Forensic Science Notes > Instituto Superior De Ciências Da Saúde Egas Moniz (Iscsem) Forensic Science Notes > Food Toxicology Notes
Food Toxicology Notes
This is a sample of our (approximately) 21 page long Food Toxicology notes, which we sell as part of the Food Toxicology Notes collection, a 14 out of 20 package written at Instituto Superior De Ciências Da Saúde Egas Moniz (ISCSEM) in 2015 that contains (approximately) 21 pages of notes across 1 different document.
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Food Toxicology Revision
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Food Toxicology Toxicology is the study of side and toxic effects of xenobiotics in living beings. This includes the substance's pharmacokinetics and pharmacodynamics, along with its absorption, distribution, metabolism and excretion. It is connected to Pharmacology, Biochemistry, Chemistry, Genetics and Pathology.
Toxic effects Toxic effects have 3 different phases, related to exposure, toxicokinetics and toxicodynamics. After taking a dose of a substance, it is available to be absorbed, which will then be dissipated or give place to the formation of active toxic substances (exposure). Then, it will be ready for the toxicokinetic phase, which consists in distributing and metabolising the substance inside the body, so it can reach the target organ or tissue and produce an effect.
Accidental Toxic food (fish, vegetables) Container (plastic, aluminum, lead) Biological contamination (mycotoxins) Chemical contamination (pesticides, growth hormones) Radiological contamination (additives)
Voluntary Homicide (biological/chemical war, fraud)
Factors that influence toxic effects Dose Quantity of xenobiotics administered by unit of weight.
Toxic agent Physical and chemical characteristics Presence of other chemicals (synergistic effects, additives)
Exposure Ways of exposure/administration Duration and frequency
Elimination Absorption, distribution, metabolism and excretion.
Individual Inter-species differences Gender Age
Among the many different types of Toxicology is food toxicology. This area studies the source and formation of toxic substances in food and drinks (foodstuffs), as well as their toxic effects and safety limits.
Hazards associated with different foodstuffs Physical Foreign materials (glass, metal, plastic, wood, insects, parts of animals)
Radiological Radioactive materials (uranium mines, nuclear accidents)
Chemical Vegetable origin - Heavy metals, use of fertilizers with high amounts of nitrogen, subterranean and superficial water contamination, pesticides Meat, dairy products, eggs - Dioxins, heavy metals, pesticides, nitrates, pharmaceuticals, additives Fishery products - Heavy metals, pharmaceuticals, additives
Biological Meat, dairy products, eggs - Fungi and mycotoxins, parasites, viruses and prions Vegetable origin - Neurotoxins (Clostridium botulinum), mycotoxins, biogenic amines (histamine) Fishery products - Fungi and mycotoxins, biotoxins
Foodstuffs alterations Group of modifications that are done in foodstuffs, destroying partially or totally its essential characteristics, by compromising its physical and chemistry properties, hygiene status and nutritive quality. In other words, it includes all the changes that cause the food to be unwanted or inadequate to its ingestion.
These alterations are reflected on:
Organoleptic characteristics Chemical composition Physical state Nutritive value Hygiene
Favourable conditions for alterations:
Harvest Omissions on the manufacturing Insufficient or incorrect conservation processes Inadequate packaging materials Transportation liabilities
Types of alterations Microbial
Mould or rotting of parts Changes in taste, smell or texture
Physical or mechanical
Impacts or physical/mechanical pressure (cracks on eggshells, cold or dehydration burns on vegetables)
Oxidative staleness/auto-oxidation (peroxides, alcohols, aldehydes, ketones - unpleasant smell). This process is accelerated by O2, light, temperature, metals and/or enzymes.
Insect and/or rodent attacks
Alterations on food due to packaging materials Food can be altered due to the inefficiency of the container's protection or its interaction with the foodstuff.
Corrosion and interaction of the metal with the content Sulfuration of cans, making the consumer reject the product due to its visual aspect
Glass containers Completely harmless. However, the constant exposure to light may cause the oxidation of very reactive compounds.
Cellulose containers Not usually used for direct contact with the food. However, when it's used, it's for dry products, so there are no interaction hazards.
Plastic containers Due to its high amount of polymers that may offer a smaller or bigger barrier, this type of container can alter the foodstuff through:
Oxidation due to light exposure
Absorption of loss of humidity
Migration of monomers, solvents or additives of the polymers
Loss or absorption of volatile compounds
Alterations to the permeability to O2 and CO2
Usual methods of fraud
Disguise or modification of the organoleptic characteristics (color, taste, consistency) Removal of parts Addition of foreign foodstuffs (that can be legal or not) Substitution of normal components for foreign products Simulation of the original product, substituting it by one with similar characteristics or artificially created products Reduction of the weight Simulation of the amount of food Illicit advertising
Adulteration of milk by adding water
Attracting the consumer by simulating a lower price and a higher amount of food
Weighing fraud, by manually compressing part of the package Misleading advertising Exposing food in better conditions at the front
Types of fraud Alteration This type includes modifications on the organoleptic characteristics, hygiene and nutritive value without human interference or action of physical, chemical (and more) agents. However, it's the economic agent that orders its commercialisation.
Addition of inferior food or substances to the product Addition of forbidden or unrevealed substances Removal of some components Simultaneous removal and addition Substitution of one or more components Substitution of the original food for an artificial one or a raw material of a lower value Simulation of the quantity/amount that is written in the package Use of unsuitable food Fraudulent retrieval of the food
Sampling Sampling and the collection of samples are necessary to obtain representative results. The sampling plan is dependant on the type of sample that is analysed. The taken sample (or fraction of it) should reflect the entire composition.
Food Toxicology Analysis
Sampling Plan Sample Collection Transportation, Storage and Pretreatment Analysis of Contaminants Analysis of Results
1. Designing the sampling plan
2. Implementing the sampling plan
Types of Sampling Random Gathering of a small number of samples from a high amount of packed samples or raw material/product in bulk. A table of random numbers is used to select the samples. Each item/package gets a number and the collecting is made according to the generated table. Used in packed foodstuffs, such as food cans. However, it's necessary that the product is not heterogeneous so that the analyte has the same chance of being included in the sample (e.g. cereal boxes).
Systematic Collecting of increasing quantities in a pre-settled period of time. The first unit is randomly chosen and the following ones will be chosen at constant intervals of K units.
Stratified Used mostly in samplings of liquids in lakes, tanks and reservoirs. The samples are collected from different layers.
Sequential Used to verify the compliance to a specification (labels). The samples are collected from the production line in pre-determined, random intervals.
Ad-hoc Used in specific foodstuffs, such as vegetarian diets. The sampling can be biased or random.
The collection and conservation of samples must be done with precision and has to obey certain requirements and norms; only then can it be considered representative of the sample in question. Lastly, a report must be presented.
Sampling Preparation Techniques The techniques used in the preparation depend on:
Physical and chemical properties of the sample
Physical and chemical properties of the analyte
Concentration of the analyte
Size reduction Drying Sample attack o fusion o dissolution Sample digestion o mineralisation
wet o solvent extraction
microwave assisted sample derivatisation extraction/concentration with adsorbent materials
Classification of toxic agents in foodstuffs according to their source
Natural source Biological contaminants Chemical contaminants Additives Toxic agents formed during processing, preparation and storage of food Natural carcinogens / nutrient-xenobiotics interactions
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