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Unit 07 - Coggle Diagram
Unit 07
FOOD TOXICOLOGY
Definition and Importance
Field of food chemistry that studies toxic substances in food
Aims to identify, assess, and control foodborne toxicants
Ensures safety and regulatory compliance of food products
Focuses on:
Identifying potential hazards
Establishing safe exposure levels
Supporting food safety regulations
Concern areas:
Toxicants
Allergens
Antinutrients
CLASSIFICATION OF FOOD TOXICANTS
Based on origin → two major categories:
Endogenous Toxicants (Internal Origin)
Naturally present within certain foods
Produced during normal metabolism or under stress
Influenced by:
Plant/animal variety
Growth and environmental conditions
Stress, injury, or infection
Processing or cooking methods
Types:
Allergens (e.g., Ovalbumin in eggs)
Toxicants (e.g., Gossypol in cottonseed)
Antinutrients (e.g., Saponins in soybeans)
Key note: naturally occurring but can be harmful in excess
Exogenous Toxicants (External Origin)
Contaminants introduced from outside sources
Enter food during:
Production
Processing
Packaging
Environmental exposure
Types:
Heavy metals (Lead, Mercury, Cadmium)
Pesticide residues
Veterinary drugs
Microbial toxins (e.g., aflatoxins)
Packaging contaminants (e.g., BPA, phthalates)
Require strict regulatory monitoring and testing
Goal:
Identify and control both endogenous and exogenous toxicants
Protect consumers and ensure food safety
KEY ASPECTS OF FOOD TOXICOLOGY
Hazard Identification
Detect and classify toxic substances, allergens, and antinutrients
Study their chemical and biological properties
Assess potential health risks
Dose–Response Relationship
Relationship between toxin dose and effect severity
Determines safe exposure limits
Helps set Acceptable Daily Intakes (ADIs)
Risk Assessment
Combines hazard identification, exposure, and dose–response data
Evaluates probability and severity of adverse effects
Forms the basis for food safety decisions
Exposure Assessment
Quantifies amount of toxicant exposure through diet
Based on population consumption data
Essential for accurate risk characterization
Toxicokinetics and Toxicodynamics
Toxicokinetics (ADME):
Absorption
Distribution
Metabolism
Excretion of toxicants
Toxicodynamics:
Mechanisms of toxic effects at cellular and tissue levels
Interaction of toxins with biomolecules
Together explain how and why toxicity occurs
Cumulative Effects
Chronic exposure to small toxin doses may lead to health issues
Evaluated for bioaccumulating substances (e.g., heavy metals)
Key for long-term safety assessments
Vulnerable Populations
Certain groups more sensitive to toxins:
Infants and children
Pregnant women
Elderly individuals
Immunocompromised persons
Require stricter safety margins
Analytical Methods
Advanced tools for toxin detection and quantification:
Chromatography (HPLC, GC)
Mass spectrometry (MS)
Spectrophotometry
Immunoassays
Ensure precise measurement and traceability
International Standards and Regulations
Global agencies establish safety frameworks:
WHO (World Health Organization)
FAO (Food and Agriculture Organization)
EFSA (European Food Safety Authority)
FDA (U.S. Food and Drug Administration)
Key principles:
Safety Data Submission
Acceptable Daily Intake (ADI)
Maximum Residue Limits (MRLs)
Functional Evaluation
Labeling and Declaration
Periodic Review
Goal: Harmonize international food safety practices
FOOD ANALYSIS
Overview
Purpose:
Ensures food quality, safety, and compliance
Supports product development and consumer trust
Detects composition, contaminants, and adulteration
Importance:
Quality Control and Standardization
Nutritional Labeling and Regulation
Product Development and Innovation
Food Safety and Authenticity
Core Idea:
Regular and accurate analysis = essential for food industry integrity
ANALYTICAL METHODS IN FOOD ANALYSIS
Gravimetric Analysis
