Midterm 2

Question 1

Why is barley the principal grain used in brewing

Answer 1

source of malted carbs, malts easily, good flavour, high in starch and low in beta glycogen

Question 2

What role do hops play in beer

Answer 2

• gives bitter flavour
• essential oils, tannins (aid in precip)
• PRESERVATION

Question 3

What is the main difference in using grains as a source of fermentable substrate compared to using fruits

Answer 3

grains have less sugar than fruits

Question 4

Explain the main function of each of the following steps in beermaking: malting, mashing, brewing, fermentation, pasteurization

Answer 4

Malting: pregermenation, beta amylase secretion will produce maltose during mashing (ROASTED)

Mashing: conversion of starch to fermentable sugars

Brewing: boiling to- inactivate enzymes, destroy microorganisms and sterile wort, hops extraction, give colour, denature

fermentation: ales: yeast cells trap CO2 therefore rise (top fermentation)
lagers: suspended yeast cells will sediment and therefore bottom fermentation
pasteurization: done in a bottle, maintain carbonation

Question 5

Explain the differences between a traditional ale and a traditional lager

Answer 5

ale: top fermentation, served at 10-8 C
lager: bottom fermentation, served at 0-10 C

Question 6

What are “adjuncts” and why would a brewer want to use them for beermaking

Answer 6

adjuncts: source of non malted carb (corn syrup)

- used to cut cost, also features such as better retention, flavours or nutritional value

Question 7

lipids vs triglycerides

Answer 7

lipids: very large group of compounds including triglycerides
triglycerides: largest group of lipids (glycerol and 3 FAs)

Question 8

fats vs oils

Answer 8

fats: solid at room temp, single bonds, saturated
oils: unsaturated, liquid at room temp and dbs

Question 9

short vs long chain FAs

Answer 9

short: 4-10 carbon chains
long: 16-18 carbons long

Question 10

saturated vs unsaturated

Answer 10

saturated: single bonds, solid at room temp
unsaturated: DB, liquid

Question 11

Cis vs Trans isomers

Answer 11

cis: unsaturated, found naturally, cause kink, harder for crystallize
trans: saturated, hydrogenation (converts oil to fat)

Question 12

n-3 vs. w-3 FAs

Answer 12

n-3: membrane structure (required in diet)

w-3: spy, canola, flax (lenolenic), fish oils- can be synthesized with sufficient linolenic acid

Question 13

n-3 vs n-6 vs n-9

Answer 13

n-3 and n-9: can’t synthesize DB in body

n-6: lenoleic acid (sunflower oil), develops brain tissue

Question 14

What does the designation “C18:3 n-3” tell you about the composition and structure of this fatty acid

Answer 14

has 3 DBs

• DB at 3rd carbon from methyl
• 18 carbons long

Question 15

Why are phospholipids and lipoproteins needed for fat transport within the body

Answer 15

because they are good emulsifiers

Question 16

role of bile in fat digestion

Answer 16

bile breaks down fat in stomach (emulsifies)

Question 17

How do the composition of an intestinal micelle and a chylomicron differ

Answer 17

micelles: formed by ingested food lipids with help of bile salts (digested fats)
chylomicron: formed by triglycerides, phospholipids, cholesterol and proteins

Question 18

Where do the components of chylomicrons and VLDLs originate

Answer 18

chylomicron: dietary fat
VLDLS: dietary proteins and carbs

Question 19

Relate the relative triglyceride, cholesterol and protein contents of a chylomicron, a VLDL, a LDL and a HDL to their roles in the body

Answer 19

chylomicron: have the highest content of triglycerides; function to transport dietary lipids from intestines to other locations of the body
VLDL: have one of the highest cholesterol levels because of their role to carry cholesterol and triglycerides out; triglycerides is 50%
LDL: triglycerides are low because most have been carried out; cholesterol highest because role to deliver cholesterol to cells
HDL: emulsifiers so lowest triglyceride level and highest protein level

Question 20

Why do people have their LDL and HDL measured?

Answer 20

LDL measured to measure cholesterol % in body

HDL measured to measure protein content in the body

Question 21

Why are these referred to as “good” cholesterol and “bad” cholesterol?

