Biotransformation of isoeugenol to vanilla flavour metabolites and capsaicin in suspended and immobilized cell cultures of Capsicum frutescens: study of the influence of β-cyclodextrin and fungal elicitor

Abstract

Suspended and immobilized cell cultures of Capsicum frutescens accumulated vanilla flavour metabolites (vanillin, vanillic acid and ferulic acid) when fed with isoeugenol. The addition of isoeugenol also stimulated its biotransformation to capsaicin. Maximum concentrations of vanillin accumulated at 566 μg/40 ml culture on the sixth day in isoeugenol (2.5 mM) treated cultures. This was twice the increase recorded in suspended cultures on the same day. The formation of ferulic acid (58 μg) was observed on the fifth day in immobilized cultures treated with isoeugenol. The addition of β-cyclodextrin together with isoeugenol, each at 2.5 mM, resulted in increase in the accumulation of vanillin (919 μg/40 ml) on the fourth day. This was 1.62 times more than in cultures treated with isoeugenol alone. Isoeugenol treated immobilized cells, when challenged with aqueous mycelial extract of Aspergillus niger, yielded maximum vanillin concentrations (735 μg/40 ml culture) on the eighth day, whereas addition of medium filtrate of A. niger led to marginal increase in the vanillin (610 μg/40 ml). Accumulation of capsaicin reached a maximum, 121 and 92 μg, on the tenth day in isoeugenol and elicitor added cultures, respectively. Biotransformation of isoeugenol was more effective in immobilized cells, and this was further enhanced by the addition of β-cyclodextrin and fungal elicitor.