CHANGES IN ORGANIC-ACID LEVELS DURING MALTING

A method. based on HPLC, was developed for analysis of organic acids i n germinating barley and finished malt. Levels of the major respirator y organic acids were examined daily during steeping, germination and k ilning in a commercial maltings. The major acids detected were citrate , malate, succinate and lactate. L-lactate but not D-lactate was produ ced in the grain during steeping but was rapidly lost during subsequen t germination. Both L- and D-lactate were accumulated in the grain dur ing late germination and kilning. Final-levels of lactate and malate i n malt were determined primarily by their rate of accumulation during kilning. A comparison of two maltings revealed that kilning time is im portant for final lactate levels in the malt, with long kilning times leading to high levels of both lactate isomers. It is postulated that lactate is produced during steeping by anaerobic respiration of barley whereas during late germination and kilning it is produced by prolife ration of grain microbes.