Answer 21

LDL is bad because it has the highest cholesterol; collects on walls of BVs
HDL is good because is removes harmful, bad cholesterol

Question 22

other biomarkers that correlate to CVD

Answer 22

smoking, diabetes; but most accurate are associated with lipids

Question 23

Distinguish between the functions of pancreatic lipase, lipoprotein lipase and hormone-sensitive lipase

Answer 23

pancreatic lipase: absorption of dietary fat
lipoprotein lipase: enzyme for more important triglyceride derived FAs by muscle for utilization and adipose tissue for storage
hormone sensitive lipase: mobilize stored fats

Question 24

How does atherosclerotic plaque develop and what effect can it have

Answer 24

develops from damage to endothelium caused by increased blood pressure, smoking or increased cholesterol; this damage leads to plaque formation and can lead to block of blood flow (ishcemia)

Question 25

Explain in lay terms (as if to your parent or roommate) what fats we should or should not be consuming.

Answer 25

we don't want to consume a significant about of saturated fats because they raise the cholesterol in our blood polyunsaturated fats can help reduce bad cholesterol levels in blood which can reduce risk of CVD

Question 26

Why are PUFAs considered a health benefit? Is there any reason why one might want to limit PUFA intake

Answer 26

health benefit because they lower risk for CVD by reducing bad cholesterol levels in the blood (PUFA long chain are high in HDL) but may want to limit intake bc excessive intakes of PUFAs may reduce HDL and promote oxidation of LDL, enhancing plaque formation

Question 27

Where do trans PUFAs come from and why are they considered a health risk

Answer 27

they increase risk for CVD because high in LDL and lowers HDL (double negative) -have more than one trans double bond (hydrogenation of polyunsaturated oils)

Question 28

What is the difference between a fat and an oil

Answer 28

the difference between a fat and an oil is MP; fats are solid and oils are liquid

Question 29

How does triglyceride composition affect melting point

Answer 29

MP depends on chain length; the higher the chain length, the higher the MP

Question 30

Describe the structure of an oil-in-water and a water-in-oil emulsion and give a few food examples of each

Answer 30

O/W- oil is dispersed and water is the dispersion medium (milk) W/O- water is dispersed with oil (margarine)

Question 31

How would you recognize oxidative rancidity of fats in a food product? Which fats are more prone to this problem

Answer 31

oxidative rancidity is evident by odours and bad flavours - polyunsaturated fats are least stable and most prone to rancidity - saturated fats are stable and resistant to rancidity

Question 32

What are the benefits of and concerns about hydrogenation? In food products, what are the alternatives to the use of hydrogenated fats

Answer 32

benefits: more stable, increases shelf life pf foods concerns: make them more saturated and therefor no health benefits, produces trans fats alternate: is to add chemical preventives that will compete for oxygen and therefore protect the oil (additives are antioxidants; they work by reacting)

Question 33

What are the major sources of food protein in the North American diet and how much protein should we eat

Answer 33

major source: peanuts, liver, hamburger, oats, cheese, beans, bread, milk we consume 150ish g/day adults should consume: 0.8 g of protein/kg of body weight/day 46g/day women 56g/day men

Question 34

What is the basic structure of an amino acid, and how do amino acids interact to form proteins

Answer 34

basic structure: amino group, carboxylic group and a central carbon with a reactive R group - AA acids interact by peptide bond formation through condensation reaction - fold by H bonds to form secondary structure and fold by reactive r groups to make 3D shape (tertiary)

Question 35

What is meant by primary, secondary, tertiary and quarternary structure of a protein

Answer 35

primary: individual sequence of AA bonded through peptide bonds secondary: AA chain could or folds to (held together by H bonds) tertiary: when secondary structure folds on itself caused by hydrophobic effect of R groups quaternary: clusters of proteins that interchain by interaction of tertiary structures

Question 36

Why does a protein take on an ordered higher structure

Answer 36

due to the intermolecular forces that cause it to coil or fold

Question 37

What is meant by protein denaturation and how does it affect nutritional properties and protein functionality

Answer 37

protein denaturation- the unfolding of a proteins tertiary or secondary structure which causes a loss of function due to extreme heat, pH, acid or base (becomes more saturated)

Question 38

What is an “essential” amino acid

Answer 38

must exist preformed in diet

Question 39

How do you determine if an essential amino acid in a food is “limiting”?

Answer 39

if its concentration in a food is lowest in relation to the AAs required for protein synthesis

Question 40

What is meant by a “limiting” amino acid

Answer 40

when a specific essential AA is limiting then protein synthesis slows down and is its all used up then synthesis stops

Question 41

If an amino acid in a food is limiting, is this significant? What is done about it?

