Chilling water in copper vessel

Question

Does chilling drinking water in copper bottle result in any chemical reaction that turns it dangerous for consumption in any way?

Few days back, in summer, I carried kokum juice in copper bottle. I had a sip of it after some time when I reached office and I felt super dizzy. I felt that traveling might have an effect on me, so I stopped. I had another sip of juice after some hours I had a strong dizzy feeling. At first, the juice tasted ok but then it started tasting very very weird. When I reached home and poured the juice back out of the bottle, to my surprise, its green! The normal color of kokum juice is pinkish-reddish. So somehow copper reacted with the juice and possible resulted in some acid, even though it was at normal room temperature (or in fact cold one as the juice was prepared from cold water). I believe there shouldn't be an issue with cooling water in a copper bottle in the fridge, I just want to know if there is any slight drawback, maybe from Ayurveda point of view? Also, I hope you get the chemistry angle to this question.

Answer 1

Do not do it !! ( putting acidic, or rather any juice to copper bottles )

You are in danger of copper poisoning.

Generally, by food processing laws, copper is not allowed to be in direct contact with food, as there is danger of copper contamination.

Especially acidic liquids, like vinegar or citrus juices, directly slowly dissolve copper in presence of oxygen.

$$\ce{4 RCOOH + 2 Cu + O2 -> 2 (RCOO)2Cu + 2 H2O}$$

Note that cold liquids contain usually more oxygen than warm ones.

For similar reasons, even if there is not copper, it is very bad idea to keep the content of conserved fruit cans in the already opened cans. You can otherwise see the juice corroding the can inner coating in air presence.

Soluble copper salts are usually blueish/greenish what with yellow/orange colour of juice gives green colour.

Long term usage of copper for keeping water is on the edge. It can cause chronical low dose sneaky poisoning, especially if water is treated by chlorine.

$$\ce{Cu + Cl2 -> Cu^2+ + 2 Cl-}$$

Oxidation can lead to partially soluble basic copper carbonates, soluble by traces of organic acids, related to minerals malachite and azurite.

$$\ce{2 Cu + CO2 + O2 + H2O -> CuCO3 \cdot Cu(OH)2}$$

$$\ce{3 Cu + 2 CO2 + 3/2 O2 + H2O -> 2 CuCO3 \cdot Cu(OH)2}$$

Plus, there is danger some people would want to store there other liquids than water as well, as the OP.

Answer 2

This is in reply to the following comment.

but if Ayurveda recommends it.... – Poutnik

The following abstract is from Journal Health Popul Nutr. 2012 Mar; 30(1): 17–21."Storing Drinking-water in Copper pots Kills Contaminating Diarrhoeagenic Bacteria" by V.B. Preethi Sudha, Sheeba Ganesan,G.P. Pazhani, T. Ramamurthy, G.B. Nair and Padma Venkatasubramanian.

Microbially-unsafe water is still a major concern in most developing countries. Although many water-purification methods exist, these are expensive and beyond the reach of many people, especially in rural areas. Ayurveda recommends the use of copper for storing drinking-water. Therefore, the objective of this study was to evaluate the effect of copper pot on microbially-contaminated drinking-water**. The antibacterial effect of copper pot against important diarrhoeagenic bacteria, including Vibrio cholerae O1, Shigella flexneri 2a, enterotoxigenic Escherichia coli, enteropathogenic E. coli, Salmonella enterica Typhi, and Salmonella Paratyphi is reported. When drinking-water (pH 7.83±0.4; source: ground) was contaminated with 500 CFU/mL of the above bacteria and stored in copper pots for 16 hours at room temperature, no bacteria could be recovered on the culture medium. Recovery failed even after resuscitation in enrichment broth, followed by plating on selective media, indicating loss of culturability. This is the first report on the effect of copper on S. flexneri 2a, enteropathogenic E. coli, and Salmonella Paratyphi. After 16 hours, there was a slight increase in the pH of water from 7.83 to 7.93 in the copper pots while the other physicochemical parameters remained unchanged. Copper content (177±16 ppb) in water stored in copper pots was well within the permissible limits of the World Health Organization. Copper holds promise as a point-of-use solution for microbial purification of drinking-water, especially in developing countries.

