Is there a healthier juice?
The makers of slow juicers (often referred to as cold-press juicers) would have you believe the juice they produce is more nutritious and stays fresher than what comes out of a high-speed centrifugal contraption. But is this true?
In this article:
How we tested the juicer claims
At CHOICE, we're not big on unproven theories, so we pitted slow juicers against centrifugal juicers (or fast juicers) in our test. How? We sent samples of carrot juice, orange juice and green juice from 15 juicers – nine slow and six centrifugal juicers – to a lab to be analysed for minerals (calcium, iron, magnesium). We also had the vitamin C measured immediately after juicing in the CHOICE labs.
Delicious and nutritious?
There's no single juicer or juicer type that consistently extracts the maximum amount of nutrients from each juice tested. For example, the Kuvings slow juicer extracts a relatively high amount of vitamin C from orange juice, but also one of the lowest quantities of calcium out of green juice. Similarly the Sunbeam Cold Press JE9000's results are relatively high for vitamin C from orange, but low in magnesium from green juice.
But while there are big differences in the amount of each mineral or vitamins extracted by each juicer, they're relatively insignificant in the bigger picture. According to the National Health and Medical Research Council (NHMRC), the recommended daily intake (RDI) of calcium for most adults is 1000mg. The amount you'd get out of a glass of our green juice produced by the best performer for extracting this nutrient is 60mg – which is just six percent of your daily requirement and only 15mg more than average.
On the other hand, the RDI of vitamin C for an adult is about 45mg, and the orange juice from most of these juicers provides about three times the RDI in a glass. The catch is that vitamin C diminishes very quickly, so drinking the juice immediately is the only way you'll get anywhere near this amount. The other nutrients measured are fairly stable though, and will be present in similar quantities after a few days as when first juiced.
What about the temperature?
Some slow-juicer manufacturers claim that centrifugal juicers heat up the juice, and so don't contain as many nutrients or vitamins as a slow juicer. We measured the temperature of the fruit and vegetables before juicing and after juicing, and there was no significant difference in temperature (with the exception of the juice from the NutriBullet). Rises in temperature, if any, were mostly within 1°C. This was the same for both slow and fast juicers.
Does slow or fast juice last longer?
Past CHOICE tests have shown that juice from a slow juicer generally stays fresher for longer. But centrifugal juicer designs have evolved since we last looked at this, so we've compared once again the taste, texture, and appearance of apple juice 48 hours after juicing.
After five minutes, all juices had separated into a frothy top, a cloudy or transparent green/brown liquid, with sediment on the bottom. At 24 hours all the juices turned brown, with further separation. By 48 hours the juice had very distinct layers – some had a transparent pale amber liquid in between the frothy top and sediment on the bottom, while others kept their cloudy amber liquid. Care was taken to remove the frothy top and to not disturb the sediment, so the amber liquid could be tasted.
We found that apart from slight variation in the amount of froth or sediment, and cloudy versus transparent liquid, all the apple juices at 48 hours had a pleasant taste. It's just a matter of whether you'd prefer to drink a transparent or cloudy-looking juice. That said, many of the manufacturers – including those of slow juicers – recommend that the juice be drunk immediately after juicing to maximise the amount and quality of nutrients consumed.
The juicer claims aren't as solid as the manufacturers would like, but the one thing we think everyone can agree on is that freshly made juice beats store-bought any day of the week.
NutriBullet, blenders and super blenders
Juicing is one way to get the goodness out of fruit, but blended fruit and veg smoothies are also increasingly popular and there's an array of gadgets that claim to be the best at blending up a super-smoothie. We included the NutriBullet in our nutritional analysis, but other options for blended drinks include blenders, super blenders, the Kambrook Blitz2Go and even all-in-one kitchen machines such as the ever-popular Thermomix, though we have not included nutritional analysis for these latter products.
The NutriBullet makes very loud and clear claims that it's the "superfood nutrition extractor" which "transforms ordinary food into superfood". Their ads would have you believe that their results would top the table – after all, you're pulverising and consuming the whole food, not just the juice. But, truth be known, compared to 250mL of juice from a juicer, the NutriBullet's extraction of nutrients is definitely low end for vitamin C, and below-average to average for calcium, magnesium, and iron. Only the calcium measurement from orange was unusually high (but still very low compared to RDI).
So why the lower results? Simple – the concentration of vitamins and mineral are diluted because you need to add water (or another liquid) to blend. You also don't use as much fruit or veggies as a juicer to create the same volume of drink – which can save you on food costs. Our NutriBullet 'carrot juice' was 350g carrot in 300mL water – more of a puree than a juice. The orange blend was just 500g of oranges (there's plenty of moisture in these, so no need to add water). And green juice was half the quantity of the produce we used in our juicer recipe, plus 250mL of water. On the 'greener' side, fibre was naturally higher in the NutriBullet (because it keeps the whole food in the mix): 4.5g in a glass of green smoothie versus 1.5–1.75g in a slow juicer, and 1g in a fast juicer.
While we haven't put other blenders and blender-style appliances to a nutritional analysis, you can probably expect broadly similar outcomes. By blending whole fruit and veg with added water, you can expect a lower concentration of nutrients for the volume when compared to pure juice, but more fibre. And if you're adding other ingredients such as milk, nuts or protein powder, you'll of course get nutrients from those ingredients too.
Also worth noting is that the NutriBullet heats the juice slightly due to its high speed. The temperature rise ranged from 3 to 5°C, depending on processing time. The longer you process, the higher the temperature.
So is it a bullet or a dud? It really comes down to personal preference – do you want to drink your juice, or eat it?