Week 7 Milk Bioactives Upload-1


Introduction to Dairy Bioactives

  • Definition: Bioactives are substances within foods that can exert physiological effects beyond basic nutrition.

Scope of Dairy Bioactives

  • Key Areas:

    • Dairy enzymes: Roles and potential applications in food.

    • Bioactive peptides: Functions and applications for health benefits.

    • Bioactive lipids: Contribution to health and technology.

    • Isolation challenges of dairy bioactives for functional foods.

Intended Learning Outcomes

  1. Roles and Functionality: Understanding the roles of dairy bioactives.

  2. Isolation: Describing the isolation process of dairy bioactives.

  3. Incorporation: Identifying challenges and potential in incorporating dairy bioactives into foods.

Historical Context of Bioactives

  • Types of Metabolites:

    • Primary Metabolites: Essential for life.

    • Secondary Metabolites: May have known or unknown health effects, giving rise to concept of bioactives.

  • More Recent Definitions:

    • Defined as substances with biological activity that can positively or negatively affect organisms.

    • Occur typically in small quantities in foods.

  • Safety and Efficacy: Importance of assessing safety of bioactives.

Examples of Dairy Bioactives

  • Naturally Occurring Components:

    • Enzymes (e.g., Peroxidases, oxidases)

    • Proteins and Peptides (e.g., Casein-derived peptides, whey proteins)

    • Lipids (e.g., Short-chain fatty acids, CLA)

    • Carbohydrates (e.g., Lactose-derived oligosaccharides)

  • Health Benefits:

    • Antimicrobial, antihypertensive, anti-thrombosis, and antioxidative properties.

Enzymatic Functions in Dairy Products

Enzymes Overview

  • Definition: Enzymes are biocatalysts with high specificity that catalyze chemical reactions.

  • Common Dairy Enzymes:

    • Lactoperoxidase

    • Various oxidases, lysozymes, superoxide dismutase, and proteases.

  • Biological Roles: Some possess antimicrobial properties, while others lead to quality deterioration.

Lactoperoxidase (LP)

  1. Presence and Properties:

    • Found in bovine milk (20-30 mg/L).

    • Heat resistance: retains activity after HTST pasteurization (up to 80°C).

  2. Mechanism of Action:

    • Oxidizes SCN- in presence of H2O2 to produce OSCN- with antibacterial properties.

  3. Health Implications:

    • Non-toxic to mammalian cells.

    • Supports infant health through antimicrobial activity.

  4. Food Preservation:

    • Recommended by FAO and WHO as a preservation method under refrigeration challenges.

Xanthine Oxidase (XO)

  • Characteristics:

    • Major protein in the milk fat globule membrane.

    • Converts hypoxanthine to uric acid, generating superoxide and H2O2.

  • Heat Sensitivity:

    • Largely inactivated by heat; processed milk retains sufficient activity for potential antibacterial effects.

Bioactive Peptides in Dairy

  • Types of Peptides:

    • Antihypertensive Properties: Lowering blood pressure via ACE inhibition (e.g., casokinins).

    • Antimicrobial Activity: Peptides inhibit growth of harmful bacteria like E. coli.

  • Casein Phosphopeptides:

    • Enhance remineralization of teeth by stabilizing calcium and phosphate ions.

Challenges in Incorporating Dairy Bioactives

  • Stability: Sensitive to environmental factors; solutions include microencapsulation.

  • Bioavailability: Influenced by food matrix and molecular size; improving formulations can help.

  • Sensory Attributes: Bioactive incorporation affects taste and texture; complementary ingredients may help.

  • Regulatory Hurdles: Compliance with health claims and regulations is necessary.

  • Consumer Acceptance: Perception issues can affect market success.

Methods of Extraction and Purification

  • Centrifugation: Separates milk fat globules from aqueous phase.

  • Ultrafiltration: Concentrates proteins and removes small molecules.

  • Enzymatic Hydrolysis: Produces smaller peptides from proteins.

  • Membrane Filtration: Size-based separation techniques.

  • Chromatography: Purifies specific bioactive compounds.

  • Spray Drying and Freeze Drying: Preserves bioactivity while drying.

Impact of Processing on Bioactives

  • Pasteurization: Can denature sensitive proteins; lower heat options are advantageous.

  • Fermentation: Enhances some bioactive components but may degrade others.

  • Storage and Packaging: Innovations are needed to protect bioactives from degradation.