Module 2 Flashcards
1
Q
List some sugars commonly found in food. [8]
A
- Glucose - a monosaccharide, the primary source of energy for somatic cells
- Fructose - a monosaccharide found in fruit, honey, and some veggies; in nature it is linked with glucose as the disaccharide sucrose
- Galactose - a monosaccharide that occurs in dairy and some plants
- Sucrose - occurs naturally in fruits and vegetables; glucose and fructose
- Lactose - found in milk and milk products; galactose and glucose
- Maltose - a disaccharide composed of two glucose units; found in molasses and used in fermentation
- Corn-based sweetener - refers to many products made from corn composed primarily of glucose and fructose, for example high-fructose corn syrup
- Agave nectar - contains fructans (oligosaccharides of fructose and glucose), and monosaccharides of fructose and glucose
2
Q
In addition to adding a sweet taste, what is the purpose of sugars in food? [10]
A
- Inhibit microbial growth by binding water
- Add texture (mouthfeel; body), flavour, and colour to baked goods
- Support the growth of yeast for leavening or fermentation
- Contribute volumn in ice cream, baked goods, and jams
- Enhance the creamy consistency of frozen desserts
- Enhance the crystallization of confectionary products
- Balance acidity in salad dressings, sauces, and condiments
- Help to maintain the natural colour, texture, and shape of preserved fruits.
- Contribute to caramalization when exposed to high temperatures
- React with proteins to produce flavours and colours in foods (Maillard browning)
3
Q
Describe the mechanism of sweet taste. [6]
A
- A dimeric G-protein coupled receptor composed of T1R2 and T1R3 subunits with multiple active sites.
- These bind sugars, amino acids, sweet proteins, and non nutritive sweeteners.
- Synergy among sweeteners many occur since binding a single subunit will activiate the sweet response, and binding a second ligand enhances the response.
- A transduction mechanism translates the chemical message through the nervous system to the brain.
- Although this pathway is not well defined, they are thought to work through the regulation of Ca2+ and ion channels.
- Some non nutritive sweeteners interfere with signal termination in the downstream elements of the transduction pathway, leading to a lingering taste.
4
Q
What does the FDA do to determine the safety of a food additive, like a non-nutritive sweetener?
A
They consider:
* Probable intake
* Cumulative effect from all uses
* Toxicological data from pharmacokinetic and metabolism studies that evaluate:
* Extent of absorption
* Tissue distribution
* Pathways and rates of metabolism
* Rates of elimination and any metabolites
- Toxicological data is used to design toxicity studies in rodents that assess:
- Long-term use
- Reproductive and developmental toxicity
- Carcinogenicity
- Potential for allergenicity
- Interactions with medications
- Effects on nutritional status and blood glucose control
5
Q
What three concepts are integral to the FDA food additive approval process?
A
- Highest no effect level - highest level of intake at which no adverse effect occurs
- Acceptable daily intake - the HNEL divided by 100 - reasonable certainty of no harm
- Estimated daily intake - overestimates consumption because it assumes the new additive will replace all sweeteners in the market; based on a consumption level to the 90th percentile; if this exceeds the ADI, there may be limitations placed on its use as an additive.
6
Q
Name some non-nutritive sweeteners. [7]
A
- Acesulfame K
- Aspartame
- Luo han guo extract
- Neotame
- Saccharin
- Stevia
- Sucralose
7
Q
What is a colloidal dispersion?
A
- The particles of one substance are distributed/dispersed in another substance without dissolving
- The substance that disperses is the dispersed phase
- The substance that extendes throughout the system and surrounds the dispersed phase is called the continuous phase
8
Q
Name 6 colloidal disperions. Give examples of each.
A
- Sol - starches; proteins, and some plant polysaccharides in water
- Emulsion - milk; mayo
- Solid emulsion - butter; margarine
- Gel - starch, pectin, or gelatin gels
- Foam - beaten egg white; whipped cake frostings
- Solid foam - meringue; ice cream; bread
9
Q
What are the dispersed and continuous phases for a sol dispersion?
A
Dispersed: solid
Continuous: liquid
10
Q
What are the dispersed and continuous phases for an emulsion dispersion?
