R. Roscher et al., L-RHAMNOSE - PROGENITOR OF 2,5-DIMETHYL-4-HYDROXY-3[2H]-FURANONE FORMATION BY PICHIA-CAPSULATA, ZEITSCHRIFT FUR LEBENSMITTEL-UNTERSUCHUNG UND-FORSCHUNG A-FOOD RESEARCH AND TECHNOLOGY, 204(3), 1997, pp. 198-201
2,5-Dimethyl-4-hydroxy-3 [2H]-furanone (Furaneol, 1), an important aro
ma constituent, was detected at concentrations of up to 2 mg/l after 4
days of growth of Pichia capsulata on casein peptone culture medium c
ontaining L-(+)-rhamnose (2). Blank samples without yeast contained no
1 after the incubation period. In parallel experiments five samples o
f 2 exhibiting different [C-13] abundance were given to P. capsulata.
The volatile compounds formed were isolated and analysed for their [C-
13]/[C-12] ratios by on-line gas chromatography/combustion/isotope rat
io mass spectrometry (GC/C/IRMS). A positive correlation between the i
sotopes in 1 and 2 was observed; thus, 2 served as the carbon source f
or 1. However, 1 was formed from a postulated intermediate of 2 genera
ted during thermal sterilization, as 1 was neither detected after ster
ile filtration of the culture medium nor after separate thermal steril
ization of the casein peptone and 2. This observation was confirmed by
an experiment investigating the time course of the formation of 1.