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Questions and Answers
What is the primary method used to obtain floral concretes?
What is the primary method used to obtain floral concretes?
Floral absolutes are less expensive and less pure than floral concretes.
Floral absolutes are less expensive and less pure than floral concretes.
False (B)
What are the products obtained from the hydrolysis of glycosides?
What are the products obtained from the hydrolysis of glycosides?
Volatile aglycones
The process of obtaining floral absolutes involves repeated extraction with __________ to remove most oxygenated constituents.
The process of obtaining floral absolutes involves repeated extraction with __________ to remove most oxygenated constituents.
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Match the following steps with their corresponding processes:
Match the following steps with their corresponding processes:
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Which volatile oil compound is associated with the plant Gaultheria?
Which volatile oil compound is associated with the plant Gaultheria?
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The qualitative analysis of volatile oils involves measuring their quantity.
The qualitative analysis of volatile oils involves measuring their quantity.
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What is the primary method used in quantitative analysis of volatile oils?
What is the primary method used in quantitative analysis of volatile oils?
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The hydrolytic enzyme for bitter almond is called _____ .
The hydrolytic enzyme for bitter almond is called _____ .
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Match the following plants with their respective non-volatile glycosides:
Match the following plants with their respective non-volatile glycosides:
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What are volatile oils primarily composed of?
What are volatile oils primarily composed of?
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Volatile oils are water-soluble and can be easily mixed with water.
Volatile oils are water-soluble and can be easily mixed with water.
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Name one method of preparation for volatile oils.
Name one method of preparation for volatile oils.
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Volatile oils can darken in color when exposed to __________.
Volatile oils can darken in color when exposed to __________.
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Which of the following is not a method used for preparing volatile oils?
Which of the following is not a method used for preparing volatile oils?
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Match the following volatile oil preparation methods with their descriptions:
Match the following volatile oil preparation methods with their descriptions:
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Volatile oils can consist of a single main component.
Volatile oils can consist of a single main component.
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What factor does NOT affect the selection of the method for preparing volatile oils?
What factor does NOT affect the selection of the method for preparing volatile oils?
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What is the preferred material for packing in distillation of oxygenated compounds?
What is the preferred material for packing in distillation of oxygenated compounds?
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The sponge method involves filtering oil collected from squeezed peels.
The sponge method involves filtering oil collected from squeezed peels.
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What is the primary distinction between non-volatile and volatile solvent extraction methods?
What is the primary distinction between non-volatile and volatile solvent extraction methods?
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In the expression methods, the ______ method is based on puncturing the surface of fruits to exude oil.
In the expression methods, the ______ method is based on puncturing the surface of fruits to exude oil.
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Match the following expression methods to their descriptions:
Match the following expression methods to their descriptions:
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Which of the following is true about water distillation?
Which of the following is true about water distillation?
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Heat sensitive oils are primarily extracted from inner fruit layers.
Heat sensitive oils are primarily extracted from inner fruit layers.
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The process of squeezing oil from the outer peels of fruits is known as ______.
The process of squeezing oil from the outer peels of fruits is known as ______.
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Which mixture of fats is used to prevent melting during the extraction process?
Which mixture of fats is used to prevent melting during the extraction process?
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The enfleurage process involves soaking flowers in hot oil.
The enfleurage process involves soaking flowers in hot oil.
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What is the final product after the enfleurage process is scraped and filtered?
What is the final product after the enfleurage process is scraped and filtered?
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In the maceration method, flowers are soaked in __________ to rupture their cell membranes.
In the maceration method, flowers are soaked in __________ to rupture their cell membranes.
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Match the extraction methods with their descriptions:
Match the extraction methods with their descriptions:
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What is a key factor in selecting a volatile solvent for extraction?
What is a key factor in selecting a volatile solvent for extraction?
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The boiling point of the selected solvent should be as high as possible.
The boiling point of the selected solvent should be as high as possible.
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What method involves the use of a Soxhlet apparatus?
What method involves the use of a Soxhlet apparatus?
