Extraction of Bioactive Compounds

Extraction of Bioactive Compounds: Detailed Course Notes

Learning Objectives

• At the end of this session, participants will be able to:

  • Explain the general steps involved in the extraction of bioactive compounds.

  • Suggest various extraction methods appropriate for specific food matrices.

  • Identify factors influencing extraction and purification processes.

Bioactive Compounds

Definition

• Bioactive compounds are nutrients and non-nutrients from food sources (both plant and animal) that provide physiological effects beyond their traditional nutritional roles.

General Extraction Procedure

• Basic steps in the extraction process:

  • Pretreatment: Prepare the material for extraction.

  • Extraction: Utilize specific techniques to retrieve bioactive compounds from the matrix.

  • Purification/Isolation: Separate and purify the desired compounds from the extract.

  • Stabilization: Ensure that extracted compounds remain stable for use.

Pretreatment

Purpose

• Understand the source material and optimize extraction.

• Assess:

  • Chemical properties (e.g., solubility - hydrophilic or lipophilic).

  • Interactions with other substances.

  • Potential transformations or stability issues.

Methods of Disruption

1. Mechanical Methods:

   • Examples include blenders, grinders, and sonication.

   • Advantages:

     • Non-selective and fast.

     • Suitable for large-scale applications.

   • Disadvantages:

     • High energy consumption.

2. Chemical Methods:

   • Using lysis agents (e.g., detergents, solvents).

   • Advantages:

     • Effective disruption.

   • Disadvantages:

     • Risk of toxicity and reduction in biocomcompound stability.

3. Enzymatic Methods:

   • Aqueous enzymatic extraction using cell-wall hydrolyzing enzymes.

   • Advantages:

     • Selective and less toxic.

   • Disadvantages:

     • Time-consuming and expensive, less suitable for large scales.

Extraction Techniques

Conventional Techniques

• Discussed techniques include:

  • Soxhlet Extraction:

  • Involves transferring target compounds from solid samples to a solvent.

  • Advantages: Simple; applies high temperatures; fresh solvent presence.

  • Disadvantages: Poor efficiency; time-consuming; inappropriate for industrial settings.

  • Liquid-Liquid Extraction:

  • Transferring compounds between liquid phases.

  • Advantages: No drying required.

  • Disadvantages: High chemical expense; manually intensive.

  • Maceration:

  • Grinding food materials to enhance extraction solvent interaction.

  • Advantages: Simple; suitable for heat-sensitive substances.

  • Disadvantages: Prolonged extraction times; lower efficacy.

  • Hydrodistillation:

  • Extracts bioactives and essential oils using steam.

  • Advantages: No organic solvent, easy separation.

  • Disadvantages: Energy-intensive, high-temperature required.

Novel Techniques

1. Microwave-Assisted Extraction (MAE):

   • Uses electromagnetic fields for efficient extraction.

   • Advantages: Faster extraction, better yield, less solvent required.

   • Disadvantages: High temperatures and pressure.

2. Supercritical Fluid Extraction (SFE):

   • Utilizes supercritical CO2 to extract compounds.

   • Advantages: High recovery rate, selectivity, and low viscosity.

   • Disadvantages: Involves high pressure.

3. Ultrasound-Assisted Extraction:

   • Enhances extraction through cavitation induced by sound.

   • Advantages: Cost-effective, rapid, reduced solvent use.

   • Disadvantages: High frequencies might damage phytochemicals.

4. Pulsed Electric Field Extraction:

   • Increases mass transfer by disrupting plant cell membranes.

   • Advantages: Higher yields, low thermal damage.

   • Disadvantages: Often requires combination with traditional techniques.

Purification/Isolation

Methods

• Centrifugation and Filtration for solid-liquid separation.

• Membrane Filtration: Size exclusion for separation.

  • Example: Gel filtration & Ion exchange processes.

• Affinity Chromatography: Utilizes specific ligands for target compound isolation.

• Reverse-phase Chromatography: Based on hydrophobic interactions.

  • Separation based on varying hydrophobicity.

Stabilization

Importance

• Extracted bioactives can be sensitive to factors like:

  • Oxidation, light exposure, temperature, pH, and enzymatic activity.

Methods of Stabilization

• Techniques to prevent degradation include:

  • Protective atmosphere packaging to limit oxidation.

  • Using dark containers, modifying pH, and adding antioxidants.

  • Methods like microencapsulation, spray drying, and nanoemulsification for improved stability.

Impact of Extraction Method

• Extraction method and molecule form can significantly affect stability.

• Importance of selecting appropriate methods to maximize yield and preserve integrity (Source: Vieira et al. 2022).

Conclusion

Key Considerations

• Source material consistency (cultivar, oil levels).

• Chemical interactions and stability of compounds during different processing methods.

• Analytical methods employed post-extraction to assess compound integrity.

Examples

Moringa Oleifera Processing Example

• Fresh moringa leaves processing to extract glucosinolates, involving:

  1. Separation into leaves and stems.

  2. Wet maceration using a specified solids-to-water ratio.

  3. Successive separation processes yielding different juice fractions.

Impact of Processing

• Influence of temperatures and extraction methods on glucosinolate stability and transformation (e.g., through blanching or ultrasonication).

Bioavailability and Bioaccessibility

• Factors affecting bioaccessibility and bioavailability include:

  • Chemical structure and concentration, food matrix interactions, processing conditions.

  • Individual factors such as age, gender, and enzymatic activity.

Health Benefits of Bioactives

• Various health benefits associated with bioactive compounds are discussed, including:

  • Reduced risks of cancer, improved cardiovascular health, anti-inflammatory effects, and more.