ABSTRACT
Olive oil was converted into methyl esters which were autoxidized at 60 degrees C. The composition of oxidized products was determined by the comparison of infrared spectra and NMR spectra of the original and acetylated samples, the sample reduced with potassium iodide and the acetylated reduced sample. Oxidized products were separated by preparative thin layer chromatography on silica gel and characterized by selective detection and by infrared spectrometry of the fractions. The oxidation products consisted of hydroperoxido butyl oleate, substituted hydroperoxides, mono- and disubstituted monomeric derivatives and a small amount of oligomers.
Subject(s)
Fatty Acids/analysis , Oils/analysis , Chromatography, Thin Layer , Hydrogen Peroxide , Magnetic Resonance Spectroscopy , Methylation , Molecular Weight , Oleic Acids/analysis , Oxidation-Reduction , Spectrophotometry, InfraredABSTRACT
During storage of green coffee beans at increased temperature and at constant humidity reducing sugars present in original beans react with free amino acids with formation of colourless unstable products. Additional reducing sugars and free amino acids are produced by hydrolysis of polysaccharides and proteins, respectively. The second stage of storage is characterized by only slight changes in the content of free amino acids and sugars but by intensive browning reactions. This latter stage was characterized by deterioration of sensory quality of coffee beverage, especially of its odour. Lysine combined in protein was involved in browning reactions via colourless intermediary products.
