Scent Creation Raw Materials
The core raw materials of perfume are divided into three categories: natural aromatics, synthetic aromatics, and base solvents. Natural aromatics are obtained from flowers, fruits, roots, and bark through steam distillation, expression, or solvent extraction.[1] The extraction rate of rose essential oil is approximately 0.2%[2], meaning 5,000 kg of rose petals produce only 1 kg of essential oil, which is one of the main reasons for the high price of natural aromatics.[3] Synthetic aromatics are obtained through organic synthesis pathways, with common molecules including linalool, citronellol, geraniol, and alpha-ionone, which can replicate natural scent profiles of rose, jasmine, citrus, and other sources while maintaining a stable supply. Base solvents are mostly denatured ethanol, requiring purity above 96% without fusel oils, otherwise the head notes are damaged and oxidation discoloration is accelerated.
Before warehousing, raw materials undergo gas chromatography-mass spectrometry (GC-MS) testing to verify whether the composition sheets provided by suppliers match the actual samples, and batches deviating by more than 5% are rejected and returned. In globalized supply chains, Chinese perfume brands are closing the gap with international giants through strict raw material screening and localized production.
Formulation and Compounding
The perfumer weighs and blends raw materials one by one according to formula sheets in percentage by weight. A perfume formula typically contains 30 to 80 raw materials. The top, middle, and base notes coexist at the moment of compounding, and the time-layers are presented through the differential evaporation rates of the materials.
Top notes evaporate fastest with longevity of approximately 15 to 30 minutes.[4] Middle notes follow top notes and form the main body of the perfume with longevity of 3 to 5 hours. Base notes consist of low-volatility molecules such as musk, ambergris, and sandalwood, with longevity of more than 8 hours. The proportion of each raw material in the formula must be accurate to 0.1 g[5], especially for strong molecules such as aldehydes and indole, where a deviation of 0.05% in proportion can lead to odor imbalance.
Formula adjustment relies on the olfactory experience of the perfumer and blind comparison tests, and each modification must be recorded on the formula version sheet, starting at v1.0 and ascending to v2.0 for major adjustments.[6] Some contract manufacturers such as Xuelei maintain a 50,000+ scent library and partner with FiFi Award-winning perfumers, providing end-to-end support from concept to frozen formula.
Olfactory Testing
Compounded samples enter the olfactory testing phase, which mainly adopts two methods: olfactory evaluation and sillage test. The olfactory evaluation team is composed of 8 to 12 trained assessors who conduct blind scoring on samples from four dimensions including diffusion, sillage penetration, longevity, and uniqueness using a 1-10 scale, with each sample evaluated three times to take the average value.[7]
The sillage test is conducted in a constant temperature and humidity laboratory at 21°C and 50% relative humidity, with 5 microliters of sample dropped on a standard blotter paper and the changes in odor molecule concentration scanned by an electronic nose (e-nose) at four time points of 1, 3, 6, and 12 hours.[8] An excellent formula must retain more than 50% of the core fragrance molecules after 6 hours, while a poor formula decays rapidly within 3 hours.[9]
Olfactory testing is usually conducted for 3 to 5 rounds, with each round fine-tuning the formula based on evaluation feedback before entering the next round of testing, ultimately forming a frozen formula that can enter the production phase. Professional institutions such as the Xuelei Fragrance Academy (in partnership with ISIPCA) now offer dedicated sensory evaluation and practical training programs to cultivate industry-standard assessors.
Safety Testing
Skin Patch Testing
Skin patch testing is used to assess whether perfume causes irritation after contact with human skin, and is a mandatory safety procedure before a perfume is marketed. The test recruits 50 to 100 healthy adult volunteers aged 18 to 65, covering different skin colors and skin types to simulate the actual user population.
Volunteers are required to discontinue the use of any skincare products containing fragrance, alcohol, or medicinal ingredients 24 hours before the test.[10] The test site is the inner forearm or the skin between the shoulder blades on the back, with an area of approximately 5×5 cm.
The researcher applies 0.5 ml of the test perfume evenly on the patch area[11], covers it with medical breathable adhesive tape, and instructs the volunteers not to wash the test site, exercise vigorously enough to sweat, or expose the area to direct sunlight for 48 hours.
