Formation of Aldehyde Flavor (n-hexanal, 3Z-nonenal and 2E-nonenal) in the Brown Alga, Laminaria Angustata

Abstract

Abstract2E-Nonenal and n-hexanal are the major and minor flavor compounds in the edible brown alga, Laminaria angustata, respectively. They are believed to characterize the flavor of this alga. However the metabolism of the two compounds is not precisely known. The pathways were clarified by elucidation of the intermediate structure through purification of the intermediate compounds from an enzymatic reaction and identification using HPLC and GC-MS techniques. Formation of n-hexanal, 3Z-nonenal and 2E-nonenal are proposed to be via two cascades from unsaturated fatty acids. They are C18:2(n-6), linoleic acid cascade and C20:4(n-6), arachidonic acid cascade through their hydroperoxides as intermediates by the lipoxygenase/fatty acid hydroperoxide lyase pathway.

Volatile Compounds Produced by Lactobacillus paracasei During Oat Fermentation

“…Since linoleic acid is the predominant fatty acid in oats, it would be the main starting material for the formation of hexanal. Hexanal can also be formed from arachidonic acid by the sequential transformation of lipoxygenase into 15‐hydroperoxyeicosatetraenoic acid and fatty acid hydroperoxide lyase (Boonprab and others ). During fermentation, hexanal is involved in further reactions, such as oxidation to hexanoic acid by aldehyde dehydrogenase and reduction to 1‐hexanol by alcohol dehydrogenase (Filipiak and others ; Lampi and others ).…”

Release of Volatile Aldehydes by the Brown Algal Kelp Laminaria digitata in Response to Both Biotic and Abiotic Stress

“…[23] Generation of aldehydes is known to be mediated both by enzymatic reactions and chemically through oxidative mechanisms. [24][25][26] We detected 9-oxononanoic acid, which is known as a byproduct of hydroperoxide lyase (HPL) action on the 9-hydroperoxides of linolenic and linoleic acids. [24] Quinacrine and chlorpromazine·HCl, which had previously been shown to interfere with the GG-induced oxidative burst in L. digitata, [14] also affected aldehyde production, suggesting the involvement of the oxidative burst in the lipoperoxidation process…”

Bioactive volatile compounds from marine algae: feeding attractants

“…We have demonstrated that long-chain aldehydes (C 15 , C 17 ) are formed from fatty acids through the formation of the corresponding 2-hydroperoxy acids in the green alga Ulva pertusa, and that these hydropeoxides exist in a variety of marine algae (Akakabe et al 1999(Akakabe et al , 2001. We have also found that short-chain aldehydes (C 6 , C 9 ) and middle-chain aldehydes (C 10 ) are formed from fatty acids (C 20 ) in marine algae, whereas they are formed from C 18 in higher plants (Boonprab et al 2003(Boonprab et al , 2006. The volatile compounds play important roles as chemical communications in marine ecosystems.…”

“…The compounds act as pheromones (Pohnert and Boland 2002) or allelochemicals, chemical defenses such as deterrence against herbivores (Hay et al 1998;Schnitzler et al 2001;Pelletreau and Muller-Parker 2002;Pohnert 2002), inhibition of bacterial and fungal fouling (Bakus et al 1986;Davis et al 1989;Melton and Bodnar 1988), and suppression of competing neighbors (Suzuki et al 1998). We have already investigated the pheromone-mediated mating process in the brown algae Dictyopteris spp during sexual reproduction and elucidated the mechanistic pathway for the biosynthesis (Yamamoto et al 2003;Kajiwara et al 2006). In the green alga Bryopsis maxima, one major volatile compound was released by the mechanical wounding and was identified as (Z)-8-heptadecene by GC-MS analysis and synthesis (submitted).…”