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113 Cards in this Set
- Front
- Back
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Sensory attributes of food
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Appearance(color, size, shape, gloss, transparency, absence of defects)
Taste Smell Texture, mouthfeel |
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Taste-5 basic tastes
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Sweet(sugars)
Sour(acids, such as citric acid) Bitter (Caffeine, quine) Salty (stable salt) Umami (MSG =monosodium glutamate) |
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Relative Sweetness
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Sucrose (table sugar) is the reference sugar
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Relative sweetness
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A measure of how sweet a specific substance is in relation to sucrose.
Sucrose 100; Fructose 120; Glucose 70; Lactose 40 |
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Umami
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Japanese for delicious taste
Is frequently described as "brothy" savory Umami taste is imparted by monosodium glutamate (MSG) and some other compounds. |
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Taste Perception
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Taste can be detected through the tongue.
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How many types of PAPILLAE on the tongue?
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4
Circumvallate Foliate Fungiform Filiform |
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What is PAPILLAE?
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Tiny projections that give the top surface of the tongue its rough, "bumpy" appearance.
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What are taste buds?
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Onion-shaped structures containing Taste cells.
Taste buds are located mainly on the tongue and soft palate. Taste different flavor: salts, sweet sugars, sour acids, savory amino acids, and bitter alkaloids. |
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Which kind of papillae is lack of taste buds?
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Filform.
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Taste sensation
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Elicited by stimulation of taste receptor cells.
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Smell sensation
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Elicited by stimulation of olfactory receptor cells.
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Flavor
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Is part taste, mostly smell.
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Taste or Gustation
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Detection of tastants
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Smell or Olfaction
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Detection of odorants
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Smell
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Ordorants or odor compounds are volatile, small molecules.
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Which two pathways do odor compounds reach the olfactory receptors?
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Orthonosal olfaction(sniffing through the nostrils).
Retronasal olfaction(while chewing and swallowing). |
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Anosmia
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Inability to smell.
It is estimated to affect 1 in 20 Americans. Fifty percent of adults over 60 years old have substantial smell loss. |
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Specific anosmia
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Inability to smell one specific compounds.
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Innate Taste Preferences
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Dislike bitter tastes(in nature, bitterness is a common warning of poisons )
Reject irritants Like sweetness |
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Other sensations
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Astringency, tingling
burning cooling |
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Different sensations
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Burning is caused by hot peppers, the stinging associated with the consumption of carbonated beverages, the cooling effect felt when eating a peppermint candy are sensations transmitted to the brain through the trigeminal nerve. The trigeminal nerve conveys information about touch, pain/irritation, and temperature from the face to the brain.
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Pungency
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Chemical irritation/pain
eg. perception of burn caused by capsaicin(chili peppers) Piperine(black pepper) Zingerone(ginger) Capsaicin: besides causing a burning type of irritation, it can provoke salivary flow, sweating and tearing. Capsaicin is also used in some pharmaceutical producers, as an external analgesic drug. o Two most popular spices of the world: chillis and black peppers o Pungency: Neither a taste nor smell, but a general feeling of irritation that verges on pain. o Caused by two groups of chemicals • The thiocyanates （small light, water repelling molecules, likely to escape from the food into the air in our mouth,） • The alkylamides (larger and heavier, less likely to escape) |
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Astringency(tactile sensation)
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Associated with the ability of some compounds to bind with portents in the saliva. Tannins present in some unripe fruits(such as banana, persimmon) bind to salivary proteins causing a dry, rough, pucker, tightening sensation in the mouth.
o Caused by a group of phenolic compounds consisting of 3 to 5 carbon rings(tannins). o The sensation of astringency is caused when tannins bond to proteins in our saliva. o Tannins cause the proteins to clump together and stick to particles and surfaces, increasing the friction between them. |
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Cooling sensation
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Peppermint, wintergreen etc.
Menthol provokes a cooling sensation (also a trigeminal stimulus); it stimulates receptors that register cold temperatures. Menthol is a common ingredient in chewing gum, candies, toothpaste, mouthwash, among other products. |
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What are probiotics
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Live organisms which when administered in adequate amounts confer a health benefit on the host. e.g.
Lactobacillus and Bifidobacterium. |
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Food fermentation
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One of the oldest methods of food preservation; applied to milk, meats, vegetables
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Robert Hooke and A. van Leeuwenhoek
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Observed microscopic organisms using a crude microscope. LATE 1600S
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Louis Pasteur
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Postulated that fermentation was a biological process. He discovered the role of microbes in alcoholic fermentation.
