Posted on Dec 23, 2018, 4 p.m.
To get the most of your spinach consider using it in the form of a smoothie or juice, as new research suggests that this is the best way to obtain the antioxidant lutein, as published in the journal Food Chemistry.
Dark green vegetables contain high levels of lutein, spinach was chosen as it contains comparatively high levels of lutein and is commonly eaten by many people all over the world; researchers from Linkoping University compared various ways of preparing fresh spinach to investigate maximize levels of lutein in finished food that is degraded by heat.
Those with atherosclerosis often have low grade chronic inflammation that can be measured in the blood, and is linked to increases risk of myocardial infarction. The team is studying the roles of the antioxidant lutein, showing it to dampen inflammation in immune cells from patients with coronary artery disease, and that it can be stored in immune cells. Previous findings suggest it is possible to build up a reserve of the antioxidant in the body, which led the team to ponder if it may be possible to influence the levels of lutein in the body by increasing dietary intake of it.
Baby spinach was purchased then used to stimulate methods of preparation used in everyday life such as steaming, frying, or boiling for up to 90 minutes to measured the levels of lutein content at different times; for example spinach cooked in stew or soup is not heated as high or for as long as in a lasagne, which is why different heating time were compared.
Heating time was shown to be important: when spinach is boiled, the longer it is boiled the less lutein is retained. Cooking method is also important: when fried at high temperatures a large portion of lutein is degraded in as little as two minutes. Reheating in a microwave appeared to compensate to some extent for the loss; more lutein is released as the plant structure is further broken down in the microwave.
The team conclude the best way to maximize lutein from spinach is to not heat it at all; and it is even better to make a smoothie as when chopped into small pieces more lutein is released from the leaves, when combined with fats it increases the solubility of the lutein in the fluid, explains Rosanna Chung.
Materials provided by Linköping University.
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Rosanna W.S. Chung, Per Leanderson, Nelly Gustafsson, Lena Jonasson. Liberation of lutein from spinach: Effects of heating time, microwave-reheating and liquefaction. Food Chemistry, 2019; 277: 573 DOI: 10.1016/j.foodchem.2018.11.023