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In a comprehensive study, more than 60 phenolic compounds were detected in methanolic extracts from different tissues of pineapple infructescence by high-performance liquid chromatography with diode array detection and electrospray ionisation multiple-stage mass spectrometry (HPLC-DAD-ESI-MS) as well as by gas chromatography-mass spectrometry (GC-MS). The analytical workflow combining both methods revealed numerous compounds assigned for the first time as pineapple constituents by their mass fragmentations. Pineapple crown tissue was characterised by depsides of p-coumaric and ferulic acid. In contrast, major phenolic compounds in pineapple pulp extracts were assigned to diverse S- p-coumaryl, S-coniferyl and S-sinapyl derivatives of glutathione, N- l-γ-glutamyl- l-cysteine and l-cysteine, which were also identified in the peel. The latter was additionally characterised by elevated concentrations of p-coumaric, ferulic and caffeic acid depsides and glycerides, respectively. Two peel-specific cyanidin hexosides were found. Elevated concentrations of isomeric N, N′-diferuloylspermidines may be a useful tool for the detection of fraudulent peel usage for pineapple juice production. Mass fragmentation pathways of characteristic pineapple constituents are proposed, and their putative biological functions are discussed. [ABSTRACT FROM AUTHOR]

Immobilized lipase from Candida antarctica (Novozyme 435) was tested for the synthesis of various phenolic acid esters (ethyl and n-butyl cinnamate, ethyl p-coumarate and n-butyl p-methoxycinnamate). The second-order kinetic model was used to mathematically describe the reaction kinetics and to compare present processes quantitatively. It was found that the model agreed well with the experimental data. Further, the effect of alcohol type on the esterification of cinnamic acid was investigated. The immobilized lipase showed more ability to catalyze the synthesis of butyl cinnamate. Therefore, the process was optimized for the synthesis of butyl cinnamate as a function of solvent polarity (log P) and amount of biocatalyst. The highest ester yield of 60.7 % was obtained for the highest enzyme concentration tested (3 % w/ w), but the productivity was for 34 % lower than the corresponding value obtained for the enzyme concentration of 1 % ( w/ w). The synthesized esters were purified, identified, and screened for antioxidant activities. Both DPPH assay and cyclic voltammetry measurement have shown that cinnamic acid esters have better antioxidant properties than cinnamic acid itself. [ABSTRACT FROM AUTHOR]