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Advantages of food fermentations
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Better keeping qualities than original raw ingredients
Desirable/ pleasing sensory qualities: taste, smell, texture, carbonation Increased food variety Products can be more nutritious(e.g. Vitamin B increases) decrease of toxic compounds(e.g.. cyanogens in cassava roots) |
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Baker's Yeast
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Saccharomyces cerevisiae
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Lactic Acid Bacteria (LAB):
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Such as Lactococcus thermophilus
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What are different shapes of bacteria?
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Bacillus(plural bacilli), rod shape
Coccus(plural cocci), spherical Spirillum Streptococcus Staphylococcus |
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What are most common molds found in cheese?
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Penicillium spp
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Food preservation methods are carried our by controlling which factors?
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water, PH, oxygen, nutrients, temperature.
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How does bacterial multiple?
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by binary fission
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Spoilage is affected by?
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Intrinsic factors: food PH, water, and other nutrients
Extrinsic factors: temperature, air/gas; presence of other bacteria. |
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Causes for food deterioration?
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Microbial spoilage,
chemical reactions(e.g., lipid oxidation) Enzymatic reactions (eg, enzymatic browning) Loss of water, germination, sprouting, etc. |
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How to prevent food deterioration?
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Adequate food processing and preservation
Appropriate packaging Appropriate food storage Food additives |
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What are food additives?
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Any substance added to food.
Most food additives are used to limit food spoilage. (preservatives). |
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Functions of food additives
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Antimicrobials: prevent spoilage from bacteria, molds, yeasts
Others: slow or prevent changes in color, flavor or texture Delay lipid oxidation (antioxidants) Maintain freshness |
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Foodborne illnesses
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Caused by consuming contaminated foods pr beverages. Each year roughly 1 out of 6 Americans get sick from food borne diseases,
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Outbreak of a food borne illness
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A cluster of 2 or more cases of an illness, caused by the same agent, linked to the same food. In the U.S., there are approx. 1000 reported outbreaks each year.
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Major cause of food borne illness in the U.S.
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Pathogenic microorganisms.
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Top 2 food borne disease-causing organisms are?
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Norovirus
Salmonella |
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Salmonella
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The leading cause of foodbonre bacterial illnesses in humans.
The infection it causes is called salmonellosis People develop fever, diarrhea, cramps. Salmonella live in the intestinal tract of animals, including birds. Usually, it is transmitted by eating foods contaminated with animal feces. We should avoid raw or undercooked eggs. |
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Norovirus
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Causes gastroenteritis, commonly referred to as stomach flu.
Viruses require a living host to survive; cannot grow outside of the body. Cannot grow in food. Norovirus spread primarily from person-to-person. |
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Foodborne Intoxications
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Staphylococcus aureus
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Staphylococcus aureus
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A common bacterium found on the skin and in the nose interior of 25-30% of healthy people. The bacterium can spread to food by direct contact, by skin fragments, or through respiratory droplets produced when people cough or sneeze.
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Enterotoxins(act on tissues of the gut). Toxins reproduced when contaminated food is left at room temperature for long period of time.
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Produced by S. aureus. Toxins reproduced when contaminated food is left at room temperature for long period of time.
S. aureus toxins cause illness; these toxins are not destroyed by cooking. |
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Major causes of food borne illnesses:
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Improper food handling
Improper cooking/ or reheating/cooling Food handling by infected employees Poor personal hygiene Cross contamination |
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Who is called the father of modern toxicology?
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Paracelsus
Be credit as saying that the dose makes the poison. The poison is the foundation of toxicology, |
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What is toxicology?
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The study of the adverse effects of chemical, physical, and biological agents on living organisms and ecosystems.
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Potential sources of toxicants in food
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Nutrients
Naturally occurring toxic compounds (in plants and animals) Contaminants (environmental chemicals,pesticides, animal drugs, such as hormone and antibiotic residues, etc.), Chemicals intentionally added to food Chemicals formed during food preparation or processing |
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Toxicity symptoms due to consumption of vitamin A in excess
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Birth defects, hair loss, skin disorders, bone pain, fractures.
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Prevention
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Limit high consumption of vitamin A rich foods (such as liver), avoid megadose vitamin supplements
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Methyl Mercury
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Methyl Mercury is an environmental contamination.
