Citron
The citron (*Citrus medica*), also known as Citrus medica L., is a large, fragrant citrus fruit belonging to the family Rutaceae, characterized by its thick, leathery rind, minimal pulp, and oblong or oval shape, often resembling a "huge, rough lemon" measuring 10-20 cm in length.[1][2] As one of the oldest cultivated citrus species, it is an evergreen shrub or small tree growing up to 4-5 meters tall, with elliptic-ovate leaves, pinkish-white flowers, and thorny branches, thriving in subtropical to tropical climates but sensitive to frost and drought.[3][2] The citron's origins are debated but likely trace to the central Himalayan foothills, southern Arabia, or Southeast Asia, with the earliest Western descriptions appearing in the works of the Greek philosopher Theophrastus in the 3rd century BCE, who noted its medicinal and aromatic properties.[4][1] It was the first citrus fruit introduced to the Mediterranean region around 325 BCE, possibly via Persian trade routes following Alexander the Great's conquests, and by the Roman era (1st century CE), it was valued for its fragrance in perfumes, as a moth repellent, and in early culinary applications like peel-based salads.[3][4] Cultivation spread to Europe by the 17th century, where it became a symbol of status in botanical gardens, such as the failed attempt at Oxford's Botanic Garden in 1648.[4] Botanically, the citron is monoembryonic and everbearing, producing fruit year-round in suitable conditions, with varieties ranging from acid to non-acid types, including the distinctive fingered form known as Buddha's hand (C. medica var. sarcodactylis), prized for its ornamental, hand-like appearance.[3][2] It prefers well-drained, loamy soils with a pH of 6.5-7.0, full sun, and temperatures between 15-27°C, typically below 1,300 meters elevation in tropical regions, though it requires protection from extreme heat and cold below -2°C.[1][2] Propagation occurs via seeds or cuttings, with trees yielding 40-100 kg of fruit annually after peaking at 8-15 years of age, and an economic lifespan of 25-30 years.[1] The citron holds significant culinary, medicinal, and cultural value; its aromatic rind is candied for marmalades, liqueurs, and desserts, while the fruit's juice and peel flavor salads, beverages, and baked goods in Mediterranean and Asian cuisines.[2][1] Medicinally, various parts—including leaves, flowers, fruits, and seeds—have been used traditionally since Roman times to treat ailments like asthma, coughs, seasickness, malaria, and digestive issues, with modern research highlighting its antioxidant, antibacterial, antidiabetic, and anticancer properties.[2][1] Culturally, it plays a central role in Jewish tradition as the etrog, a ritual fruit waved during the Sukkot festival to symbolize harvest and divine favor, with varieties specifically grown for their beauty and imported from regions like Israel, Italy, and Morocco.[5][6] Additionally, it features in classical mythology, possibly as the "golden apples" of the Hesperides, and in Eastern practices for ornamental and perfumery purposes.[4]Taxonomy and etymology
Scientific classification
The citron is classified in the genus Citrus under the binomial name Citrus medica L., within the family Rutaceae and subfamily Aurantioideae.[7][8] Citrus medica is recognized as one of the three primary ancestral species of the Citrus genus, along with the pomelo (Citrus maxima) and mandarin (Citrus reticulata), from which the majority of modern cultivated citrus fruits—such as sweet oranges (Citrus × sinensis) and lemons (Citrus × limon)—have derived through a combination of natural interspecific hybridization and human selection.[8] Genomic analyses of diverse Citrus accessions reveal that the divergence of these ancestral taxa, including C. medica, occurred approximately 8–12 million years ago in the eastern Himalayan foothills, a region identified as the likely center of origin for the genus based on phylogenetic and biogeographic evidence.[8] The species exhibits notable heterozygosity, a characteristic prevalent across Citrus due to ancient admixture events and subsequent clonal propagation, though C. medica shows relatively lower levels compared to many derived hybrids.[8][9] Accepted synonyms for Citrus medica include Citrus cedra Link, while the fingered citron variant is denoted as Citrus medica var. sarcodactylis (Hoola van Nooten) Swingle.[10]Etymology and nomenclature
