In this article I’ll be explaining how to extract juices from fruit and how to best preserve them.
Fruit juices in bars, whether they be night or day bars, are used quite a lot. They can be ingredients for drinks and cocktails or they can be consumed at breakfast or brunch.
For some years now, in bars, in addition to the usual bottled juices, clients can consume fresh juices obtained by using a centrifuge or an slow juicer. I call them both fresh fruit juices because that’s basically what it boils down to, despite being obtained with different technologies.
The juices obtained with the two technologies are not the same, actually they differ quite a bit in flavour and texture. The juice extracted with the centrifuge is more watery and has a lot of foam, while the juice extracted with the slow juicer has a more intense flavour and is fuller. Juice extracted with the centrifuge also tends to separate quickly.
The centrifuge has a disk with small teeth, which rotates at high speeds (3,000 rpm), and it blends the fruit and separates the fibers from the juice by making use of the rotation and the different weight of the components.
The slow juicer, on the other hand, has a slow rotating cochlea (about 40 rpm), which crushes the fruit and separates the fibers from the juice via a filter. The extractor carries out an extraction that is very similar to a press.
With regard to the quality of the juice, I prefer to a great extent the one obtained with the extractor; however the centrifuge is faster. Professional centrifuges can extract up to two liters of juice per minute. Furthermore, the slow juicer is more complicated to clean. Finally, there are some fruits and types of vegetables that can only be best processed by using just one of the two tools.
Let’s now have a look at the core of this article, or rather how to keep the juices fresh, while maximizing shelf-life as much as possible.
This need is particularly felt in cocktail bars that use a lot of citrus fruit or other fruit juices.
Squeezing the juices in advance has some advantages: it speeds up service and ensures that the juice has a homogeneous flavour, because limes or oranges do not all have the same flavour. Squeezing 2, 3 or 5 kg of oranges (for example) makes the juice homogeneous. By this I don’t mean that squeezing the juices in advance is always the best choice, especially if you don’t have the means to preserve it. Furthermore, squeezing on the spot, in front of a customer who doesn’t necessarily know all the technicalities of our work, can give a higher qualitative perception because he sees that you are using a fresh product (think about all those clients who like to sit at the bar counter…).
The main problem is the loss of flavour during juice storage. How can we ensure that orange, lemon, lime, strawberry or pineapple juice, for example, squeezed at the beginning of the shift, will keep their organoleptic features unaltered (or close to unaltered)?
In order to prolong juice life, it is necessary to keep it cool, in the dark and protected from oxygen.
Keeping juice fresh and in the dark is simple enough: place the juice in dark glass bottles, and store it in the fridge.
Slowing oxidation, however, is a little more complicated, yet there are several ways to go about doing it.
The first method, which is the cheapest and simplest, is to use “vacuum wine saver” caps. After pouring the juice into the bottle, apply the rubber stopper and, with a special pump, extract the air. After which, place the bottle in the fridge.
The second method, which is more expensive, but probably more effective, is to use inert gas inside the bottle. The concept is the same as the Coravin method or the preservation of foods in a modified atmosphere. After pouring the juice inside the bottle, spray argon (the inert gas that is easiest to find) on the juice and immediately close the bottle with its stopper. Argon is a heavier gas than air and will stratify over the juice preventing oxygen from coming into contact with the it. Caution: you need to leave some space for the argon, do not overfill the bottle.
There is also another tool which I have not yet been able to test: it is a special type of wine cap that slows oxidation. If it can be useful for this purpose, I shall talk about it in the future.
Another problem is linked to how quickly juice is used during service hours. It is useless to preserve it perfectly if, while serving, you leave the bottle with the metal pourer on the counter for two hours in the summer.
Solving this problem is quite simple: use small bottles, half a liter or even less. In this way usage will take place much faster and the juice will remain in contact with the air far less time.
These preservation techniques are very effective for some types of juices, however they are not as adequate with fruit that turns brown quickly, such as apple juice. When you open a bottle of apple juice, it will inevitably turn brown, even using small bottles and using it as quickly as possible.
To conclude, I’d like to point out that it is always necessary to taste the juice in order to assess its preservation state. In any case, with regard to citrus fruits, even those preserved with argon, preservation shouldn’t exceed 48 hours.
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