Search results for "analytical"
showing 10 items of 9586 documents
Solvent dependence of the νs(OD) bandshape in 2,6-dichlorophenol
1994
Abstract The infrared bandshape of νs(OD) of 2,6-dichlorophenol is measured in a series of solvents of increasing polarity, and is quantitatively analysed. The bandshape is described in terms of band indices, moments, correlation functions and correlation times. A distinct solvent dependence of bandshape and relaxation parameters has been found. The changes of the νs(OD) bandshape with increasing solvent polarity are compared in detail with those obtained earlier for analogous solvents for νs(OH) of 2,6-dichlorophenol. The overall behaviour of the spectral and relaxation parameters is similar, but the changes are less distinct for the weaker OD ⋯ Cl bond.
Densities, Viscosities, and Refractive Indices of the Binary Systems Methyl tert-Butyl Ether + 2-Methylpentane, + 3-Methylpentane, + 2,3-Dimethylpent…
2000
This paper reports experimental densities, viscosities, and refractive indices of the binary systems methyl tert-butyl ether (MTBE) + 2-methylpentane, + 3-methylpentane, + 2,3-dimethylpentane, and + 2,2,4-trimethylpentane over the entire range of composition, at 298.15 K and atmospheric pressure. Excess molar volumes and viscosity deviations were evaluated from the experimental data. These excess or derived properties were fitted to the Redlich−Kister equation to estimate the binary interaction parameters. The experimental values of viscosity have been compared to values predicted by means of the GC−UNIMOD model.
Shelf life improvement of the loaf bread using allyl, phenyl and benzyl isothiocyanates against Aspergillus parasiticus
2017
Abstract Fungal growth inhibition and aflatoxins (AFs) reduction using allyl (AITC), benzyl (BITC) and phenyl (PITC) isothiocyanates were studied in loaf bread contaminated with Aspergillus parasiticus . Two inoculated loaf bread slices were introduced into a plastic tray together with paper filters or small plastic bags paper filters soaked with AITC, BITC or PITC, the final concentration inside the package was of 0.5, 1 or 5 μL/L. The plastic trays, incubated at room temperature, were visual examined for the shelf life evaluation during 8 days. The quantification of the AFs was carried out using liquid chromatography coupled to mass spectrometry (LC-MS/MS). Shelf life increase of three an…
Cheese flavour : instrumental techniques
2004
This chapter discusses instrumental techniques to analyze cheese flavor. It focuses on recent advances made to study and identify the taste-active components present in the water-soluble fraction of cheese. A general procedure for the preparation of fractions involves an extraction of grated cheese by water followed by a fractionation scheme, generally adapted from the fractionation protocol used to isolate cheese nitrogen fractions in the study of proteolysis in cheese during ripening. However, as sub-fractions have to be evaluated sensorially to assess their relative sensory impact and try to link it to their chemical composition, a suitable eluent has to be used in the chromatographic st…
The Potential Use of Raw and Deodorized Non-Conventional Protein Powder in Human Food
2014
This study aimed to evaluate the potential use of a non-conventional protein source, a powder made from earthworms, as human food. Sensory analyses were done in order to assess the acceptability of cookies that were fortified with Eisenia foetida (Ef) protein powder. Cocoa and cinnamon were used as taste-masking agents. The acceptability of cookies fortified with deodorized Ef protein powder (off-flavor reduced) was also evaluated. We demonstrated that cocoa cookies can be fortified with 3.9% of raw Ef proteins and that cocoa/cinnamon cookies can be fortified with 5.2% of raw Ef proteins without any loss in their acceptability. Cookies fortified either with a raw protein powder or with a de…
Evaluation of taste compounds in water-soluble extract of goat cheeses
2000
Abstract The water-soluble fractions of two goat cheeses — one denomination of origin commercial trade mark (crottin de Chavignol®) and one bought in a local cheese making establishment (Bouton de culotte®) — containing many taste and flavour molecules were studied. Ultrafiltration with a 1000 Da threshold membrane, followed by gel filtration on Toyopearl HW-40S gel using water as eluent, led to the production of edible fractions. Physicochemical and sensory analysis of these fractions showed that the most tasty fractions contained, essentially, the free amino acids and mineral salts. Some of these tasty fractions also imparted some flavours. The quantity of small peptides (MW
Emerging extraction
2015
Traditional extraction methods include usually high temperature treatment (more than 100°C) with the subsequent risk of thermal denaturation or transformation of the target molecules. Moreover, these techniques are very time-consuming and require relatively large quantities of solvents. On the other hand, the use of environmentally friendly technologies has led researchers and the food industry to develop new alternative processes that can extract valuable compounds from different sources and food wastes of different origin. This chapter describes the potential use of emerging technologies such as ultrasound-assisted extraction (UAE), laser ablation, pulsed electric fields (PEF), high volta…
Presence of trichothecenes and co-occurrence in cereal-based food from Catalonia (Spain)
2011
The most important trichothecenes are HT-2 toxin (HT2) and T-2 toxin (T2) from type A and deoxynivalenol (DON) from type B. Thus, the aim of the current study was to assess the occurrence of these trichothecenes in the Catalonian market. 479 food samples were taken from the most susceptible to trichothecenes contamination and most commonly consumed in Catalonia commodities. DON, T2 and HT2 toxin were determined in breakfast cereals, snacks and pasta samples following extraction, clean-up, derivatization and finally analysis by GC–ECD. Moreover, these mycotoxins were determined in sliced bread, sweet corn and beer by LC–DAD. Our results showed that DON was the main trichothecene present in t…
Capillary Electrophoresis in Wine Science
2016
International audience; Capillary electrophoresis appeared to be a powerful and reliable technique to analyze the diversity of wine compounds. Wine presents a great variety of natural chemicals coming from the grape berry extraction and the fermentation processes. The first and more abundant after water, ethanol has been quantified in wines via capillary electrophoresis. Other families like organic acids, neutral and acid sugars, polyphenols, amines, thiols, vitamins, and soluble proteins are electrophoretically separated from the complex matrix.Here, we will focus on the different methodologies that have been employed to conduct properly capillary electrophoresis in wine analysis.Two examp…
Bread aroma
2020
: This chapter will review the different synthetic pathways of bread volatiles in conventional white bread. The influence of traditional and innovative raw materials and breadmaking processes on the formation of volatiles will then be discussed. Next, extraction and analytical methods used to identify volatiles that participate in bread aroma will be presented. Volatiles that have been identified in freshly baked white bread will be listed and the ones that are potent odorants highlighted. Finally, the techniques employed by the baking industry to enhance bread aroma will be described.