Is frozen orange juice healthier than fresh orange juice? When it comes to antioxidants, you might actually be better off drinking frozen (and thawed) orange juice than fresh, according to new research from the University of Seville.
Antioxidants have a protective effect on body tissue and DNA in cells. They protect against the effects of free radicals that have the potential to damage tissue and cells. Free radicals are formed during metabolism. When the body is unable to sufficiently neutralize these free radicals, the state we call oxidative stress occurs.
Several negative health effects are associated with increased free radicals, especially over the long term. Think of cardiovascular diseases, but also the formation of cancer cells [1]. Antioxidants are substances we ingest from food that can counteract this oxidative stress. Therefore, a balance between antioxidants and free radicals is important to prevent free radicals from taking over.
For many substances claimed to act as antioxidants, this could not be proven in research. Substances whose antioxidant activity is now established include vitamin E, vitamin C, and beta-carotene. These substances also have a preventive effect against, for example, cardiovascular diseases and cancer [1-4].
Antioxidants in orange juice
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Citrus fruits, including oranges, are a rich source of both vitamin C and beta-carotene. However, the fact that certain substances are in food does not necessarily mean that you can (fully) utilize them. It is important for these substances to pass through digestion in a way that they end up in an available form in the blood.
The 'biological availability' of beta-carotene was found to be disappointing in research from Wageningen University. Only a small part of the substance, also called 'provitamin A', is converted into vitamin A in the body.
Processing oranges by freezing or heating reduces the amount of beta-carotene in them. However, the Spanish research shows that the biological availability increases to such an extent that possibly more beta-carotene ends up in its active place. Especially in the case of freezing, the end result would have the greatest effect.
Frozen vs. fresh orange juice
Researchers from the University of Seville tested orange juice in five ways [5]:
Fresh
Frozen and thawed at room temperature
Frozen and thawed in the refrigerator
Frozen and thawed in the microwave
Pasteurized (heated)
Their analysis focused mainly on two carotenoids, phytoene and phytofluene. Both are colorless substances (unlike carotenoids often used as coloring agents). "Science is showing more and more interest in these two carotenoids due to the increasing number of studies demonstrating various health effects." According to Paula Mapelli of the University of Seville.
Both freezing and thawing methods led to the loss of carotenoids, but still resulted in better biological availability. The processing reduced the size of the particles and broke down cellular material. As a result, more carotenoids are ultimately absorbed by the intestines.
Heating caused the greatest loss of carotenoids in the juice. However, the researchers speak of the highest 'total' biological availability of the colorless carotenoids after pasteurization. This is also evident from the above image. However, in the conclusion, they state: "The best source of biologically available (colorless) carotenoids is frozen orange juice, thawed in the microwave."
So, if you look at what you ultimately get in a usable form, frozen and thawed in the microwave would be the best option. Carotenoids from heated juice are absorbed better, but the greater decrease in concentration in the juice results in a smaller end result than after freezing. Whether this is a smaller result than with fresh juice is not mentioned.
"Fresh juice not always the healthiest"
What they do make clear is that fresh orange juice is not necessarily healthier than juice processed with temperature.
However, this does not (yet) mean that fresh juice is unhealthy. After all, no research has been done on the biological availability of other healthy substances in orange juice, such as vitamin C and other carotenoids than those studied.
Moreover, these findings still need to be tested in practice. These and earlier similar studies were conducted in vitro, in cell cultures. Now, the researchers want to test whether this translates to the amount of carotenoids absorbed in the blood of people.
By the way, the research was not sponsored by Coolbest.
References
Lobo V, Patil A, Phatak A, Chandra N. Free radicals, antioxidants and functional foods: Impact on human health. Pharmacognosy Reviews. 2010;4(8):118-126. doi:10.4103/0973-7847.70902.
Poppel GV, Golddbohm RA. Epidemiologic evidence for β – carotene and cancer prevention. Am J Clin Nutr. 1995;62:1393–5.
Glatthaar BE, Horing DH, Moser U. The role of ascorbic acid in carcinogenesis. Adv Exp Med Biol. 1986;206:357–77.
Sokol RJ. Vitamin E deficiency and neurologic diseses. Annu Rev Nutr. 1988;8:351–73.
en) K.H. van Het Hof, C.E. West, J.A. Weststrate, et al.(2000) - Dietary factors that affect the bioavailability of carotenoids, J Nutr, jrg.130 (nr.3): pp. 503-506
Paula Mapelli-Brahm, Carla M. Stinco, María J. Rodrigo, Lorenzo Zacarías, Antonio J. Meléndez-Martínez. Impact of thermal treatments on the bioaccessibility of phytoene and phytofluene in relation to changes in the microstructure and size of orange juice particles. Journal of Functional Foods, 2018; 46: 38
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