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Chapter 12

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University of Guelph
Food Science
FOOD 2010
Massimo Marcone

Chapter 12: Food Toxicology 12.1 What is a Food Toxicant? -toxicant = any chemical substance that can elicit a detrimental effect in a biologic a biological system. Subdivided into 3 categories -Endogenous Toxicants -produce by tissue cells in plants and other biological raw materials. They protect the plant tissue from pests and pathogenic organisms. Transmission to people can occur through the consumption of toxic plants by animals that are then used for human food -Naturally Occurring Toxicants -produced by organisms that contaminate the food product. Upon consumption can cause disease. Their stability, varies per toxin. -Synthetic Toxicants -synthetically produced but find way into our food supply through contamination of the food processing environment. 12.2 Risk Assessment For Chemical Hazards -EPA est 1970 to regulate and assess environmental chemical hazards -risk assessment = evaluation of the severity of the threat -dose-response assessment - determination of the concentration of a particular toxicant needed to cause an unfavorable effect on a biological system -exposure assessment - the determination of the risk of exposure of a biological system to a toxicant -acute effects - take place quickly (mins-days after exposure) -chronic - appear after weeks, months, even years of exposure -epidemiological studies - provide us with information on the frequency of occurrence of a toxic effect in a human population - animal studies (bioassays) - used to gather info in risk assessment. Used to predict the effects that toxicants would have on humans based on results obtained with animals -modes of action of toxicant -toxicants work by changing the speed of certain body functions or by decreasing them (heart rate, BP etc) -can have a widespread effect or specific effect on the body -assessing dose-response -the dose determines the poison -dose-response is based on the principle that there is a relationship between a toxic reaction and the amount of the toxicant received -threshold level - no toxic effect is observed -dose-response curve - after the threshold level the effect increases until it reaches its maximum -effective dose (ED50) that will cause an adverse effect in 50% of the animals -lethal dose (LD50) will cause death in 50% of the animals -carcinogen testing Chapter 12: Food Toxicology -carcinogen - chemical toxin that are known to cause cancer -epidemiological studies and bioassays are used to determine if a certain dose will lead to an increased risk of developing cancer 12.3 Endogenous Toxicants -6 categories -flavonoids -goitrogens -coumarins -cyanide compounds -herbal extracts -mushroom toxicants -Flavonoids in Fruit and Veg -important to flavor and color of food - 7 groups of flavonoids (flavones, flavonols, flavononols, flavones, leucoanthocyanins, anthocyanins, catechins) -some have antioxidant activity -not considered harmful by most but instead recognized for their benefits to health as anticancer agents, and more recently, as nutraceutical substances. Benefits due to antioxidant effect. -however, some such as quercetin, can cause mutations in mouse tissue culture cells. ( IT IS TOXIC IN ANIMALS, NOT HUMANS) -Giotrogens in Cruciferous Vegetables -cruciferous vegetables (broccoli, cauliflower, brussel sprouts) contain some compounds that are bad for health. -goitrogens are responsible for the development of goiter in humans -goiter is a condition caused by enlargement and atrophy of the thyroid gland -Coumarins in Citrus -primarily found in the peel of citrus fruit -dermatitis - inflammatory irritation of the skin, can occur in some ppl -Cyanide Compounds -plants can contain cyanogenic glycosides that when ingested become HCN, a powerful toxicant -cyanide containing compounds inhibit respiration of body cells -found in seeds of peaches, cherries, plums, almonds, apples, pears, apricots and cassava -herbal extracts -considered to be superior than synthetic meds by some , but WRONG -pyrrolizidine alkaloids are toxic compounds found in comfrey -inhibit enzyme cholinestrase which serves to break down acetylcholine -results in overstimulation of nerve cells -other effects : stomach pain, nausea, vomiting,, rapid respiration, etc -chamomile -if used over time = diarrhea, seizures Chapter 12: Food Toxicology -sassafras root contains safrole = a known carcinogen -ros
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