A
Dispersed and continuous: liquid
11
Q
What are the dispersed and continuous phases for a solid emulsion dispersion?
A
Dispersed: liquid
Continuous: solid
12
Q
What are the dispersed and continuous phases for a gel dispersion?
A
Dispersed: liquid
Continuous: solid
13
Q
What are the dispersed and continuous phases for a foam dispersion?
A
Dispersed: gas
Continuous: liquid
14
Q
What are the dispersed and continuous phases for a solid foam dispersion?
A
Dispersed: gas
Continuous: solid
15
Q
What is an emulsion?
A
- A suspension of liquid (fat or water) in a liquid (fat or water)
- May be oil in water (milk) or water in oil (margarine)
16
Q
What is proximate analysis?
A
Quantification of the amount of CHO, fat, protein, water, and ash in a food
17
Q
What are the major components of food systems?
A
- Carbohydrates
- Fats
- Proteins
- Water
These are found in the largest amounts in foods. Each has a variety of functional properties which affects the physical and sensory characteristics of food during processing and storage.
18
Q
What are the minor components in food? [5]
A
- Organic acids
- Pigments
- Aroma compounds
- Vitamins
- Minerals
19
Q
What are monosaccharides?
A
- The monomers of carbohydrates which include glucose, fructose, and galactose.
- They are referred to as ‘simple carbs’
- Main function is to impart a sweet sensation
20
Q
What are disaccharides?
A
- Formed by the union of two monosaccharides
- Also considered ‘simple carbs’
- Include sucrose, lactose, and maltose, which differ in solubility, sweetness, and other properties
21
Q
What is table sugar?
A
- From sugar cane or sugar beet, mainly purely sucrose (glucose and fructose bound together)
22
Q
What is invert sugar and why is it used?
A
- Produced by hydrolyzing sucrose with the enzyme invertase or with acid, to produce a mixture of glucose and fructose
- Used because of the inherently greater sweetening power per unit weight of fructose as compared to sucrose.
- The primary sugars in honey are glucose and fructose in a 40:60 ratio since most of the nectar contains sucrose which is hydrolyzed by invertase in the saliva of the honey bee. (Some of the glucose is converted to gluconic acid and hydrogen peroxide by glucose oxidase, which act as preservatives)
23
Q
Sweetness is related to caloric contribution of the sweetening agent.
True or False?
A
False.
(For instance, fructose and lactose both produce 4 calories of energy per gram, but lactose is only 1/7 as sweet as fructose)
24
Q
Sweetness has no relation to caloric contribution of the sweetening agent.
True or False?
A
True.
25
What is lactose?
* Milk sugar - glucose and galactose bound together
* Found in the milk of all animals (human milk contains more than cow milk)
* Can be broken down by lactase
* Can be fermented by LAB into lactic acid, which is the acidulant and presevative agent in yogurt and cheeses.
26
What is maltose?
* Two glucose units linked together
* Obtained when starch is hydrolyzed by amylase or by heating with dilute acid
27
Describe the production of High Fructose Corn Syrup.
* **Amylase** (or dilute acid) hydrolyzes starch into maltose
* **Maltase** hydrolyzes maltose into its D-glucose units
* **Glucose isomerase** converts glucose to fructose
* HFCS has 42% Fructose, 52% glucose, and 6% starch.
## Footnote
By passing the syrup through an ion-exchange column that retains fructose, 90% HFCS may be obtained. Today, HFCS90 is blended with HFCS42 to create HFCS55, which has a sweetness profile similar to sucrose. This syrup is cheaper than sucrose or even invert sugar, hence its use by the food and beverage industry.
28
What is hot supersaturated sugar?
* With controlled crystallization during cooling, this is the basis of hard candy products, toffees, and related products.
29
Describe caramelization.
* Involves sugars heated to high temperatures
* Non-enzymatic browning
* Occurs with both reducing and non-reducing sugars.
* Brown pigments formed contribute to colour of caramel candies and toffees (not the same as the melanoidins formed during the Maillard reaction)
30
What is a reducing sugar?
