The arbelos An arbelos is the region enclosed by three mutually tangent semicircles; it is the region inside the larger semicircle and outside the two smaller semicircles (see figure). a. Given an arbelos in which the diameter of the largest circle is 1, what positions of point B maximize the area of the arbelos? b. Show that the area of the arbelos is the area of a circle whose diameter is the distance BD in the figure.
Food Safety and Food T echnology Microbes and Food Safety • On average, each day: – 200,000 people in US get ill with food-borne illness – Of those, 14 die from the illness… • 80% of food-borne illness is caused by error in a commercial setting!!! – Improper handling – Uncooked foods © 2006 Thomson-Wadsworth Food-borne Illness • Dependent on does and susceptibility of individual • At-risk groups: – Pregnant women – Children – Elderly – Those with a weakened immunity Types of Hazards Causing Foodborne Illness • Biological: bacteria, viruses, things we cannot see • Chemical: pesticides, cleaning products • Physical: finger nails, h,ir Band-Aids, gloves, bugs, Something that isn’t suppose to be there • Microbial foodborne illness • Commonly called food poisoning • Transmitted to human beings through food and water • Caused by an infectious agent (foodborne infection) or a poisonous substance (food intoxication) Microbes and Food Safety • If digestive tract disturbances are the only major symptom of your next bout of “stomach flu” chances are excellent that what you really have is a foodborne illness Microbes and Food Safety • Get medical help if these symptoms occur –Bloody stools –Diarrhea 3+ days –Fever 24 hours + –Headache with muscle stiffness –Muscle weakness, tingling sensations in the skin –Rapid heart rate, fainting, dizziness © 2006 Thomson-Wadsworth How Do Microbes in Food Cause Illness in the Body • Infection –Infectious agents infect and multiply in the tissues of the body • Intoxication –Some microorganisms in foods produce –Bacteria makes toxin that makes you sick • Enterotoxins – Poisons that upon mucous membranes • Neurotoxins – Poisons that act upon the cells of the nervous systems © 2006 Thomson-Wadsworth Which foods are most likely to make people sick • Meats and poultry – Cook thoroughly (use thermometer) – Ground meats more susceptible to contamination Eggs Eat only cooked eggs Seafood – Only safe when completely cooked © 2006 Thomson-Wadsworth Which foods are most likely to make people sick • Fruit and Vegetables – Wash thoroughly Picnics and Lunch Bags Keep cold with cold packs Honey – May contain dormant microbes – **Don’t give to children less than 2 years old © 2006 Thomson-Wadsworth © 2006 Thomson-Wadsworth Which Foods Are Most Likely to Make People Sick • Dangers posed by seafood have grown in recent years –As population density increases offshore waters are becoming more pollutes Bioaccumulation of Toxins in the Food Chain © 2006 Thomson-Wadsworth Food Safety from Farm to T able • Careful food handling is required to prevent microbes from becoming a problem Food Safety from Farm to T able • Majority of food-poisoning cases –Result of errors consumers make in handling foods after purchase –Commercially prepared food is usually safe Food Safety from Farm to T able • Protect yourself –Inspect the seals and wrappers –Reject open, leaking packages Food Safety in the Kitchen • Food can provide ideal conditions for bacteria to thrive or produce toxins –Disease-causing bacteria require • Warmth – 41 degrees F – 132 degrees F – Moisture • Nutrients © 2006 Thomson-Wadsworth Food Safety in the Kitchen • To defeat bacteria –Keep hot food hot –Keep cold food cold –Keep raw foods separate –Keep your hands and kitchen clean © 2006 Thomson-Wadsworth Food Safety in the Kitchen • Keep Hot Food Hot • After cooking, foods must be held at 135 degrees F or higher until served Food Safety in the Kitchen • Keep Cold Food Cold • Upon arrival home, load foods into refrigerator or freezer immediately • Applies to defrosting foods –Thaw meats or poultry in the refrigerator –Marinate meats in the refrigerator Food Safety in the Kitchen • You cannot rely on your senses of smell and sight