Development of a new continuous homogenous liquid phase microextraction procedure based on in-situ preparation of deep eutectic solvent; application in the analysis of aliphatic amines in urine samples by GC-MS

In the present work, a new microextraction procedure combined with gas chromatography-mass spectrometry has been developed for the analysis of several aliphatic amines from urine sample. The sample preparation method was a continuous homogenous liquid phase microextraction that was based on in-situ preparation of 4-chlorophenol: choline chloride deep eutectic solvent. The deep eutectic solvent was prepared by passing the mixture of related compounds through a syringe barrel filled with exothermic salts (calcium chloride and potassium bromide). The released heat by dissolving the salts and increasing the solution ionic strength assists the formation of the deep eutectic solvent. The influence of various factors on the efficiency of the proposed procedure including salts amount, flow rate, pH, salting-out effect, and extraction solvent volume was studied. The calibration curves were linear broadly over the concentration range of 1.2-250 ng mL-1 with coefficient of determinations ≥0.996. The enrichment factors were in the range of 188-246 and the limits of detection and quantification were 0.16-0.37 and 0.56-1.2 ng mL-1, respectively. Based on the results, the offered method was sensitive, rapid, eco-friendly, and efficient for extracting and determining aliphatic amines in urine samples.

Integrated analytical approaches for the characterization of Spirulina and Chlorella microalgae

Microalgae are well-known for their content of bioactive molecules such as pigments, proteins, fatty acids, polysaccharides, vitamins and antioxidants, all of which are of great interest in the preparation of a wide range of products such as food, cosmetics and nutraceuticals. The purpose of this project was the analytical characterization of commercial dry microalgal biomass: four samples of Chlorella and five of Spirulina were analysed in order to highlight their content in terms of micro/macro nutrients. The research was oriented towards the development and validation of accurate, fast and reproducible methods for the nutritional assessment of algal biomasses, aiming to provide a guiding methodology. The lipid profiles of algal matrixes were analysed for the content of saturated, unsaturated and polyunsaturated fatty acids. The process was divided into two phases: firstly, the extraction and determination of the total lipids and pigment content; secondly, the trans-esterification of the extracted lipid-pigment portion in order to analyse fatty acid methyl esters (FAMEs) with a GC-MS method. A fingerprinting of MUFAs and PUFAs was obtained regarding microalgae species. The determination of total carotenoids and chlorophylls content in the lipid extracts was evaluated through a fast UV-Vis spectrophotometric analysis, which was validated by a new HPLC-DAD analysis. Furthermore, the total antioxidant activity of each lipid extract was determined along with the determination of the microalgae protein content. Then, with the aid of the principal component analysis (PCA) plots, the two microalgae were clustered in terms of their micro/macro nutrients, for differentiating their properties. Spirulina, resulting to have a greater antioxidant activity, supposedly due to a higher content in pigments and higher protein concentration, could be suggested for an appropriate diet for sporting people. Chlorella, instead, showed a more balanced profile of PUFAs and MUFAs and its use could be suggested for cosmetics and vegan diets. This paper puts forward an overall analytical approach, sustained by a multivariate analysis, for emphasising content differences and activity of two different microalgae strains, in order to underline specific claims for each class, addressed to defined final users.

Antimicrobial activity of four essential oils against pigmenting Pseudomonas fluorescens and biofilmproducing Staphylococcus aureus of dairy origin

Essential oils (EOs) are mixtures of secondary metabolites of plant origin with many useful properties, among which the antimicrobial activity is also of interest for the food industry. EOs can exert their antimicrobial potential both directly, in food products and active packaging, and indirectly, as sanitizing and anti-biofilm agents of food facility surfaces. Aim of this research was to evaluate the antimicrobial activity of four EOs (bergamot, cinnamon, manuka and thyme) against Pseudomonas fluorescens and Staphylococcus aureus isolated from milk and dairy products. The chemical composition of EOs was evaluated by Gas Chromatography-Mass Spectrometry analysis. Minimum Inhibitory Concentration values were determined by a microplate method against 9 Ps. fluorescens from marketed mozzarella with blue discoloration defect, and 3 biofilm-producing S. aureus from milk. Reference ATCC strains were included. Pigment production activity by Ps. fluorescens was assessed both in culture and in cheese. EOs of manuka (leptospermone 23%) and thyme (carvacrol 30%, pcymene 20%, thymol 15%) showed the highest antimicrobial activity against S. aureus, MIC values were 0.012%-0.024% and 0.024% v/v, respectively; meanwhile EOs from thyme and cinnamon (cinnamaldehyde 55%) exhibited the best activity against Ps. fluorescens with MIC values of 0.098%-0.195% and 0.195%-0.391% v/v, respectively. The antimicrobial activity of these EOs is promising and they could be exploited in the dairy production chain.