6.1 Organoleptic and chemical analysis (aroma, color, purity)

Here’s a structured guide on organoleptic and chemical analysis of essential oils, tailored for REHD or hydrodistillation outputs:

1. Introduction

Quality assessment of essential oils involves organoleptic (sensory) evaluation and chemical analysis. Together, these ensure the oil meets industry standards, preserves desired aromatic profiles, and is suitable for fragrance, therapeutic, or cosmetic use.

2. Organoleptic Analysis

Purpose: Evaluate sensory properties such as aroma, color, and viscosity.

Key Attributes

  1. Aroma / Fragrance
    • Evaluate freshness, intensity, complexity, and typical notes of the plant species.
    • Use panel testing or trained perfumers for consistency.
  2. Color
    • Visual inspection in clear glass bottles.
    • Compare to standard reference oils; color may indicate freshness, degradation, or oxidation.
  3. Clarity & Viscosity
    • Oil should be free of sediment, cloudiness, or water droplets.
    • Measure viscosity if needed for standardization or product formulation.
  4. Taste (if applicable)
    • Only for culinary-grade oils; taste profile should match expected characteristics.

3. Chemical Analysis

Purpose: Confirm purity, composition, and identity of the essential oil.

Common Analytical Methods

  1. Gas Chromatography (GC)
    • Separates and identifies volatile compounds.
    • GC-FID or GC-MS provides compound profiling, quantification, and fingerprinting.
  2. Refractive Index
    • Indicates purity and concentration; deviations may signal adulteration.
  3. Optical Rotation
    • Measures chirality of specific compounds, especially in floral or citrus oils.
  4. Specific Gravity
    • Compares oil weight to water; useful for quality and adulteration checks.
  5. UV-Vis Spectroscopy
    • Detects oxidation products or impurities, often in aged oils.
  6. Moisture Content / Water Content
    • Karl Fischer titration or drying method; high water may reduce shelf life.
  7. Other Tests (Optional)
    • Acid value, saponification value, and solubility tests for specialty oils.

4. Integrated Evaluation Workflow

  1. Sample Collection
    • Collect oil after separation, store in dark glass vial, labeled.
  2. Organoleptic Assessment
    • Record aroma intensity, color, clarity, and any off-notes.
  3. Chemical Analysis
    • Perform GC profiling, refractive index, specific gravity, and other tests.
  4. Comparison to Standards
    • Match data to ISO, AFNOR, or in-house reference profiles.
  5. Documentation
    • Maintain batch records with sensory notes, chemical data, and yield for traceability.

5. Practical Tips

  • Conduct organoleptic assessment at room temperature under consistent lighting.
  • Use clean, dry, and airtight containers for chemical analysis samples.
  • Fractional analysis can help identify early, mid, and late fractions in REHD for aroma profiling.
  • Consistent sampling improves reproducibility and quality control.

6. Visual / Infographic Concept

Title: “Organoleptic & Chemical Analysis of Essential Oils”

  • Sections:
    1. Organoleptic: aroma, color, clarity, viscosity
    2. Chemical: GC profile, refractive index, specific gravity, moisture
    3. Workflow: sample → sensory evaluation → chemical testing → documentation
  • Icons: nose/aroma, droplet/color, microscope, GC column, bottle, data sheet
  • Optional: show comparison to standard/reference profile for quality verification.

I can create a clear infographic showing organoleptic and chemical analysis of essential oils, highlighting the workflow from sensory assessment to chemical validation, suitable for training or lab manuals.

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