Many see lemon juice as a natural super-disinfectantbut is it really like that? Molecules like the limonene or the linalool, are present in large quantities in the juice, which also contains vitamin C, and especially in theessential oil of this citrus fruit and have been shown to damage bacteria and inhibit their growth. But there is an even more relevant detail: research on these compounds is taking place in vitroi.e. under controlled laboratory conditions. For these reasons, in real life, the antibacterial effect of lemon juice it’s not comparable to the results obtained in the research. However, lemon juice remains an excellent ally for degreasing, removing odors and leaving a feeling of freshness, thanks to its very volatile aromatic compounds. However, if we talk about “disinfect” in its strict sense – that is, the ability to neutralize safely viruses and bacteria – then lemon juice certainly cannot give the same results as real disinfectants alcohol ethyl or bleach (sodium hypochlorite). In short: useful, yes, but not miraculous.
The molecules of lemon juice and essential oil: the properties
The term essential oil indicates a mixture of extremely concentrated volatile compounds extracted, for citrus fruits, from the peel of the fruit. The lemon juice it is instead an aqueous solution where these molecules are diluted together with others, such asascorbic acid (vitamin C), molecule known to have activity antioxidantol’citric acidwhich is instead an organic acid responsible for the sour taste of lemon juice. We therefore note how essential oil and lemon juice they are not the same thingbut they share some types of molecules, such as limonene.
This compound showed activity broad-spectrum bactericide, that is, it is capable of killing different types of microorganisms, includingEscherichia Coli el’Aspergillus Niger. In a study published in Molecules The bactericidal activity of limonene was tested against Lysteria monocytogenesa bacterium that is very widespread in various foods, such as meat, vegetables and dairy products. The researchers observed that limonene inhibited the growth of the bacterium when it was at a concentration of at least 20 mL/L: this value is called minimum inhibitory concentration (in English minimum inhibitory concentrationabbreviated to MIC), that is, the lowest amount of a substance to prevent bacterial growth.
Limonene is one of the main components of lemon juice and essential oil with important in vitro bactericidal activities. Through scanning electron microscopythe study demonstrated that bacterial cells treated with limonene suffered evident damage to the cell membrane and wall: deformations, loss of regular shape, and, in many cases, rupture and therefore death of the bacterial cells. Limonene also alters the permeability of the bacterium’s membrane, causing the leakage of fundamental macromolecules such as proteins and nucleic acids, and also inhibits enzymes involved in the respiratory chain. Simply put, limonene compromises the energy metabolism of the bacterium. Also other components of lemon essential oil (and, in lower concentrations, of the juice), such as linalool ol’α-pinenehave demonstrated antibacterial activities similar to that of limonene.
So is lemon juice a disinfectant?
Molecules such as limonene (present both in the essential oil and in lemon juice) have been shown to make the life of certain bacteria difficult, but these results come from studies in vitro. The activity observed in the laboratory it can’t be automatically transferred to real life: experiments are done in cultivation media which have controlled conditions and use concentrations of limonene much higher than those naturally present in lemon juice.
So, does lemon juice really disinfect? In the technical meaning of the term “disinfect“, that is, if we talk about its ability to reliably eliminate viruses and bacteria as well as alcohol orsodium hypochlorite (what we know by the name of bleach), then the lemon juice can’t compete. However, it can reduce unpleasant odors, degrease and give a sensation of freshness, thanks to the molecules of the essential oil which are highly volatile and therefore easily pass into the gaseous state, diffusing into the air.