* Contains a free aldehyde or ketone group; will contain a free -OH group on the position next to the O in the ring structure
* Includes: glucose, fructose, galactose, and lactose
* Note: sucrose is not a reducing sugar because it does not have the free hydroxyl group.
31
Describe when the Maillard reaction occurs and its byproducts.
* When reducing sugars react with nitrogenous compounds (e.g., amino acids, proteins or amines)
* Responsible for the formation of brown pigments that appear on bread when they are toasted
* Many low molecular weight compounds are formed during the MR that are often aroma and flavour compounds that contribute to desirable (toasted bread; roasted coffee) or undesirable flavours (form in skim milk powder during storage or in canned peaches during long term storage)
* The brown colours are high molecular weight pigments that form (melanoidins) formed as a result of polymerization of some of the low molecular weight intermediate fractions.
32
What are polysaccharides?
* High molecular weight, long chains of monosaccharides (e.g., glucose)
* Classified as 'complex carbs'
* Insoluble in water and generally tasteless
33
Discuss the characteristics and functional properties of pectin.
* Structural polymers in plants
* Form the cementing material between individual plant cells
* Pectin affects the texture of plant tissues
* Used in jams and jellies as gelling agents in the presence of sufficient sugar and acid
* Contribute to the viscosity of ketchup
* Contribute to the mouthfeel and maintenance of particles in suspension (e.g., orange juice)
## Footnote
A polysaccharide
34
Discuss the characteristics and functional properties of agar.
* Extracted from seaweed (kelp)
* Used as a thickener agent
## Footnote
A polysaccharide
35
Discuss the characteristics and functional properties of alginates.
* Extracted from certain types of seaweed
* Used as gelling agents
* Keep solids and liquids in suspension in fruit juices
## Footnote
A polysaccharide
36
Discuss the characteristics and functional properties of gum arabic/aracia.
* A plant exudate from the bark of acacia trees
* Used as a thickener and stabilizer in products like beer, soft drinks, and ice cream
## Footnote
a polysaccharide
37
Discuss the characteristics and functional properties of carrageenan.
* Extracted from certain types of seaweed (red algae)
* Used as a suspending agent to keep cocoa particles in suspension in chocolate milk
## Footnote
a polysaccharide
38
Discuss the characteristics and functional properties of xanthan gum.
* Produced by bacteria
* First isolated from rotting cabbage, now cultured in fermentation tanks and purified
* Used in salad dressings as a thickening agent, which enables the dressing to cling to the salad components
* Used as a suspending agent to maintain pieces of onion, red peper, and spices in a stable emulsion
## Footnote
a polysaccharide
39
Discuss the characteristics and functional properties of cellulose and hemicellulose.
* Present in many plant tissues as supporting structures (e.g., the fibres in celery)
* Are polymers of glucose that are indigestible
* Along with pectin and the other carbohydrate gums, form the indigestible portion of our carbohydrate intake that is known as dietary fibre
## Footnote
polysaccharides
40
Discuss the characteristics and functional properties of starch.
* Polymers of glucose
* Digestible when cooked (e.g., rice, potatoes)
* Used as thickening, suspending, or gelling agents
## Footnote
polysaccharides
41
What is starch made up of?
* Polymers of glucose joined by an alpha 1,4 linkage
* Amylose - a straight linear chain
* Amylopectin - branched
* Can be anywhere from 400 to several hundred thousand glucose units.
* The length and bulkiness of the molecules prevent interaction with receptors on tongue, and are therefore bland.
42
What are starch granules?
* Amylose and amylopectin are tightly packed.
* Not digestible
* Not soluble unless heated
43
What is gelatinization?
* When starch is heated in water, the granules absorb water and swell, so the bonds between starch molecules are loosened.
* Hydrogen bonds form between water and starch
* The starch granule eventually bursts, becoming soft and pliable
* This is the phenomenon that occurs when flour is used as a thickening agent when making gravies and the conversion of hard rice to soft cooked rice.
44
What is retrogradation?
* Involves the reassociation of starch molecules (especially the amylose polymers) into ordered sturctures, upon cooling and/or during refrigerated storage.
