The identification and behaviour of branched dextrins in the production of Scotch whisky

Application of high performance anion chromatography (HPAEC) to distillers worts was able to resolve a series of individual fractions (A, B, C, D, E and F) which eluted between alpha (1-4) linear dextrins (DP4-7) and which were ubiquitous in worts. Their positions in the chromatogram and their behaviour suggested that they might be alpha (1-6) branched dextrins. Two of these fractions (C and D) were purified and shown to be alpha (1-6) branched dextrins by treatment with an alpha (1-6) debranching enzyme (pullulanase), Further characterisation by HPAEC and Matrix Assisted Desorption Ionisation/Time of Flight (MALDI-TOF) mass spectrometry revealed that the unknown fractions, C and D, were alpha (1-6) branched dextrins consisting of 6 and 7 glucose units respectively. Possible structures were suggested for these two fractions and it was shown that they were comprised of maltosyl and maltotriosyl branches attached by alpha (1-6) links to maltotriose, maltotetraose and maltopentaose. The behaviour of these dextrins teas studied in the conte,vt of the Scotch whisky process under both laboratory and production conditions and they were found to be important substrates for the debranching enzyme, limit dextrinase, during fermentation. The study of these dextrins provided a useful tool for monitoring the effects Of Enzymes (alpha-, beta -amylase and limit dextrinase) in the Scotch malt whisky production process.