7

Question 1

Unit of heat - food

Answer 1

1 calorie = amount of heat required to increase the temperature of 1 gram of H2O by 1c. 1J = 0,239cal (1cal = 4,184J)
Calorie = kcal because calories are too small

Question 2

Method to assess energy content of food

Answer 2

Bomb calorimeter is not used to determine the energy content of certain foods because it doesn’t take into account digestibility (1g cellulose = 1g starch but not for humans). Method used: analytical chemistry to determine the amounts of each of the macronutrients in a food sample and multiply by corresponding standard value. Organic acids 3. Polyols 2,4. fiber 2 because of microorganisms.

Question 3

Energy content of fats

Answer 3

Much higher number of carbon and oxygen atoms because they are compact and hydrophobic.

Question 4

Low caloric foods are

Answer 4

Made of alternative sweetener or (carbohydrate of protein-based) fat-replacers.

Question 5

Sugar alcohols

Answer 5

Sugar alcohols: Xylitol, sorbitol, mannitol, maltitol, etc. Nutritive sweeteners because they contribute (1,5-3kcal). Not metabolized the same way, but share lots of functional properties with sugars (i.e: bind water by hbonds to have moisture).

Question 6

Non-nutritive sweeteners (not metabolized or too small quantities)

Answer 6

Non nutritive sweeteners: no calorie but no functional properties.
Acesulfame K= 200x sweeter than sucrose, bitter aftertaste so combined with other sweetenerss
Aspartame: phenylalanine + aspartic acid (methyl ester of dipeptide). Same caloric content as proteins but used in such tiny amount that no calorie. 200x sweeter than sucrose. PKU patients should not consume it.
Neotame: similar to aspartame but peptide bond cannot be hydrolyzed so phenylalanine is not produced. 7000x-13000x sweeter.
Sucralose: sucrose molecule with 3 hydroxyl groups replaced by Cl- (chlorine). 600x sweeter. Not metabolized

Question 7

Simplesse

Answer 7

Low-calorie fat replacer. Made of microparticulated milk and/or egg-white proteins. Microparticulation provides the same mouthfeel of fat with less than half the calories. Not suitable to frying du to thermal denaturation of proteins.

Question 8

Olestra

Answer 8

Low-caloric fat replacer. Sucrose molecule in which 6-8 OH groups are esterified with fatty acids. Same properties as fat, heat-stable and indigestible (0calories). Approved in 1996 for fried snack foods. Causes unpleasant side effects tho.

Question 9

Carbohydrate-based fat replacers

Answer 9

Reduced calorie fat replacer. Indigestible polysaccharide, but sometimes contribute calories (starch gels). Used in salad dressings, ice cream, cheeses, margarines, dips, baked goods, chocolate.

Question 10

Special role of CHO

Answer 10

Sugars and starch assist the body in utilizing fats more efficiently by producing organic acids that are required to convert fats fully to CO2 and water (extract maximum energy from fat)

Question 11

Incomplete proteins sources are

Answer 11

Grains lack lysine, legumes lack methionine. Protein digestibility and the effects of amino acid balance/imbalance are important factors so we do animal studies.

Question 12

Protein quality

Answer 12

Protein efficiency ration (PER): Measure of animal’s weight gain/gram of protein consumed. (egg>casein>beans>bread>gelatin)
Biological value (BV) measures overall nitrogen retention
Net protein utilization (NPU)= BV x digestibility factor
Net protein value (NPV) = NPU x % protein in food
Protein digestibility corrected amino acid score (PDCAAS): amino acid profile from 0 to 1 (1 = provides 100% or more of all essential amino acid, after digestion!)Crude protein digestibility
Digestible indispensable amino acid score (DIAAS): At the end of small intestine, proposed in 2013 to replace PDCAAS

Question 13

Vit A

Answer 13

Retinol, Retinal and retinoic acid. Found only in animal-derived products but B-carotene is found in plants and is a precursor (pro-vitamin A, but not a vitamin itself).
Retinol: Strengthens mucous membranes, keeps skin flexible
Retinal: Plays fundamental role in vision
Retinoic acid: gene expression, protein production in cell nucleus.
No toxicity for b-carotene but vit A yes. Milk in Canada is supplemented with vit A.