It is toxic to there nervous system. Fish absorb methyl mercury from the environment. |
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Which kind of fish can accumulate high levels of the toxicant?
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Predatory fish: Eg.Swordfish, king mackerel,
Canned white, or albacore. |
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For safety
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Assurance that food will not cause harm ro the consumer.
Food safety hazards can be of biological, physical or chemical nature. |
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Food defense
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Targets the intentional contamination of foods.
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Food Terrorism
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An act or threat of deliberate contamination of food for the purpose of causing injury or death to civilian populations and/or disruption of social, economic or political stability.
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What are some organic acids?
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citric, malic, tartaric, oralic
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Bitter taste:
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Eg. coffee, cocoa beans, which contain alkaloids
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What is MSG?
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• Monosodium glutamate is the sodium salt of the common amino acid glutamic acid.
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How is MSG made?
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MSG occurs naturally in many food, eg. Tomatoes and cheese.
• In 1908, a Japanese professor named Kikunae Ikeda was able to extract glutamate from seaweed broth and determined that glutamate provided the savory taste to the soup. |
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sucrose:
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take some time to detected on the tongue, and its sweetness lingers.
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Fructose
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Register quickly and strongly, but it also fades quickly.
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o Tannins
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• Plant kingdom’s chemical defenses
• Counteract bacteria & fungi (interfere surface, digestive enzymes and protein) • Found in immature fruit. |
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Vanilla
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o Vanilla is one of the most popular flavorings in the world. , second costly, after saffron
o True vanilla comes from the pod fruit, often called the bean, of a climbing orchid native to Central and northern South America. o There are about 100 species in the tropical. |
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Vanilla
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o Genus Vanilla. V. planifolia was first cultivated by the Totonac Indians along the eastern coast of Mexico near Veracrus, perhaps as long as 1000 years ago.
o They sent it north to the Aztecs, who flavored their chocolate drinks with it, o The first Europeans to taste vanilla were the Spanish.(sheath,husk) o 19 C Belgian botanist , Charles Morren, figured out how to pollinate vanilla flowers by hands. o Today, Indonesia and Madagascar are the world’s largest producer. |
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Vanilla’s rich flavor is the creation of three factors:
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• The pod’s wealth of phenolic defensive compounds, preeminently vanillin.
• A good supply of sugars and amino acids to generate browning-reaction flavors • The curing process. |
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The key to making good vanilla is
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deliberate damage to the pods, followed by a prolonged drying process that develops and concentrates the flavor, and prevents the pod from spoiling.
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How to make vanilla?
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o First step in curing is to kill the pod so that it doesn’t use up its sugars and amino acids, and to damage the pod’s cells and allow the phenolic storage compounds to migrate to the liberating proteins.---high temperature.
o Wrapped in cloth to “sweat” with the residual heat.—vanillin(the main flavor components of vanilla) are freed from their bondage to sugar molecules. o Strengthened and smoothed by hands, dried for several weeks, then aged or stored for some times to develop flavor further. |
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The flavor of vanilla
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o The cured pod is bout 20%water by weight, 20%fiber, 25%sugars, 15%fat, and the reminder amino acids, phenolic compounds, other flavors and brown pigments.
o Sugar-sweetness o Free amino acids-savoriness, fat richess, and tannins some astringency. |
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Kinds of vanilla
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o Bourbon vanilla from Madagascar and neighboring islands is the finest, with the richest, most balanced flavor.
o Indonesian beans seem lighter with less vanillin, and sometimes smoky quality. o Mexican beans contain about half the vanillin of Bourbon beans, and have distinctive fruity and winy aromas. o Rare Tahitian vanilla beans have much less vanillin than Bourbon beans, but carry unique flowery and perfumed notes. |
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Vanilla Extracts and Flavorings
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o Made by chopping whole vanilla beans and repeatedly passing a mixture of alcohol and water over them for several days, then aging extract to develop a more complex, full flavor.
o The higher the flavor content desired in the extract, the higher the proportion of alcohol necessary to carry it. |
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Cooking with Vanilla
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o Half of the vanilla flavoring consumed in the USA goes into ice cream.—soft drinks and chocolate
o The flavor of the whole vanilla bean residues in two different parts of the bean: the sticky, resinous material in which the tiny seeds are embedded, and the fibrous pod wall. |
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Mints
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o The true mints are mainly small natives of damp habitats in Europe and Aisa. Eg. Spearmint, peppermint
o Spearmint(distinctive aroma): L-carvone, pyridines, nitrogen-containing compounds o Pepper-mint(simpler and clearer): no carvone, no pyridines---terpene called menthol • Menthol actually binds to receptors on temperature-sensing nerve cells in the mouth, and causes those cells to signal the brain that they are cooler than they really are. • Peppermints usually are not cooked. |
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Scientists connect taste and temperature
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o Mint and menthol feel and taste cool and soothing.
