Lemon peel
(Citrus limon (L.) Osbeck; flavedo + albedo; food and ingredient uses)

Description

• The outer yellow rind (flavedo) rich in essential oils and the inner white pith (albedo) rich in pectin and fiber. Supplied as fresh zest, dried peel/powder, candied peel, extracts/distillates (peel oil, hydrosol), and pectin raw material.
• Aroma profile: bright citrus–lemon notes (d-limonene, citral), with potential bitterness from limonoids if albedo/seed carryover is high.

Indicative nutrition values (per 100 g raw peel; typical—culinary use is much smaller)

• Energy: ~45–55 kcal
• Carbohydrate: ~15–17 g — sugars ~4–5 g
• Dietary fiber: ~10–12 g (pectins/hemicelluloses)
• Protein: ~1–2 g • Fat: ~0.3–0.5 g — SFA negligible
• Vitamin C: ~90–130 mg • Folate: ~10–20 μg • Potassium: ~160–200 mg • Calcium: ~130–140 mg
• Note: at use levels (zest teaspoons/grams per portion), nutrient contribution is modest; candied peel reflects the recipe’s added sugar.

Key constituents

• Essential oils (flavedo): d-limonene (major), β-pinene, γ-terpinene, citral (neral/geranial), linalool, minor aldehydes.
• Flavonoids: eriocitrin, hesperidin, diosmin; polymethoxylated flavones (PMFs) (e.g., nobiletin, tangeretin) mainly in peel.
• Limonoids (limonin, nomilin) → delayed bitterness if released.
• Pectins (high-methoxyl), hemicelluloses, cellulose (albedo).
• Trace furanocoumarins in cold-pressed peel oil (phototoxicity issue for skin products; food use levels are low).

Production process

• Raw peel/zest: select fruit labeled “edible peel” when surface-treated; wash, optionally dewax, zest/pare, separate from pith as needed.
• Dried peel/powder: controlled drying (low T, airflow) → milling/sieving to particle spec; or freeze-dry for top-note retention.
• Candied peel: blanch (reduce bitterness, soften) → multi-stage sugar infusion → drying and optional coating.
• Peel oil: cold expression of flavedo (more complete aroma; carries furocoumarins) or steam distillation (cleaner, low FCs).
• Pectin: acid extraction from albedo → purification → drying and standardization.
• All under GMP/HACCP with pesticide/wax compliance.

Physical properties

• Appearance: fresh zest bright yellow; dried peel/powder pale-yellow to light brown; candied peel translucent.
• Aroma: high-impact, volatile; oxidation-sensitive (terpenes, aldehydes).
• Bitterness: rises with albedo/seed carryover (limonoids).
• Water activity: low in dried powders (stability), high in fresh/candied (require control).

Sensory & technological properties

• Top-note enhancer at very low dose; withstands short heating but top notes flash off with prolonged heat—add part late.
• Pectin source (albedo) for gelation and viscosity (high-methoxyl pectin gels with sugar + acid).
• Natural flavor “fixative”: peel powders help carry aroma in dry mixes; fiber adds body and reduces syneresis in fillings/jams.
• Can contribute yellow hue slightly; primary function remains flavor/aroma.

Food applications

• Culinary: zest in sauces, marinades, dressings, pastries, leavened goods; candied peel in bakery/confectionery; infusions for syrups, spirits (e.g., limoncello).
• Beverages: peel macerates, cold-brews, flavoring for soft drinks/teas.
• Industrial: bakery inclusions, seasoning blends, dairy desserts, jam/gel systems (pectin), citrus flavor bases.

Nutrition & health

Lemon peel delivers dietary fiber (pectin) and bioactives (flavonoids/PMFs) with negligible fat and SFA. In typical culinary amounts it can support flavor enrichment with minimal calories and contributes small amounts of vitamin C and polyphenols.
Safety/attention points: choose fruit with edible peel declarations when zest is consumed; rinse thoroughly. Cold-pressed peel oil contains furanocoumarins that are phototoxic on skin—relevant to cosmetics and handling; in foods, usage levels are low and typically safe. Allergenic fragrance components (limonene, citral, linalool, geraniol, citronellal) may oxidize to more sensitizing species—store well and avoid stale materials. Bitterness increases if excessive pith/seed is included; blanching/deseeding controls it. No grapefruit-like drug interaction is known for lemon.
Portion note: typical culinary use 1–2 tsp zest (~2–4 g) per serving; candied peel 10–20 g per portion in bakery; peel powder 0.2–1.0% in formulations; food-grade peel oil 0.02–0.10% (or flavor-house guidance).