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Study Notes
Volatile Oils: Definition
- Complex liquid mixtures of odoriferous compounds
- Varying chemical compositions
- Easily evaporate at ordinary temperatures
- Also known as ethereal oils or essential oils
- Used therapeutically, for flavoring, and perfuming
- Starting materials for semi-synthesizing other compounds
Volatile Oils: Combined with
- Sugars forming the aglycone part of certain glycosides
- Gums, resins, or both to form oleo-gums, oleoresins, or oleo-gum-resins
Physical Properties
- Volatile liquids
- Pleasant smells
- Steam-distilled (e.g., fixed oils)
- Immiscible with water but soluble enough to impart a distinct fragrance to water (aromatic waters)
- Soluble in common organic solvents and lipids (liposoluble)
- May darken in color when exposed to light (due to oxidation and resinification)
Chemical Composition
- Complex mixtures of constituents
- Hydrocarbons
- Oxygenated compounds (e.g., alcohols, ketones, aldehydes, ethers, oxides, phenols, esters)
- Some oils consist of one main component (e.g., volatile oil of mustard (93% allylisothiocyanate), oil of clove (85% eugenol))
Methods of Preparation: Factors Affecting Selection
- Plant material condition (dry or fresh)
- Degree of comminution (intact, crushed, or powdered)
- Oil localization in the plant (superficial or deep)
- Amount of oil
- Nature of constituents
Methods of Preparation
- Distillation
- Expression
- Extraction
- Enzymatic hydrolysis
Distillation Methods
- Water distillation method: Dry plant material directly contacts boiling water (e.g., turpentine oil)
- Water and steam distillation: Plant material (dry or fresh) is supported on a perforated screen, with water below the screen, only steam contacts the material (e.g., cinnamon, cloves)
- Direct steam distillation: No water in the still; steam is introduced through a steam coil (e.g., peppermint, spearmint)
Precautions in Handling Plant Material
- Crush plant material just before distillation to prevent loss through volatilization
- Dried plant material subjected to saturated steam distillation should be wet before packing
- Even packing/charging to facilitate "hydro diffusion"
- Use stainless steel for oxygenated compounds (avoid iron)
Different Types of Distillation Apparatus
- Diagrams of water distillation, water & steam distillation, direct steam distillation
Expression Methods:
- Mechanical procedures at room temperature
- Used for heat-sensitive oils present in large amounts in fruit peels (e.g., Citrus fruits, orange, lemon).
- Methods: Sponge method, Expression of rasping, Scarification method, Machine processes
Extraction Methods:
- Used for delicate flowers oils (e.g., jasmine, violet, narcissus)
- Contains small amounts of oils easily lost in large volumes of distillation water
- Oils that decompose with heat
- Methods include non-volatile and volatile solvent extraction
Non-Volatile Solvent Extraction
- Used for preparing natural flower oils (e.g., perfumes)
- Based on the liposolubility of fragrant plant components
- Uses highly pure lipids (e.g., fats such as lard and tallow—a 2:1 mixture to avoid melting; fixed oils such as olive oil)
- Methods: Enfleurage Process - a method using glass plates, fat layers, and flowers to extract oils, followed by scraping and cooling to yield a floral pomade product
Volatile Solvent Extraction
- Select solvents based on selectivity, stability, boiling points, volatility, and safety (non-toxic, non-flammable) like absolute alcohol to prepare concretes & absolutes
- Uses the Soxhlet apparatus (details shown pictorially) for hot extraction at constant temperatures
Preparation of "Floral Concretes":
- Extraction by percolation/maceration at room temperature or continuous hot extraction in a Soxhlet apparatus at a constant temp (no over 50°C). 2.Removal of the solvent by distillation under reduced pressure. 3."Floral concrete" of jasmine is a semi-solid yellowish-orange product. 4."Floral concrete" consists of fragrant constituents with liposoluble impurities (e.g., fats, waxes, pigments).
Preparation of "Floral Absolutes":
- More expensive & purified products compared to concretes.
- Repeated extraction with absolute alcohol to extract oxygenated constituents.
- Followed by chilling and decantation to remove waxes and fat-soluble pigments.
- Resulting absolutes are richer in oxygenated constituents that yield the characteristic odor.
- Used at lower concentrations than concretes in perfume industry.
Enzymatic Hydrolysis of Glycosides
- Many glycosides yield volatile aglycones upon hydrolysis
- Enzymes used in plants for hydrolysis of glycosides
- Aglycones belong to different classes. Procedure steps for enzymatic hydrolysis.
Determination of Volatile Oil: Quantitative Analysis
- Evaluates plant species quality and raw material suitability for commercial preparation to differentiate genuine from adulterated oil
- Uses Clavenger’s apparatus (pictured) for analysis
Determination of Volatile Oil: Qualitative Analysis
- Odor analysis: Abnormal odor implies adulteration/deterioration
- Solubility analysis: Solubility in different alcohol strengths (e.g., varied percentage ethyl alcohol solutions)
- Optical rotation analysis: Rotations of polarized light, using a polarimeter, show activity of chemical products
- Chemical tests: chemical tests of isolated plant volatile oils to determine functional groups present
Chemistry of Volatile Oils
- Single-component oils (e.g., benzaldehyde, methyl salicylate)
- Complex mixtures of hydrocarbons known as terpenes and related oxygenated compounds
- Definition of terpenes: natural products with formulas divisible into isoprene units, with a "head-to-tail" arrangement (isoprene rule)
- Classification of terpene types (e.g., monoterpenes, sesquiterpenes) shown visually (tables)
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Description
Test your knowledge on the extraction methods and characteristics of floral concretes and volatile oils. This quiz covers various processes, compounds, and qualitative analyses related to essential oils in plants. Perfect for students of botany and aromatherapy enthusiasts!
