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What is in your food? Flashcards

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1
Q

What is food science?

A

The discipline in biology, physical sciences and engineering used to study the nature of foods, the causes of their deterioration and the principles underlying food processing.

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2
Q

The estimated total value of food loss and waste in Canada in 2014 was $____?

A

The estimated total value of food loss and waste in Canada in 2014 was $ 31 billion

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3
Q

Which regulator enforces these acts? -Canada Agricultural Products Act -Consumer Packaging and Labelling Act -Meat Inspection Act -Plant Inspection Act

A

Canadian Food Inspection Agency

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4
Q

Standardized Foods- Butter or Dairy Spread? Must contain min of 80% milk fat, may contain milk solids, salt, permitted food color, permitted bacterial culture.

A

Butter, Must contain min of 80% milk fat, may contain milk solids, salt, permitted food color, permitted bacterial culture. Dairy spread, min 39% milk fat, max 80%, may contain as above plus emulsifying and stabilizing agents.

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5
Q

On nutrition panel what does DV stand for and what does it mean?

A

DV= percent daily value. Based on the 2000 calorie diet/day. The portion of each nutrient in your aprox. daily value by percent.

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6
Q

With a %DV= 15, is that a a little or a lot of the nutirent?

A

15% DV or more is a lot of a nutrient!

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7
Q

What were some changes that will be implemented on Canadian Food Labelling?

A

-Different sugar types will be separated in brackets -Food colours listed by name -Same portion size for similar products -Implimented in 2022 (5 year transition period)

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8
Q

Macronutrients: 1. 2. 3. 4. Micronutrients 1. 2.

A

Macronutrients: 1. Water 2. Lipids 3. Carbs 4. Proteins Micronutrients: 1. Vitamins 2. Minerals

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9
Q

Fat- soluable vitamins: (4 of them) Water soluable vitamins: (2 of them)

A

Fat- soluable vitamins: vit- K,A,D,E Water soluable vitamins: Vit C and B

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10
Q

What is the major distinguishing feature between fats and oils>

A

Fats are generally solid at room temp, while oils are generally liquid at room temp.

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11
Q

What are fats and oils composed of?

A

Fats and oils are esters of fatty acids and glycerol –> Known as triacylglycerol (3 FA esterified w/ 3 OH groups of glycerol)

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12
Q

What classifies as a short, medium and long chain FA?

A

short chain FA: 4-10 carbons) Medium: 12-14 carbons Long: (>14 carbons)

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13
Q

What does saturated have to do with double bonds?

A

NO double bonds

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14
Q

Where will omega bonds be if they are present? (ex. omega 3 bond)

A

Omega 3 bond… Will be located on the double bond the third carbon away from the terminal methyl group

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15
Q

Who is kinky? Saturated or unsaturated?

A

Those KINKY unsaturated bois!!!!

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16
Q

All naturally occurring vegetable oils and fats contain only (cis or trans?) fatty acids

A

All naturally occurring vegetable oils and fats contain only cis-fatty acids. -Animal fat contains trans-fatty acids (TFA’s) -Hydrogenation of veg oils creates TFA’s

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17
Q

Milk fats: Principal FA’s Examples Importance

A

Milk Fats: Principal FA’s- Mryrstic (C14), Palmitic (C16), steric (c18) and oleic (c18:1) Examples- fats from milk of cows, goats and buffalos Importance- Wide melting points due to FA composition.

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18
Q

Lauric Oils: Principal FA’s Examples Importance

A

Lauric oils: Principal FA’s- C12 Examples- coconut, palm kernel Importance- Particularilty for soap making. Low in unsaturation.

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19
Q

Palmitic oils: Principal FA’s Examples Importance

A

Palmitic oils: Principal FA’s- 44% C16:0 (plamitic acid), also large amount of oleic and some linoleic acids. Examples- Palm Importance- World’s largest producers are malasia and indonesia. Highest global production of an oil.

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20
Q

Veg butter: Principal FA’s Examples Importance

A

Vegetable butter: Principal FA’s- solid fats from veg sources. Rich in saturated Fa’s. PALMITIC AND STERIC. ALSO RICH IN OLEIC. Examples- cocoa butter, mango, kernel Importance- cocoa butter, main fat for chocolate.

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21
Q

Animal fats: Principal FA’s Examples- Importance-

A

Animal Fats: Principal FA’s- High content of palmitic, oleic and steric. Also contains trans-FA’s. High content of fully saturated TAG (high melt pt) Examples- Lard, tallow Importance- Edible as well as industrial soap use.

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22
Q

Oleic/ linoleic oils: Principal FA’s Examples- Importance-

A

Oleic/ linoleic oils: Principal FA’s- Oleic and linoleic acids 80-90% Examples- soybean, sunflower, canola, corn, rice bran oil Importance- Most common type of veg oils

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23
Q

High oleic oils: Principal FA’s Examples- Importance-

A

High oleic oils: Principal FA’s- oleic acid nearly 80% Examples-soybean, canola, olive, sunflower Importance- (either traditional or genetic breeding)

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24
Q

Linolenic oils: Principal FA’s Examples- Importance-

A

Linolenic oils: Principal FA’s- Oleic and linoneic acids Examples- Flaxseed/lindseed, camelina, borage. Importance- Very good source of Omega 3 FA. Excellent drying properties (painting), high unsaturation leads to auto oxidation and rancidity.

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25
Q

Erucic acid oil Principal FA’s Examples- Importance-

A

Erucic acid oils: Principal FA’s- Erucic acid (C22:1) Examples-Rapeseed, mustard oil. Importance- Mainly used in industrial oil in norther america. Edible oil in China and India.