Quality & specifications (typical topics)

• Identity: botanical, part (flavedo/albedo), origin, “edible peel” compliance for fresh.
• Dried peel/powder: moisture (e.g., ≤10%), volatile oil content, particle size, color (CIELAB), ash, micro (low counts; pathogens absent/25 g).
• Peel oil: assay (limonene %, citral %), optical rotation, refractive index, peroxide value, furocoumarins (if cold-pressed).
• Contaminants: pesticide residues ≤ MRL, heavy metals within limits; absence of foreign matter; EO (ethylene oxide) not permitted.
• Candied peel: °Brix, aw, crystal quality, preservative status.

Storage & shelf-life

• Fresh zest/peel: use promptly or freeze zest; protect from light/air.
• Dried/powder: cool, dry, dark in moisture-barrier packs; 12–24 months typical.
• Peel oil: amber glass, oxygen/light barrier, cool storage; antioxidants as specified; 12–24 months depending on spec.
• Candied peel: ambient sealed; refrigerate after opening and use within stated period.

Safety & regulatory

• Fresh fruit must declare postharvest surface treatments (waxes/authorized fungicides) where applicable; only peels labeled edible should be zested.
• Peel oil is generally recognized as safe at GMP flavoring levels; observe labeling for allergens (flavor compounds) where required.
• Production under GMP/HACCP; pectin per food additive specs when marketed as such.

Labeling

• “Lemon peel/zest,” “dried lemon peel,” “candied lemon peel,” “lemon peel oil,” “lemon hydrosol,” or “pectin” as applicable; declare surface treatment on fresh fruit; list added sugar for candied products.

Troubleshooting

• Flat aroma after baking → over-volatilization/oxidation → add part of zest late, use encapsulated flavors, or raise inclusion slightly.
• Bitter off-taste → excess albedo/seed breakage → trim pith, gentle extraction, seed removal.
• Oxidized/soapy notes in oil → old or poorly stored EO → refresh stock, improve headspace/O₂ control, add permitted antioxidants.
• Sticky candied peel/crystallization → poor syrup control → adjust °Brix/temperature, proper drying, anticrystallization steps.
• Wax interference when zesting → heavy postharvest wax → select edible-peel fruit or lightly abrade/peel surface layer.

Sustainability & supply chain

• By-product valorization: peel from juicing can yield EO, pectin, fiber, and d-limonene (green solvent/fuel).
• Priorities: reduce postharvest waste, efficient water/heat use, wastewater to BOD/COD targets, recyclable packaging, and residue compliance via IPM in orchards.

INCI functions (cosmetics)

• Citrus Limon (Lemon) Peel Oil — fragrance/perfuming, masking; prefer FCF (furocoumarin-free) or respect IFRA limits due to phototoxicity risk of cold-pressed oils.
• Citrus Limon (Lemon) Peel Extract — skin-conditioning, antioxidant (flavonoids/PMFs), mild astringent/toning; used in toners/serums/creams for combination skin.
• Citrus Limon (Lemon) Peel Water / Distillate — fragrance/tonic, low-oil aromatic vehicle.
• Citrus Limon (Lemon) Peel Powder — absorbent/opacifying, gentle mechanical exfoliant; mild deodorizing potential.
• Allergenic fragrance components to declare above thresholds: limonene, citral, linalool, citronellal, geraniol.
• Formulation notes: use distilled or FCF oils for leave-on; in rinse-off risk is lower but manage oxidation (antioxidants) and surfactant/emulsion compatibility.

Conclusion

Lemon peel is a high-impact aromatic and functional ingredient: zest and oils deliver fresh citrus top notes, the albedo provides pectin/fiber for texture, and peel powders enhance body and stability. Quality depends on edible-peel sourcing, freshness/oxidation control, and bitterness management; safety hinges on proper handling of furocoumarins in oils (FCF/IFRA) and compliance with residue limits.

Mini-glossary

• Flavedo/Albedo — colored outer peel rich in essential oil / inner white layer rich in pectin.
• PMFs — polymethoxylated flavones typical of citrus peels with antioxidant/stabilizing roles.
• Limonoids (limonin/nomilin) — compounds behind delayed bitterness.
• FCF — furocoumarin-free lemon oil for improved photostability/safety in leave-on products.
• IFRA — guidelines on safe fragrance ingredient use/limits.
• SFA — saturated fatty acids (negligible in peel).
• MRL — maximum residue limits for pesticides.

Studies

The chemical composition of the lemon includes mainly citric acid and limonene.
It contains flavonoids, which are extremely useful components for the immune defense of the human body and therefore to combat degenerative diseases such as cancer. In particular, Rutin, Quercetin, Neoeriocitrin (1).

