Orange peels (Citrus sinensis)

Orange peel comprises the flavedo (colored outer layer rich in essential oil) and the albedo (white inner layer rich in fiber and pectin). In food supply chains it appears as fresh or dried zest, candied peel (sometimes chocolate-coated), aromatic pastes, and expressed essential oils/oleoresins from the flavedo.

Commercial forms
Fresh or grated zest; dried and milled peel; candied peel strips or cubes (in syrup or glazed); pastry pastes; sweet orange essential oil for flavoring.

Caloric value (100 g)
Fresh peel: about 90–110 kcal/100 g (typical ≈ 97 kcal/100 g; moisture dependent).
Dried peel: about 250–320 kcal/100 g (solids concentrated).
Candied peel: about 300–380 kcal/100 g (depends on syrup °Brix and any glazing).

Average composition (indicative)
Water (fresh): ~70–75 g.
Total carbohydrates: ~20–28 g (fresh; added sugars dominate in candied products).
Dietary fiber: ~10–12 g (pectin and insoluble fiber; higher in the albedo).
Protein: ~1–2 g.
Fat: ~0.2–0.5 g (mostly from flavedo).
Micronutrients: vitamin C, folates; minerals (K, Ca).
Phytochemicals: flavanones (hesperidin, narirutin), polymethoxyflavones (tangeretin, nobiletin), carotenoids; essential oil dominated by d-limonene with myrcene, linalool, and aliphatic aldehydes (e.g., decanal).

Sensory and technological properties
Flavedo contributes a bright, floral–citrus aroma; albedo adds body and mild bitterness. Essential oil rich in monoterpenes is volatile and light/oxygen sensitive; drying and storage should limit loss. In candied peel, osmotic sugar infusion lowers aw and stabilizes the product; pre-blanching moderates bitterness and astringency.

Processing and controls
Zest production: Take only the flavedo to avoid excess albedo bitterness.
Drying: Use gentle convective air or freeze-drying to reach low moisture while preserving color/aroma.
Candying: Apply stepwise osmotic cycles to target °Brix (typically medium–high), then glaze/dry as needed.
Essential oil: Obtain by cold pressing or distillation, then filter and standardize for food use.
Hygiene and safety: Operate under GMP and HACCP (cleaning, foreign-body prevention, temperature/time control).

Food applications
Bakery and pastry (panettone/colomba, cakes, biscuits), gelato and semifreddi, jams and marmalades, cereals and bars, savory sauces and light marinades, salads and infusions/teas. Candied peel is used as inclusions or décor; fresh zest elevates emulsions and dressings.

Nutrition and health
Orange peel supplies fiber and polyphenols; flavanones and pectin contribute prebiotic/viscosifying functionality in culinary matrices. Candied versions carry significant added sugar and should be portioned sensibly. Compared with grapefruit, sweet orange peel generally contains fewer furanocoumarins; drug–food interaction potential is considered lower, though individual sensitivity varies.

Quality and specification themes
Appearance: vivid color, uniform cut, no browning.
Aroma: fresh and clean, free from oxidized/terpenic “tired” notes.
Moisture/aw: low for dried and candied forms to ensure stability and anticaking.
°Brix: compliant with candying specification (texture and sweetness).
Contaminants: post-harvest residues on whole fruit and heavy metals within legal limits.
Microbiology: counts appropriate to category; control osmophilic yeasts in candied products.

Storage and shelf life
Fresh zest: Refrigerate in airtight containers and use promptly to preserve aroma.
Dried peel: Store cool and dry, protected from light/oxygen; control ambient RH to prevent caking and volatile loss.
Candied peel: Hold at 10–18 °C in barrier packaging; avoid condensation that promotes sugar bloom.

Allergens and safety
Sulfites may be present in candied peel as preservatives (label when above thresholds). Manage potential residues from post-harvest fruit treatments via sourcing and washing. Essential oil can cause dermal sensitization in predisposed individuals; culinary use levels are typically low.

Troubleshooting
Excess bitterness: Too much albedo or insufficient blanching → increase blanch/rinse cycles.
Sticky or “wet” candied cubes: Final °Brix too low or drying incomplete → extend osmotic steps and optimize drying.
Sugar bloom or surface crystals: Moisture diffusion/thermal swings → improve packaging barrier and control RH and cooling.
Aroma loss in dried peel: Exposure to light/air/heat → upgrade barrier packaging and apply FIFO rotation.

Sustainability and supply chain
Orange peel valorizes a by-product of juice processing. Peels can be used for pectin and essential-oil extraction, reducing waste and BOD/COD in effluents. Traceable sourcing and compliant post-harvest practices improve both safety and environmental profile.

