Is there any difference between the phenolic content of organic and conventional tomato juices?

The present study aims to compare the phenolic and hydrophilic antioxidant profiles of organically and conventionally produced tomato juices. Comparisons of analyses of archived samples from conventional and organic production systems demonstrated statistically higher levels (P < 0.05) of phenolic compounds in organic tomato juices. This increase corresponds not only with increasing amounts of soil organic matter accumulating in organic plots but also with reduced manure application rates once soils in the organic systems had reached equilibrium levels of organic matter. Using principal component analysis, results show that phenolic compounds and hydrophilic antioxidant capacity were responsible for the differentiation between organic and conventional tomato juices. Thus, there appear to be genuine differences in the bioactive components of organic and conventional tomato juices not previously reported.     

Effect of tomato industrial processing on phenolic profile and hydrophilic antioxidant capacity

Industrial processing of tomatoes involves juice addition and heat treatment that may affect (increase or decrease) the levels of phenolic compounds. In this work, we evaluated the effect of each processing step in the paste-making process. Four technological processes were investigated on an industrial scale: Hot Break 28/30, Hot Break 22/24, Cold Break 28/30 and Passata 10/12; and four stages were monitored in each process: (1) fresh tomatoes; (2) juice after scalders and cream addition; (3) tomato paste from evaporators and (4) final paste. The effect of each processing stage was evaluated by different analyses: first, hydrophilic antioxidant capacity was evaluated using ABTS⁺ and DPPH assays and total phenolics using Folin–Ciocalteau method; then, individual polyphenols were quantified using HPLC-ESI-MS/MS. This multifaceted approach has revealed that each processing stage induces different changes in the antioxidant and phenolic profile. The results of this study indicated that cream addition increases the hydrophilic antioxidant capacity and the amount of phenolic compounds positively, while heat treatment and, to a lesser extent, the sterilization stage during the paste-making process affect these compounds negatively.