It also contains a large amount of vitamin C, one of the most important antioxidants found in nature and an element of contrast to free radicals that are the cause of aging and many diseases related to the oxidation process of cells. However, the fruit that contains the highest amount of vitamin C is the kiwi.

A lemon juice, you know is a remedy against colds and flu and cooling diseases.

It also acts as a protector against rheumatoid arthritis.

Thin-skinned lemons are preferable as they have more juice.

The lemon have been recognized by scientific studies antimicrobial activity both in the form of nanoemulsions in essential oil and in the form of pure essential oil juice (2).

Among the various phenolic components present in lemon peel, Eriocitrin, for its anti-aging properties, has been the subject of specific studies in rats (3).

Lemon extract has also demonstrated antimicrobial activity against bacteria such as Pseudomonas aeruginosa and Klebsiella pneumoniae (4).

Lemon studies

References_________________________________________________________________

(1) Aliberti L, Caputo L, De Feo V, De Martino L, Nazzaro F, Souza LF. Chemical Composition and in Vitro Antimicrobial, Cytotoxic, and Central Nervous System Activities of the Essential Oils of Citrus medica L. cv. 'Liscia' and C. medica cv. 'Rugosa' Cultivated in Southern Italy. Molecules. 2016 Sep 18;21(9):1244. doi: 10.3390/molecules21091244. 

Abstract. Citrus medica cv. 'liscia' and C. medica cv. 'rugosa' are two taxa of citron, belonging to the biodiversity of South Italy, in particular of Amalfi Coast, in the Campania region. The chemical composition of the essential oils (EOs) from fruit peels of both C. medica cultivars was studied by gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS) analyses. In all, 100 compounds were identified, 82 for C. medica cv. 'liscia', accounting for 91.4% of the total oil, and 88 for C. medica cv. 'rugosa', accounting for 92.0% of the total oil. Monoterpene hydrocarbons are the main constituents in both oils of C. medica cv. 'liscia' (79.1%) and C. medica cv. 'rugosa' (80.2%). In both oils, limonene (67.2%-62.8%) and camphene (8.5%-10.9%) are the main constituents. The antimicrobial activity of the EOs was assayed against some bacterial strains: Bacillus cereus (DSM 4313), Bacillus cereus (DSM 4384), Staphylococcus aureus (DSM 25693), Pseudomonas aeruginosa (ATCC 50071), and Escherichia coli (DSM 8579). Low concentrations of C. medica cv. 'rugosa' EO showed an inhibitory effect on P. aeruginosa and higher concentrations inhibited more B. cereus (4384) and E. coli than S. aureus. The cytotoxicity of the EO was evaluated against SH-SY5Y cell line. The influence of the EO on the expression of adenylate cyclase 1 (ADCY1) was also studied. The antimicrobial activity registered confirm their traditional uses as food preserving agents and led us to hypothesize the possible use of these oils as antimicrobials. The alterations in ADCY1 expression suggested a role for limonene in effects on the central nervous system.

(2)  Ledesma-Escobar CA, Priego-Capote F, Luque de Castro MD. Comparative Study of the Effect of Sample Pretreatment and Extraction on the Determination of Flavonoids from Lemon (Citrus limon). PLoS One. 2016 Jan 25;11(1):e0148056. doi: 10.1371/journal.pone.0148056.

Abstract. Background: Flavonoids have shown to exert multiple beneficial effects on human health, being also appreciated by both food and pharmaceutical industries. Citrus fruits are a key source of flavonoids, thus promoting studies to obtain them. Characteristics of these studies are the discrepancies among sample pretreatments and among extraction methods, and also the scant number of comparative studies developed so far. Objective: Evaluate the effect of both the sample pretreatment and the extraction method on the profile of flavonoids isolated from lemon. Results: Extracts from fresh, lyophilized and air-dried samples obtained by shaking extraction (SE), ultrasound-assisted extraction (USAE), microwave-assisted extraction (MAE) and superheated liquid extraction (SHLE) were analyzed by LC-QTOF MS/MS, and 32 flavonoids were tentatively identified using MS/MS information. ANOVA applied to the data from fresh and dehydrated samples and from extraction by the different methods revealed that 26 and 32 flavonoids, respectively, were significant (p≤0.01). The pairwise comparison (Tukey HSD; p≤0.01) showed that lyophilized samples are more different from fresh samples than from air-dried samples; also, principal component analysis (PCA) showed a clear discrimination among sample pretreatment strategies and suggested that such differences are mainly created by the abundance of major flavonoids. On the other hand, pairwise comparison of extraction methods revealed that USAE and MAE provided quite similar extracts, being SHLE extracts different from the other two. In this case, PCA showed a clear discrimination among extraction methods, and their position in the scores plot suggests a lower abundance of flavonoids in the extracts from SHLE. In the two PCA the loadings plots revealed a trend to forming groups according to flavonoid aglycones. Conclusions: The present study shows clear discrimination caused by both sample pretreatments and extraction methods. Under the studied conditions, liophilization provides extracts with higher amounts of flavonoids, and USAE is the best method for isolation of these compounds, followed by MAE and SE. On the contrary, the SHLE method was the less favorable to extract flavonoids from citrus owing to degradation.

