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Distinguishing floral and honeydew honey using chemical analysis is generally problematic. This work solved this problem by determining the trisaccharide melezitose in honeys, which was identified as a potential marker for identification of the type of honey. The newly developed method for determination of melezitose reduces the analysis time by approximately 10 times and significantly simplifies sample preparation during derivatization of saccharides. A two-step procedure of silylation with hexamethyldisilazane followed by N, O-bis(trimethylsilyl)trifluoroacetamide was developed for derivatization without the formation of degradation products. The limit of detection of the method for melezitose was 4.9 mg·kg-1 based on the selected ion m/z of 361 with relative standard deviation for real samples of = 15 %. The simplicity and speed of the method enables its use in screening tests. The method was successful at determination of a significant difference in the melezitose content of floral (103-2 880 mg·kg-1) and honeydew honeys (10 600-26 100 mg·kg-1), which allowed differentiation between the types of honey. [ABSTRACT FROM AUTHOR]

A generally known problem of gas chromatographic (GC) separation of trans-7,cis -9, cis-9,trans-11, and trans-8,cis-10 conjugated linoleic acid (CLA) isomers was studied by GC on a 200 m capillary column coated with a cyanopropyl silicone phase at 130 °C. The resolution of these CLA isomers obtained at given experimental conditions was not high enough for direct quantitative analysis but it was, however, sufficient for the determination of their peak areas by a commercial deconvolution software. Relative retentions and resolution factors of CLA isomers with overlapped peaks determined by the separation of a commercial CLA standard mixture as well as CLA isomer fractions obtained by the HPLC semi-preparation of ewe milk were used as input data in the deconvolution procedure. The milk of pasture-fed ewes with higher cis-9,trans-11 isomer contents showed higher contents of trans-7,cis-9 as well as trans-8,cis-10 CLA isomers in comparison with milk fat of total mixed rations (TMR)-fed ewes. For cow milk samples showing lower CLA contents, no such trends were evident. [ABSTRACT FROM AUTHOR]

Aromatic compounds, such as green note volatiles, belong to highly demanded chemicals in food and cosmetics industries. Their production, isolation and purification often represents a difficult challenge. The natural sources are often scarce and difficult to process, while chemical synthesis produces forms that do not occur naturally or even burden the environment. Production of aromatic compounds by recombinant enzymes have proven to represent the best of two worlds, as it enables preparation of economically sufficient quantities of the product while keeping its quality at required levels. The aim of our work was to develop sustainable laboratory-scale processes allowing production of two key enzymes used in biotransformation of highly valued, but volatile and unstable, aromatic compound trans-2-hexenal to a more stable trans-2-hexenol. We also demonstrated the ability of alcohol dehydrogenase coupled to formate dehydrogenase to catalyse this conversion at desired levels in a one-pot reaction at conversion rates above 90 %. [ABSTRACT FROM AUTHOR]

High-temperature gas chromatography with mass spectrometry detection (HTGC-MS) was applied to separation and identification of iridoids (aucubin, catalpol), flavonoid aglycone (quercetin, apigenin, luteolin) and flavonoid glycosides (quercetin 3-O-a-d-arabinoside, quercetin 3-O-β-d-galactoside and quercetin 3-O-β-d-glucoside) in standard mixtures and 26 real natural matrices. Conditions of HTGC-MS were set in accordance with the best achieved separation of analytes and the highest value of signal in the used system. The developed two-step derivatization process allowed direct silanization of polar analytes in the plant material without the need of extraction. For the tested analytes, the calculated limits of detection were in the range of 2-35 mg·kg-1 and the values of retention indices ranged from 2 858 for aucubin to 3 859 for quercetin 3-O-a-d-arabinoside. [ABSTRACT FROM AUTHOR]