PH and trace‐elements content in raisin extract industrial‐scale alcoholic fermentation

Abstract

The ability of all kinds of Greek raisins for the industrial-scale fermentation related to pH and trace-element contents is discussed. In the case of raisin extracts of pH 3.2 larger ethanol productivities, yields, and a continuous use of the same yeast culture at a level of 300 batches was obtained. Metals such as Co, Fe, Zn, Cu, Cd, and Pb in all kinds of raisins have been determined using atomic absorption spectroscopy. The raisin variety Trechumena contains the smallest amount of Cu, and the variety Psilla contains 7 times higher concentration than Trechumena. This is in agreement with the fact that Psilla is the worst kind of raisin and Trechumena the best for spirit production. This observation is related with experimental results obtained by alcoholic fermentation in a series of synthetic media containing sacharose and different concentrations of copper.