* The linear amylose molecules orient themselves in crystalline regions, leading to the syneresis of water and a loss of tenderness of the food (e.g., bread staling) or the development of a gritty texture (e.g., pudding stored in fridge)
45
Can retrogradation be avoided or reversed?
* Avoided to a certain extent through use of dextrins and/or modified starches to reduce the tendency for the alignment of amylose chains
* Partially reversed by heating - though retrogradation will quickly occur again upon cooling
46
How are dextrins produced?
* Partial hydrolysis of starches
47
What bonds exist in cellulose?
* Beta 1,4 linkages
* Humans lack the enzyme to break down this bond.
48
What is the structure of xanthan gum?
* Beta-D-glucose backbone like cellulose, but every second glucose unit is attached to a trisaccharide
## Footnote
Produced by *Xanthamonas campestris*
49
What are fats and oils?
* Lipids
* Lipids can be found in the form of triglycerides, phospholipids, and sterols
* Triglycerides make up the largest class of lipids as most of the fats and oils we consume
50
What are fats?
* A type of macronutrient
* Composed mainly of triglycerides
* Essential for energy storage and cell function
51
What is the correct name for fat?
* Lipid
* Triglyceride is the name for common dietary fat
52
What is the nutritional value and calories of fat?
* 9 kcal/gram
* Essential for absorption of fat-soluble vitamins (A, D, E, K)
53
Discern between saturated, monounsaturated, and polyunsaturated fatty acids.
* **Saturated**: no double bonds; solid at room temperature
* **Monounsaturated**: one double bond; usually liquid at room temperature
* **Polyunsaturated**: multiple double bonds; usually liquid at room temperature
54
What is an omega-3 fatty acid?
* A type of polyunsaturated fatty acid
* Contains a double bond at the third carbon from the end of the carbon chain
* Essential for heart health and brain function
55
What are cis and trans fatty acids?
* **Cis** - hydrogen atoms are on the same side of the double bond; naturally occurring
* **Trans** - hydrogen atoms are on opposite sides of the double bond; often artificially created through hydrogenation
56
Why are some fats solid and others liquid at room temperature?
* **Saturated** : tightly packed structure (no double bonds, no 'kinks' in chain); solid at room temperature
* **Unsaturated**: Double bonds ('kinks') in chain prevent tight packing; liquid at room temperature
57
What is the term used to convert a liquid oil into solid or spreadable margarine?
Hydrogenation
58
What are some functions of fat in foods?
* Flavour and texture
* Enhances satiety
* Acts as a medium for cooking and heat transfer
* Contributes to the structure and mouthfeel of food products
59
Summarize the functional properties of fats (and oils). [7]
* **Lubricant** - makes foods more palatable, easier to chew and swallow
* **Tenderizing power** - coat flour (protein and starch) to create a flaky texture - works best when crystals are in beta-prime form
* **Aeration** - fats surround gas in batter; contribute to formation of the dispersion by decreasing viscosity
* **Aroma** - many aroma molecules are fat soluble
* **Soften** - when heated, contributes to desirable features like chocolate melting in your mouth
* **High temperatures** - foods fried in hot oil cook fast because temperatures that can be attained are high before the oil smokes/vaporizes
* **Emulsifiers** - fats can form emulsions (dispersed or continuous phase) or act as emulsifiers that assist in stabilizing the dispersion
60
What are emulsifiers?
* Compounds that promote the formation of emulsions (i.e., the dispersion of one phase in the form of small droplets, in the second continuous phase)
61
What types of fat molecules can act as emulsifiers?
* Phospholipids (e.g., lecithin - found in egg yolk and soybean oil)
* Structurally similar to triglycerides, except that only two fatty acids are linked to the glycerol (making it a diglyceride), and a charged group (negatively charged phosphoric acid esterified with positively charged choline group) is linked to the third position
62
What is an amphiphillic molecule?
* Have a hydrophilic (water loving) portion and a hydrophobic (water hating) portion
* Emulsifiers like lecithin are amphiphillic
63
How do emulsifiers stabilize emulsions?
* Their amphiphillic nature means that they can interface with both phases in the dispersion, thereby reducing the interfacial tension between oil and water phases, and preventing the dispersed droplets from coalescing.
