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Irrigation with saline water affects tomato fruit quality. While total fruit yield decreases with salinity, inner quality characterized by taste and health-promoting compounds can be improved. For a detailed description of this relationship, the influence of three different salt levels [electrical conductivity (EC) 3, 6.5, and 10] in hydroponically grown tomatoes was investigated. Rising salinity levels in the nutrient solution significantly increased vitamin C, lycopene, and beta-carotene in fresh fruits up to 35%. The phenol concentration was tendentiously enhanced, and the antioxidative capacity of phenols and carotenoids increased on a fresh weight basis. Additionally, the higher EC values caused an increase of total soluble solids and organic acids, parameters determining the taste of tomatoes. Total fruit yield, single fruit weight, and firmness significantly decreased with rising EC levels. Regression analyses revealed significant correlations between the EC level and the dependent variables single fruit weight, total soluble solids, titrable acids, lycopene, and antioxidative capacities of carotenoids and phenols, whereas vitamin C and phenols correlated best with truss number, and beta-carotene correlated best with temperature. Only pressure firmness showed no correlation with any of the measured parameters. As all desirable characteristics in the freshly produced tomato increased when exposed to salinity, salinity itself constitutes an alternative method of quality improvement. Moreover, it can compensate for the loss of yield by the higher inner quality due to changing demands by the market and the consumer. This investigation is to our knowledge the first comprehensive overview regarding parameters of outer quality (yield and firmness), taste (total soluble solids and acids), nutritional value (vitamin C, carotenoids, and phenolics), as well as antioxidative capacity in tomatoes grown under saline conditions.

Multielement isotope ratio analysis was checked for its suitability as a means for the discrimination between agricultural products from integrated/conventional or organic production, respectively. Differences were mainly found for delta15N-values. Paprika and tomatoes from organic production in greenhouses showed delta15N-values above+7 per thousand, whereas corresponding products from conventional cultivation had delta15N-values near 0 per thousand. Lettuce, onions, cabbage and Chinese cabbage from field production had delta15N-values in the range of+5 to+6 and+5.5 to+7.5 per thousand, respectively (conventional and organic production); these overlapping differences do not permit a reliable discrimination. The same is true for wheat, showing average delta15N-values of+2.3+/-1.0 and+3.6+/-1.6 per thousand, respectively. The unexpected relative high 15N-enrichments of vegetables from integrated production are discussed as originating, at least partially, from 15N-enrichment in the soil by NH3 evaporation and denitrification.

Low-density lipoprotein oxidation is believed to play an important role in the development of atherosclerosis and therefore a high resistance of LDL against oxidation may prevent atherogenesis and accompanying disorders. Several secondary plant metabolites have been tested for their ability to prevent oxidation of LDL and many phenolics as well as carotenoids have been shown to enhance LDL oxidation resistance. We showed that the quercetingylcoside rutin is able to inhibit copper-induced formation of conjugated dienes and loss of tryptophan fluorescence in LDL. However, enrichment of LDL with the carotenoids lutein or lycopene did not result in an alleviation of LDL oxidation. Since there is an agreement that not one antioxidant alone can lead to health benefits but the combination, as found for example in fruits and vegetables, is the active principle, we tested whether the combination of a phenolic compound (i. e. rutin) and carotenoids (i.e. lutein or lycopene) leads to synergistic effects. Both combinations were shown to exert supra-additive protection of LDL towards oxidation, which is most likely due to different allocation of the antioxidants in the LDL-particle and to different mechanisms of antioxidant action.