alone to warn you Food Safety in the Kitchen • Keep Raw Foods Separate –Prevent cross-contamination of foods Food Safety in the Kitchen • Keep Your Hands and the Kitchen Clean –Requires • Using freshly washed utensils • Laundered towels • Washing your hands properly – Artificial nails, long nails, and chipped polish harbor more bacteria than do natural, clean, cut nails © 2006 Thomson-Wadsworth Food Safety in the Kitchen • If you are ill, or have open sores, stay away from food preparation PESTICIDES Do Pesticides on Foods Pose a Hazard to Consumers Chemicals used to control diseases, weeds, insects that hinder growth of produce or animals High risk for: elderly and children PESTICIDES Regulation of Pesticides How much is safe Regulated by EPA and RDA EPA: sets tolerance level FDA: monitors produce and livestock feed PESTICIDES • FDA collects and analyzes domestic and imported foods – 4 times/years FDA buys > 200 products from grocery stores and analyzes for: • Pesticide levels • Essential minerals • Industrial chemicals • Heavy metals • Radioactive materials © 2006 Thomson-Wadsworth © 2006 Thomson-Wadsworth Possible Pathways of Pesticide Residues to a Fast-Food Meal W ays to Reduce Pesticide Intake “Organic” Crops • Food cannot be: – Irradiated – Genetically engineered (hormone injections) – Fertilized with sewage sludge – Produced with synthetic chemicals © 2006 Thomson-Wadsworth USDA Seal and Organic Foods © 2006 Thomson-Wadsworth Food Additives • Functions – Prevent food-borne illness – Enhance nutrient quality –Preservatives: prevent spoilage – Improve appearance/taste Food Additives • Approved by FDA under following conditions: – Effective – Detectable in final food product – Safe • When fed in large doses to animals, no cancer, birth defects, or other injury © 2006 Thomson-Wadsworth Food Additives • Additives cannot by used: – To disguise faulty/inferior products – To deceive consumer – If significantly destroy nutrients © 2006 Thomson-Wadsworth Intentional Food Additives (on purpose) • Antimicrobial Agents: preserve flavor, color, and inhibit bacterial growth • Antioxidants prevent foods from undergoing changes in color/flavor due to oxygen exposure • Artificial colors only a few approved Most investigated of all additives • Artificial flavors/ flavor additives Largest group of additives © 2006 Thomson-Wadsworth Intentional Food Additives • Nutrient Additives • Grains: thiamin, riboflavin, niacin, folate, iron • Salt: iodine • Milk: vitamins A and D – Enrichment = To replace lost nutrients after processing – Fortification = Or add extra nutrients © 2006 Thomson-Wadsworth Incidental Food Additives (by accident) • Get into food during harvesting, production, processing, storage, or packaging – Microwave packaging: package components migrate into food at high temp – Dioxins: from bleached paper like coffee filters, paper, plates, milk cartons – Decaffeniated coffee: toxin (methylene chloride) is used to remove caffeine © 2006 Thomson-Wadsworth Incidental Food Additives Hormones: 12 are approved Bovine Growth Hormone (BGH) used in cows: leaner meat, more milk BGH is a peptide and digested by humans, therefore NO health risk Incidental Food Additives • Antibiotics (Ab) – Small amount of residues may remain – Consumers may suffer allergic reaction – Too much Ab in livestock may contribute to increased resistance of humans to Ab © 2006 Thomson-Wadsworth Food Biotechnology • Genetic Engineering – FDA assumes foods genetically engineered are similar to other “natural” foods – Nature selects plants that are most genetically fits and other die – Examples: • Tomatoes that ripen slowly when picked • Soybeans with a gene to make amino acid composition similar to milk (high quality protein) • Crops that produce their own natural pesticides © 2006 Thomson-Wadsworth The Precision of Genetic Engineering © 2006 Thomson-Wadsworth Natural Cross-Pollinating and Selective Breeding native corn colorful carrots © 2006 Thomson-Wadsworth Genetic Engineering Basics • These salmon are all of the same age and type. The largest one received a growth-enhancing gene, greatly accelerating its growth rate. Transgenic T omatoes