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Production of flavour precursors by Penicillium candidum using selected polyunsaturated fatty acids
Author(s) -
Hall Colin E.,
Husson Florence,
Kermasha Selim
Publication year - 2005
Publication title -
flavour and fragrance journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.393
H-Index - 70
eISSN - 1099-1026
pISSN - 0882-5734
DOI - 10.1002/ffj.1622
Subject(s) - chemistry , bioconversion , polyunsaturated fatty acid , linoleic acid , arachidonic acid , lipoxygenase , substrate (aquarium) , biochemistry , enzyme , fatty acid , fermentation , oceanography , geology
Biomass of Penicillium candidum was harvested and homogenized prior to centrifugation. The resultant supernatant, considered as the crude enzymatic extract, was enriched by ammonium sulphate precipitation. The enriched enzymatic extract was assayed for its lipoxygenase (LOX) activity, using selected polyunsaturated fatty acids (PUFAs) as substrates. Two pH optima for LOX activity were determined at 6.0 and 8.5. The results indicated a wide range of LOX activity towards free PUFAs, including linoleic, linolenic and arachidonic acids, as well as preferential substrate specificity towards linoleic acid over its alkyl esters. The catalytic efficiency values, defined as the ratio V max : K m , were 214, 163 and 160 for linolenic, linoleic and arachidonic acids, respectively. It was shown that the LOX activity produced many mono‐hydroperoxy regio‐isomers of the PUFAs, and there was a predominance of conjugated diene hydroperoxides. Significant production (16%) of the unconjugated 10‐hydroperoxides of octadecadienoic acid (HPOD) and octadecatrienoic acid (HPOT) was also obtained by the enriched LOX activity. Four major hydroperoxy‐eicosatetraenoic acid (HPETE) regio‐isomers, including the 8‐, 9‐, 12‐ and 15‐HPETEs, were obtained from the bioconversion of arachidonic acid. Chiral studies of end products indicated varying degrees of enantio‐selectivity, producing excesses in favour of the ( S ) stereo‐isomer, for the hydroperoxide end‐products resulted from the bioconversion of linoleic, linolenic and arachidonic acids. Copyright © 2005 John Wiley & Sons, Ltd.