The Technical Journey of Rose Oil Production
Rose oil production in Isparta is a multi-stage, meticulous process executed to reveal the essence of Rosa damascena, one of nature’s most precious flowers. From the cultivation of seedlings to the careful harvesting of flowers, and through the distillation and purification steps, every stage is carried out using a blend of scientific and traditional methods to preserve the essential oil’s quality, yield, and aromatic integrity. In this process, factors such as soil selection, climatic conditions, flower development, biosynthesis, and metabolic profiles are considered to obtain the chemical components of rose oil at the highest purity and intensity.

Production Stages: From Flower to Oil:

Rose oil production in Isparta is a time-sensitive process requiring extreme attention to detail. The following steps outline the general production line and methods:

              Agricultural Preparation and Garden Establishment

  • Soil Selection: The rose prefers well-drained, nutrient-rich soils with a suitable slightly acidic-alkaline balance.
  • Seedling Selection: Disease-resistant seedlings of the Rosa damascena Mill. species with high essential oil yield potential are used.
  • Garden Establishment: Procedures such as planting distance, row arrangement, irrigation systems, and maintenance (pruning, pest, and disease control) are implemented.

              Determination of Flowering and Harvest Time

  • Blooming period usually begins from late May/early June. The flowering season lasts approximately from May 10th to July 1st.
  • Harvesting is performed early in the morning (05:00 ‑ 10:00). As the temperature rises, the loss of essential oils from the flower petals increases due to volatilization.
  • Flowers that are fully open but have not yet lost their oil due to the sun’s heat are preferred.

Collection / Transport

  • Flowers are hand-picked; they are snapped off just below the calyx (flower head) without using tools or by careful clipping.
  • Harvested flowers are transported to the processing area rapidly. Extended transport times can lead to oxidation, staining, and evaporation of the oil (fermentation).
  • Flowers are transported to factories in sacks or baskets, under cool conditions and shade.

Initial Preparation / Cleaning

  • Flowers are separated from foreign matter (dust, insects, leaves, etc.).
  • In facilities, washing or moisture control may be performed before the flowers are processed in heavy machinery.

Distillation (Hydro-distillation)

  • Rose oil in Türkiye, particularly in Isparta, is produced using the hydro-distillation (water distillation) method.
  • A specific ratio of water and flowers is mixed and heated. Through the heat of the steam or water, the essential oil and water vapor are separated from the flowers.
  • Large copper stills (alembics) are traditionally used in factories.

Condensation / Separation

  • The mixture obtained from distillation contains both oil and water (hydrosol/rose water). The oil component is separated into a different container (the oil is separated from the water surface using specific density methods).
  • The water content of the oil must be low; processes such as purification, filtration, and temperature control are used to remove water and other non-volatile substances.

Extraction / Concrete / Absolute Processes

  • Rose Concrete: Extraction of fresh rose petals with solvents; this is different from oil and is used in industrial perfumery products.
  • Absolute: A purer product with a more potent aroma, obtained from concrete or after various extraction methods.

Purification, Quality Control, and Analysis

  • Ratios of volatile components such as Geraniol, Citronellol, Nerol, Linalool, etc., are analyzed (using Gas Chromatography methods like GC‑MS, GC‑FID).
  • Essential Oil Yield: Varies depending on flower type, harvest time, waiting period, transport, and drying. Isparta rose oil yields typically range between 0.030% ‑055%.
  • In additon, quality standards such as TS 1040:1971 are utilized in Türkiye.

Packaging and Storage

  • Since the oil is sensitive to light, heat, and oxygen, it is stored in dark (amber) glass bottles under cool storage conditions.
  • Strict adherence to sealing, hygiene, and labeling rules is maintained during transport and export.

Technical and Quantitative Values

  • Approximately 1 kilogram of rose oil is extracted from 3‑4 tons of fresh rose flowers.
  • The amount of essential oil varies between 0.03% and 0.055% relative to the total mass of the flowers.
  • Production Scale: Rose gardens in the Isparta region cover tens of thousands of acres, with the number of producers expressed in thousands.

Ecological and Climatic Suitability, Soil Conditions

Altitude, slope, aspect, climate

  • Rose cultivation in Isparta mostly occurs at an altitude range of 800‑1,400 m.
  • A minimum of 240 mm of precipitation is required between March and June; maximum temperatures should not exceed 28°C, and minimum temperatures should range between 1.4°C and 3.7°C.
  • An average temperature not falling below 13°C is determined for ideal production.
  • Annual precipitation is around 500‑600 mm, making Isparta’s climate features the most suitable region for oil rose in Türkiye.
  • While land slope is not critical, South, Southeast, and Southwest aspects are preferred.
  • Climatically a dry spring, frost-free regions, and mornings with dew during the flowering period increase oil yield.

Soil Characteristics

  • The rose prefers slightly sandy-loamy, deep, and well-drained A relatively high amount of organic matter in the soil increases yield.
  • Isparta Soil Profile: Alkaline reaction, low in organic matter and nitrogen, rich in lime, sufficient in phosphorus, potassium, magnesium, and calcium, poor in sodium, and free from salinity problems.
  • Soil pH between 6.0 and 6.5 is generally considered ideal.