The paper has tabulated results of Antibacterial activity of copper pot and also Physical and chemical parameters in a copper pot as shown below.

• Antibacterial activity of copper pot on drinking-water inoculated with enteric pathogens.

• The level of copper that had leached into the test samples was 177±16 ppb which was well within the WHO limit of 2000 ppb in the test samples (copper pot) after incubation for 16 hours .

Discussion as per the paper.

• None of the test pathogens was recovered from drinking-water stored in copper pots even after enrichment culture.

• The level of copper leached in the former is far less (177±16 ppb) than that in distilled water (~420 ppb).

• Safety of leached copper does not appear to be an issue since studies have shown that the current WHO guideline of 2 mg Cu/L is safe , and the levels leached in the study were 1/20th of the permissible limits.

• It has been observed in the present study that the other physicochemical parameters of drinking-water remain unchanged after copper intervention, which makes them amenable for public use.

Since ancient times Ayurveda has advocated the benefits of drinking water from a copper vessel.

Scientifically speaking$^1$,

when water is stored in a copper vessel for over eight hours, very small quantities of copper get dissolved in this water. This process is called “oligodynamic effect” and has the ability to destroy a wide range of harmful microbes, molds, fungi etc. due to the toxic effect it has on living cells.

The oligodynamic effect $^2$,

(from Greek oligos "few", and dynamis "force") is a biocidal effect of metals, especially heavy metals, that occurs even in low concentrations. The health effect was known in India for more than 2700 years as their ancient texts prescribe.

In conclusion,Ayurvedic system$^4$ of medicine has great antiquity, dating back to about 5000 years B.C. Its Materia Medica contain resources in the form of drugs derived from plant, animal, metal and mineral sources.Ayurveda system prescribes dose in limits and not in excess.

References

$^1$https://saiayurvediccollege.com/ayurveda-benefits-of-drinking-from-a-copper-vessel/

$^2$https://en.wikipedia.org/wiki/Oligodynamic_effect

$^3$https://saiayurvediccollege.com/ayurveda-benefits-of-drinking-from-a-copper-vessel/

$^4$https://saiayurvediccollege.com/ayurveda-benefits-of-drinking-from-a-copper-vessel/

Answer 3

There are two parts of your question. We should not mix historical medical practices with modern scientific truths. Also, this does not mean that all old medical knowledge is bad or useless. In older medicine, gold foil arsenic compounds, silver foil, crushed pearls and mercury oxides were added in medicines,. It does not mean that if these practices were done in ages ago, they are safe by today's standards.

1. Is it okay to store kokum juice in copper vessels?

For western readers, kokum juice is a berry juice (Garcinia indica), which is rich in hydroxycitric acid.
Acids in Garcinia indica. The berry is quite sour. A layman can do a quick test. Take a copper vessel and store this berry juice for half an hour. Immediately you will see discoloration and a "brand" new shiny copper surface. I have seen that on a copper cup. This implies that a significant amount of copper has dissolved. We should not store acidic juices in copper vessels.

Secondly, in older times water was not chlorinated. Chloride ions corrode copper so quickly. Add some lemon juice, salt, to a copper cup and it will corrode soon to a green color.

However, it is very much true that in older South Asian culture, copper and tin lined pots and pans were used. The coating would wash away with cooking and people would re-coat them. Aluminum took their place. Finally stainless steel came in.

Regarding storing natural water in a copper vessel, it should be fine for a shorter time (day or so). Silver vessel is a better as an anti-bacterial surface and far more inert than copper. However, nobody is rich enough to use silver (or to be born with a silver spoon as they say). Yes silverware is good for the kings and queens.

Copper is a long term liver toxin. It is also a trace essential element.

You know the Goldilock principle: Everything in moderation. Too little copper in the body, bad. Too much copper-liver damage. You just need the right amount of copper. .