Answer 41

it is significant bc if the shortage is chronic then the cells begin to break down their protein making machinery and the cells function less and less effectively even which essential AA is consumed again

Question 42

Describe the fate of essential and non-essential amino acids after absorption

Answer 42

used to build part of growing protein | altered to make another needed compound, such as the vitamin niacin (fuel)

Question 43

How do protein allergies develop

Answer 43

develop when mucosal cells are damaged through disease they may function poorly, and take in peptides; these absorbed proteins are often the cause pf allergies where the antibodies produced against these proteins cause anaphylaxis

Question 44

What is meant by the isoelectric point of a protein and of what relevance is it

Answer 44

pH at which charges are neutralized (most proteins at neutral pH are negatively charged due to side groups) Ip is significant in protein purification because it represents the pH where solubility is typically minimal

Question 45

Why does heating usually cause a protein solution to thicken

Answer 45

when heated they are denatured which gives them a viscous property

Question 46

Explain the role of proteins in stabilizing emulsions and foams

Answer 46

- they form a cohesive protein layer on the emulsion droplets. - stabilize air bubbles within foams

Question 47

How do the objectives of dry milling and wet milling differ

Answer 47

dry milling: produces a flour for bread and cake- breaks the seed and separates it into a number of pieces wet milling: produces grains and corn- separates based on chemical composition rather than anatomical composition

Question 48

What is the importance of protein in flour with respect to baking quality

Answer 48

the higher the extraction rate the more protein in the flour - soft flour for cakes has low protein bc low extraction rate hard flour for bread has high extraction rate and therefore high protein

Question 49

What is all-purpose flour

Answer 49

for both pastry and bread **it contains more hard flour than soft

Question 50

What is meant by extraction rate? What would be approximate extraction rates for cake/pastry flour, whole-wheat flour

Answer 50

extraction rate is the weight of flour/ wt of grain x100% - cake and pastry has low extraction rates 25% - whole wheat has rate greater than 95%

Question 51

What is the consequence to the dough of a gluten structure that is too strong? too weak?

Answer 51

if gluten is too weak: can't stretch in thin films around the air bubbles produced during fermentation and gas bubbles swell and burst therefore product lacks volume -if gluten is too strong is won't stretch so bubbles can't expand therefore causing a dense loaf

Question 52

What does "leavening" mean? How is a dough leavened?

Answer 52

leavening - the rising of bread due to dough holding CO2 from adding product such as yeast

Question 53

What role does shortening play in dough formation

Answer 53

makes dough more easily workable and the final product more tender and soft, flaky texture

Question 54

What is responsible for the gradual lowering of pH in meat after slaughter? Why is this beneficial?

Answer 54

conversion of glycogen to lactic acid causes oH drop which tenderizes meat

Question 55

Describe the structure of a sarcomere. Why would sarcomere length affect meat tenderness?

Answer 55

sarcomeres are the smallest unit of a muscle fibre and include actin and myosin filaments. - when they are contracted and shorter they're less tender -when long they are tender this is because the greater the overlap between thick and thin filaments the less tender the meat

Question 56

What is responsible for the bright red colour of raw meat? How can it be maintained

Answer 56

oxygen is responsible for the bright red colour of raw meat | hemoglobin and myoglobin both contain Fe and Fe++ state meat is fresh and looks red and this is maintained by no heat

Question 57

Why is it safe to eat a good steak or roast rare* while hamburgers must be well done

Answer 57

rare steak is safe bc bacteria and viruses are on the outside of the meat and are eliminated when outside is cooked - but burgers are ground beef and therefore the bacteria can be anywhere with in the meat

Question 58

Explain the effects of location of muscle and marbling on meat tenderness

Answer 58

marbled appearance is more tender

Question 59

general structure of a carb

Answer 59

carbon, hydrogen and oxygen | monosaccharide, disaccharide, polisaccaride

Question 60

structural differences btw monosaccharides, disaccharides and polysaccharides? Give food examples of each

Answer 60

mono- simple sugar, mostly hexose sugars ex. glucose, fructose, galactose di- 2 monosacaride sugars ex. sucrose, maltose, lactose poly- 10 or more sugar units attached, ex. starches and fibres

Question 61

What are the end products of digestion in the small intestine for: starch, glucose, sucrose, & lactose?

