,6,6-Tetramethylpiperidine-1-oxyl-4-amino-4-carboxylic acid (TOAC) is a topographically and conformationally restricted, nitroxide containing, C(alpha)-tetrasubstituted alpha-amino acid. Here, we describe the molecular and crystal structures, as determined by X-ray diffraction analyses, of a TOAC terminally protected derivative, the cyclic dipeptide c(TOAC)(2).1,1,1,3,3,3-hexafluoropropan-2-ol (HFIP) solvate, and five TOAC-containing, terminally protected, linear peptides ranging in length from tetra- to hepta-peptides. Incipient and fully developed, regular or distorted 3(10)-helical structures are formed by the linear peptides. A detailed discussion on the average geometry and preferred conformation for the TOAC piperidine ring is also reported. The X-ray diffraction structure of an intramolecularly cyclized side product resulting from a C-activated TOAC residue has also been determined.

The pyrolysis can be an attractive way to reduce the plastic waste and, in the same time, to obtain alternative conventional fuels. In this respect, four polymers (low-density polyethylene, high-density polyethylene, propylene and polystyrene) were used in the pyrolysis process. The experiments were carried out by using an in-house plant, which allowed a maximum test temperature of 450 �C. The product oil and the derived gas from the pyrolysis process were evaluated using different techniques, such as elemental analysis (EA), calorimetry, gas chromatography (GC), gas chromatography coupled with mass spectrometry (GC-MS). Furthermore, for a comparative study two catalysts, zeolite and lignite, were also used for the pyrolysis process, in order to observe their influences on the final products. The higher heating value obtained for the oil was in the 40.17-45.35 MJ/kg range, acceptable for the use of these oil as an alternative fuel for diesel engine. Also, the sulphur content from the obtained oil does not cause environment problems, being lower than the allowed limits (10 mg/L). In addition, the pyrolysis derived gas was rich in hydrocarbons, conducting to a high calorific value, in the 73.42 - 121.18 MJ/kg range.

Oancea S., Drághici O. (2013): pH and thermal stability of anthocyanin-based optimised extracts of Romanian red onion cultivars. Czech J. Food Sci., 31: 283-291.Total phenolics and anthocyanins in ten samples of Romanian red onion cultivars, extraction optimisation and pH/ thermal stability were investigated. Extraction with 80% aqueous ethanol leads to an increased anthocyanin yield. The level of phenolics and anthocyanins in bulbs is highly variable and was found higher in the Red of Turda cultivar. The highest value of 99.66 mg/100 g FM was obtained for red onion dry skins. Strong acidic conditions favoured the better stability of anthocyanin extracts during 10-day storage. The first order rate constant value of anthocyanin degradation during storage calculated at different pH increased almost 17 times when pH increased from 1.0 to 9.0. Results of thermal analysis performed by differential scanning calorimetry showed that temperatures over 45°C already induced anthocyanin degradation in extracts. These results may become useful for establishing the appropriate conditions of processing and storage of anthocyanin-based foods. The obtained data on total phenolics and anthocyanins in Allium cepa L. may become relevant for future estimation studies of their daily consumption and for completing the national food composition databases.