Limonene

Limonene is a colorless liquid hydrocarbon classified as a cyclic monoterpene, primarily found in the oil of citrus fruit peels. It’s widely used as a flavoring agent in food manufacturing, as well as in cleaning products and for its pleasant citrus scent in cosmetics and perfumes. Limonene also has potential uses in medicine and as a biofuel. Its presence in cannabis contributes to the plant’s distinctive aroma and may have therapeutic effects.

Chemical Properties of Limonene

• Limonene is a colorless liquid aliphatic hydrocarbon.
• It is classified as a cyclic monoterpene.
• Boiling point: 176°C.
• Solubility: Insoluble in water.
• Miscible with benzene, chloroform, ether, CS, and oils.
• Relatively stable and distillable without decomposition.
• Oxidizes easily in moist air to produce carveol, carvone, and limonene oxide.
• Undergoes dehydrogenation to -cymene with sulfur.
• Can racemize at 300°C.
• Reacts preferentially at the disubstituted alkene with anhydrous hydrogen chloride.

Biosynthesis and Plant Use of Limonene

• Formed from geranyl pyrophosphate through cyclization of a neryl carbocation.
• Final step involves loss of a proton to form the alkene.
• Major component in coniferous and broadleaved trees’ scents.
• Contributes to the aroma of orange peel and citrus fruits.
• Typically removed from citrus peel waste for recovery of valued components.

Safety, Research, and Uses of Limonene

• (+)-Limonene may cause skin irritation, is flammable, and toxic to aquatic life.
• Used in food manufacturing, medicines, perfumery, and personal care products.
• Acts as a fragrance, botanical insecticide, organic herbicide, and solvent.
• Added to cleaning products for fragrance and oil-dissolving properties.
• Used as a solvent in 3D printing, paint stripping, and as a biofuel.

Significance of Limonene in Fresh Squeezed Orange Juice

• Major component contributing to the aroma of orange juice.
• Fresh squeezed orange juice contains significant amounts of limonene.
• Responsible for the citrusy scent of orange juice.
• Importance of limonene in the sensory profile of orange juice highlighted.

Economic, Environmental Value, and Safety Assessment of Limonene

• Extraction from citrus waste offers economic benefits.
• Reduces environmental impact by repurposing citrus by-products.
• Contributes to sustainable practices in the citrus industry.
• Safety evaluation and risk assessment are crucial for various applications.
• Contact sensitization studies emphasize the importance of assessing sensitization to prevent adverse reactions.

Limonene Data Sources