Kinetics of temperature increase during tomato processing modulate the bioaccessibility of lycopene.

The nutritional benefit of bioactive metabolites depends on their bioavailability, i.e. the proportion that leaves the food matrix, and crosses the enteral barrier to reach their cellular target. The present study focused on lycopene, the major and bioactive tomato carotenoid, the bioavailability of which is known to be enhanced in cooked products. To better understand how processing may facilitate lycopene release, we assessed whether hot-break (HB) or cold-break (CB) treatments influence the tomato lycopene bioaccessibility. HB and CB are used in the tomato industry to modulate texture of purees through endogenous cell-wall lytic enzymes activity. HB and CB processes were mimicked through microwave heating, leading to a differentiated temperature rise in the product. The HB and CB models led to the expected differences, i.e. more viscous puree for HB with low methanol. The ability of the tomato matrix to release lycopene was measured as the extractability of lycopene to oil under standardized mixing conditions. We expected that CB treatment, by enhancing cell-wall degradation, would lead to enhanced lycopene bioaccessibility. The opposite was observed: oil contained three times less lycopene when mixed by CB (around 0.3 μgml(-1); similar to results obtained with fresh purees) than when mixed by HB (around 0.9 μgml(-1)), although HB caused more lycopene degradation. Kinetics studies indicated that the quick rise of temperature at the beginning of HB treatment was a key parameter.