The term "citron" originates from the Latin citrus, denoting the citron tree and serving as the basis for the botanical genus Citrus. This Latin word is believed to derive from the ancient Greek kitron (κιτρόν), referring to the fruit, or possibly from the Persian turunj, ultimately linked to Sanskrit roots associated with citrus trees.[11][12][13] Across cultures, the citron has borne various historical names reflecting its early spread along trade routes from Asia to the Mediterranean. In Hebrew, it is called etrog (אֶתְרוֹג), a term used since biblical times for the fruit in religious observances. The Sanskrit name bijapura (बीजपूर) translates to "seed-filled," highlighting the fruit's abundant seeds and its mention in ancient Indian texts. In Arabic, it is known as utrujj (أترج) or utrunj (أترنج), borrowed from the Persian bāzārang (باذرنگ), indicating its introduction via Persian commerce.[14][15][13] The nomenclature evolved significantly with the advent of modern botany; in 1753, Carl Linnaeus established the binomial Citrus medica in Species Plantarum, with medica alluding to the fruit's medicinal reputation originating from ancient Media (modern-day Iran). Common names in European languages often draw from perceived resemblances, such as the French cédrat, derived from cèdre (cedar) due to the fruit's aromatic similarity to cedar wood. In East Asian languages, the names tie to cultural symbolism and trade dissemination: Chinese fó shǒu (佛手, "Buddha's hand") evokes the finger-like form of certain varieties, introduced through Buddhist trade networks, while the Japanese term bushukan (仏手柑) similarly reflects this shape and continental influences.[16][17][18][19]Botanical description
Tree morphology
The citron tree (Citrus medica) is a small evergreen shrub or tree that typically attains a height of 2 to 4 meters, characterized by a slow growth rate, an open and straggly habit, and irregular branches bearing stout, sharp spines up to 4 cm long.[20][2][21] Young shoots are often purplish, pubescent, and emit a strong aromatic scent when crushed, contributing to the tree's distinctive citrus fragrance.[22][18] The leaves are simple, alternate, and evergreen, appearing large and leathery with an ovate to elliptic shape, glossy dark green coloration, and lengths of 10 to 15 cm.[23][21] They feature serrate or undulate margins, prominent venation that creates a slightly wrinkled or rumpled surface, and short articulate petioles with broad wings, which are a hallmark of citron foliage.[18][22] The leaves are also faintly lemon-scented when bruised.[20] The bark on mature stems is grayish and rough, while younger stems remain smoother and more flexible.[2] The root system consists of shallow, fibrous roots that spread widely near the surface, facilitating adaptation to well-drained soils in subtropical and Mediterranean environments.[24]Fruit and flower characteristics
The flowers of the citron (Citrus medica) are highly fragrant and typically measure 3 to 5 cm in diameter, featuring five white petals that may be tinged with pink, especially in the buds.[25] They are hermaphroditic and self-fertile, allowing for effective pollination without external agents, though bees and other insects are attracted to their scent.[1] These blooms emerge in small axillary clusters or racemes throughout the year in suitable climates, with peak production in spring and fall.[26] The fruit is notably large, ranging from 10 to 30 cm in length, and adopts an ovoid or oblong shape reminiscent of an oversized lemon.[2] Its rind is thick—often up to several centimeters—and bumpy or rough-textured, turning from green to bright yellow upon ripening, while containing numerous oil glands that contribute to its intense aromatic profile.[20] The interior features minimal pulp that is mildly acidic, with flesh varying from dry and spongy in some forms to slightly juicier in others, alongside numerous white seeds that are typically monoembryonic.[27] Citron fruits require 8 to 12 months to mature from flowering, ripening primarily in late fall to winter depending on the cultivar and growing conditions.[28] A distinctive trait is their ability to remain on the tree for extended periods—sometimes over a year—without significant deterioration, maintaining quality due to the protective thick rind.[20]Varieties and hybrids
Pure citron varieties
Pure citron varieties encompass distinct cultivars of Citrus medica that have been selected and maintained without hybridization, preserving their ancestral traits such as thick rinds and minimal pulp. These varieties differ primarily in fruit shape, rind texture, and regional adaptations, reflecting centuries of cultivation in the Mediterranean and Asia. Notable examples include the etrog, diamante, and fingered forms, each valued for unique morphological features and cultural roles.