Based on: Measurement of mass
Principle: Quantification through weight change
Applications:
Moisture content
Ash content
Contaminant residue
Pros: Simple and accurate for solid quantification
Volumetric Analysis (Titrimetry)
Based on: Volume of a reagent of known concentration
Principle: Reaction between analyte and titrant
Applications:
Acidity or alkalinity (pH)
Vitamin C determination
Mineral ions (e.g., chloride, calcium, iron)
Pros: Rapid and suitable for routine analysis
Optical Methods
Based on: Interaction of light with matter
Techniques:
Spectroscopy (UV-Vis, IR, NIR)
Polarimetry (optical rotation, sugar concentration)
Refractometry (refractive index measurement)
Applications:
Color, concentration, and purity analysis
Identification of compounds
Pros: Non-destructive and sensitive
Mass Spectrometry (MS)
Based on: Mass-to-charge ratio of ions
Principle: Fragmentation and detection of compounds
Applications:
Detection of pesticides and toxins
Flavor and aroma compound analysis
Food additive identification
Pros: High specificity and sensitivity
Chromatography
Based on: Separation between stationary and mobile phases
Types:
Gas Chromatography (GC) → volatile compounds (aromas, solvents)
Liquid Chromatography (LC)
High-Performance Liquid Chromatography (HPLC) → non-volatiles (vitamins, preservatives)
Applications:
Separation and quantification of compounds
Detection of contaminants and nutrients
Pros: Versatile and accurate for complex mixtures
Integration of Methods
Combination of multiple techniques yields comprehensive results
Example: Chromatography + MS = accurate compound identification
Ensures food meets quality and safety standards
SAMPLING AND SAMPLE PREPARATION
Importance:
Representative sample → accurate analysis
Incorrect sampling = major source of error
Homogeneity is crucial
Steps:
Sampling → representative selection
Homogenization → uniform mixture
Drying / Grinding → increase consistency
Preservation → prevent degradation
Key Rule: Handle samples carefully to avoid contamination or alteration
KJELDAHL METHOD – CRUDE PROTEIN DETERMINATION
Purpose: Quantify total nitrogen (→ protein content)
Principle: Nitrogen → Ammonium → Ammonia → Titration
Steps:
Digestion:
Boil sample in sulfuric acid
Convert organic nitrogen → ammonium sulfate
Catalyst speeds conversion
Distillation:
Add alkali → release ammonia gas
Capture NH₃ in boric acid solution
Form ammonium borate
Titration:
Titrate with standard H₂SO₄
Determine volume difference (V₁ - V₀)
Calculate nitrogen and protein content
Equations:
Nitrogen (%) = [(V₁ - V₀) × C × 14] / Ws
Protein (%) = Nitrogen (%) × Conversion Factor (usually 6.25)
Notes:
Assumes all nitrogen from protein
Non-protein nitrogen may cause slight overestimation
Used for total nitrogen reporting
Applications: Protein analysis in dairy, cereals, meats, and feed
SOXHLET METHOD – TOTAL FAT DETERMINATION
Purpose: Quantify total extractable fat from solid food samples
Principle: Continuous solvent extraction of lipids
Apparatus Components:
Extraction flask (holds solvent)
Extraction chamber with thimble (holds sample)
Condenser (recycles solvent)
Sample Preparation:
Dry sample (remove moisture)
Grind finely (increase surface area)
Avoid oxidation (low-temp drying or lyophilization)
Extraction Process:
Solvent (e.g., hexane, petroleum ether) heated → evaporates
Vapor condenses and drips over sample in thimble
Solvent dissolves fats and carries them to flask
Process continues 6–24 hours (continuous extraction)
After extraction, solvent evaporated → residual fat weighed
Applications:
Determination of total fat in foods (e.g., nuts, dairy, cereals)
Standard reference method for fat content
Basis for nutritional labeling
Notes:
Sample drying essential (solvents immiscible with water)
Avoid residual solvent in final extract
Accurate mass measurement crucial
Provides total lipid fraction (not composition)