unit12.3web.ppt
- 2. A food additive is anything intentionally added to a food to produce a specific, beneficial result. In Canada there are almost 3000 compounds(~ 1500 of these are 'flavours') deliberately added to foods*. There are approximately the same number in other developed countries but not always the same compounds. Many have multiple uses. *another ~5000 are accidentally added during growing, harvesting and packaging
- 3. Since ~1960 all new food additives must undergo safety testing, however additives that were used prior to this date are 'grandfathered' unless new safety issues are discovered. The GRAS list is a list of food additives that are generally recognized as safe by a panel of experts, but that have not been subjected to laboratory testing.
- 4. Added to foods to: Make more appealing - flavours (& enhancers), colours, acidity Make more nutritious - vitamins, minerals Preserve freshness/keep unspoiled - preservatives, antioxidants(sequestrants) Make easier to process - anticaking agents, humectants Keep stable during storage - stabilizers, thickeners, emulsifiers Categories of Food Additives
- 5. Food Preservation Oxidation and microorganisms (bacteria, fungi, other) are the major causes of the decomposition of food. Drying (grain, fruit, meat/fish) is one of the oldest preservation techniques, since water is necessary for both the growth of micro- organisms and oxidation reactions. Salting (meat/fish) and preserving in concentrated sugar solution(fruit) also dehydrates(-H2O). Other methods include: Pasteurization(heat to ~140oF)), Smoking, Canning(remove O2), (vacuum) Freezing(slow oxidation), Irradiation.
- 6. Preservation is effective if it prevents multiplication of microorganisms during the shelf life of the product. Sterilization( heat, radiation) or inactivation by freezing are two common 'physical' techniques. Two of the most common chemical preservatives in packaged foods are: sodium benzoate - fruit juices, margarine, pickles, nonalcoholic beverages, olives, salads, pie fillings, jams & jellies sodium propionate - bread, chocolate products, cheese, pie crust and fillings.
- 7. Chemical Preservatives Chemical preservatives are usually derivatives of acids that kill the microorganisms by increasing slightly the acidity of the food. They can be: Organic: Benzoates; Propionates; Sorbates : antimicrobial agents-act vs. mould etc. Inorganic: Sulfites (SO2 2-); Nitrites/Nitrates(NO2 -/ NO3 -) for botulism
- 8. The nitrite dilemma (risk balancing) • Sodium nitrite (NaNO2) : prevents growth of the Botulinum toxin in meat (botulus L sausage) and improperly canned fruits/vegs • But it may also produce nitrosoamines (potentially carcinogenic) in humans • Pick your poison!
- 9. Antioxidants The action of oxygen in the air is the chief cause of the destruction of the fats in food. Oxidation produces a complex mixture of volatile aldehydes, ketones and acids that cause the rancid odor/taste. Antioxidants can be: Organic - Ascorbates Butylated hydroxyanisole (BHA) Butylated hydroxytoluence (BHT) Lecithin (a 'natural' phospholipid) Inorganic - Sulfur Dioxide and Sulfites
- 10. OH OCH3 OH CH3 Common Synthetic Antioxidants (like Vit. E) BHT(Butylated Hydroxy Toluene BHA (Butylated Hydroxy Anisole)
- 11. Sequestrants Metals get into food from the soil and from the machinery of harvesting and processing. Copper, iron and nickel catalyze the oxidation of fats. Sequestrants are able to bond with a metal ion so firmly that it removes the metal from any chemical reaction with other substances. They have multiple 'arms'/functional groups to 'envelope' (or chelate) the metal atoms. Common sequestrants are: EDTA(ethylenediaminetetraacetic acid), Citric acid, Pyrophosphate, Sorbitol
- 12. EDTA structure • 4 arms!
