Mobilization of primary metabolites and phenolics during natural fermentation in seeds of Pangium edule Reinw.

Fermented seeds of the tropical tree Pangium edule Reinw, are a speciality in Indonesia and have been used as spices. The fermentation process of the seeds is a natural spontaneous process, which occurs 40 days following seed maturity and treatment. This study reports some biochemical changes, espec ially primary metabolites. and antioxidant activity associated with mobiliz ation of lipids and phenolics during seed fermentation. The lipid content i ncreased slightly (46.07-50.95% db) although the dominant fatty acid compos ition did not change. The dominant fatty acids were oleic acid (C-18:1 n-9) and linoleic acid (C-18:2 n-6). During fermentation, the decrease in fatty acid content in lipid coincided with the increasing acid value, which indi cated that free fatty acids increased in seeds during fermentation. The dom inant tocol in the seed, gamma-tocotrienol, increased (69.8-123.3 mu g g(-1 ) freeze-dried seed) during fermentation. In general, overall protein conte nt and amino acid composition did not change but non-soluble protein increa sed while soluble protein decreased. The changes in carbohydrate fraction s howed that total crude carbobydrate, neutral detergent fibre (NDF, as cellu lose, hemicellulose, and lignin) decreased, but reducing sugar increased an d starch content did not change. Enzyme assays showed that microorganisms m ay be involved in the fermentation process. beta-glucosidase, an enzyme tha t can cleave glycosidic bonds of conjugated phenolics and guaiacol peroxida se (GPX) activities increased. The total phenolics content in seeds increas ed substantially corresponding to the increase in beta-glucosidase but anti oxidant activity of phenolic extracts did not change. (C) 1999 Elsevier Sci ence Ltd. All rights reserved.