Plant Development, Physiology, and Metabolism

Flower development and essential oil synthesis

  • Biosynthesis of essential oils (fragrant components) occurs in the leaf and petal cells (specifically epidermis cells) of the rose.
  • These volatile components can be categorized into three major classes based on synthesis pathways: Phenylpropanoids, Terpenoids, and Fatty Acid Derivatives.
  • When Isparta rose oil is analyzed (GC‑MS, GC‑FID), it is found to contain 70‑85% monoterpene alcohols (specifically citronellol, geraniol, nerol, linalool) and 15‑30% stearoptenes (paraffins such as nonadecane, nonadecene, eicosane, etc.).
  • Components such as β‑damascenone, β‑damascone, and β‑ionone are present in low concentrations but contribute significantly to the scent character.
  • Example Ratios: Citronellol 30.0‑6%, Geraniol 7.8‑24.5%, Nerol 4.6‑10.2%, Linalool 1.1‑3.1%.

Seedling Production & Vegetative Propagation

  • Vegetativepropagation (e.g., cuttings) is generally preferred in rose production to preserve the characteristics of the parent plant (essential oil composition, adaptation).

Technical Stages of the Production Process

Pre-Harvest and Flower Processing

  • Flowers are harvested in the early morning hours between 05:00 and 10:00 to avoid excessive heat.
  • Harvested flowers are transported to the processing facility as quickly as possible; extended transport times increase the loss of volatile components.

Distillation

  • The primary method used in Türkiye is hydro-distillation (mixing steam and water).
  • During the distillation process, the flower and water mixture is loaded into stills (vessels); volatile components are separated by heating the mixture or introducing steam.
  • The resulting vapor consists of an oil and water mixture; this mixture is condensed to facilitate oil-water separation.

Condensation / Separation

  • After distillation, the oil-water vapor mixture liquefies in the condenser.
  • The oil collects on the water surface or is separated using special separator systems (based on solubility and density differences).
  • The components in the aqueous phase (hydrosol / rose water) are collected separately and are typically offered for commercial use.

Purification, Filtration, and Quality Control

  • The water content (microscopic water) of the oil must be minimal. If necessary, moisture control can be achieved through drying, vacuum, or low-heat applications.
  • Quality Control Analyses: Volatile component profiles are examined using gas chromatography (GC‑MS, GC‑FID).
  • For example, component ratios (citronellol, geraniol, etc.) are verified through these analyses.

Packaging and Storage

  • The oil is sensitive to light and heat; therefore, it must be stored in dark (amber) glass bottles in cool and ventilated environments.
  • An inert gas atmosphere (e.g., nitrogen) can be used to protect against oxidation.
  • Labeling, sealing, and logistics conditions must comply with national/international commercial standards.

Biosynthesis, Metabolic Networks, and Genetic Regulation

Terpenoid / Volatile Compound Biosynthesis Pathways

Volatile compounds—especially monoterpenes (C₁₀), sesquiterpenes (C₁₅), and some carotenoid derivatives—are the components that determine the scent of rose oil.

  • Plant terpenoid synthesis uses two main pathways: The MEV (mevalonate) pathway and the MEP / DOXP pathway.
    – MEV pathway (cytosolic): Generally contributes to sesquiterpene synthesis.
    – MEP/DOXP pathway (plastidic): Generally provides monoterpene and diterpene synthesis.
  • In roses, a TPS-independent pathway (independent of traditional Terpene Synthase enzymes) has been identified. Research suggests that NUDX hydrolase family enzymes function directly from GPP or FPP to form geraniol/farnesol derivatives. This is a plant-specific modification distinct from traditional terpene synthesis.
  • One study suggests that the copy number of the NUDX1-1a gene in different rose species is a factor determining citronellol content.
  • In addition, rose aroma components also include carotenoid-derived compounds (e.g., β-ionone, damascenone); these are produced from carotenoid molecules via the action of CCD (carotenoid cleavage dioxygenase)
  • In summary, the major volatile components constituting the rose scent (monoterpene alcohols such as citronellol, geraniol, nerol, and linalool) are synthesized via modifications specific to rose species, alongside traditional terpene pathways.”

Developmental stage, flower maturation, and metabolite changes

  • Metabolite profiles in rose petals change across different developmental stages. A study analyzing five developmental stages (such as the bud stage and opening stages) identified 37 volatile compounds and found that components like nonadecane, β-citronellol, and n-heneicosane were dominant at every stage.
  • As development progresses, the quantity of certain monoterpene components increases; however, levels may drop as the flower ages (senescence). Some aroma compounds decrease after the peak flowering stage.
  • Additionally, a study determined that the application of the hormone MeJA (methyl jasmonate) stimulates volatile compound synthesis and upregulates gene expression in the MEP pathway.
  • There is a link between scent composition and flower color production (pigment pathways); for example, carotenoid degradation products contribute to aroma compounds.

Analysis Techniques and Methods (Chemical Analysis)

Various analytical techniques are used to determine the component profiles of rose oil and related derivatives:

Gas Chromatography – Mass Spectrometry (GC-MS / GC-FID)

  • This is the most common method; ideal for separating (chromatography) and identifying (mass spectrometry) volatile compounds.
  • Components are retained via GC and then ionized and fragmented via MS to be identified based on their mass-to-charge ratios.
  • Through this method, the percentage distributions of components such as citronellol, geraniol, nerol, linalool, nonadecane, ionone, and damascenone are determined.
  • Some facilities use GC-FID (Flame Ionization Detector) and GC-MS together — FID for quantitative analysis and MS for component identification.

In conclusion, rose oil production in Isparta is made possible through a combination of meticulously executed agricultural preparation, precise harvesting, careful distillation, and advanced quality control processes. Natural and chemical factors are carefully managed at every step. Thus, the resulting oil achieves the highest quality in terms of both volatile component profile and aromatic richness. This process transforms rose oil from merely a natural product into a value where scientific precision meets traditional expertise.