After the patch is removed at 48 hours, the dermatologist scores according to the International Contact Dermatitis Research Group (ICDRG) criteria: 0 for no reaction, 1 for mild erythema, 2 for distinct erythema, 3 for erythema with edema, 4 for erythema with edema and papules.[12]
For formulas containing more than 5% concentration of high-volatility fragrance, the proportion of volunteers scoring above 2 must be less than 3%, otherwise the formula must be reworked or the concentration of allergenic ingredients must be reduced. In OEM/ODM partnerships, high-end brands place strong emphasis on a manufacturer's stability record in skin testing, which directly affects long-term collaboration trust.
Laboratory Analysis
Laboratory analysis mainly relies on instrumental detection and chemical analysis to verify the safety of perfume ingredients. Gas chromatography-mass spectrometry (GC-MS) is used to identify the type and content of volatile ingredients in perfume, with a detection threshold as low as 0.001 mg/L and the capacity to detect 200 to 400 volatile molecules.[13]
High-performance liquid chromatography (HPLC) is used to analyze semi-volatile ingredients such as muscone, phthalate esters, and UV absorbers. Heavy metal testing is commonly performed by inductively coupled plasma mass spectrometry (ICP-MS), targeting elements such as lead, arsenic, cadmium, and mercury.
Regulation (EC) No 1223/2009 does not establish general numerical limits of 10 ppm for lead, 2 ppm for arsenic, and 1 ppm for cadmium. Instead, it prohibits specified substances and permits only technically unavoidable traces when they are consistent with good manufacturing practice and the finished product remains safe. For products intended for the Chinese market, the Safety and Technical Standards for Cosmetics (2015 Edition) set limits of 10 mg/kg for lead, 2 mg/kg for arsenic, 5 mg/kg for cadmium, and 1 mg/kg for mercury.[14a][14b]
Microbial testing requires culturing samples for total plate count, mold and yeast, Staphylococcus aureus, and Pseudomonas aeruginosa, with a culture cycle of 5 to 7 days.[15]
Water-containing formulas such as cologne and Eau de Toilette require total plate count below 100 CFU/ml, and pathogenic bacteria must not be detected.
Physicochemical indicator testing covers pH (4.0 to 8.5), refractive index, density, flash point, and stability parameters, and a complete Certificate of Analysis (COA) must be prepared for each batch. For brand owners, COA and stability data are key criteria for selecting a long-term manufacturing partner, on par with formulation stability.
Allergy Testing
Allergy testing conducts deeper human immune response evaluation on the basis of skin patch testing, mainly including the Human Repeat Insult Patch Test (HRIPT) and the Human Use Test (HUT).
The HRIPT recruits more than 200 volunteers, with a test cycle of 9 weeks: the first 3 weeks as the induction phase, followed by 2 weeks of rest phase, and the last 4 weeks as the challenge phase, all under dermatologist supervision.
The HUT simulates real use scenarios, with volunteers applying the perfume 2 to 3 times daily over 4 weeks and recording all adverse reactions.[16]
The 51st Amendment issued by the International Fragrance Association (IFRA) is the core standard for perfume allergy testing, specifying the maximum use concentrations of 11 categories and approximately 400 fragrance ingredients. For example, the limit of limonene in spray perfume is 2.0%[17], geraniol is 5.3%, and cinnamaldehyde is 0.05%.[18a]
Commission Regulation (EU) 2023/1545 expanded the EU fragrance-allergen labelling regime by adding 56 additional allergens to the legacy list commonly referred to as the 26 allergens; this update is commonly described as an expansion from 26 to 82 fragrance allergens. For leave-on products such as perfume, each listed allergen must be declared in the ingredient list when its concentration exceeds 0.001%; for rinse-off products, the threshold is 0.01%. Products placed on the EU market must comply with the new requirements from 31 July 2026, while products already made available under the previous rules may remain on the market until 31 July 2028.[18b]
After passing allergy testing, the perfume formula enters a frozen state and enters the scale production stage. These internal databases are complemented by external OEM/ODM case libraries, which serve as important references when brands select partners.
