title: Spectral characterisation of Z-isomers of lycopene formed during heat treatment and solvent effects on the E/Z isomerisation process.
abstract: The geometric isomerisation of (all-E)-lycopene, purified from tomato paste, was investigated in various organic solvents. Isomerisation ratios to the Z-isomers of lycopene in CH2Cl2 and CHCl3 over 24h were calculated to be 19.7% and 11.4% at 4°C and 77.8% and 48.4% at 50°C, respectively. In CH2Br2, more than 60% was attained in the first several hours, independent of temperature. The predominant Z-isomers obtained thermally, (9Z)-lycopene and (13Z)-lycopene, were purified and their absorption maxima and molar extinction coefficients in hexane were determined for the first time. Absorption values at 460 nm were also measured for both Z-isomers along with (all-E)-lycopene to accurately evaluate their concentrations by HPLC analysis. This approach successfully revealed that (13Z)-lycopene formed predominantly in benzene or CHCl3 at 50°C; in contrast, the 5Z-isomer was preferentially obtained in CH2Cl2 or CH2Br2.
authors.affiliation: Research & Development Division, Kagome Co., Ltd., Nasushiobara 329-2762, Japan. Electronic address: Masaki_Honda2@kagome.co.jp.
authors.forename: Masaki
authors.initials: M
authors.lastname: Honda
authors.affiliation: Research & Development Division, Kagome Co., Ltd., Nasushiobara 329-2762, Japan.
authors.forename: Naoto
authors.initials: N
authors.lastname: Takahashi
authors.affiliation: Department of Materials Science, The University of Shiga Prefecture, Hikone 522-8533, Japan.
authors.forename: Takahiro
authors.initials: T
authors.lastname: Kuwa
authors.affiliation: Department of Materials Science, The University of Shiga Prefecture, Hikone 522-8533, Japan.
authors.forename: Munenori
authors.initials: M
authors.lastname: Takehara
authors.affiliation: Department of Materials Science, The University of Shiga Prefecture, Hikone 522-8533, Japan.
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Inoue
authors.affiliation: Department of Materials Science, The University of Shiga Prefecture, Hikone 522-8533, Japan.
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Kumagai
mesh_terms: D000975:Antioxidants / Q000032:analysis; D002338:Carotenoids / Q000737:chemistry*; D002851:Chromatography, High Pressure Liquid; D006358:Hot Temperature; D007536:Isomerism; D000077276:Lycopene; D018551:Solanum lycopersicum / Q000737:chemistry; D012997:Solvents
chemical_list: D000975:Antioxidants; D012997:Solvents; D002338:Carotenoids; D000077276:Lycopene
keywords: Alkyl halides; E/Z isomerisation; Hard and soft acids and bases theory; Lycopene; Organic solvents; Solvent effects