Investigation of donkey milk bacterial diversity by 16S rDNA high-throughput sequencing on a Cyprus donkey farm

The interest in milk originating from donkeys is growing worldwide due to its claimed functional and nutritional properties, especially for sensitive population groups, such as infants with cow milk protein allergy. The current study aimed to assess the microbiological quality of donkey milk produced in a donkey farm in Cyprus using culture-based and high-throughput sequencing techniques. The culture-based microbiological analysis showed very low microbial counts, whereas important food-borne pathogens were not detected in any sample. In addition, high-throughput sequencing was applied to characterize the bacterial communities of donkey milk samples. Donkey milk mostly composed of gram-negative Proteobacteria, including Sphingomonas, Pseudomonas, Mesorhizobium, and Acinetobacter; lactic acid bacteria, including Lactobacillus and Streptococcus; the endospores forming Clostridium; and the environmental genera Flavobacterium and Ralstonia, detected in lower relative abundances. The results of the study support existing findings that donkey milk contains mostly gram-negative bacteria. Moreover, it raises questions regarding the contribution of (1) antimicrobial agents (i.e., lysozyme, peptides) in shaping the microbial communities and (2) bacterial microbiota to the functional value of donkey milk.     

A facile NMR method for the quantification of total,free and esterified sterols in virgin olive oil

This study describes a simple analytical technique based on NMR spectroscopy for the determination of free and esterified sterols in olive oil. Free sterols were determined by ³¹P NMR upon derivatization of free sterols with a phosphorous reagent, whereas total (free + esterified) sterols were obtained from ¹H NMR. The present NMR method was validated by performing a comparison study with the reference method of gas chromatography. The agreement between NMR and GC methods was evaluated by using the Bland and Altman statistical analysis. The distribution of the data points in the bias plot showed that ∼96% of the measurements of total, free and esterified sterols in 24 extra virgin olive oil samples from various regions of Greece were within the limits of agreement of the two methods.     

Functionalized polymers derived from the reaction of polymaleic anhydride with amines and alcohols

In the present study the application of polymaleic anhydride as a reactive polymer is illustrated in its reactions with didodecylamine, diphenylamine, and dodeecanol. These polymers consisting of lipophilic segments (originating from the long aliphatic chains) or of the mesomorphic diphenyl moiety coupled with the polar carboxylic or carboxylate group can in principle exhibit mesomorphism in the melt and aggregate in dispersion. Of these derivatives didodecyl derivative froms mesomorphic-like structure in the melt, dodecanol monoester derivative dissolves freely in water whereas the sodium salts of the polymers disperse in water due to the presence of distinct polar and lipophilic moieties in their molecules.     

Microbiological quality of white-brined cheeses: a review

White-brined cheeses are widely produced in the North-east Mediterranean area and the Balkans. Traditionally, they were manufactured as artisanal cheeses, and nowadays they are manufactured on an industrial scale, and rigorous control of the production and maturation processes is essential. Aspects of the microbiology of white-brined cheeses and their significance with respect to the quality and safety of the final products are discussed in this review.     

Motion Planning for Drift-Free Nonholonomic Systems under a Discrete Levels Control Constraint

We solve the Motion Planning Problem for nonholonomic systems without drift when their inputs are restricted to take values in a prescribed discrete levels set of finite cardinality. In particular, we propose algorithms that produce the proper sequence of input levels as well as the corresponding switching times providing exact steering when the system is nilpotent or feedback nilpotentizable. For a general drift-free system, i.e. for a drift-free system that is neither nilpotent nor feedback nilpotentizable another algorithm provides approximate steering within a permissible error. Finally, we apply the proposed algorithms in motion planning for a car-like mobile robot.     

Determination of Glycerol in Wines Using <Superscript>31</Superscript>P-NMR Spectroscopy

³¹P-NMR spectroscopy was employed to detect and quantify glycerol in red wines from various regions of Greece. This novel analytical method was based on the derivatization of the hydroxyl groups of glycerol with 2-chloro-4,4,5,5-tetramethyl dioxaphospholane, and identification of the phosphitylated compound on the basis of ³¹P chemical shifts. Quantification of glycerol in wines was accomplished by integration of appropriate signals in the ³¹P-NMR spectrum and the use of the phosphitylated cyclohexanol as the internal standard. The method was reproducible (CV (%) = 2.35) and accurate (CV (%) = 1.34). Its applicability to glycerol quantification in wines was tested against a weighted amount of a glycerol-model compound by linear regression analysis (R = 0.999; intercept = 0.074 ± 0.078; slope = 0.998 ± 0.003; p = 0.000). Furthermore, the NMR method was compared to the AOAC official method (HPLC) using the Bland and Altman statistical analysis. The distribution of the data points in the bias plot showed that 100% of the measurements of glycerol in 16 wine samples from various regions of Greece were within the limits of agreement of the two methods.     

Assessment of donkey milk chemical,microbiological and sensory attributes in Greece and Cyprus

This study aimed to assess the nutritional, hygienic and sensory characteristics of donkey milk produced in Greece and Cyprus. The average values for pH, fat, protein and lactose were 7.14, 0.52 g/100 mL, 1.22 g/100 mL and 7.01 g/100 mL, respectively, whereas aflatoxin M1 and beta‐lactam residues were not detected in any sample. The microbiological analysis revealed very low somatic cell counts and total microbial counts, while Escherichia coli, Salmonella spp and Listeria monocytogenes were not detected in any sample. The sensory evaluation classified the milk as white, thin, with a slightly sweet pleasant taste, pleasant milky aroma, sweet flavour and no persistent aftertaste.     

High-Resolution NMR Spectroscopy: An Alternative Fast Tool for Qualitative and Quantitative Analysis of Diacylglycerol (DAG) Oil

Multinuclear (¹H, ¹³C, ³¹P) and multidimensional NMR spectroscopy was employed for the analysis of diacylglycerol (DAG) oil and the quantification of its acylglycerols and acyl chains composition. A number of gradient selected two dimensional NMR techniques (TOCSY, HSQC-DEPT, HSQC-TOCSY, and HMBC) facilitated the assignment of the complex one dimensional ¹H- and ¹³C-NMR spectra. In several cases, the aforementioned 2D-NMR techniques offered solid proof of earlier assignments based on chemical shift changes induced by the presence and relative positions of double bonds within the acyl chains. Integration of the appropriate signals in the NMR spectra of the three nuclei allowed the determination of DAG oil composition, which was found to be within the limits accepted for this oil, namely 1-monoacylglycerols 0.40–0.60%; 2-monoacylglycerols 0.40–0.50%; 1,3-diacylglycerols 57–62%; 1,2-diacylglycerols 28–32%; triacylglycerols 9–11%; saturated fatty acids 3–5%; oleic acid 37–45%; linoleic acid 49–53%; and linolenic acid 5–6.5%; tocopherols 0.24–0.27%. The compositional results obtained from the NMR spectra of the three nuclei were compared and discussed in terms of repeatability and ease of performance.