- 13. pH Control in Foods Weak organic acids when added to such foods as cheese, beverages and dressings give a mild acidic taste. They often mask undesirable aftertastes. Weak acids react with bicarbonate to form CO2 in the baking process. Acid and buffer examples: acetic acid, citric acid, phosphoric acid( & salts), lactic acid(& Ca salt), potassium acid tartrate These versatile acidulants also function as anti- microbial agents, antioxidants(to prevent rancidity and browning)and viscosity modifiers in dough.
- 14. Stabilizers/Thickeners/Emulsifiers Stabilizers and thickeners(to improve the texture and blends of foods) are usually polysaccharides. The hydroxyl groups, using H-bonds, provide a more even blend of the water and oils in the food. Stabilizers and thickeners are particularly effective in icing, frozen desserts, whipped cream, confections and cheeses. Eg. agar, algins, carrageenan. “Phycocolloids” Emulsifying Agents (detergent-like) keep oil/water mixtures, ie. peanut butter, salad dressing, from separating. They are mono - and diglycerides of fatty acids.
- 15. Phycocolloids • Carrageenan, agar, alginates • All come from red and brown algae • Polysaccharides (lots of H bonds) • Help blend water and oil
- 16. Monoglyceride • Hydrophobic and hydrophilic parts-good emulsifier
- 18. Anticaking Agents / Humectants Anticaking agents react readily with water. They are added, (1% or less), to hygroscopic foods, eg. table salt, which absorb water from the air. This prevents 'caking' of such foods in humid weather. Anticaking Agents: Silicates, Silicon Dioxide, Iron ammonium citrate (Table salt has NaCl, KI and SiO2) Humectants do the opposite, ie. keep foods “moist”, by 'interfacing' with both the food & water, eg. glycerine(shredded coconut), glycerine monostearate(marshmellows)
- 19. Presence of one additive leads to another! • Table salt: 4 ingredients: NaCl, KI, SiO2 and sodium thiosulfate • Sodium thiosulfate is present to stabilize the iodide-ie keep salt from discoloring if salt gets wet!
- 20. Food Flavours Much of the sensation of taste in food is from our sense of smell. Natural 'flavours, like coffee or apple juice, are determined largely by mixtures of 100's of small, volatile compounds. Most flavor additives and perfume ingredients originally came from plants. Today synthetic preparations of the same flavors are common food additives. Some examples: iso(banana)pentyl(pear) ethanoate, iso(strawberry) butyl(raspberry)ethanoate, methyl butanoate (pineapple), ethyl formate/butyl propanoate(rum) Ethylbutyrate: Oranges –in flavor packs (processed OJ: CBC 2009)
- 21. O O NH2 CH3 O O OH CH3 O H OH O O H CH2 CH3 O CH CH2 CH CH O H O H CH3O H O C H2 CH CH2 S S CH2 CH CH2 Some Natural Flavours grape wintergreen almond cloves peppermint garlic cinnamon vanilla
- 22. Flavour Enhancers Compounds that have little/no flavour themselves but that amplify/enhance the flavours of other compounds, or can cover unwanted flavours. First used in meat/fish but now present in vegetables, baked goods, fruits, beverages. Some examples: Monosodium glutamate - the MSG of Chinese restaurants (also present in Parmesan cheese!) 5'-Nucleotides (for meat, salt)
- 23. Artificial Sweeteners: Why? • Weight reduction • Dental health • More variety in food for diabetics • But…….recent study………….
- 24. Feb 11/08 Study on Rats • Those fed artificially sweetened yogurt gained more weight than those on yogurt with sugar!! • Seemed to be an appetite stimulating effect of saccharin! • Q: is the obesity epidemic related?
