Influence of cultivar, processing and thermal treatment on bioactive compounds of industrial tomato derivatives

The nutritional value of tomatoes (vitamins, carotenoids and phenolic compounds) is inevitably decreased during processing. Use of high lycopene cultivars, alternative electro-heating technologies and transformation in specific products, can potentially be exploited to get a final product with still a high nutritional value. Industrial samples of aseptically packed tomato pulp and diced tomatoes, obtained from normal or high lycopene cultivars, and stabilised with conventional or ohmic thermal treatment, were, then, analysed for the functional profile. In particular, the total phenolic content (TPC) (expressed as gallic acid equivalents, GAE, based on the Folin-Ciocalteu assay), the lycopene content and antioxidant capacity AC (using the ABTS+ assay), were analysed. TPC ranged from 384 to 563 mgGAE/kgproduct and from 556 to 789 mgGAE/100 gTotal Solids. The lycopene content ranged from 80 to 140 mg/kgproduct and from 123 to 200 mg/100 gTotal Solids. The lycopene fraction contributed, on an average, 80% of the products AC. Processing of high lycopene cultivars and transformation into pulp rather than diced tomatoes, did not significantly influence the evaluated functional profile. Only ohmic heating (with a 74% shorter holding time at a 8% higher temperature than conventional heating) showed a significant and positive effect on the AC of the lycopene fraction. AC of ohmic treated pulp samples was almost 100% higher than for the conventionally treated pulp.