Conclusion
Orange peel combines intense citrus aroma, useful technological functions (pectin/fiber, color), and wide culinary versatility. Careful control of bitterness, moisture, aw, and packaging maximizes sensory quality, stability, and safety across applications.

Mini-glossary
aw — Water activity: The fraction of “free” water available for reactions and microbial growth; lower aw improves stability.
RH — Relative humidity: Percentage of water vapor in air; high RH promotes caking, condensation, and sugar bloom.
°Brix — Degrees Brix: Percentage by mass of soluble solids (sucrose equivalents) in a syrup; proxy for sweetness/consistency.
GMP — Good Manufacturing Practice: Procedures and controls ensuring hygiene, consistency, traceability, and quality.
HACCP — Hazard Analysis and Critical Control Points: Preventive food-safety system identifying hazards and defining CCPs, limits, monitoring, corrective actions, and verification.
CCPs — Critical control points: Steps at which control can be applied to prevent, eliminate, or reduce a food-safety hazard.
FIFO — First in, first out: Inventory rotation principle—use the oldest lots first to preserve quality and aroma.
BOD/COD — Biochemical oxygen demand / Chemical oxygen demand: Indicators of organic load in effluents; higher values signal greater pollution potential.

From the orange peel we obtain an essential oil that is interesting for health, the Citrus aurantium dulcis peel oil.

Citrus aurantium dulcis peel oil is an oil obtained with a chemical process from the orange peel, it is a sesquiterpene with antioxidant properties.

It is used as aroma in food, beverages, in cosmetics and in body cleansers with a function:

• Tonic
• Astringent
• Revitalizing

Extraction and antioxidant activity

The current method used in most countries for the production of cold-pressed orange oil is the simultaneous extraction of an emulsion of juice and oil from the whole fruit. Cold pressed orange oil contains waxes, pesticide residues and carotenoids (1). The current method used in most countries for manufacturing cold-pressed orange oil is simultaneous extraction of a juice and oil emulsion from the whole fruit. Cold-Pressed orange oil contains waxes, pesticide residues and carotenoids. For this reason it would be appropriate to adopt a molecular distillation method to remove them as this oil can be used in the clinical treatment of patients with malignant brain tumors (2), to inhibit angiogenesis, metastasis and cell death in human colon cancer cells (3).

In this study, the orange peel of 12 cultivars of Citrus sinensis from central-eastern Sicily was employed to obtain essential oils and extracts. The ones were extracted through steam distillation, the others through extraction in hexane. Chemical constituents were evaluated in terms of qualitative and quantitative analyses by gas chromatography/mass spectrometry. Fifty-four components were identified in the steam essential oils and 44 in the extracts. In all the cultivars, the main component is d-limonene (73.9-97%); discrete percentages of linalool, geraniol and nerol were also found. Cluster analysis based on essential oils composition showed a certain degree of affinity between cultivars of the same type. The antimicrobial activity was investigated against three micro-organisms (Staphylococcus aureus, Listeria monocytogens and Pseudomonas aeruginosa). 'Sanguinello' and 'Solarino Moro' essential oils are significantly active against L. monocytogenes, while 'Valencia' hexanic extract against all the tested micro-organisms(4).

Acute otitis media (AOM) animal model was built and diet containing orange peel essential oil microcapsules were administrated to AOM animals. Pharmacological test showed that orange peel essential oil treatment could decrease serum and cochlea malondialdehyde (MDA), immunoglobulins A (IgA), immunoglobulins G (IgG), immunoglobulins M (IgM) levels and increase antioxidant enzymes activities. It can be concluded that orange peel essential oil treatment could decrease oxidative injury in acute otitis media rats.

Typical chemical composition of an orange essential oil

Twenty four compounds, accounting for 97.9% of the total oil, were identified based on their mass spectra. The main components were terpenic molecules, and the oil was composed of 97.3% monoterpenes (which include 19.0% oxygenated monoterpenes) and 0.5% sesquiterpenes. The main constituents were limonene (74.6%), limonene 1,2-epoxide (3.5%), cis-p-mentha-2,8-dien-1-ol (3.2%) and (E)-carveol (2.4%) (6). 

CAS: 8008-57-9 Orange peel oil

Orange studies

References________________________________________________________________________

(1) Yang C, Chen H, Chen H, Zhong B, Luo X, Chun J. Antioxidant and Anticancer Activities of Essential Oil from Gannan Navel Orange Peel. Molecules. 2017 Aug 22;22(8):1391. doi: 10.3390/molecules22081391. 