[17] The etrog, a traditional variety central to Jewish religious practices, produces oblong fruits measuring 10-15 cm in length with a thick, bumpy, and ridged rind that is glossy and dotted with prominent oil glands. This rind emits a strong floral aroma combining lemon, violet, and pine-like citrus notes, while the interior features minimal acidic pulp and large vesicles. Primarily grown in Israel and Morocco, the etrog is selected for its unblemished, tapered form and the intact pitam (dried stigma), ensuring ritual purity during Sukkot observances.[29][30][17] The diamante citron, originating from Calabria in southern Italy, yields large, pear-shaped or ellipsoid fruits with square shoulders, thick white albedo, and a smooth to faintly ribbed yellow rind that is highly aromatic. Fruits typically weigh 0.5-1 kg, with fleshy, lemon-like acidic pulp enclosed in strong membranes, and the rind's intense scent makes it ideal for candying and culinary uses. This variety thrives in the Tyrrhenian coastal "Riviera dei Cedri," where it has been cultivated for centuries, distinguishing it from rougher Mediterranean types by its refined, glossy texture.[31][17][32] The Corsican or fingered citron (Citrus medica var. sarcodactylis), known as Buddha's hand, features elongated fruits 15-30 cm long that split into 5-20 finger-like segments resembling a hand, with no central pulp or seeds in standard strains. Its bright yellow rind is smooth yet corrugated, exuding a potent fragrance of violet, osmanthus, and citrus due to compounds like beta-ionone, and the solid albedo is edible when candied. Of Chinese origin and widely grown in East Asia, this variety was introduced to California in the 1970s, prized for ornamental and aromatic qualities rather than juice yield.[18][33][17] Other pure types include the Eretz Yisrael etrog, a knobby Israeli cultivar with cone-shaped fruits exhibiting a deeply corrugated, rough rind that contrasts with smoother etrogs, grown mainly in regions like Nablus and Jerusalem for its robust texture and traditional symbolism. The liscio, a smooth Italian variant akin to the diamante but with an even more uniform, unribbed rind, produces medium-large oval fruits with bright green lanceolate leaves on thorny trees, emphasizing its glossy, aromatic peel in Calabrian cultivation. These varieties highlight C. medica's diversity in rind profiles—from bumpy and aromatic to smooth and fleshy—adapted to specific locales without crossbreeding.[17]Hybrids and derivatives
The lemon (Citrus × limon) is a well-known hybrid derived from the citron (Citrus medica) and the bitter orange (Citrus aurantium), with the bitter orange acting as the maternal parent based on cytoplasmic inheritance patterns.[8] This cross imparts the lemon's characteristic thick, aromatic rind from the citron and intense acidity influenced by both progenitors.[34] Genetic analyses confirm this parentage through nuclear markers, highlighting the citron's paternal role in shaping the lemon's morphology and flavor profile.[8] The lime (Citrus × aurantifolia), exemplified by the Mexican lime, arises from a hybridization between the citron and a papeda relative such as Citrus micrantha, where the papeda serves as the maternal parent as evidenced by chloroplast DNA haplotypes.[34] These hybrids exhibit compact fruit size and exceptionally high juice content, traits that distinguish them from pure citron varieties while reflecting the papeda's influence on vigor and the citron's contribution to aroma.[8] Among other derivatives, the limetta or sweet lemon (Citrus limetta) represents another citron-bitter orange hybrid, sharing a similar parentage with the standard lemon but yielding mildly sweet, low-acid juice suitable for fresh consumption.[34] Molecular markers, including chloroplast DNA sequencing, provide genetic evidence of the citron's foundational role in citrus evolution, demonstrating its predominant role as the paternal parent in key hybrids like lemons and limes.[34] These analyses underscore the citron's pervasive influence across Citrus taxonomy, with nuclear and organelle data aligning to trace interspecies crosses.[8]History and distribution
Ancient origins
The citron (Citrus medica), one of the ancestral citrus species, is native to the Himalayan foothills in Northeast India and adjacent regions of Southeast Asia, where wild forms of the species and related progenitors persist.[8] Genomic analyses indicate that domestication likely occurred around 3000–4000 BCE in this area, involving selection for larger fruits and self-fertile traits through human cultivation, marking the beginning of its role as a prestige crop.[8] This early domestication is supported by the species' low genetic diversity, suggestive of a bottleneck event during initial human propagation.[35] Possible but disputed carbonized seeds, potentially of citron, have been reported from Mesopotamian sites like Nippur in southern Iraq, dating to approximately 4000–3500 BCE, though their identification remains tentative.