ANALYSIS OF POLYPHENOLIC COMPOUNDS OF DIFFERENT VINEGAR SAMPLES

A method for the determination of low-molecular-mass polyphenolic comp ounds in vinegars has been optimized and applied to different samples. Ethyl acetate has been used for the extraction of the polyphenolic co mpounds in a continuous rotatory system, furnished with a special devi ce that allows for the simultaneous extraction of twelve samples. The extracts obtained were submitted to HPLC separation using a C18 revers ed-phase column and gradient elution. The identification of polyphenol ic compounds was carried out using a photodiode detector. Important di fferences were found in the phenolic content of the different samples. Best extraction yields were obtained when using 80 ml ethyl acetate a nd 300 steps (2 h 5 min) at a velocity of 0.8 rpm. The reproducibility of the method may be considered quite good. The method has been succe ssfully applied to the analysis of real samples of very different kind s of vinegar. There are very interesting differences between the low-m olecular-mass phenolic fraction of the vinegar analysed. Some interest ing low-molecular-mass phenolic compounds have been identified. Their concentration, as well as the concentrations of other so far non-ident ified substances, depend upon the type of sample. The individual inves tigation of these phenolic compounds may furnish hints enabling the or igin and type of vinegar to be traced. The elaboration type used in co nnection with the starting wine can be ascertained and differentiated, together with the ageing system used, through inference from the anal ytical data obtained from different vinegars.