The University of Granada released a study demonstrating that the anti-oxidant value of citrus juices and other fruits is ten times higher than previously thought. Orange juice and juices from other foods have been touted as possessing health benefits. The new study results reveal that the benefits are much healthier than previously thought.
“The problem is that the antioxidant activity of the solid fraction (the fibre) isn’t measured, as it’s assumed that it isn’t beneficial. However, this insoluble fraction arrives at the large intestine and the intestinal microbiota can also ferment it and extract even more antioxidant substances, which we can assess with our new methodology,” José Angel Rufián Henares, professor at the University of Granada.
The research team has developed a new method for investigating antioxidant content called ‘global antioxidant response’ (GAR), which includes an in vitro simulation of the gastrointestinal digestion that occurs in our body, whilst taking into account the ‘forgotten’ antioxidant capacity of the solid fraction.
The method was used to analyze commercial and natural orange, mandarin, lemon and grapefruit juices and reveal an increase in the actual antioxidant content. For example, in the case of orange juice, the value ranges from 2.3 mmol Trolox/L (units for the antioxidant capacity) registered with a traditional technique to 23 mmol Trolox/L with the new GAR method.
“The antioxidant activity is, on average, ten times higher than that which everyone thought up until now, and not just in juices, but also in any other kind of food analysed with this methodology,” said highlights Rufián Henares. “This technique and the results derived from it could allow dieticians and health authorities to better establish the values of the antioxidant capacity of foods.”
The researchers did not compare the difference between freshly squeezed citrus fruit juice and commercially produced juice.
J. Álvarez, S. Pastoriza, R. Alonso-Olalla, C. Delgado-Andrade, J.A. Rufián-Henares. “Nutritional and physicochemical characteristic of commercial Spanish citrus juices”. Food Chemistry 164: 396-405, 2014.