o there are probably some separate receptors: some detect heat, some detect cold, and some of those also detect painful stimuli. o Menthol Receptor • what menthol is doing is mimicking a sensation of cold because in the end, or really upfront, they're doing the same thing. They're acting on the same detector, and thereby stimulating the same set of nerve cells that encode this response. o Pepper—Capsaicin |
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Fermentation and Pickling: Sauertkraut and Kimchi, Cucumber Pickles, Olives
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o Fermentation is one of the oldest and simplest means of preserving foods. Eg. Olives and sauerkraut
o Overlapping category: Pickle |
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The Nature of Fermentation
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o Based on the fact that plants are the natural home of certain benign microbes which in the right conditions will flourish and suppress the growth od other microns that cause spoilage and disease.
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Fermented Cabbage: Sauerkraut and Kimchi
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o European Sauerkraut is a refreshing side dish for rich meats
• Sour Cabbage-By fermenting finely shrebbed head cabbage with a small amount of salt at a cool temperature o Korean kimchi is a strong accompaniment to bland rice. • By fermenting intact stems and leaves of Chinese cabbage together with hot peppers and garlic and sometimes other vegetables, fruits and fish source. • Fermentation temperature is lower, and more salt is used. |
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Yeast
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o Louis Pasteur---leavening process
o The key is the gas-pro-ducing metabolism of a particular class od fungus the yeasts. o Sacchsromyces cerevisiae(brewer’s sugar fungus) |
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Yeast Metabolism
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o C6H12O6—2C2H5OH+2CO2
o Beer and wine: CO2 escapes from the fermenting liquid and alcohol accumulates. o Bread, CO2 and alcohol trapped in the dough, and both are expelled from the dough by the heat of baking. |
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Yeast and Alcoholic Fermentation
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o They can survive on little oxygen
o C6H12O6—2CH3CH2OH+2CO2+energy o Yeasts produce savory succinic acid, combine alcohols with acids to make fruity-smelling esters, produce sulfur compounds synthesize proteins and B vitamins. |
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Vinegar
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o Vinegar is alcohol’s fate, the natural sequel to an alcoholic fermentation.
o Bacterial that can use oxygen to metabolize alcohol and extract energy from it convert it into acetic acid, which is a far more potent antimicrobial agent than alcohol, and came to be one of the most effective preservatives od ancient and modern times. |
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Acetic acid contributes two different flavor or elements to foods:
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• Acidity on the tongue
• Its characteristic aroma in the nose. |
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Acetic acid exists in two forms:
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The intact molecule(volatile and can escape from the vinegar or food, travel through the air, and reach the nose)
• Broken into its main portion and a free hydrogen ion. |
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Acetic Acid
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o Higher boiling point than water—236F/118C
o Better solvent than water |
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The Acetic fermentation
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o Three ingredients: An alcoholic liquid, oxygen, and bacteria(use alcohol as an energy source).
o CH3CH2OH+O2-CH3COOH+H2O |
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Lactic Acid Bacteria
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o Bacteria specialize in digesting lactose, and they extract energy from lactose by breaking it down to lactic acid, Then they release the lactic acid into the milk, where it accumulates and retards the growth of most other microbes, including those that cause human disease.
o Make some antibacterial substances---puckery tartness o Two major groups of lactic acid bacteria: • Small genus Lactocossus , more widespread in nature (Plants) • Streptococcus, (animals) |
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Probiotics
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o Probiotics are live microorganisms that are wither the same as or similar to microorganisms found naturally in the human body and may be beneficial to health.
o Prebiotics: non digestible substances that stimulate the growth or activity of potentially beneficial microorganisms. |
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Danger Zone
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40-140F
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Discoloration: Enzymatic browning
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o Caused by three chemical ingredients:
• 1- and 2- ring phenolic compounds, certain plant enzymes, and oxygen. • In the intact fruit or vegetable, the phenolic compounds are kept in the storage vacuole, the enzymes in the surrounding cytoplasm. • When the cell structure is damaged and phenolics are mixed with enzymes and oxygen, the enzymes oxidize the phenolics, forming molecules that eventually react with each other and bond together into light-absorbing clusters. |
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Minimizing Brown Discoloration
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o Coat cut surface with lemon juice.
