Effect of extraction method on lycopene isomerization

 　Effect of extraction method on lycopene isomerization

Lycopene needs to consume a lot of activation energy to complete isomerization.

The 5-cis isomer is relatively stable during the conversion of all-trans lycopene to the mono-cis isomer and is insufficient to obtain the energy for further conversion to other cis isomers.In contrast,13-cis lycopene became the most productive isomer due to its lower activation energy. During isomerization, it is affected by light and heat and is readily converted to all-trans lycopene or other isomers.

 To effectively extract lycopene and its cis-isomers, various methods have been used, including microwave-assisted extraction,ultrasound-assisted extraction, and supercritical CO2 extraction.

 Microwave treatment breaks cell membranes through thermal, electrical, and magnetic effects, which release lycopene. Under the action of a microwave, the lycopene molecules deform and vibrate at high temperatures, which then improves the isomerization degree and improves the extraction efficiency.

 The ultrasound-assisted extraction rule uses the cavitation effect(rupture of cavitation bubbles)and the thermal effect(release of heat)to destroy the matrix cell walls and promote the release of bioactive compounds. The highly reactive hydroxyl radicals and heat generated by the cavitation effect provide the required activation energy for isomerization. When these two effects reach equilibrium with temperature, the extraction rate of all-trans-lycopene will be the highest.

 There is a new extraction technology called supercritical CO2 fluid extraction. In this approach, the CO2 fluid enables better diffusion into the extracted solute, reducing the chance of contact between the solute and oxygen, and it is therefore particularly suitable for the extraction of thermally unstable compounds. During lycopene extraction, CO2 was better able to dissolve cisisomers, thus increasing the proportion of lycopene cisisomers and enhancing the bioavailability of lycopene. This method is safer and more efficient than organic solvent extraction.

 Moreover, increasing the contact area of the sample and the extractant also helps to improve the extraction rate of lycopene isomers.

 Given the excellent properties of the lycopene cis-isomers, the isomerization is regarded as an important target in the storage and processing of lycopene and its products. However, the isomerization process of lycopene is often accompanied by degradation, resulting in diminished activity. Therefore, the urgent problem to be solved is to clarify the factors affecting lycopene isomerization and take measures to avoid its degradation.