Question 14

Vit D

Answer 14

Synthesized from vit D upon exposure to sunlight (UV-B). Essential for absorption of Ca/P from kidneys. Deficiency = rickets (bone deformities). Milk in Canada is supplemented with vit D. From UV radiation of ergosterol produced by yeasts. Fish, liver, dairy products, eggs.

Question 15

Vit E

Answer 15

A-tocopherol. Membrane stability + antioxidant. Present in most unprocessed vegetable oils but may be lost with processing.

Question 16

Vit K

Answer 16

Blood clotting. Spinach/cabbage. Synthesized by microorganisms in the intestinal tract.

Question 17

Vit C

Answer 17

L-ascorbic acid. Scurvy: anemia, tooth loss, gum generation, hemorrhaging in the skin, mucous membrane and death. Easily oxidized but only active in its reduced form so must be protected. 75-90mg/day RDA. L and D ascorbic are food additives employed as antioxidants. Cheaper but 20x less vitamin activity

Question 18

B vitamin (Complex)

Answer 18

Enzyme cofactors. RDA vary from mg to um.
B1: thiamin. Animal and grains. Beriberi leads to muscle atrophy and death. Destroyed by reaction with sulfite so forbidden as food additives of sulfite to meat (good source of thiamin).
B2: Riboflavin. Animal, leafy vegetable and yeast. Yellow/green color to whey. Heat resistant but light sensitive.
B12:Cobalamine. Cobalt + poryphrin ring. Animal. RDA 3ug/day.
B3niacin, B5pantothenic acid, B6 pyridoxine, B7 biotin (Vit H), B9folate, Choline

Question 19

Trace amounts

Answer 19

Selenium and cobalt are required in trace amounts but toxic at higher levels.
Lead and arsenic are just toxic.
Enzyme cofactor: Mg
Digestion/Metabolism of proteins: Zn

Question 20

Absorption of iron

Answer 20

1-10% of iron is absorbed. Depends on chemical form.

Question 21

Stability of vitamins and minerals

Answer 21

K= oxidation stable
Thiamine (B1) = light stable
Riboflavin (B2) = oxidation stable
Minerals = light stable
EAA = both light and oxidation stable

Question 22

ANFs

Answer 22

Phytate : Inositol hexaphosphate. Strong chelator of cations. 6P groups that bind Ca, Fe, P to reduce bioavailable. Genetic modification can help. In grains and legumes.
trypsin inhibitor: Heat denatures it. In soybeans

Question 23

Nutrition content of food

Answer 23

Protein: Determination of nitrogen content (conversion factor to turn it into Protein content 6,25) = Kjeldahl
Moisture: Weight difference before and after drying = vacuum oven
Fat: Ether extraction = Soxhlet
Ash (inorganic): Combustion = ashing
Carbohydrate (with fiber): 100 - (P+M+F+A)

Question 24

Causes of unsafe foods

Answer 24

1. Pathogenic organism: Microorganisms (virus, bacteria, molds, protozoa) and parasitic nematodes (trichina worm)
2. Natural toxin: poisonous mushrooms, cyanogenic glucosides in cassava.
3. Extraneous matter: stones, glass, seeds, bones
4. Environmental contaminants: pesticides, heavy metals in fish
5. Harmful additives
6. Allergens: proteins, only certain individuals at risk

Question 25

Causes of pathogenic organisms

Answer 25

Globalization of trade, food distribution, new foodborne pathogens, Ecoli 0157: H7

Question 26

Consequences of food poisoning

Answer 26

> 75 millions in USA, 30%. 5000 deaths.
20-45billions/year.
Food loss/waste

Question 27

Contamination

Answer 27

Milk is sterile but not for long.
Bruising of Fandv are entry points
Bacteria reproduce by binary fission = double every 20-30

Question 28

Microbiological analysis

Answer 28

Detection, enumeration and identification. Standard plate count is used to count (total microbial load). Standards that set an upper limit on total microbial load. Standard for Grade A raw milk prior to pasteurization 100,000 per ml.

