ABSTRACT
A low-resolution gas-phase FT-IR method for the fast analysis of supercritical CO2-extracted caraway fruit oils has been developed. The limonene/carvone ratio of extraction product was determined within seconds, yielding a coefficient of variation of <5% (n = 10). A selection of experimental parameters is discussed on the basis of the analysis of 52 extracted samples. GC-FID was used as a reference method. A correlation of 0.983 (n = 24) between the two methods was observed. This method is suitable for the analysis of a large number of caraway fruit extracts due to its speed, repeatability, and minimum sample preparation.
Subject(s)
Carbon Dioxide/isolation & purification , Plant Oils/analysis , Spectroscopy, Fourier Transform Infrared/methods , Cyclohexane Monoterpenes , Cyclohexenes , Limonene , Monoterpenes , Reproducibility of Results , Sensitivity and Specificity , TerpenesABSTRACT
Four apple wine fermentation processes have been observed by means of direct-inlet gas-phase FTIR spectroscopy. The apple juice concentrates were each fermented by two species of Saccharomyces cerevisiae starters, and the experiment was repeated. The development of the concentrations of 1-propanol, 4-methylpyridine, acetaldehyde, acetic acid, and ethyl acetate was monitored. Two different sampling methods were used--static headspace and direct injection of the must. The performance of the FTIR method is limited by the high ethanol concentration. It can be mathematically proven that the amount of sample can be selected so that any distortion due to ethanol is minimized. Headspace GC-MS was used for preliminary compound identification.
Subject(s)
Fermentation , Gas Chromatography-Mass Spectrometry/methods , Spectroscopy, Fourier Transform Infrared/methods , Wine/analysis , 1-Propanol/analysis , Acetaldehyde/analysis , Acetates/analysis , Acetic Acid/analysis , Malus/chemistry , Pyridines/analysis , Saccharomyces cerevisiaeABSTRACT
The detection and the correction of instrumental line-shape distortions have been studied. Some common distortion principles have been mathematically examined. A procedure for error correction is presented. In addition to a theoretical study, we also investigated simulated and experimental examples. An application for the procedure is presented.
