The antioxidant activity of orange juice and juices from other citrus fruits is undervalued, suggests a new technique developed by researchers from the University of Granada.
Current techniques involve analyzing only the antioxidant capacities of those substances that can potentially be absorbed in the small intestine- the liquid fraction of what we eat, and not measuring the antioxidant activity of the solid fraction (the fiber), whilst assuming that it is not beneficial.
AdvertisementJosngel Rufin Henares, professor at the University of Granada, said, "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."
The new technique called 'global antioxidant response' (GAR), which includes an in vitro simulation of the gastrointestinal digestion that occurs in our body, taking into account the 'forgotten' antioxidant capacity of the solid fraction. On applying the technique to commercial and natural orange, mandarin, lemon and grapefruit juices, it has been proved that the values generated are ten times higher than those indicated by current analysis methods. For example, in case of orange juice, the value ranges from 2.3 mmol Trolox/L registered with a traditional technique to 23 mmol Trolox/L with the new GAR method.
These results suggest that tables on the antioxidant capacities of food products used by dieticians and health authorities must be revised. Using this method, scientists have created a mathematical model to classify juices according to their natural and storage conditions, which ensures that the correct raw materials and sterilization and pasteurization processes are used.
The study is published in the journal 'Food Chemistry'.