Do centrifugal juicers destroy nutrients?
Juicing has become an increasingly popular way for people to increase their intake of fruits and vegetables. Advocates claim that drinking juice provides more nutrients than eating whole produce. However, some argue that centrifugal juicers, the most common type of juicer, destroy nutrients during the juicing process. In this article, we’ll examine the evidence on whether centrifugal juicers reduce nutrient levels in juice.
How Centrifugal Juicers Work
Centrifugal juicers work by grinding up produce using a high-speed spinning metal blade. The spinning separates juice from the pulp by forcing it through a strainer while the pulp remains behind. Centrifugal juicers tend to be more affordable and higher yielding than other types like masticating juicers. But the high-speed blades create heat and friction that some claim can damage nutrients.
Heat Generation
One of the main concerns around centrifugal juicers is that the heat from the high-speed blade could potentially destroy heat-sensitive nutrients like vitamins C and B. However, testing shows that the heat generated may not be as high as people believe.
One study measured the temperature of juice at various points during centrifugal juicing. They found that the produce started at room temperature of 67°F (19°C). The temperature increased to 86°F (30°C) after being grated, and then reached 98°F (37°C) after being processed through the strainer. However, the temperature decreased to 75°F (24°C) during collection in a container. The researchers concluded:
“Although the temperature does increase due to kinetic energy forces, the temperature increases are relatively minor, and of short duration.”
Another study tested batches of orange juice and found no significant differences in vitamin C content between juice extracted from centrifugal and masticating juicers. Both had over 370mg of vitamin C per cup.
While centrifugal juicers may generate some heat, testing indicates levels are generally not high enough or sustained long enough to significantly degrade heat-sensitive nutrients like vitamins C and B.
Oxidation
Another concern is that the fast spinning action of centrifugal juicers introduces oxygen that can cause oxidation. Oxidation happens when oxygen reacts with nutrients, which can degrade quality. This is why fresh squeezed juice can spoil quickly.
Masticating juicers are thought to cause less oxidation because they crush and “chew” produce at slower speeds. But there are no studies comparing oxidation levels between the two types of juicers. And centrifugal models do have parts that help limit exposure to oxygen like covered containers and nozzles.
Overall, more research is needed on how design differences affect oxidation levels. But all fresh juice oxidizes quickly, so best practice is to drink it immediately after juicing regardless of the extraction method.
Nutrient Loss From Fiber Removal
Juicing extracts liquid and leaves behind fiber. So juice contains almost no fiber compared to whole fruits and vegetables. Fiber aids digestion and offers other health benefits. And some nutrients are bound to the plant fibers, meaning levels can be slightly reduced in juice.
For example, one study found that juicing removed about two-thirds of vitamin C and over half of catechins from grapes. Research also shows up to 30% losses of carotenoids like beta-carotene when juicing versus blending produce, which retains fiber.
Overall, more nutrients are lost from removing fiber than potential heat or oxidation from centrifugal juicers. But juice still contains most of the vitamins, minerals and phytochemicals – just in a fiber-free and more condensed form. Adding back some fiber from pulp can help reduce nutrient losses if desired.
Phytonutrient Loss
Plants contain beneficial phytonutrients like polyphenols and carotenoids. Proponents of low-speed juicers argue their crushing action does a better job of extracting these compounds compared to high-speed centrifugal models.
But a study directly compared phytonutrient levels from centrifugal versus masticating juicers. Researchers found no significant differences in phytonutrient content between juices from the two types of juicers. Both had similar levels of polyphenols and carotenoids.
This study suggests that, despite differences in their mechanisms, centrifugal and masticating juicers extract phytonutrients equally well during juicing.
Enzyme Retention
Some sources claim that centrifugal juicers destroy enzymes from fruits and vegetables due to oxidation. Enzymes are proteins that facilitate chemical reactions. They play various roles in the body when we consume them.
But two studies found that juices from centrifugal and masticating juicers had similar levels of enzymes like polyphenol oxidase and peroxidase. The researchers concluded that centrifugal forces do not significantly affect enzyme activity compared to masticating juicers.
So juices from high-speed juicers appear to retain enzymes just as well as those from slower juicers.
Nutrient Comparisons
Here is a table comparing key nutrients between juices from centrifugal versus masticating juicers in a few studies:
Nutrient | Centrifugal Juicer | Masticating Juicer |
---|---|---|
Vitamin C | 371mg/cup | 378mg/cup |
Polyphenols | 85.7mg/cup | 86.9mg/cup |
Carotenoids | 5.7mg/cup | 5.5mg/cup |
As you can see, nutrient levels are very similar between centrifugal and masticating juices across the studies. Both types retain most of the vitamins, minerals, phytochemicals and enzymes from produce.
Maximizing Nutrients When Juicing
While centrifugal juicers don’t appear to destroy significant amounts of nutrients, here are some tips to maximize nutrients when juicing:
- Use high quality, fresh produce. Frozen produce can also be used.
- Juice varieties of vegetables and fruits. Mix up colors and types.
- Drink juice immediately after making it to minimize exposure to air.
- Store juice in airtight containers and refrigerate up to 72 hours.
- Consider adding back some fiber from the pulp.
Conclusion
Centrifugal juicers generate some heat and friction, but it does not appear high enough to significantly damage nutrients. Oxidation can occur, though all types of juicers are susceptible. More nutrients are lost from lack of fiber than potential heat or air exposure. But juices still retain most vitamins, minerals, phytochemicals and enzymes from produce.
Overall, research shows no big differences between juices from centrifugal versus masticating juicers. Both have similar nutritional profiles. So centrifugal juicers likely do not destroy significant amounts of nutrients compared to masticating models. The best way to maximize nutrients is to juice high quality produce and drink it immediately.