Limonene studies: 'Paucity of data' around safe levels in food products

By Cheryl Tay

- Last updated on GMT

Limonene is a main volatile constituent of citrus peel oil, with up to 95% often obtained through the steam distillation of citrus peels and pulp from juice and cold-pressed oil production. ©Getty Images
Limonene is a main volatile constituent of citrus peel oil, with up to 95% often obtained through the steam distillation of citrus peels and pulp from juice and cold-pressed oil production. ©Getty Images
More detailed investigation is needed into the effects of flavour Limonene on modern food processing techniques, the degradation products generated, and the toxicity from such products, say researchers in India.

Limonene — a monocyclic terpene found in over 300 plants in different parts of the world — is a common flavour additive in food, beverages and fragrances, thanks to its lemon-like scent.

Because of its widespread usage, researchers at India's National Institute of Food Technology Entrepreneurship and Management sought to better understand its possible toxicological effects and the associated risk.

Toxicological effects

They conducted a review of existing studies that had performed toxicological assessments of limonene, and noted its rapid absorption via oral administration in both experimental animals and human beings.

Human consumption distributes it to the blood, kidneys and liver, which leads to metabolites such as perillic acid, dihydroperillic acid, limonene-1,8-diol, and limonene-1,2-diol, being formed.

The researchers wrote that in rodents, oral intake of limonene resulted mainly in severe hyaline droplet nephrotoxicity, but only in male rats because of specific protein α2u-globulin, a major urinary protein.

The same effect, however, has not been observed in humans. Other toxicological effects of limonene found in rodents were hepatotoxicity and neurotoxicity.

Despite this, limonene has not displayed any genotoxic, immunotoxic, or carcinogenic properties. Based on the available information, the researchers classified limonene as a low-toxicity additive.

Foods and flavours

A major by-product of the citrus industry, limonene is a main volatile constituent of citrus peel oil, with up to 95% often obtained through the steam distillation of citrus peels and pulp from juice and cold-pressed oil production.

The study reported that 96% of human exposure to limonene is through food and drink, with the remaining 4% through ambient air.

The study also looked at limonene's stability during processing, saying that there was "paucity of information"​ on whether different processing techniques resulted in the generation of toxic metabolites, or harmful degradation products.

Limonene is less sensitive to high-pressure treatment than it is to thermal processing, but "in the case of ultra high-pressure treatment of orange juice…limonene concentration decreased up to 75%"​. Under acidic conditions, limonene can degrade to an off-flavour in citrus juices during storage.

Concerns over consumption

The researchers wrote that limonene intake in general may increase due to more citrus juices being consumed and the popularity of the Mediterranean diet, which is rich in limonene.

They added that lemonade or lemon juice contained almost 10 to 20 times more limonene than commercial orange juices. These factors could, over a prolonged period, prove toxic despite limonene being a GRAS ingredient.

The researchers concluded: "Future research should evaluate the effect of conventional and emerging food processing techniques on food products containing limonene in detail, especially with respect to generation of new metabolites of limonene, toxicity of these metabolites and safe level / limits of such metabolites in food products, as there is paucity of data regarding the same."

 

Source: Food and Chemical Toxicology

https://doi.org/10.1016/j.fct.2018.07.052

"Review of toxicological assessment of d-limonene, a food and cosmetics additive"

Authors: Chandrakala Ravichandran, et al.

Related news

Related products

Analyzing the unknown threat from Microplastics

Analyzing the unknown threat from Microplastics

Content provided by Agilent Technologies | 06-Nov-2023 | Infographic

Microplastics are any plastic-derived synthetic solid particle or polymeric matrix, ranging in size from 1 µm to 5 mm and insoluble in water.

Functional Beverage Market Insights in ASPAC

Functional Beverage Market Insights in ASPAC

Content provided by Glanbia Nutritionals | 06-Jul-2023 | Product Brochure

High growth ahead for protein beverages makes Asia Pacific (ASPAC) the market to watch. Consumer research shows new usage occasions, key consumption barriers,...

The latest plant-based beverage trends in SEA

The latest plant-based beverage trends in SEA

Content provided by Tetra Pak | 27-Mar-2023 | White Paper

Data shows that consumers’ liking and thirst for plant-based beverages is growing rapidly, especially in Malaysia, Singapore, Philippines and Indonesia....

Related suppliers

Follow us

Webinars

Food & Beverage Trailblazers