Question 29

Identification of microorganisms is difficult

Answer 29

> 80% food poisoning cases are unidentified

Question 30

Bacteria

Answer 30

Unicellular, spherical rod-like or spiral. 1-4microns (um). Some species form spores, which form back as vegetative cells as environment gets better.
Thermophilic: >45-82
Mesophilic: 20-45
Psychrophilic: <10
Psychrotrophic <4

Question 31

Yeast

Answer 31

20microns (um). Spherical or ellipsoidal. Alcoholic fermentation and leavening of dough (CO2 production)

Question 32

Molds

Answer 32

Largest. Grow in multicellular filaments called hyphae. Spoilage and cheese production. More resistant to low moisture environments than bacteria and yeasts.

Question 33

2 types of foodborne illness

Answer 33

Infection: organism establishes itself in the intestines
Intoxication: toxin produced by microorganism causes the illness

Question 34

Microbial taxonomy

Answer 34

Genus: capital letter and can be abbreviated
Species: low case letter
Other stuff refers to a subspecies or a serotype

Question 35

Food infections

Answer 35

Salmonellosis. 1million/year. 380 deaths (#1). Poultry
Listeriosis: listeria moncoytogenes, refrigerator disease because psychrotrophic. (#3). Raw-milk cheeses and ready to eat meats. Maple Leaf scandals
Campylobacteriosis: C.jejuni. #1world. Usually not serious but can have long term consequence in some individuals = 40% of guillain barré syndrome are triggered by campylobacter.Poultry.

Question 36

Food intoxications

Answer 36

Clostridium botulinum. Rare but lethal. Obligate anaerobe. Low acid foods. Incapable of germinating below 4,6.
Staphylococcal enterotoxins: food handlers. Toxins are not destroyed by cooking. Only act on intestines so not that serious.
Mycotoxins: produced by molds. Ex: Aspergillus flavus in grains, cereals and peanuts produce aflatoxin (hepatotoxins) = liver failure and death in animals but not humans (liver carcinogens in humans).

Question 37

Combined food infection and food intoxication

Answer 37

E.coli O157:H7. Enterohemorrhagic toxin producing strain. Shiga toxin producing Ecoli (STEC) colonize intestinal tract: cause enteric infection and produce toxin that cause lysis of RBCs. 5-10% of people with STEC develop hemolytic uremic syndrome that lead to kidney failure/damage and death. 90 deaths/year USA. Unpasteurized milk, raw-milk cheeses, raw meat and other raw foods.

Question 38

Viruses

Answer 38

More difficult to detect. Noroviruses (like Norwalk virus). 50% of foodborne illness but not serious. Easily transmissible. Hepatitis A and polio through food, water.

Question 39

Protozoans foodborne illnesses

Answer 39

Toxoplasmosis (toxoplasma gondii): 2nd leading cause of death (after salmonellosis and before listeriosis). Unicellular eukaryote as cyst, egg or cell. Transmitted in food and water as cyst in warm blooded animals. Cats have a special role of host. Undercooked meat. Patients don’t know they have it. Serious disease for weakened immune system and infants.
Amoebic dysentery caused by entamoeba histolytica

Question 40

Macro-biological parasites

Answer 40

Trichinosis nematodes. Undercooked meat. Larvae (<3mm) in the intestines and end up in bloodstream. Caused by low quality feed of pork so only a few cases in USA.
Anisakis: Anisakiasis in marine foods (raw saltwater fish and raw shellfish and can cause severe intestinal symptoms. Freezing is good. Blast frozen to -35C for 15hours or -20C for 7 days. <10 cases/year USA. Can trigger allergic response in some individuals.

Question 41

Novel and weird preservation methods

Answer 41

Ohmic heating, microwave processing, high pressure processing.
Food additives: Sodium benzoate
Smoke: formaldehyde/pyrolysis
Controlled atmosphere storage (CAS) and MAP replace air by N2 and CO2.