Effects of food processing on flavonoids and lycopene status in a Mediterranean tomato variety

This research is focused on the antioxidant properties of dietary components, in particular phenolics and carotenoids and the assessment of the contribution of the combined antioxidants to the total antioxidant activity (TAA) of tomato fruit. The aim of this study was to analyse the effects of processing on the antioxidant properties of tomato. The effects of three different methods of processing fresh tomatoes into tomato sauce were investigated with respect to the antioxidant properties of the fruit. Identification and quantification of the main carotenoids and flavonoids present in tomatoes was achieved by HPLC analysis and the effect on the concentration and availability of these compounds was investigated at different stages of the processing. The processing affected mainly naringenin causing a reduction in the concentration. Conversely, levels of chlorogenic acid were increased suggesting an improvement in availability of this compound to extraction. The concentration of all-trans-lycopene was also increased following processing. Less than 10% isomerisation of all-trans-lycopene to the cis form was detected for all the methods analysed. The effects of processing on the overall antioxidant activity support the theory of a general improvement in availability of individual antioxidants. For both hydroplilic and lipophilic extracts TAA values were increased.