Eating fruits is very essential to our bodies. They along vegetables are the main providers of vitamins and minerals.
Consuming a variety of fruits supplies the body with a variety of these micronutrients as their availability and quantity varies across different fruits. Accordingly, the WHO recommends a consumption of more than five servings of fruits across most days of the week.
Fruits can be consumed in different ways, the most common being eating the whole fruit. However, an increasingly popular method nowadays is to juice fruits. The fruits juices are extracted from the one fruit or mixed with those from other fruits.
Often at times, the fruit juices are also mixed with vegetable juices for purposes of enriching or simply as a means of improving flavour. Such juices however seem to be mostly consumed for purposes of “detoxing”.
Nevertheless, not all fruits are “juiceable” making this method only suitable for certain fruits. For those that can be juiced however, it’s important to consider the perishability of their juices, especially with regards to their nutrients.
How Exposure to Air Causes Loss of Nutrients in Fruits
Fruits are very perishable especially when the flesh is exposed to air. This explains the swift colour change witnessed after peeling fruits like bananas or apple.
This discolouration is as a result of a process called oxidation that happens on the fruit’s surface. What happen is that oxygen in the air reacts with phenolic compounds in the fruit to form substance called quinones with the help of some fruit enzymes.
Quinones later react with amino acids in the fruit causing loss of nutrients and discoloration. The same reaction happens in the fruit juices.
Juices however spoil faster than whole fruits as there is much larger surface exposed to the air hence a big surface area for reaction.
Therefore, to ensure you get the most out of your fruit juices, it’s advisable to have them within 20 minutes to 48 hours after preparation. This time frame is however not absolute as its further affected by the method used to extract the juice.
How the Lifespan of Juices is affected by method of Extraction
There are two main ways of extracting juice from fruits:
- by centrifuge, or
- by mastication
In the centrifuge method the juice is extracted by a machine rotating at a high speed (e.g. a blender) while in mastication the extraction is through cold-pressing.
The centrifuge method of juice extraction has a higher rate of spoilage than the mastication one. This is because the rotation introduces more oxygen in the process causing it to react well with the juice. In addition to this, there’s generation of heat which further degrades the quality of the juice.
Juices extracted this are thus ideally supposed to be drunk within 20 minutes because the rate of spoilage is quite high.
In the mastication process, there is less reaction with oxygen as compared to the centrifuge method and heat generation is minimal or not present. Juice extracted this way can for up to 48 hours.
To be on the safe side however, drink the juice immediately after preparation when the enzymes and vitamins are still active or refrigerate after preparation for at most 4 days.
Other factors that can increase rate of spoiling of juices and that you should consider when juicing include:
- Light – this increases rate of spoilage
- Storage – it’s good to store the juice in clean opaque containers that are well covered to minimize air from getting in
- The type of fruit – some fruits spoils faster than others
- Heat – the higher the heat, the higher the rate of spoilage (hence refrigeration)