Hint: The lemons comprise citric acid as a major acid which constitutes to around 5-6% of the lemon juice. Apart from citric acid, other acids (like malic acid) are also present in much lower concentrations compared to citric acid.
Complete answer:
Lemon juice is acidic in nature as it contains citric acid. Citric acid has the tendency to react with iron in order to form iron oxide as well as hydrogen gas. Thus, lemon juice becomes unfit for the consumption. Moreover, lemon juice is considered to be highly corrosive. If lemon juice comes into an extensive contact with the metals or metallic containers (even metals like stainless steel quality), containers can lead to micro-particle metal leaching. This could mean that a consumer could also inadvertently ingest the micro-metal particle from corrosion. As a result, lemon juice should not be stored in an iron container.
Additional information:
Aluminium, steel, copper and iron are all considered to be reactive. However, all these metals are supposed to be reactive with both acidic as well as alkaline foods. You should take care that when you are cooking food involving ingredients such as lemon juice or even tomatoes, your food can adopt a metallic flavour, if you keep your food in any of the aforementioned metallic containers.
Note:
In spite of its acidic content, lemon juice even possesses the tendency to promote the bacteria growth when kept at room temperature. So, avoid storing the lemon juice even in glass bottles as light can decompose down the juice more quickly. Rather, it must be stored in either a plastic container or coloured glass container which is not transparent.