- 25. How Sweet It Is! Artificial Sweeteners Compound Index Sorbitol 0.6 Glucose 0.7 Xylitol 0.8 Sucrose 1.0 Fructose 1.7 Cyclamate 30 Aspartame 160 Acesulfame 200 Saccharin 500 Sucralose 600 Alitame 2000 P-4000 4000 World-wide the artificial sweetener market is $1 billion(US). Aspartame had ~75% of that (2004) Nutrasweet/Equal = aspartame Splenda = sucralose
- 26. The Saga of Sweeteners in NA Saccharin(1879) was first banned in ~1905 but reinstated during World War 1. Cyclamate(1937) when combined with saccharin leaves no bitter aftertaste. Animal studies in Canada & US in 60s & 70s implicated both as cancer causing. Cyclamates were banned in US (not Canada or 40 other countries) in 1969 but when FDA tried to ban saccharin the public forced US Congress to allow it, with warning labels. Aspartame approved in early '80s, acesulfame in '96, sucralose in '98 in US (Canada always ~2 years later). The 'sugar alcohols' sorbitol & xylitol are not broken down in the mouth, thus used for chewing gum.
- 27. SO2 N O Na + - N H SO3 Na + - CH2 C H N H C H H3N CH2 COO O O OMe + - O S N O C H3 O O K + - O O O OH O H CH2Cl Cl OH O H CH2OH ClCH2 CH2OH CHOH CHOH CHOH CHOH CH2OH CH2 OH CHOH CHOH CHOH CH2OH Artificial Sweetners cyclamate aspartame saccharin sorbitol xylitol acesulfame sucralose
- 28. Aspartame • The most widely researched food additive ever! • Cannot be used in cooked or baked foods: breaks down and thus loses its sweetening power • one controversy concerns MeOH metabolic product (but apple juices have 2x)
- 29. Other issues with Aspartame • Aspartic acid (humans biosynthesize it) • Phenylalanine (an essential a.a.) • Some children (1/20,000) cannot metabolize phenylalanine • Phenylketonurea (Folling’s disease) results
- 30. PKU (Phenylketonurea) • Symptoms in infants: lethargy, poor feeding “mousy” urine odour • Enzyme is lacking for phenylalanine metabolism; thus accumulates in blood • Can lead to mental retardation • Also low tyrosine levels: use tyrosine supp’s
- 31. Sweetener Wars (2007) • Companies duke it out over Splenda ads! • “unfair advantage in advertising” to Splenda • “Splenda is made from sugar, so it tastes like sugar” –ad misleads customers into thinking that it is more “natural” than Aspartame
- 32. Synthesis of Sucralose • Sucrose >>>>> 5 step synthesis gives trichlorosucrose • Metabolism: controversial!! • Partially broken down (20%) : remainder is excreted unchanged • Questions: are the chlorofructose metabolic products harmful?
- 33. Advantage to sucralose! • Can withstand the high temps used in cooking and baking! • Market share is increasing (2008)
- 34. Decision • Court ruled no unfair advantage to sucralose makers • No damages awarded to makers of aspartame
- 35. Sorbitol in your chewing gum • Sorbitol ~same sweetness index as sucrose • Not metabolized • Stimulates colonic movement • Pro-anorexia websites tout it as weight-loss aid • 20 sticks of sugar free gum/day. 25% loss/yr • But..severe abdominal pain, diarrhea
- 37. OCH2CH2CH3 NH2 NO2 OCH2CH2CH3 NO2 NH2 OCH2CH2CH3 NO2 NO2 CH2 HOOC C H NH2 O N H CH CH3 O N H S Sweetners of the Future? P-4000 (extremely sweet) Cmpd I (tasteless) Cmpd. II (bitter) Alitame
- 38. Q: What makes a molecule taste sweet? • Huge research area (BIG$$) • Molecule needs both a H bond donor and an acceptor • Molecule must have a hydrophobic (water repelling) part • “handedness” may be important: (L!) • X-ray crystal structures of aspartyl based sweeteners compared
- 39. Looking at Compd II • Has only H bond acceptors! • Bitter taste • Position is imp (Compd I vs. P-4000) • Alitame and P-4000 look promising!