[36] Further robust finds include fossilized pollen grains from a Persian royal garden at Ramat Rahel near Jerusalem, indicating cultivation by the 5th–4th centuries BCE, while artistic depictions on Achaemenid Persian reliefs from the same period portray the fruit as a symbol of luxury.[37] These remains highlight the citron's integration into elite horticulture, likely transported as seeds or grafts due to its thick rind aiding preservation. Early written records further document the citron's significance. The Greek botanist Theophrastus, in his Enquiry into Plants (c. 310 BCE), described the "Persian apple" (mēle Persikón) as a thorny tree bearing aromatic fruits used medicinally against poisons and digestive ailments, noting its introduction from Media (modern Iran).[38] Similarly, Pliny the Elder, in Natural History (c. 77 CE), detailed the citron's import to Rome from Persia and Media, emphasizing its value as an exotic remedy preserved in clay pots for trade, underscoring its status as a high-end commodity.[39] The citron's initial spread occurred via ancient trade routes, such as the Royal Road and incense trails, reaching Egypt by the late first millennium BCE—evidenced by textual references in Ptolemaic records—and Greece around 300 BCE following Persian influences and Alexander the Great's campaigns.[40] This diffusion positioned the citron as a cultural emblem in the Mediterranean, tied to ancient names like the "Median apple," reflecting its Persian provenance.[41]Historical spread and modern cultivation
The citron (Citrus medica), one of the ancestral citrus species, originated in the central Himalayan foothills, where it was domesticated before migrating westward as the first citrus crop, facilitated by its thick albedo and extended shelf life.[37] Pollen evidence indicates its gradual spread from Southeast Asia through Persia to the Mediterranean Basin, with the earliest archaeobotanical remains—citron pollen and seeds—dating to the 5th century BCE in a Persian royal garden near Jerusalem.[37] By the 4th century BCE, Greek botanist Theophrastus documented its cultivation in Media (modern Iran), describing it as the "Median fruit" and noting its use in perfumery and medicine.[37] Jewish communities adopted the citron for religious rituals, such as the etrog in Sukkot, by the 1st century CE, playing a key role in its further dissemination across the Mediterranean during the diaspora starting in the 2nd century BCE.[42] Following the destruction of the Second Temple in 70 CE, citron cultivation expanded into southern Italy through Jewish settlers, where it became integrated into local agriculture alongside other citrus.[42] By the late 16th century, the citron accompanied the rising popularity of orange cultivation in Europe, spreading to regions like France and Spain as ornamental and medicinal plants in formal gardens.[43] Its introduction to the Americas occurred with Spanish and Portuguese explorers in the 16th century, though it remained niche compared to more versatile citrus hybrids.[44] Throughout these expansions, the citron's cultural significance—particularly in Jewish Sukkot rituals as the etrog—ensured its persistence in religious and ceremonial contexts, even as commercial interest waned.[42] In modern times, citron cultivation is concentrated in subtropical and Mediterranean climates, with primary production in the Mediterranean region, particularly Italy's Calabria along the "Riviera dei Cedri," where about 79 hectares yield approximately 1,160 metric tons annually (as of 2015), centered in Santa Maria del Cedro.[42] Significant production also occurs in Israel for religious etrog use. Smaller-scale cultivation occurs in Corsica (France) and Crete (Greece), often for local candied peel production and religious use.[42] In Asia, it thrives in warmer areas of China, including Yunnan and Sichuan provinces, where varieties like Buddha's hand (C. medica var. sarcodactylis) are grown for medicinal, ornamental, and culinary purposes, with Sichuan emerging as China's largest hub for fingered citron.[45][46] Limited cultivation also persists in northeastern India, Myanmar, and parts of Southeast Asia, though often as an ornamental or wild relative rather than a major crop.[47] Globally, production remains modest due to the tree's sensitivity to cold winds and intense heat, favoring well-drained, loamy soils in temperate zones with optimal temperatures of 15–27°C.[48]Cultivation and production
Growing conditions and propagation
