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This Wikipedia page lists common sequestrants (with respect to food science). As stated on the page:

A sequestrant forms chelate complexes with polyvalent metal ions, especially copper, iron and nickel, which can prevent the oxidation of the fats in the food.

To me, this behavior makes sense for every example listed except calcium chloride. I can certainly see chloride complexing these metal ions, but even then, I typically don't expect the chloride ion to reduce catalytic capabilities much.

I assume the calcium cation has an effect on these processes somehow, too. Otherwise, I would expect regular table salt to have the same effect, but, while discouraging bacterial growth, I don't think sodium chloride reduces the rate of oxidative rancidification.

Could it be as simple as the desiccant effect of calcium chloride keeping the polyvalent metal ions from dissolving? It would seem like a massive amount of calcium chloride would be needed to have the desired effect if that was the preservation mechanism involved.

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    $\begingroup$ Sodium chloride actually increases the rate of rancidification as per this paper: onlinelibrary.wiley.com/doi/pdf/10.1111/…. Astonishingly, calcium chloride increases rancidification even more than sodium chloride. $\endgroup$ – Shoubhik Raj Maiti May 10 '18 at 3:53
  • $\begingroup$ @ShoubhikRajMaiti So, that would suggest that the Wikipedia page is inaccurate? Or that the using the term "sequestrant" for calcium chloride is inappropriate? The Wikipedia page for calcium chloride also says that the EU considers it a sequestrant. $\endgroup$ – SendersReagent May 10 '18 at 18:38
  • $\begingroup$ If think that if the poster of the question wants to know how calcium chloride acts as a sequestant, then they should make sure it truely acts as a squestering agent. And also please tell us what substance the calcium chloride sequesters. I know that calcium chloride can sequester ammonia, but unless we know what is being sequestered we can not be able to explain how the sequestering occurs. $\endgroup$ – Nuclear Chemist May 11 '18 at 16:15
  • $\begingroup$ @NuclearChemist well, seems pretty obvious that the "poster of the question" put the quote from the Wikipedia page, which specifically mentions chelating polyvalent metal ions (specifically copper, iron, and nickel) directly in the text. Since a sequestrant in food science refers to a compound that chelates polyvalent metal ions, I'd guess those polyvalent metal ions were what the calcium chloride is supposed to be sequestering. $\endgroup$ – SendersReagent May 12 '18 at 3:53
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    $\begingroup$ @ShoubhikRajMaiti The more I look into it, the more I think that calcium chloride is called a sequestrant in food science even though it doesn't meet the food science definition of a sequestrant. I think it's more of a general preservative, but I'm not completely (or even mostly) sure what the deal is here. $\endgroup$ – SendersReagent May 15 '18 at 15:20
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Food Scientist here. Calcium chloride is typically used in high concentrations in pickles to keep them firm (give that desired bite) and also add a slight salty flavor without increasing sodium content. It is also used in potato chips to reduce formation of acrylamide. Calcium chloride is highly soluble in water and will dissociate into Ca2+ and 2Cl-. It is used to sequester metal cations. The metal ion complexes with the free Cl-. It has also been found that calcium ions may reduce iron absorption, and is a divalent cation that can form complexes of its own. Calcium chloride can stabilize colors, flavors, antioxidants, and also improve oxidative stability. Fats and oils readily oxidize in the presence of metal ions, so a sequestrant such as calcium chloride is used to form a complex with the metal. Additionally CaCl2 is used to stabilize gels such as those formed with alginate. Another popular sequestrant, or chelating agent is EDTA.

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    $\begingroup$ As I mentioned in the question, though chloride can complex metal ions, I wouldn't expect it to do much in that case. Chloride is pretty weakly coordinating, so I wouldn't expect it have much effect on the metals' catalytic abilities. $\endgroup$ – SendersReagent Oct 6 '18 at 21:26
  • $\begingroup$ Is it possible the calcium excess can cause competitive inhibition of metal ions taking part in redox reactions ? So it could achieve the similar effect by different, non chelating way. $\endgroup$ – Poutnik May 4 at 6:09

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