64
What factors influence emulsion stability?
* Droplet size
* Viscosity of continuous phase
* Downward pull of gravity must be balanced by upward forces of buoyancy (reduce tendency for 'creaming'/floating to the top of less dense phase
65
What is the difference between stabilizers and emulsifiers?
* **Stabilizer** - compounds that increase the viscosity of the continous phase, keeping the droplets suspended/dispersed to reduce rate of creaming (e.g., xanthan gum)
* **Emulsifier** - compounds that promote the formation of an emulsion
66
What is the major function of milk homogenization?
* Formation of a stable emulsion to prevent fat separation, such as that which occurs in non-homogenized milk
67
* Can you imagine what a piece of pie would look and taste like without the presence of fat in the crust?
* What functional properties of fat are involved in the pie crust formation?
* Some people use oil in their pie crust recipe, and some use lard. Which contains more saturated fat?
* Appearance: crust would be pale and dry
* Texture: hard, tough, crumbly
* Taste: bland and less rich, missing buttery/savory notes provided by fat
* Fat functional properties: tenderness, flakiness, moisture, flavor
* Oil: more unsaturated fats
* Lard: more saturated fats
68
What make up protein molecules?
* Long chains of amino acid units linked by peptide bonds, a type of organic acid made up of an amino group (NH2) and a carboxyl group (COOH) attached to the same carbon atom
69
How many different amino acids are there?
* 20
* 9 cannot be synthesized by human tissues and are therefore required in the diet
70
What are the essential amino acids?
* Isoleucine
* Leucine
* Lysine
* Methionine
* Phenylalanine
* Threonine
* Tryptophan
* Valine
* Histidine (for infants only)
## Footnote
PVT TIM HALL
71
Name some functions of proteins in foods.
* Emulsions
* Foaming
* Gelling
* Enzymes
72
Give examples of protein foams.
* Egg white proteins being whipped introduces air and denatures proteins; the proteins then coagulate to form a fine film around the air pockets - solid foams like meringues
* Ice cream is a solid emulsion and solid foam involving protein
* Gluten, a protein in wheat flour, traps air bubbles in bread making.
73
Discuss protein gel formation.
* Gelatin (from collagen) forms gels by trapping large volumes of water within a semi rigid 3D protein matrix
* Heating of meat proteins creates gelation in production of products like bologna (which is also an emulsion)
* Milk protein forms gels when acidified, such as in the making of yogurt or cheese - the gel holds water and has a smooth texture
74
Describe these functions of milk proteins.
* A: milk protein traps air bubbles to form the foam structure
* B: casein, a milk protein, acts as an emulsifier preventing fat globules from separating from the skim milk portion
* C: casein forms a gel structure in the curd
75
Discuss proteins as enzymes.
* Invertase in candy making
* Amylase can ruin a starch gel (or be used in HFCS manufacture)
* Lipases can cause lipolytic rancidity
* Enzymes in living systems are responsible for ripening and unless inactivated can cause spoiling
* Many heating processes are designed to inactivate enzymes (in addition to destroying microbes)
* Proteases are used in coagulation during cheese production
* Pectinases enhance juice recovery in apple juice production
* Invertase converts sucrose to invert sugar
* Isomerases are used in HFCS production
76
What is the relation between food proteins and allergies?
* Intolerance to certain proteins is the basis for many allergies
77
What is free water?
* Some water is present within intergranular spaces, within pores of the food matrix, and as a thin film on the surface of many foods
* Free water can be found in tissue systems and dispersions
* Water that is free and not bound generally retains its usual physical properties, and can also function as a dispersing agent for colloidal substances, or a solvent for microorganisms.
78
What is bound water?
* Some water can be adsorbed on the surfaces of macromolecules like starches and proteins through forces like van der Waals and hydrogen bonding
* This water does not display all of its normal physical properties and is not readily available for use by microbes or chemical/enzymatic reactions
* Another form of bound water is water of hydration
* Sugars and salts can bind substantial amounts of water and are often added for the purpose of decreasing free water in a food system to prevent microbial growth
79
What is water activity?
