No abstract

The separation of organic acids on the column Aminex HPX-87H from Bio-Rad is described. The relationship between column temperature and retention time was studied for both sulphuric and phosphoric acid eluants and an analytical scheme using 0.2% (v/v) phosphoric acid was developed. While the procedure is designed for the commonly occurring non-volatile acid metabolites it was demonstrated that conditions could be established for the analysis of fatty acids to C^. Difficulties in the qualitative and quantitative analysis of organic acids in beer are discussed.

A survey using four strains of yeast was made to establish whether the organic acid metabolites produced by growth on synthetic medium using glucose substrate could provide a means of differentiation. While concentrations of the various acids produced were different, they were insufficiently unique to allow predictability of the strain from which they arose.High performance liquid chromatography on the resin Aminex HPX-87H provided an ideal monitoring base but a number of components could not be identified from retention times of commonly occurring organic acid metabolites. Chromatograms and charts showing changes occurring throughout the ferment ation are included.

A study of the organic metabolites produced by four selected strains of yeast when grown on single carbon substrates is described. The products were chromatographed on Aminex HPX-87H resin as described previously (Part 1). Examples are given for glycerol, raffinose, cr-methyl glucoside, ethanol, lactate and succinate to illustrate how the methodology can be used to differentiate yeast strains.Some of the results obtained are in conflict with generally accepted classification.