Effect of enzymatic treatments on lycopene in vitro bioaccessibility in high pressure homogenized tomato puree and chromoplast fraction

Abstract

Lycopene is a micro-nutrient to which health benefits have been ascribed. After high pressure homogenization, a decrease in lycopene in vitro bioaccessibility in tomato puree was reported. It was suggested that a new fiber network was formed entrapping lycopene.  In addition, the chromoplast sub-structure also constitutes an important physical structural barriers influencing lycopene release from the matrix and subsequent incorporation into micelles. In order to increase the lycopene in vitro bioaccessibility in tomato puree, enzymatic treatments using different cell wall degrading enzymes (Pectinex Ultra SP-L and Viscozyme) were applied to the homogenized tomato puree. Enzymatic treatments using phospholipase D and protease were also applied to a fraction enriched with chromoplast in order to enhance lycopene in vitro bioaccessibility. An in vitro digestion assay was used to investigate the effect of enzymatic treatments on lycopene bioaccessibility. Results showed that the enzymes worked effectively on solubilizing the new fiber network that was formed upon homogenization. However, no significant increase in lycopene in vitro bioaccessibility was found after any of the enzymatic treatments. By applying phospholipase D and protease enzymes on the fraction enriched with chromoplast, no further increase in lycopene in vitro bioaccessibility was found. Therefore, it is suggested that the chromoplast sub-structure, meaning how lycopene crystals are embedded within the chromoplast organelle, constitutes the most important barrier for lycopene bioaccessibility in tomato fruit.