FRUITY AROMA PRODUCTION IN SOLID-STATE FERMENTATION BY CERATOCYSTIS-FIMBRIATA - INFLUENCE OF THE SUBSTRATE TYPE AND THE PRESENCE OF PRECURSORS

Wheat bran, cassava bagasse and sugar cane bagasse were shown to be ad equate substrates for the growth and aroma production by the mould Cer atocystis fimbriate. Among the nutritive media tested, sugar cane baga sse complemented with a synthetic medium containing glucose (200 g l(- 1)) gave a fruity aroma while the leucine or valine-containing medium gave a strong banana aroma. Aroma production was dependent on growth a nd the maximum aroma intensity was detected at about the time of the m aximum respirometric activity. Twenty-four compounds have been separat ed by GC headspace analysis and 20 were identified, among them: 1 alde hyde, 7 alcohols, 4 ketones and 8 esters. It was dearly demonstrated t hat the chromatographic profile of the headspace of the culture was de pendent on the substrate used and on the eventual precursor added. Whe n leucine or valine was added to the substrate, the production of tota l volatiles in the headspace reached values up to tenfold higher than that for ripe bananas. The Gompertz model, a logistic-like equation, w as used to fit the integrated CO2 and volatiles production data.