I came across this question while researching coconuts and couldn’t find a suitable answer so decided to look a little deeper to see if there had been some research papers published to answer this question. I found a few surprising answers and facts that I would like to share with you about this question. But first, Why Coconut Water is Pink?
Coconut water turns pink due to the enzyme action of the polyphenol oxidase already present in the water and the phenol compounds such as catechin and epicatechin also present in coconut water. The phenol compounds are safe and nutritious and act as an antioxidant. So, it is safe to drink pink coconut water as it is merely an oxidation process, much like when an apple turns brown when sliced open and exposed to oxygen.
The activity of the polyphenol oxidase enzyme can be further enhanced by the presence of copper along with exposure of the coconut water to high temperature during processing.
In this article we will discuss the following:
- Benefits of Pink Coconut Water and Coconut Meat
- Why Is Some Coconut Water Pink While Others Are Not?
- Further Explanation on Why Coconut Water Turns Pink.
- How Can You Prevent the Pink Discolouring of Coconut Water from Occurring?
We will now discuss a little deeper into what benefits this pink colour implies (it’s interesting to note that the same reason, process and nutrition also applies to the meat of the coconut turning pink) along with more about why it occurs and how you can stop the pink discolouring from occurring in the first place.
First, be assured that there is nothing wrong with your coconut water and that is it safe to drink. In fact, if anything, it is a good sign that your coconut water is actually full of good nutrition and the phenol compounds present are also a good sign that there is plenty of healthy antioxidants present unless of course, the pink colour is due to high-temperature processing.
A study on polyphenols showed they are effective in reducing Inflammation such as in coronary artery disease. Polyphenols and phenol compounds being present as indicated by the pink colour are actually a good sign that these compounds are active and capable of providing health benefits.
As mentioned above the presence of copper metal ions in the coconut water can enhance the activity of the enzyme Polyphenol Oxidase responsible for turning the water pink.
The optimum copper concentration to begin pinking in coconut water is 3.96 x 10-04 mM. This means that if the copper present in the coconut water is below this level pinking may not occur.
Also, the Polyphenol Oxidase level was shown to vary among different coconut varieties and different ages. So, if a particular variety of coconut had a low Polyphenol Oxidase level or the coconuts were older the water would not turn pink.
When optimum conditions for polyphenol activity was present, the water from younger coconuts, around 7 – 8 months old turned pink while the more mature coconuts, around 9 – 10 months old, showed no discolouration.
The above clearly explains why some coconut water turns pink while other coconut water does not. It comes down to how much polyphenol oxidase is present in the coconut along with the amounts of copper. The older the coconut, the less polyphenol oxidase present. Also, different varieties naturally exhibit lower polyphenol oxidase regardless of age. Check Table 1 and Figure1 below.
Table 1. Polyphenol oxidase activity for different varieties of coconuts
|Coconut Variety||Reaction Rate|
|Coconiño (Green Dwarf)||0.005|
|Aromatic Green Dwarf||0.011|
|Pilipog Green Dwarf||0.0018|
|Malayan Yellow Dwarf (MYD)||0.0048|
|Malayan Red Dwarf (MRD)||0.0022|
|Tacunan Green Dwarf||0.0012|
Fig 1. Illustration of Polyphenol Oxidase Activity
Different varieties of coconuts in Fig 1 and Table 1 above: Coconiño (Green Dwarf), Aromatic Green Dwarf, Pilipog Green Dwarf, Malayan Yellow Dwarf (MYD), Malayan Red Dwarf (MRD), Laguna Tall and Tacunan Green Dwarf
All coconut water when still in the coconut and on the tree is clear, however as outlined above due to the reaction of Polyphenol oxidase with phenols, enhanced by the presence of copper, when exposed to oxygen and sunlight will oxidise, turning a pink colour if there is enough Polyphenol Oxidase present.
It takes time for the oxidising reaction to turn the coconut water a noticeable pink colour. Generally pinking will occur at the 3 to 4 hours the coconut water is exposed to oxygen. Check Table 2 below.
Table 2. Rate of reaction of the different ages of coconut
|Time (hr)||7 months||8 months||9 months|
You can prevent the pink discolouring of coconut from occurring if your coconut is freshly picked by making sure you refrigerate it quickly. When removing the coconut water from the coconut, add a little vitamin C and/or lemon juice. These will act as an antioxidant which will block the oxidation process from occurring.
It’s the same process for apples that are cut and exposed to oxygen. Placing a little lemon juice or vitamin C will prevent them from browning.
Another common method that is used to prevent pinking of coconut water is to mix various ages of coconut water together. The older coconut water helps to prevent the younger coconut water from pinking.
You cannot change the colour if the coconut water is already pink, you can only prevent it from pinking if it is still a clear liquid. So, if you are buying your coconut water from the supermarket or local store and it is pink then you cannot change the colour back to clear. However, it is safe to drink.
Finally, you may buy a coconut from a store that is unopened, only to crack it open at home to find that the coconut meat and water have already turned pink. Should you be concerned? No, it does happen, again due to the above reasons this is why it has turned a pink colour, although it is not so common in unopened coconuts.
Usually, it will occur in young picked coconuts due to the high polyphenol oxidase levels. If it is a very bright red/pink then it may taste rancid due to extreme oxidation and you may prefer to return it or throw it away.
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