The antioxidant activity of citrus juices and other foods is undervalued.
A new technique developed by researchers from the University of Granada for measuring this property generates values that are ten times higher than those indicated by current analysis methods.
The results suggest that tables on the antioxidant capacities of food products that dieticians and health authorities use must be revised.
Orange juice and juices from other citrus fruits are considered healthy due to their high content of antioxidants, which help to reduce harmful free radicals in our body, but a new investigation shows that their benefits are greater than previously thought.
Citrus fruits are very high in vitamin C, which decreases the stress hormone cortisol. Cortisol and testosterone are counterproductive, and even the slightest decrease in cortisol levels will help your body to preserve more of testosterone.
They are also anti-estrogenic, and have a aromatase blocking effect. That’s mainly due to compounds called limonenes which have shown promise to both prevent and treat cancer. They effectively inhibit the conversion from testosterone to estrogen. Limonenes also strongly enhance detox enzymes in the liver increasing the body’s ability to process accumulated toxins.
Antioxidant Activity in Fibre Was Previously Ignored
In order to study these compounds in the laboratory, techniques that simulate the digestion of food in the digestive tract are used, which analyze only the antioxidant capacities of those substances that can potentially be absorbed in the small intestine: the liquid fraction of what we eat.
“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,” Jose Angel Rufian Henares, professor at the University of Granada, explains to SINC.
His team has developed a technique 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, the details of which are published in the journal ‘Food Chemistry‘, includes assessments of various physical and chemical parameters, such as colour, fluorescence and the relationship between the concentrations analyzed and compounds indicators such as furfural.
Upon applying the technique to commercial and natural orange, mandarin, lemon and grapefruit juices, it has been proven that their values greatly increase. 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 analyzed with this methodology,” highlights Rufian Henares, who notes its possible application: “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.”
Beware of Pasteurized and Flavored Citrus Juices
It is important to note that when citrus juice is stripped of oxygen it is also stripped of flavor providing chemicals. Juice companies therefore hire flavor and fragrance companies, the same ones that formulate perfumes for Dior and Calvin Klein, to engineer flavor packs to add back to the juice to make it taste fresh.
Flavor packs aren’t listed as an ingredient on the label because technically they are derived from orange essence and oil. Yet those in the industry will tell you that the flavor packs, whether made for reconstituted or pasteurized orange juice, resemble nothing found in nature.
The packs added to juice earmarked for the North American market tend to contain high amounts of ethyl butyrate, a chemical in the fragrance of fresh squeezed orange juice that, juice companies have discovered, Americans favor. Mexicans and Brazilians have a different palate. Flavor packs fabricated for juice geared to these markets therefore highlight different chemicals.