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The stability of lycopene with high Z-isomers content during thermal treatment and light irradiation was investigated. Purified (all-E)-lycopene was thermally isomerized to the Z-isomers in dichloromethane (CH 2 Cl 2 ) at 50 °C for 24 h. The total content of the Z-isomers of lycopene reached 56.1%. Then, the mixture of lycopene isomers was stored in the dark at 4, 25, and 40 °C for 30 days, and under light irradiation using a fluorescent light at 4 °C for 336 h. The degradation rate of lycopene during thermal treatment rose with increasing temperature and the activation energy for decomposition of the mixture of lycopene isomers was calculated to be 71.0 kJ mol -1 . The degradation rate of lycopene isomers was almost the same under thermal treatment. On the other hand, during light irradiation, isomerization was promoted rather than decomposition, i.e. (9Z)- and (13Z)-lycopene converted to the (all-E)-isomer., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

The effect of Z-isomerization of (all-E)-lycopene on its solubility in organic solvents and physical properties was investigated. Lycopene samples containing different Z-isomer contents (23.8%, 46.9%, and 75.6% of total lycopene) were prepared from high-purity (all-E)-lycopene by thermal Z-isomerization in dichloromethane (CH 2 Cl 2 ). As the Z-isomer content increased, the relative solubility of lycopene significantly improved. Although (all-E)-lycopene barely dissolved in ethanol (0.6 mg/L), the solubilities of lycopene containing 23.8%, 46.9%, and 75.6% Z-isomers were 484.5, 914.7, and 2401.7 mg/L, respectively. Furthermore, differential scanning calorimetry (DSC), powder X-ray diffraction (XRD), and scanning electron microscopy (SEM) analyses clearly indicated that (all-E)-lycopene was present in the crystal state, while Z-isomers of lycopene were present in amorphous states. A number of studies have suggested that Z-isomers of lycopene are better absorbed in the human body than the all-E-isomer. This may be due to the change in solubility and physical properties of lycopene by the Z-isomerization., (Copyright © 2017 Elsevier Inc. All rights reserved.)

As a potent antioxidant with numerous health benefits, lycopene finds multiple applications. Among the geometric isomers of lycopene, the Z‐isomers have greater bioavailability than the all‐E‐isomer but are less stable and hence, less suitable for practical applications. Herein, highly stable Z‐isomer‐rich lycopene nanodispersions are produced through the thermal isomerization of (all‐E)‐lycopene in a flow reactor followed by continuous dispersion in an aqueous emulsifier (Tween 20, sucrose fatty acid ester, or polyglycerol fatty acid ester [PFAE]) solution upon agitation with an in‐line swirl mixer. The effects of emulsifier type and other processing conditions (flow rate, pressure, temperature, lycopene Z‐isomer ratio) on dispersion efficiency and properties are examined in detail, and finally, Z‐isomer‐rich lycopene nanodispersions (>60% of total Z‐isomer ratio and <10 nm of mean particle size) are successfully obtained. Moreover, it is found that lycopene Z‐isomers have greater encapsulation efficiency for dispersions with emulsifiers than that of the all‐E‐isomer. The storage test of the resulting dispersions clearly shows that the highest storage stability is achieved in the case of using PFAE, which effectively inhibits lycopene degradation and reverse (Z‐ to all‐E) isomerization. Practical applications: To practical use of lycopene Z‐isomers, it is essential to improve their storage stability as well as usability (i.e., dispersibility in water). The present study reveals that when producing the lycopene dispersions, the use of PFAE as an emulsifier allows to improve the stability of lycopene isomers and inhibit the Z‐ to all‐E‐isomerization during storage. Given the high demand for stable Z‐isomer‐rich lycopene formulations, the obtained results promote the practical use of lycopene Z‐isomers in diverse (e.g., food and cosmetic) industries. [ABSTRACT FROM AUTHOR]

The effects of high‐temperature supercritical CO2 (SC‐CO2) extraction on Z‐isomerization and recovery of carotenoids (astaxanthin, adonirubin, and adonixanthin) from Paracoccus carotinifaciens are investigated. The high‐temperature extraction, especially at >100 °C, not only increases the total Z‐isomer ratio of carotenoids in the resulting extracts but also improves carotenoid recovery. For example, when the SC‐CO2 extraction is performed at 60 °C and 30 MPa with an entrainer (ethanol), the total Z‐isomer ratio and the recovery of astaxanthin are 11.1% and 28.4%, respectively, whereas at 120 °C, the values increase to 54.2 and 56.4%, respectively. The significant improvement in the extraction efficiency of carotenoids at high temperatures can be attributed to the increase in the ratio of carotenoid Z‐isomers with high solubility in SC‐CO2. Moreover, the effects of extraction pressure and entrainer content on Z‐isomerization and recovery of carotenoids are also investigated. The results show that higher pressure and ethanol content resulted in lower Z‐isomer ratios and higher recoveries of carotenoids. As the Z‐isomers of carotenoids have greater bioavailability and potentially exhibit superior biological activities than the all‐E‐isomers, high value‐added carotenoids, and higher yield can be simultaneously achieved with high‐temperature extraction. Practical applications: As carotenoid extraction is usually performed using toxic organic solvents, residual solvents are a serious concern. In addition, naturally occurring carotenoids (mainly the all‐E‐isomers) have low bioavailability. These are important issues that need to be overcome for the industrial use of carotenoids. The Z‐isomer‐rich carotenoids obtained by SC‐CO2 extraction under high‐temperature conditions have great potential to solve these issues simultaneously. [ABSTRACT FROM AUTHOR]

This study aims to improve the efficiency of lycopene extraction from gac (Momordica cochinchinensis Spreng.) by the Z‐isomerization induced with microwave irradiation pre‐treatment. Although 93.6% of lycopene exist as all‐E‐isomers in dried gac aril, the total Z‐isomer content reaches 35.6 and 58.5% by microwave irradiation at 900 W for 40 s and at 1050 W for 60 s, respectively. The 35.6 and 58.5% Z‐isomerization treatment improves lycopene content of extract (by 6.0 or 8.5 times for press extraction, 7.8 or 13.5 times for ethanol extraction, and 4.5 or 6.1 times for supercritical CO2 (SC‐CO2)extraction, respectively) compared with no treatment. In addition, the extracts containes high amounts of lycopene Z‐isomers, which have higher bioavailability and antioxidant capacity than (all‐E)‐lycopene. Practical Applications: This study clearly shows that lycopene recovery by press, organic solvent, and SC‐CO2 extraction from dried gac aril improved by the increase in the Z‐isomer content. It indicates that the Z‐isomers are more soluble in oil, organic solvent, and SC‐CO2 than the all‐E‐isomer. Moreover, the thermal Z‐isomerization pre‐treatment increases the content of lycopene Z‐isomers in the extract. Therefore, this procedure is important not only for improving the productivity of lycopene, but also for providing a highly functionalized extract. The effect of the Z‐isomerization, induced by microwave irradiation pre‐treatment of gac (Momordica cochinchinensis Spreng.) aril, on the lycopene recovery and lycopene content of the extracts obtained using press, ethanol, and SC‐CO2 extractions is investigated. For all extraction methods, as the content of Z‐isomers in the raw material increases, the recovery and lycopene content of gac extracts improve. [ABSTRACT FROM AUTHOR]