- 40. Food Colouring It's Everywhere! Natural: -carotene, beet juice, saffron, paprika Synthetic: Inorganic - titanium dioxide(white frosting), iron oxide(egg shells, food colouring) Organic - tartrazine (yellow#5; corn, cheese, pasta) erythrosine (red#3; cherry pie, ice cream) amaranth(red#2; candy, jello, orangeskins) allura red (red#40; cereals, " ", puddings) sunset yellow (yellow#6; soft drinks) indigotine (blue#2; soft drinks, 'koolaid')
- 41. O H N N SO3Na N N NH2 NaO3S N N O H SO3Na SO3 Na NH2 N N C H3 Orange #1 Yellow #3 Red # 2 Yellow # 4 Synthetic Food Colours – recently banned in USA
- 42. Why do you think these were banned? • Look at the nature of the structures (planar)? • DNA Intercalators?
- 43. Vitamins & Minerals - Nutritional Additives Some of the essential micronutrients are added, by law, to 'basic' foods to enrich / fortify our diet as a public health / preventative measure. Vitamins: vit. D / vit. A(milk), carotene (margarine), B-complex, ie. B1, B2, B3, sometimes B6, B9(flour). Minerals: calcium(milk), iodine ('iodized' salt). Others are added for various reasons, eg. labeling regulations (mandatory / voluntary).
- 44. Some possible definitions - A junk food is a food that supplies a large number of calories but few micronutrients. That means - Empty calories are contained in foods, such as highly refined sugar, that provide many calories but few or no micronutrients to accompany them. => => Good Food ? Bad Food ?
- 45. The larger the variety and amount of micronutrients provided by a food and the fewer calories, the more healthful it is. A healthy food supplies a large number of micronutrients compared with its calories. (ie. green vegetables: spinach)
- 46. Yum, Yum – Breakfast ! Scrambled Eggs: ovalbumin, ovomucoid, mucin, amino acids, globulins, lipovitellin, cholesterol, lecithin, lutein, triglycerides, fatty acids, butyric acid, acetic acid, sodium chloride, zeaxanthin, vitamin A, B, E, Ham(sugar-cured): actomycin, myosin(muscle proteins), nucleoproteins, peptides, amino acids, myoglobin, lipids, fatty acids, lecithin, sucrose, ATP, glucose, collagen, elastin, creatine, sodium chloride, sodium nitrate/ nitrite, sodium phosphate.
- 47. Lutein and zeaxanthin in eggs • Both are carotenes: provide colour to yolk and may “protect vision” • Zeaxanthin tablets are new “eye supplements” • Possibly protect vs. macular degeneration age related:light sensing cells in the central area of vision (macula) degrade and then die
- 48. Yum, Yum – Breakfast(cont’d) ! Toast/Coffee Cake: gluten(protein in wheat, barley, oats, amylose, amino acids, iron, methyl ethyl ketone, dextrins, starches, sucrose, thiamine, triglycerides, sodium chloride, riboflavin, phosphates, calcium, mono-/diglycerides, niacin, ethyl lactate, pantothenic acid, vitamin D, maltol, acetic/propionic/butyric/valeric/caproic acids, ethyl acetate. Coffee: caffeine, essential oils, methanol, acetaldehyde, methyl formate, ethanol, dimethyl sulfide, butanol, acetone, propionaldehyde, methyl acetate, (methyl)furan, isoprene, pentanol.
- 49. Our Daily Prayer ! To the editor of Times Union (Albany, New York): Give us this day our daily calcium propionate(spoilage retarder), sodium diacetate(mold inhibitor), calcium phosphate monobasic(dough conditioner), chloramine T (flour bleach), monoglyceride (emulsifier), potassium bromate(maturing agent), aluminum potassium sulfate (acid baking powder), sodium benzoate (preservative), butylated hydroxy anisole (antioxidant), mono-isopropyl citrate (sequestrant), plus synthetic vitamins A & D. Forgive us, O Lord, for calling this stuff BREAD! from J. H.Read
- 50. End of material covered on Friday June 12, 2009 Midterm!! (Azrielli Theatre (AT) 101) 5-7 PM