Effect of High Hydrostatic Pressure Processing on Lycopene Isomers

Abstract

Lycopene is known for its preventive mechanism of action against various types of cancers and chronic diseases. It is an acyclic C40 non-polar carotenoid that is found in tomatoes in various geometrical isomeric forms. In nature, the predominant form is the all-trans isomeric form (80-97%) in tomato and tomato related products. However research indicates that >50% of the lycopene in human body is found in the cis isomeric form, thereby leading to the hypothesis that the cis form is the more bioavailable /bioactive form in the human body.Today’s consumers seek processed products that are minimally processed and have retained their overall quality. This has lead scientists to explore non–thermal processing technologies like High Hydrostatic Pressure (HHP) processing technology. Our hypothesis that energy input can cause isomerization lead us to study the increase in cis isomer content on using HHP processing technology. Semi preparative scale HPLC method was used to purify the isomers. Lycopene isomers in tributyrin (model systems) and tomato homogenate (real food systems) were used. The HHP equipment was manufactured by Elmhurst Research, Inc. It is a 10L tilt vessel assembly with horizontal loading and vertical operation. The pressure treatment varied from 320Mpa-620Mpa for 3 minutes at ambient conditions. Treatment of both the systems showed an increase in the cis isomer content compared to the control. The all-trans content reduced by ~70% in model systems and the cis content increased by ~44% in model systems. The all-trans content increased by ~50% in food systems and the cis content also increased by ~35% in food systems. The results indicate that pressure causes conformational change from the all-trans to cis isomer form; thereby indicating that high-pressure application can induce cis isomerization.