Citron trees (Citrus medica) require subtropical climates with minimal frost risk, as they are highly sensitive to cold temperatures below 5°C (41°F), which can cause wilting or tree death. They thrive in full sun, receiving at least 6–8 hours of direct sunlight daily, and benefit from moderate humidity and consistent moisture without waterlogging. Well-drained soils rich in organic matter are essential, with an optimal pH range of 6.0–7.5 to support nutrient uptake and prevent root issues.[33][48][2] Propagation of citron can occur through seeds, which produce true-to-type plants but result in slow growth taking 3–5 years to fruit; semi-hardwood cuttings treated with rooting hormones like 500–1000 ppm indole-3-butyric acid (IBA); or grafting onto disease-resistant rootstocks such as trifoliate orange (Poncirus trifoliata) to enhance vigor and adaptability. For ritual varieties like etrog, seeds or cuttings from certified pure strains are preferred to maintain varietal purity, avoiding grafting. The best propagation timing is spring or early summer in warm conditions.[33][5][49] Ongoing care involves annual pruning in late winter or early spring to shape the canopy, remove dead wood, and promote airflow, using citrus-specific fertilizers with balanced NPK ratios applied 3–4 times per year during the growing season. Watering should keep soil evenly moist, particularly for young trees, while established ones tolerate short dry periods. Fruits are harvested when the rind turns yellow, typically November to January in subtropical regions, though some varieties produce year-round.[33][28] Citron cultivation faces challenges including relatively low yields of 40–100 kg per mature tree and a tendency toward biennial bearing, where heavy cropping alternates with light or no production years, requiring management techniques like controlled pruning to mitigate.[2][50]Pests, diseases, and management
Citron trees (Citrus medica), like other citrus species, are susceptible to several insect pests that can damage foliage, twigs, and fruit. Aphids, such as the black citrus aphid (Toxoptera aurantii), feed on new growth, causing leaf curling and honeydew production that promotes sooty mold. Scale insects, including red scale (Aonidiella aurantii) and California red scale, attach to stems and leaves, extracting sap and weakening the plant while secreting honeydew.[51] The citrus leafminer (Phyllocnistis citrella) mines serpentine trails in young leaves, distorting growth and providing entry points for pathogens. Additionally, the Mediterranean fruit fly (Ceratitis capitata) targets ripening fruit, with larvae burrowing into the pulp and causing premature drop or internal decay, making it one of the most destructive pests for citron production in Mediterranean regions.[52] Key diseases affecting citron include bacterial, fungal, and viral pathogens that threaten tree vigor and yield. Citrus greening, or Huanglongbing (HLB), caused by the bacterium Candidatus Liberibacter asiaticus, is vectored primarily by the Asian citrus psyllid (Diaphorina citri) and leads to mottled leaves, stunted fruit, and eventual tree decline; it has devastated citrus groves worldwide, including potential impacts on citron.[53] Phytophthora root rot, induced by soilborne oomycetes like Phytophthora citrophthora and P. nicotianae, thrives in poorly drained conditions and causes root decay, girdling, and canopy wilt. Citrus tristeza virus (CTV), transmitted by aphids, induces stem pitting and decline, particularly when citron is used as rootstock for other citrus, though tolerant varieties exist. Management of these threats relies on integrated pest management (IPM) strategies that combine cultural, biological, and chemical controls to minimize environmental impact. Biological controls include releasing natural enemies such as lady beetles for aphids and parasitic wasps (Aphytis melinus) for scales, alongside conservation of predatory mites against leafminers.[54] For fruit flies, trapping with protein baits and sterile insect techniques are effective non-chemical options.[55] Disease control involves using copper-based fungicides, such as copper hydroxide, applied preventively to suppress Phytophthora and bacterial infections, though resistance management is essential.[54] Quarantine protocols ensure propagation from HLB-free stock, while grafting onto resistant rootstocks like trifoliate orange (Poncirus trifoliata) mitigates tristeza and root rot risks.[53] Regular scouting and soil drainage improvements further support IPM efficacy.[54] As of 2025, climate change is exacerbating fungal pathogen pressures on citron in Mediterranean cultivation areas, with warmer temperatures and erratic rainfall favoring emerging threats like Phytophthora inundata root rot and increased incidence of Alternaria brown spot, necessitating adaptive IPM adjustments such as enhanced monitoring and resilient cultivars.[56][57]Global production and economic importance