o Cjhilling the food below 40F o Immersing the cut piece in cold water o For lettuce: Immersing the freshly cut leaves in a pot of water at 115C(Destroy the enzyme) for three minute before chilling and bagging them(Reduce phenolic oxidation). o Sulfur compounds (applied in dried fruits) o Ascorbic acid or V c |
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Fat Saturation and Rancidity
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o Saturated fats are also more stable, slower to become rancid than unsaturated fats.
o Oxygen, water, metal |
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Meat and Food-Borne Infections
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o Bacterial Infection
• Two main causes—Salmonella and E. coli o Salmonella沙门氏菌 • Caused by recycling animals by products as feed for the next generation of animals, and by crowding the animals together in very close confinement. • Salmonella often have no obvious effect on the animal carriers, but in humans can cause diarrhea and chronic infection in other parts of the body. o Escherichia Coli大肠杆菌 • A collective name for many related strains of bacteria that are normal residents of the intestines of warm-blooded animals, including humans. • The most dangerous one is called O157-H7 that causes bloody diarrhea 腹泻， and sometimes kidney failure.(cattle) • • Norovirus -the stomach bug o Cause gastroenteritis -diarrhea, vomiting and stomach pain. o 5 tips to prevent Norovirus From Spreading • Practice proper Hand Hygiene • Wash fruits and vegetables and cook seafood thoroughly • When you are sick, do not prepare food or care for others. • Clean and disinfect contaminated surfaces • |
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What is mercury?
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• Mercury is a natural element found in rocks, coal, and soil.
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Source od mercury?
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o Sources: soil and rocks decay; volcanoes erupt; human activities
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Which fish have the most mercury?
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o Mercury is found in most freshwater and saltwater fish
o Larger, older fish tend to have more mercury than younger fish, o Fish that eat other fish have the most mercury.(ocean: sharks and swordfish; Lakes and rivers: bass) o What are the health effects of eating high-mercury fish? • Damage the brain while it is growing. • Pregnant mothers’ unborn babies and children are most sensitice. |
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Alkaloids
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eg. potato accumulates potentially troublesome alkaloid levels, which make greened potatoes and potato sprouts bitter and toxic.
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Cyanogens
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Cyanogens are molecules that warn and poison animals with bitter hydrogen cyanide, a deadly poison of the enzymes that animals use to generate energy.
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Oxalates
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Oxalates are various salts of oxalic acid, a waste product of plant metabolism found in a number of foods, notably spinach, chard, beets, amaranth, and rhubarb.
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Cassava
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Bitter cassava has bitter cyanide, which is toxic to humans.
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Rhubarb
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Rhubarb leaves are said to be toxic in part dur to their high oxalate content.
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Three general kinds of hazardous materials that contaminate fish and shellfish:
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Industrial toxins, biological toxins, and disease-causing microbes and parasites.
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Which kind of fish accumulates most toxic substances?
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Long-lived and eat other creatures.
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Scientists have identified three families of chemicals created during meat preparation that damage DNA and cause cancers in laboratory animals, and that may increase our risk of developing cancer of the large intestine.
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Heterocyclic Amines;
Polycyclic Aromatic Hydrocarbons Nitrosamines |
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Heterocyclic Amines
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HCAs are formed at high temperatures by the reaction of minor meat components with amino acids.
It is generally greatest at the meat surface where the temperature is highest and the meat juices collect, and on meats that are grilled, broiled or fried well done. Acid marinades and vegetables, fruits cn reduce HCA production. |
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Polycyclic Aromatic Hydrocarbons
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PAHs are created when nearly any organic material, including wood and fat, is heated to the point that it begins to burn.
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Nitrosamines
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Nitrosamines are formed when nitrogen-containing groups on amino acids and related compounds combine with nitrite, a chemical that has been used for millennia in salt-cured meats, and that suppresses the bacterium that causes botulism.
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Drawbacks of the browning reactions
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Nutritional value of the foods is slightly reduced because amino acids are altered or destroyed.
It can damage DNA and may cause caner. |
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Scombroid poisoning
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Caused by the toxins of histamine.
Symptoms: temporary headache, rash, itching, nausea, and diarrhea. |