* Measurement to monitor the availability of free water in foods that support microbial growth, and chemical and enzymatic reactions
* Measured as the ratio of vapour pressure of water in the food to the vapour pressure of pure water, at the same temperature
## Footnote
Water activity = 0 (no free water); 1.0 (all water is free)
80
What is the difference between water activity and moisture content?
* **Moisture content** - commonly conducted quality assurance measurement, but does not indicate whether the water is bound or free
81
List four organic acids (that aren't amino acids) and what food they come from.
* Malic acid: apples
* Citric acid: citrus fruits, tomatoes, strawberries
* Tartaric acid: grapes
* Lactic acid: yogurt, cheese, olives, sauerkraut
82
What are the major uses of organic acids? [4]
* Adjust pH/ acidify food
* Impart flavour
* Antimicrobial agents
* Textural effects (due to reactions with proteins, starches, pectins, or other constituent)
83
What is pH?
* A measure of acidity
84
What is the difference between an acidic food and a low-acid food?
* Acid foods have pH 4.6 or less
* Low-acid foods have pH greater than 4.6
* Acid foods will not support the growth of disease-causing microorganisms.
85
What is green pigment?
* Chlorophyll
* A - has blue green hue (e.g. broccoli florets)
* B - has yellow green hue (e.g., broccoli stems)
86
What are red, orange, and yellow pigments?
* Carotenoids - can be subclassified into carotenes and xanthophylls
* E.g., tomatoes, carrotes, pineapples, shrimp
87
Which pigments predominate in blueberries, cherries, cranberries, plums, and red cabbage?
* Anthocyanidins and anthocyanins
* Particularly sensitive to pH
88
Discuss aroma constituents.
* Very complex
* No single compound can be attributed as the sole source of an aroma
* Specific mixture of compounds creates an aroma
* Volatile constituents contribute to aroma are present in low concentrations but are still important
* Flavour constituents are present as part of the food matrix, or are modified/created during cooking
89
Discuss vitamins as additives.
* Vitamin C - used as a bleaching agent and preservative
* Vitamin E - preservative
90
Discuss how minerals affect food systems.
* Active participants in chemical and biochemical reactions that affect chemical properties and textural characteristics of food systems.
91
Traps air to form foams and water to form gels.
Proteins
92
Carries food aromas, therefore, contributes to food flavour
Fats
93
Often used as a thickening agent or stabilizer
Carbohydrates
94
It is the required part of emulsions and gels and also helps with mixing of the ingredients.
Water
95
A and B represent?
A: dispersed phase
B: continuous phase
96
If A is solid and B is liquid
Sol
97
If A is gas and B is solid
Solid foam
98
If A and B are liquid
Liquid emulsion
99
If A is gas and B is liquid
Foam
100
If A is liquid and B is solid
Gel
101
Egg yolk is an emulsifier.
True or False?
True
102
Mustard proteins are emulsifiers.
True or False?
True
103
Soap is an emulsifier.
True or False?
True.
104
Cream is an emulsifier.
True or False?
False.
105
Order from sweetest to least sweet: Glucose; invert sugar; fructose; sucrose; lactose
1. Fructose
2. Invert sugar
3. Sucrose
4. Glucose
5. Lactose
106
Starch is indigestible and forms part of dietary fiber.
True or False?
False.
107
Starch does not interact with taste receptors.
True or False?
True.
108
Starch granules are insoluble in hot water.
True or False?
False.
109
Starch undergoes gelatinization which results in a loss of water.
True or False?
False.
110
Bound water is a measure of water activity.
True or False?
False.
111
Bound water contributes to enzymatic activity and microbial growth.
True or False?
False
112
Bound water participates in chemical reactions.
True or False?
False
113
A water activity of 0 means all water is bound,
True or False?
True
114
List 4 low acid foods.
* Cheddar cheese
* Meat
* Milk
* Carrots
115
Hydrolytic rancidity can only happen in unsaturated fats.
True or False?
False.
116
Name the pigment in cranberries.
Anythocyanins
117
Name the pigment in tomatoes.
Carotenoids
118
Name the pigment in parsley.
Chlorophyll
