Cover Picture: Structure–Activity Relationship Analysis of the Peptide Deformylase Inhibitor 5‐Bromo‐1H‐indole‐3‐acetohydroxamic Acid (ChemMedChem 2/2009)

The cover picture shows a “reverse” indole derivative in complex with Bacillus stearothermophilus peptide deformylase (PDF). This compound was selected from a structure–activity relationship study as a potent inhibitor of bacterial PDFs and shows antibacterial activity toward Bacillus subtilis as well as other pathogens such as Streptococcus pneumoniae and Staphylococcus aureus. For more details, see the Full Paper by I. Artaud et al. on p. 261 ff.

     

Investigating the Short Peptidome Profile of Italian Dry-Cured Ham at Different Processing Times by High-Resolution Mass Spectrometry and Chemometrics

Short peptides have been spiking interest owing to their significant contribution to the taste and functional properties of dry-cured ham. In this study, a suspect screening approach based on high-resolution mass spectrometry was employed for the comprehensive characterization of the short endogenous peptidome in dry-cured ham samples at different processing stages (14, 22, and 34 months). After careful manual spectra interpretation, a chemometric approach based on principal component analysis was employed for highlighting the differences between the three sets of samples. A total of 236 short peptide sequences was tentatively identified, including 173 natural short peptides and 63 sequences containing non-proteinogenic amino acids, the highest number ever reported for endogenous sequences in dry-cured ham. Samples in the latest processing stages presented a generally higher abundance of dipeptides, indicating residual proteolytic activity. Moreover, the several annotated modified short peptides, mainly pyroglutamination and lactoyl conjugation, allowed hypothesizing several reactions occurring over time. For the first time, several lactoyl-dipeptides were tentatively identified in dry-cured ham samples with maximum concentration in the late processing stage samples. The presented results significantly contribute to the understanding of the reaction involving short peptides that affect the sensory and functional properties of dry-cured ham.     

Experiments on C nanotubes synthesis by Fe-assisted ethane decomposition

We performed experiments on the synthesis of carbon nanotubes (CNTs) by iron-catalyzed chemical vapor deposition (CVD) in C₂H₆ + H₂ atmosphere. We varied flow-rates of reactant gases (ethane: 30–120 sccm, hydrogen: 0–120 sccm), as well as their ratio, in order to study the evolution of the growth kinetics. We used scanning electron microscopy, high-resolution transmission electron microscopy and Raman spectroscopy to investigate the morphologies, dimensions and crystalline structure of the samples. Our results demonstrate the crucial role played by H₂ in the enhancement of C diffusion-rate and in the consequent development of ordered and smooth graphene layers. A faster growth-rate is achieved by the increase of C₂H₆ flow-rate. However, if H₂ flow-rate is not adequately enhanced, the improvement is only apparent. The excess of C supplied gives rise to deposition of amorphous carbon onto the CNT walls, and to the co-production of different nanostructures. A substantial agreement is found with results reported for CVD growth of CNTs by the use of different catalysts, reactants and gas-flowing setups.     

Spectroscopic investigation of homoepitaxial CVD diamond for detection applications

Three-layer structures consisting of intrinsic/B-doped homoepitaxial CVD diamond grown onto commercial HPHT Ib substrates have been studied by means of Raman spectroscopy and photoluminescence (PL). The intrinsic layers have been deposited, at fixed methane to hydrogen ratio (1%), by systematically changing the substrate temperature (620–820 °C). Raman measurements point out the excellent crystalline quality and phase purity of the samples. Moreover, flat PL spectra in a wide energy range (1.7 eV–2.7 eV) indicate also their great purity. As the free-exciton recombination can be used to further probe the quality of synthetic diamond, measurements of free-exciton emission at room temperature have been also performed. The excitation was produced by a 5 ns pulsed tunable laser irradiation. The results have been compared with the detection characteristics of simple alpha-particle detector prototypes based on the analyzed samples. A clear correlation between excitonic emission and detector sensitivity is demonstrated. On the basis of these results, low methane concentrations (approx. 1% CH₄/H₂) in the deposition gas mixture and intermediate substrate temperatures (approx. 720 °C–770 °C) have been identified as the best working conditions of our growth reactor.     

University-industry research interactions: A guide to the proceedings

Concern for economic growth in the industrialized countries has focused attention on society's use of technical resources. One mechanism for enhancing the effectiveness of the reservoir of science and engineering is university-industry interactions. There are growing indications that such linkages are now becoming more formal, more frequent, more planned. Why is this so? What objectives are served? How can these interactions produce the most effective use of our technical resources to serve universities, industry, and society? These questions are addressed from different viewpoints in the papers contained in this collection. There are different objectives, and, therefore, different emphases from the many countries represented. There are different characteristics for each major industry sector, and there are indications that the nature of the industry is at least as important in determining the degree of university-industry cooperation as the nature of the country. And there are a number of issues of particular interest that call for special attention, such as the role of research institutes or the problems of regional economic development.     