Citron (Citrus medica) is a niche crop within the global citrus industry, with worldwide production primarily geared toward specialized markets rather than mass consumption. Estimates indicate that annual global output for commercial purposes, such as candied peel production, totals approximately 7,000 metric tons, cultivated on around 1,000 hectares, predominantly in Mediterranean regions.[58] In Israel, etrog varieties contribute an additional roughly 400 metric tons annually, derived from about 1 million fruits grown on 150 hectares dedicated to religious and ceremonial use.[59] Leading producers include Italy, where the Diamante variety dominates cultivation in Calabria, alongside Israel and smaller contributions from China and other Mediterranean countries like Greece and Turkey.[60] Economically, citron holds value as a high-margin specialty fruit, with the global market estimated in the tens of millions of USD, driven by premium pricing for etrogim ($20–$100 per fruit depending on quality and origin) and candied Diamante peels used in confectionery.[61] In Calabria, Italy, citron farming provides essential income for local families, supporting small-scale operations that integrate traditional methods with emerging sustainable technologies like agrivoltaics to combat climate challenges.[62] The crop's economic role is amplified by its non-perishable rind, which commands high prices in processed forms for marmalades, liqueurs, and essential oils. Trade in citron is concentrated in niche channels, with Israel exporting around 300,000 etrogim annually—primarily to the United States for Sukkot celebrations—generating significant seasonal revenue through kosher-certified supply chains.[14] Italian Diamante exports target European and North American markets for industrial applications, while overall global trade remains modest compared to major citrus like oranges, emphasizing quality over volume. Sustainability efforts focus on smallholder farming, which prevails in production areas; innovations such as solar-integrated orchards in Italy enhance resilience to drought and heat, fostering potential for expanded cultivation amid rising demand for natural, bioactive products.[60]Nutritional composition
Macronutrients and micronutrients
The citron fruit (Citrus medica) exhibits a low-calorie profile, providing approximately 25–73 kcal per 100 g of fresh weight, making it a nutrient-dense option with minimal energy contribution.[63] Macronutrients are present in modest amounts, with carbohydrates ranging from 9–17 g per 100 g fresh weight (primarily dietary fiber rather than sugars), trace protein at 0.8–3 g, and negligible fat at 0.4–0.6 g; the pulp, in contrast, consists largely of water (82–86 g per 100 g), contributing to the fruit's overall low density of macronutrients.[63] Sugars such as glucose (0.9–2.3 g), fructose (1.6–3.0 g), and sucrose (0.3–1.0 g) per 100 g are notably lower than in sweeter citrus varieties like oranges.[63] Among micronutrients, vitamin C (ascorbic acid) stands out, with concentrations of 50–100 mg per 100 g across the fruit, highest in the juice (around 54 mg per 100 g), with lower concentrations in the peel (e.g., 3–8 mg per 100 g in exocarp and mesocarp).[63] Vitamin B vitamins are also present, particularly in the peel, with B6 ranging from 0.75–10.12 mg per 100 g, B1 (thiamine) 1.32–3.65 mg, and B2 (riboflavin) 0.37–1.16 mg.[63] Key minerals include potassium (126–263 mg per 100 g, averaging about 150 mg) and calcium (107–196 mg per 100 g), both more abundant in the peel than the pulp; other trace elements like iron (0.8–2.9 mg) and magnesium (6–16 mg) are also present.[63] Flavonoids such as naringin contribute to the micronutrient profile, particularly in the rind.[64] Scientific analyses, akin to USDA compositional data for related citrus, emphasize the peel as the primary edible portion due to its higher nutrient density, while the bitter, fibrous pulp is less consumed raw.[63] In comparison to other citrus fruits like lemons or oranges, citron features elevated dietary fiber (up to 11 g per 100 g in dried equivalents, higher proportionally in fresh peel) and reduced sugar content, enhancing its suitability for low-glycemic applications.[65] Nutrient levels vary between rind and pulp—the former richer in vitamins and minerals, the latter in moisture—and can fluctuate seasonally based on maturity and environmental factors like sunlight exposure.[63]| Nutrient Category | Key Components (per 100 g fresh weight, approximate ranges) | Primary Location |
|---|---|---|
| Macronutrients | Calories: 25–73 kcal Carbohydrates: 9–17 g (mostly fiber) Protein: 0.8–3 g Fat: 0.4–0.6 g Water: 82–86 g | Pulp (high water); peel (fiber) |
| Micronutrients | Vitamin C: 50–100 mg Potassium: 126–263 mg Calcium: 107–196 mg Naringin (flavonoid): Present (quantitative data variable) | Rind (richest in vitamin C, minerals) |