Processing tomato pulp in the presence of lipids: The impact on lycopene bioaccessibility

Abstract

Industrial processing of tomatoes into different end-products includes mechanical treatments, several thermal treatment steps, and the addition of ingredients which might induce changes in lycopene bioaccessibility. Here the influence of high pressure homogenisation (HPH) (100bar) and microwave heating (20min at 70, 90, and 120°C) of tomato pulp was evaluated in the absence and in the presence of three different oils (5%) with distinct fatty acid composition (coconut oil, olive oil, and fish oil). Lycopene bioaccessibility in the processed samples was studied by quantifying the fraction of lycopene that was transferred from the food matrix to the aqueous micellar phase during in vitro digestion.Adding lipids prior to processing clearly enhanced the lycopene bioaccessibility. However, the type of lipid added was of minor importance compared to the process conditions applied. HPH or microwave heating of tomato pulp in the presence of lipids during 20min at 70 and 90°C did not improve the lycopene bioaccessibility significantly. When HPH was applied prior to the heat treatment, microwave heating at 90°C could improve the lycopene bioaccessibility. It is hypothesised that HPH damages the cellular barriers for lycopene bioaccessibility, which can be further disrupted by thermal processing improving lycopene release during digestion. Finally, applying conditions of 20min at 120°C as such facilitated the lycopene bioaccessibility remarkably. HPH preceding this thermal treatment was of no extra value in terms of lycopene bioaccessibility.