(3) Yazgan H, Ozogul Y, Kuley E. Antimicrobial influence of nanoemulsified lemon essential oil and pure lemon essential oil on food-borne pathogens and fish spoilage bacteria. Int J Food Microbiol. 2019 Oct 2;306:108266. doi: 10.1016/j.ijfoodmicro.2019.108266.

(4) Shimizu C, Wakita Y, Inoue T, Hiramitsu M, Okada M, Mitani Y, Segawa S, Tsuchiya Y, Nabeshima T. Effects of lifelong intake of lemon polyphenols on aging and intestinal microbiome in the senescence-accelerated mouse prone 1 (SAMP1). Sci Rep. 2019 Mar 6;9(1):3671. doi: 10.1038/s41598-019-40253-x.

Abstract. Polyphenols have been examined for their beneficial effects on health, particularly in rodents, but their lifelong effects are unclear. Lemons (Citrus limon), containing lemon polyphenols (LPP), are widely consumed but the effects of LPP on aging are unknown. Therefore, we examined the effects of LPP on aging such as aging-related scores, locomotor activity, cognitive functions, and intestinal microbiome using senescence-accelerated mouse prone 1 (SAMP1) and senescence-accelerated resistant mouse 1 (SAMR1). All mice had ad libitum access to water (P1_water group, SAMR1) or 0.1% LPP (P1_LPP group). In the P1_LPP group, LPP intake prolonged the lifespan by approximately 3 weeks and delayed increases in aging-related scores (e.g., periophthalmic lesions) and locomotor atrophy. The P1_water group showed large changes in the intestinal microbiome structure, while the R1 and P1_LPP groups did not. The phylum Bacteroidetes/Firmicutes, which is associated with obesity, in the P1_water group was significantly lower and higher than that in the P1_LPP and R1 groups, respectively. Although the relative abundance of Lactobacillus significantly increased in both P1 groups with aging, the P1_LPP group showed a significantly lower increase than the P1_water group. Thus, lifelong intake of LPP may have anti-aging effects on both phenotypes and the intestinal environment.

(5) Liya SJ, Siddique R. Determination of Antimicrobial Activity of Some Commercial Fruit (Apple, Papaya, Lemon and Strawberry) Against Bacteria Causing Urinary Tract Infection. Eur J Microbiol Immunol (Bp). 2018 Aug 16;8(3):95-99. doi: 10.1556/1886.2018.00014. 

 Abstract. Urinary Tract Infection (UTI) is a worldwide phenomenon in modern times, in which the dependency on antibiotics for its treatment is increasing. The current study was conducted in order to find alternatives to antibiotics by investigating some commercial fruits for their antimicrobial activity. The fruits in this study included green apple (Malus domestica), papaya (Carica papaya), lemon (Citrus limon), and strawberry (Fragaria ananassa), which were used to prepare methanolic and ethanolic extracts through Soxhlet extraction technique. The extracts were used against bacteria that cause UTI, and five different strains were selected: E. coli (ATCC: 15922), E. coli (ATCC: 25922), Pseudomonas aeruginosa (ATCC: 27853), Enterococcus faecalis (ATCC: 29212), and Klebsiella pneumoniae. Antimicrobial tests of the extracts were conducted by following the agar well diffusion method, where ciprofloxacin was used as a positive control, and autoclaved distilled water was used as a negative control. Among the fruits, apple and papaya extracts did not show any zone of inhibition against any of the tested bacteria. However, both lemon and strawberry extracts showed inhibition zone against all of the mentioned bacteria. The ethanolic extracts of lemon and strawberry were more potent than their methanolic extracts. Lemon ethanolic extract showed the highest zone of inhibition against Pseudomonas aeruginosa (ATCC: 27853) (18.34 ± 0.58) and lowest one against Klebsiella pneumoniae (16.00 ± 1.00). Strawberry ethanolic extracts showed the highest zone of inhibition against Pseudomonas aeruginosa (ATCC: 27853) (16.33 ± 0.58) and the lowest one against Klebsiella pneumoniae (13.33 ± 0.58). As antibiotic resistance is paving the way for multi-drug resistant bacteria, the results of lemon and strawberry can be considered to be used as an antimicrobial agent in treating urinary tract infections.