A new way of squeezing apple juice has quadrupled its benefits
German scientists have described the benefits of a new technology for industrial apple juice production using the spiral filter press method. Researchers have found that it allows to quadruple the content of healthy substances in the juice compared to the more traditional method of pressing.
Apples, like other fruits, contain polyphenols. These natural plant compounds have antioxidant properties and are also known for their positive effects on the heart, brain and the body's ability to resist disease. Past studies have shown that a group of flavonoids (the largest class of plant polyphenols) called flavan-3-ols help normalize blood pressure, cholesterol and blood sugar levels.
Although processing apples for juice impairs their health benefits, experts at the Institute of Beverage Research (Institute of Beverage Research, Geisenheim University) in Germany say the loss can be reduced by using a spiral press method with filtration, in which oxygen is removed by vacuum pressing.
Co-author Stefan Dussling explained that in the presence of oxygen, beneficial substances in apple juice, such as flavan-3-ols and vitamin C, are rapidly destroyed. This happens both when the juice is pressed at home and when it is produced in factories.
"We hope that in the future, the new method will spread more widely and people can get more of the beneficial natural compounds just by drinking one glass of juice," the researcher said.
In the paper, which was published by Food Research International journal, the scientists compared apple juices produced using a spiral press filtered method and a conventional decanter centrifuge using mass spectrometry and liquid chromatography. Decanters are horizontally arranged screw centrifuges with a cone drum. They are designed for continuous centrifugation of liquids with high solids and sediment content. Decanters are widely used in the food industry, including juice production.
It turned out that the juice squeezed by the new method was less oxidized and contained four times more flavan-3-ols and other phenolic compounds than a similar product made using a decanter (1016 milligrams per liter versus 262 milligrams per liter). In addition, the former was able to protect the ascorbic acid in the apple juice from degradation.
However, the researchers noted that regardless of the pressing technology, all juice variants were similar in terms of the content of dry soluble substances, concentration of sugars and total titratable acidity.
Nutritionists advise not to forget that apple juice has a lot of sugar. According to experts, even if the new method of production makes the juice richer in flavanols, it will not become healthier than the apple itself. Therefore, doctors still recommend eating whole fruits, not replacing them with juices.