Study Finds Higher Phenolic Content for Organic Tomato Juice

The research, funded by the Spanish Ministry of Science and Innovation, brings new data to the debate over organic and conventional crops, from a study of polyphenols in tomato juice.

Sep 28 2011 --- Organic tomato juice contains more phenolic components than juice from conventionally grown crops, according to a new study published in the journal Food Chemistry directed by Rosa M. Lamuela, a lecturer from the Department of Nutrition and Bromatology of the University of Barcelona (UB) and researcher for the Nutrition and Food Safety Research Institute (INSA) and the Spanish Biomedical Research Centre-Physiopathology of Obesity and Nutrition (CIBERobn). Also participating in the study are Anna Vallverdú-Queralt and Alexander Medina-Remón, from INSA and CIBERobn, and Isidre Casals-Ribes and Olga Jáuregui, from the UB’s Scientific and Technological Centre (CCiTUB).

The research, funded by the Spanish Ministry of Science and Innovation, brings new data to the debate over organic and conventional crops, from a study of polyphenols in tomato juice – particularly relevant as the tomato is the most widely consumed fresh and processed vegetable in Spain. According to the lecturer Rosa M. Lamuela, head of the UB’s Natural Antioxidants Group, “This is an innovative scientific study to determine the phenolic compounds found in organic and conventional tomato juice and their possible health benefits. Strangely, although tomatoes are consumed in large quantities across the world, until now only certain components with nutritional value had been studied, such as carotenes (lycopene), whereas little work had been done on polyphenols.”

Polyphenols are a family of natural compounds with important nutritional properties that can protect the body against cardiovascular and degenerative diseases and some forms of cancer. These substances neutralize free radicals and are capable of regulating enzyme activity, producing numerous health benefits. The team behind the study analysed the total content of flavonols and hydroxycinnamic acids in commercial tomato juices and revealed significant differences – undescribed until now – between the levels of bioactive components in organic tomatoes and the levels found in conventionally grown crops.

The researcher Anna Vallverdú-Queralt, first author of the study, explains that “the results could be explained by the defence mechanisms of plants according to the type of manure used in organic and conventional production. In any form of cultivation, the most important factor for the growth of the plant is the availability of nitrogen. In conventional agriculture, the nitrogen can be added in soluble form, as a fertilizer, whereas in organic production the plant receives no artificial nutrients and therefore responds by activating defence mechanisms that increase the levels of polyphenols. As a result, conventionally grown plants can lose resistance to disease and present lower levels of nutrients, minerals and secondary metabolites.”

Scientific literature has for years reflected widespread disagreement over the relative benefits of organic and conventional foodstuffs, and the results of studies published in scientific journals are often contradictory. “It should be noted that the study published in Food Chemistry only analyses the phenolic components present in tomato juice,” points out Rosa Lamuela, “and is part of a much wider project to analyse the factors that may increase the content of bioactive components in tomatoes and tomato products.”

The UB’s Natural Antioxidants Group, headed by the lecturer Rosa M. Lamuela, is part of the Generalitat’s Food Technology Reference Network (XaRTA) and INSA. The group has participated extensively in international projects for the study of polyphenols in foods, their bioavailability and the effects of these substances on human health. The researchers are currently working on a range of clinical and epidemiological studies, focusing on resveratrol, grapes, wine and archaeological remains, as well as citrus fruits, cocoa, chocolate, beer and olive oil, and other common components of the human diet.

• Full bibliographic informationVallverdú-Queralt, A.; Medina-Remón, A.; Casals-Ribes, I.; Lamuela-Raventós, R.M. “Is there any difference between the phenolic content of organic and conventional tomato juices?” Food Chemistry, July 2011, vol. 130(1), p. 222-227.