Abstract. China is one of the leading producers of citrus in the world. Gannan in Jiangxi Province is the top navel orange producing area in China. In the present study, an essential oil was prepared by cold pressing of Gannan navel orange peel followed by molecular distillation. Its chemical composition was analyzed by GC-MS. Twenty four constituents were identified, representing 97.9% of the total oil. The predominant constituent was limonene (74.6%). The anticancer activities of this orange essential oil, as well as some of its major constituents, were investigated by MTT assay. This essential oil showed a positive effect on the inhibition of the proliferation of a human lung cancer cell line A549 and prostate cancer cell line 22RV-1. Some of the oil constituents displayed high anticancer potential and deserve further study.

(2) Chen TC, Fonseca CO, Schönthal AH. Preclinical development and clinical use of perillyl alcohol for chemoprevention and cancer therapy. Am J Cancer Res. 2015 Apr 15;5(5):1580-93.

Abstract. Perillyl alcohol (POH) is a naturally occurring dietary monoterpene isolated from the essential oils of lavender, peppermint, and other plants. Medical interest in this compound was generated by research findings showing that POH was able to inhibit the growth of tumor cells in cell culture and exert cancer preventive and therapeutic activity in a variety of animal tumor models. Based on this promising preclinical work, POH was formulated in soft gelatine capsules and orally administered to cancer patients several times a day on a continuous basis. However, such clinical trials in humans yielded disappointing results, also because the large number of capsules that had to be swallowed caused hard-to-tolerate intestinal side effects, causing many patients to withdraw from treatment due to unrelenting nausea, fatigue, and vomiting. As a result, efforts to treat cancer patients with oral POH were abandoned and did not enter clinical practice. Intriguingly, clinical trials in Brazil have explored intranasal POH delivery as an alternative to circumvent the toxic limitations of oral administration. In these trials, patients with recurrent malignant gliomas were given comparatively small doses of POH via simple inhalation through the nose. Results from these studies show this type of long-term, daily chemotherapy to be well tolerated and effective. In this review, we will present the vicissitudes of POH's evaluation as an anticancer agent, and its most recent success in therapy of patients with malignant brain tumors.

(3) Chidambara Murthy KN, Jayaprakasha GK, Patil BS. D-limonene rich volatile oil from blood oranges inhibits angiogenesis, metastasis and cell death in human colon cancer cells. Life Sci. 2012 Oct 5;91(11-12):429-439. doi: 10.1016/j.lfs.2012.08.016. Epub 2012 Aug 20. PMID: 22935404.

(4)  Geraci A, Di Stefano V, Di Martino E, Schillaci D, Schicchi R. Essential oil components of orange peels and antimicrobial activity.  Nat Prod Res. 2017 Mar;31(6):653-659. doi: 10.1080/14786419.2016.1219860. 

Abstract. In this study, the orange peel of 12 cultivars of Citrus sinensis from central-eastern Sicily was employed to obtain essential oils and extracts. The ones were extracted through steam distillation, the others through extraction in hexane. Chemical constituents were evaluated in terms of qualitative and quantitative analyses by gas chromatography/mass spectrometry. Fifty-four components were identified in the steam essential oils and 44 in the extracts. In all the cultivars, the main component is d-limonene (73.9-97%); discrete percentages of linalool, geraniol and nerol were also found. Cluster analysis based on essential oils composition showed a certain degree of affinity between cultivars of the same type. The antimicrobial activity was investigated against three micro-organisms (Staphylococcus aureus, Listeria monocytogens and Pseudomonas aeruginosa). 'Sanguinello' and 'Solarino Moro' essential oils are significantly active against L. monocytogenes, while 'Valencia' hexanic extract against all the tested micro-organisms.

(5)  Lv YX, Zhao SP, Zhang JY, Zhang H, Xie ZH, Cai GM, Jiang WH. Effect of orange peel essential oil on oxidative stress in AOM animals.  Int J Biol Macromol. 2012 May 1;50(4):1144-50. doi: 10.1016/j.ijbiomac.2012.02.002. Epub 2012 Feb 10.

(6)  Yang C, Chen H, Chen H, Zhong B, Luo X, Chun J. Antioxidant and Anticancer Activities of Essential Oil from Gannan Navel Orange Peel.   Molecules. 2017 Aug 22;22(8). pii: E1391. doi: 10.3390/molecules22081391.

 Abstract.China is one of the leading producers of citrus in the world. Gannan in Jiangxi Province is the top navel orange producing area in China. In the present study, an essential oil was prepared by cold pressing of Gannan navel orange peel followed by molecular distillation. Its chemical composition was analyzed by GC-MS. Twenty four constituents were identified, representing 97.9% of the total oil. The predominant constituent was limonene (74.6%). The anticancer activities of this orange essential oil, as well as some of its major constituents, were investigated by MTT assay. This essential oil showed a positive effect on the inhibition of the proliferation of a human lung cancer cell line A549 and prostate cancer cell line 22RV-1. Some of the oil constituents displayed high anticancer potential and deserve further study.