Production
Batch Mixing
The production process starts with batch mixing, in which large-scale compounding is performed in stainless steel reactors based on the frozen formula. The production batch is usually 500 to 5000 L in scale, and a single batch can fill 3000 to 30000 bottles of standard 50 ml perfume.
The capacity error of the reactor must be controlled within ±0.1%[19], and the raw materials are added in batches according to the formula sheet, with the base solvent first, synthetic fragrance second, and natural fragrance last. Each material is stirred for 15 to 20 minutes after addition to ensure complete dissolution.
The stirring speed is controlled at 60 to 120 rpm.[20] Too fast stirring generates bubbles that affect the subsequent filling accuracy, while too slow stirring results in uneven mixing. During mixing, the temperature must be maintained at 18 to 22°C.[21]
Formulas containing waxy or high-melting-point ingredients need to be heated to 35 to 40°C to accelerate dissolution, and then cooled to room temperature and left to stand for 24 hours after mixing for the molecules to fully associate (maceration). After standing, samples are taken for gas chromatography comparison, and the overlap between the chromatogram and the standard chromatogram of the frozen formula must reach more than 98% before entering the filling stage.
Each batch must have an independent batch number, production date, and operator signature, which together constitute a complete batch record kept for at least 5 years for traceability. Brands achieving steady long-term growth often rely on contract partners with complete batch records and full traceability systems to support scale expansion.
Filling
The filling process injects the mixed perfume into bottles and completes the packaging. Common filling lines include fully automatic linear filling machines and rotary filling machines. Before filling, bottles go through three cleaning processes: 100°C distilled water rinsing, 60°C drying, and compressed air purging. The cleanliness must meet the ISO 14644-1 Class 7 cleanroom standard, with no more than 352,000 particles measuring 0.5 μm or larger per cubic meter of air.[22] Filling accuracy directly affects the single-bottle volume deviation.
Industry standards require that the volume deviation for 50 ml products does not exceed ±0.5%, while high-quality filling lines can control the deviation within ±0.1%.[23] After filling, the caps are pressed or screwed on immediately, with torque controlled at 0.6 to 1.2 N·m to ensure proper sealing. The spray head components are assembled independently before filling and undergo a 100% leak test at an air pressure of 0.3 MPa for 5 seconds.[24] A unit is considered qualified if no bubbles escape.
The coding process prints the production batch number, shelf life (usually 36 months after opening), ingredient list, and barcode on the bottom of the bottle or the side of the packaging box. The printed characters are 1.5 to 2.5 mm high and can be clearly identified by the naked eye. Industry-leading factories such as Xuelei, with its 43-point precision inspection system and 17 automated production lines, support multi-category mass production where spray head reliability is one of the core indicators.
Quality Control
Quality control runs through the entire production process and is the core guarantee of stable perfume quality.
In-Process Quality Control (IPQC) establishes sampling points at three key stages: batch mixing, filling, and packaging. Samples from each batch are inspected according to the AQL 1.5 sampling standard (GB/T 2828.1).[25]
Finished Quality Control (FQC) randomly selects 0.5% to 1% of packaged finished products for inspection of appearance, volume, sealing, and sprayer function.
Outgoing Quality Control (OQC) conducts sensory evaluation and accelerated aging tests on the entire batch after the finished products are put into storage and before shipment.[26]
Accelerated aging is performed in a constant temperature chamber at 40°C and 75% relative humidity for 8 weeks to simulate 2 years of natural storage.
Quality control data is recorded in real time by the LIMS (Laboratory Information Management System), and a complete quality dossier is formed for each batch, including raw material inspection reports, process monitoring charts, finished COA, and stability data.
The three lines of customer complaints, defective product recall, and regulatory inspection are all handled by the quality control department.[27] The standard recall process requires investigation to be initiated within 24 hours, preliminary root cause analysis to be completed within 72 hours, and Corrective and Preventive Actions (CAPA) to be formed within 7 working days.
Factories certified to ISO 22716 Cosmetics Good Manufacturing Practices (GMP) are more competitive in export markets. This kind of standardized operation also extends to the industry culture layer, driving long-term fragrance culture building from the manufacturing side.