Non-hydrolytic sol–gel route to a family of hybrid mesoporous aluminosilicate ethanol dehydration catalysts

Journal of Materials Science - Hybrid materials are intensely studied for potential applications in heterogeneous catalysis. Organic groups at the catalyst surface can modify not only its...     

The effect of salivary amylase on the viscosity behaviour of gelatinised starch suspensions and the mechanical properties of gelatinised starch granules

The digestion of gelatinised starch suspensions by salivary amylase was studied using a viscometric assay and also by measuring the mechanical properties of individual granules. Viscosity decay as a function of time was approximately exponential. A comparison with a reducing group assay showed that a 50% fall in viscosity corresponded to the scission of about 0.05% of the glycosidic bonds. The half-time for the reduction of viscosity by the enzyme was found to be proportional to enzyme concentration but independent of starch concentration over a wide concentration range. This result suggests that the starch concentrations used were well below the saturating point for the enzyme, which was thus largely in the free state, and that the enzyme attacked the gelatinised granules throughout their structure rather than just at the surface. Measurements of the forces required to deform individual granules supported this hypothesis by showing that the gelatinised granules lost nearly all their mechanical strength during initial contact with salivary amylase, without any apparent change in diameter.     

Sheep milk kefir sweetened with different sugars: Sensory acceptance and consumer emotion profiling

The objective of this study was to determine the sensory acceptance and emotional profile of sheep milk kefir sweetened with different sugars (demerara sugar, brown sugar, fructose, coconut sugar, and honey, 100 g/L). Consumers (n = 100) assessed sensory acceptance (appearance, aroma, taste, texture, and overall impression), and expressed their emotions (satisfied, active, loving, calm, comfortable, energetic, happy, healthy, refreshing, disgusted, worried, and upset). The emotions “satisfied,” “active,” “comfortable,” “energetic,” “healthy,” and “refreshing” were found between moderate and very high levels, indicating that they are important emotions for the characterization and sensory acceptance of kefir samples. The use of different sugars had no influence on the intensity of the emotions “calm,” “comfortable,” “happy,” or “disgusted,” and resulted in a greater sense of satisfaction. The use of demerara sugar or fructose did not alter the acceptance of the products or the intensity of emotions. The use of brown sugar decreased acceptance (taste, texture, and overall impression) and the intensity of the emotions “active,” “loving,” “energetic,” “healthy,” and “refreshing.” The use of coconut sugar decreased acceptance (appearance, aroma, and taste) and the intensity of the emotions “refreshing” and “upset.” The use of honey improved acceptance in appearance and aroma but reduced the intensity of the emotions “active,” “loving,” “energetic,” and “healthy.” Based on sensory data, it is recommended to use demerara sugar or fructose as a substitute for sucrose. In conclusion, the study of emotions can be used as an additional tool for obtaining data related to the sensory acceptance of products.     

Effect of probiotic Minas Frescal cheese on the volatile compound and metabolic profiles assessed by nuclear magnetic resonance spectroscopy and chemometric tools

This study aimed to evaluate the effect of Lacticaseibacillus casei 01 as a probiotic culture on the production of volatile organic compounds and metabolic profile of Minas Frescal cheese. Lactose (α-lactose and β-lactose), fatty acids (unsaturated and saturated), citric acid, tryptophan, and benzoic acid were the main compounds. Compared with the control cheese, probiotic cheese was characterized by the highest concentration of tryptophan and presented a higher number of volatile acids. The control cheese was characterized by the highest concentration of benzoic acid and fatty acids, resulting in a higher number of volatile alcohols and esters. No differences were observed for α-lactose, β-lactose, and citric acid contents. A clear separation of probiotic and control Minas Frescal cheese was obtained using ¹H nuclear magnetic resonance spectra, demonstrating that the addition of probiotic culture altered the metabolic profile of Minas Frescal cheese. Overall, the findings suggested that the addition of probiotic culture promoted the proteolysis in the fresh cheeses, decreased the lipolysis, and altered the volatile compounds. Furthermore, nuclear magnetic resonance spectroscopy coupled to chemometrics tools could be used to differentiate probiotic and conventional cheeses.     

Occurrence of bisphenol A in the milk chain: A monitoring model for risk assessment at a dairy company

Bisphenol A (BPA) as a chemical hazard may enter the milk chain during primary production at the farm and, successively, during milk processing at a dairy company. To identify the potential pathways that play a role in the occurrence of BPA, a monitoring model for risk assessment based on the identification of the hazards at each stage of milk processing was investigated. Milk samples were analyzed using liquid chromatography with fluorescence detection. Quantifiable levels were detected in samples obtained from the raw milk storage tank, pasteurized milk from the storage tank, and packaged milk. The highest BPA contamination levels were detected in raw milk from the storage tank (mean 0.265 µg/L). Despite the fact that dietary exposure levels were below the temporary daily intake, BPA may have adverse effects, particularly for vulnerable population groups. New monitoring programs involving each stage of milk processing should therefore be applied.