Answer 61

starch: pancreatic amylase secreted to SI and completes breakdown into glucose molecules for energy sucrose: broken down into glucose and fructose by sucrase lactose: lactase in small intestine breaks down to glucose and galactose for absorption glucose: is the end product ready for absorption

Question 62

Distinguish between glucagon and glycogen

Answer 62

glycogen is stored in the liver and liver will break it down to glucose by the release of glucagon secreted by the pancreas

Question 63

Describe the opposing functions of glucagon and insulin in terms of blood glucose homeostasis after a meal and during fasting

Answer 63

after a meal (high glucose): pancreas secretes insulin, glucose in converted to glycogen and stored in the liver, and muscles and fat storing cells use glucose/ glycogen during fasting (low glucose): pancreas secretes glucagon which converts stored glycogen in the liver to convert to glucose and secrete it in the blood, and gluconeogenises: breakdown of lactate, pyruvate or protein to amino acids, which go to liver to synthesize glucose

Question 64

What are the differences between Type I and Type II diabetes

Answer 64

``` type 1 (insulin dependent diabetes mellitus): where absorption of glucose must be assisted with insulin typeII (non insulin dependent diabetes mellitus): insulin resistant, tends to be associated with diets high in sugars and starches (obesity) ```

Question 65

What is the difference between glycemic index and glycemic load?

Answer 65

high GI raises blood sugar more than medium to low GI. But the glycemic index does not take into account the amount of carbohydrate in a food %%%% glycemic load is a better indicator of how a carbohydrate food will affect blood sugar gx%

Question 66

Give examples of foods with low and with high glycemic indices. What can you suggest about food composition/structure that affects these values

Answer 66

low GI: 55 or less- more slowly digested, absorbed and metabolized and cause lower and slower rise in blood glucose and call for less insulin (kidney beans, pasta, apples) high GI: 70 or more- these carbs breakdown quickly and have sharp rise in blood glucose (ex pure glucose)

Question 67

What are the limitations of reporting a GI value for specific foods

Answer 67

type of starch, type of sugar, whether and how food is processed or cooked, whether there is any fat with the carb (fat slows rate of stomach emptying and do slows digestion), presence o any viscous fibre accompanying the carb (increases viscosity of contents of intestines and slows down interaction btw enzymes and starch slowing down digestion), and acidic foods slow down stomach emptying

Question 68

How are volatile fatty acids formed in the colon? Name some examples of volatile fatty acids

Answer 68

formed when dietary finer is fermented in colon - acetic acid - propionic acid - butyric acid

Question 69

Does fibre increase or reduce transit time though the stomach? small intestine? large intestine? Why?

Answer 69

presence of any viscous fibre accompanying the carb: increases viscosity of contents of intestines and slows down interaction btw enzymes and starch slowing down digestion

Question 70

What is the basis for the belief that increasing the fibre content of the diet decreases potential for development of coronary heart disease

Answer 70

dietary fibre plays a key role in reduction of blood cholesterol -by reducing bile re-cycling, more bile must be synthesized and this uses cholesterol -– the bile that is not re-cycled is excreted, which also serves to reduce cholesterol

Question 71

What is the basis for the belief that increasing the fibre content of the diet decreases potential for development of diabetes

Answer 71

-slow rate of stomach emptying and passage in small intestine gives more time for digestion and helps to reduce glucose levels (spikes) in the blood, hence reduces glycemic index value

Question 72

Why would some people want to include Jerusalem artichoke flour as a component of their diet

Answer 72

good source of inert carbohydrate medium glycemic index, therefore digested slowly - improve diabetes control and reduce risk for heart disease and stroke, successful for weightloss

Question 73

How do starch and cellulose differ chemically and nutritionally?

Answer 73

starch is glycemic and cellulose is non glycemic (non hydrolyzed or absorbed in the SI) starch is made of glucose polymers and cellulose makes up fibres - stable structure

Question 74

What role do sugars play in food preservation? fermentation?

Answer 74

act as food preservative- by lowering water activity and reducing microbial growth fermentation- Serves as a growth substrate for microbes in various foods (sugars are used to make acids, alcohols and carbon dioxide)

Question 75

What role do sugars play in food colour?

Answer 75

browning reactions with heat (caramelization) | browning reactions with heat and amino acids (mallard browning- chips, bread)