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26
Q

Marine and fish oils: Principal FA’s Examples- Importance-

A

Marine and fish oils: Principal FA’s- monounsaturated FAs, omega 3 polyunsaturated FA’s (EPA, DHA, DPA). Examples- Seal blubber oil, menhaden oil Importance- Very low melt pt, allows for their life underwater. Susceptible to auto-oxidation (needs cold to avoid oxidation).

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27
Q

What are the steps in the industrial production of veg oil?

A

-Seed collection and cleaning -Extraction of crude oil (pressing, solvent extraction) -Refining of crude oil –> Removal of phospholipids (degumming) –> Removal of FFA’s (alkali neutralization) –> Removal of undesirable colorants (bleaching) –> Removal of undesirable odours (deodorizing)

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28
Q

Describe what these are: Acid value Iodine value Smoke point

A

Acid value- free FA content. (Acid can react with the oils and other ingredients and cause rancidity) Iodine value- Degree of unsaturation. (based on ability of iodine to break double bonds and attach). Smoke point- Oil stability during frying. Temp at which first smoke is visable.

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29
Q

How is IV expressed? FULLY SATURATED LIPIDS HAVE AN IV OF ZERO!

A

Expressed as number of iodine (g) absorbed by 100 g of oil. Iodine values of oils: Canola oil (110-126), Coconut (6-10), Palm oil (50-55)/ 100 g of oil.

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30
Q

What decreases the smoke pnt?

A

Refining decrease small particles and therefore smoke pnt. The presence of free FA’s, unsaturated fats and low molecular weight compounds decrease smoke point of oils and fats.

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31
Q

What is lipid oxidation?

A

The reaction between oxygen and lipid. Leads to generation of free radicals and other things that cause rancidity. The degree of increased unsaturation makes it easier to oxidize.

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32
Q

How to prevent lipid oxidation?

A

Reduce polyunsaturated FA’s, replace with saturated. Partial hydrogenation. Inert gas at top to prevent oxygen and light. Add antioxidants.

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33
Q

What do antioxidants do?

A

Neutralize lipid free radicals by donating their electrons. They are stable in free of neutral form. They can be synthetic or natural.

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34
Q

What is hydrogenation of fats and oils, and why do we do it?

A

The rxn of veg oil w/ hydrogen at high temp and pressure in presence of catalyst. Decreases unsaturation-reduces the oxidation. Increase solid fat … spreadability. Makes for crispy texture of fried products.

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35
Q

What does PHO stand for?

A

PHO- partially hydrogenated oils. (trans fats)

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36
Q

PHOs- how do we feel about them? Canada’s labelling?

A

Trans fat are present in foods contain partially hydrogenated fats (PHOs). Frien, hard margarine, baked products. Links to coronary heart disease w/ plaque build-up, increasing cholesterol levels. If a food contains less than 0.2g of trans fat, it can be labeled as ‘0g’ trans fat or ‘trans fat free’!

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37
Q

What are CLA’s?

A

CLA’s- conjugated linoleic acids GOOD trans-fat!!!

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38
Q

Where are CLA’s found, what are they made of? What are they good for?

A

CLA’s are gemetric isomers of octadecadieonic acid (C18:2). Generated in the rumen of animals. Highest concentration in dairy prods –> Milk fat content of CLA 2-30 mg/g of fat. Potencially anticarcinogenic effect, prevent cardiovascular disease, etc. (not human proven yet).

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39
Q

What do double bonds do to melting point? What does molecular weight do to melting pt?

A

As number of double bonds increase they lower the melting point of the substance. Higher the molecular weight the higher the melting point (more chains to break to melt).

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40
Q

What does EFA stand for?

A

Essential fatty acids

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41
Q

What are EFA’s? What must we consume to get them?

A

Fatty acids that cannot be synthesized in our body and are essential for good health –> Alpha-linolenic acid, Linoleic acid Must eat: Fish oil, soybean oil, canola oil, flaxseed oil, sunflower oil.

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42
Q

Is Butyric acid a saturated or unsaturated Fa?

A

Butyric acid is saturated

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43
Q

Which two oils are very rich in lauric acid?

A

Coconut oil and palm oil are very rich in lauric acid.

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44
Q

What type of oil is very high in EPA?

A

Fish oil is very high is EPA.

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45
Q

Globally which oil is produced in the largest quantity?

A

Palm oil

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46
Q

Sucrose is composed of…?

A

Glucose and fructose

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47
Q

Lactose is composed of

A

Glucose and galactose

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48
Q

Maltose is composed of

A

two glucose units

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49
Q

How many monosaccharides need to be covalently bonded to be classified as an oligosaccharide? What is an example of one?

A

2-10 monosaccharides to be an oligosaccharide. Example is Raffinose (composed of glucose, fructose and galactose).

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50
Q

How many monosaccharides need to be covalently bonded together to be classified as a polysaccharide? Examples?

A

Greater than 10 to be a polysaccharide. Starch(carb storage for plants), cellulose (plant cell wall) and glycogen (‘animal starch’) are all polysaccharides.

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51
Q

What is the reaction to convert glucose to fructose?

A

Isomerization Ron. Using glucose isomerase. This run is the basis of High Fructose Corn Syrup (HFCS).

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52
Q

Which sugar is known as table sugar?

A

Sucrose (glucose-fructose).

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53
Q

What is the sweetness index?

A

A relative sweetness scale that went from 1-100, but now goes higher cause we have sweeter things.

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54
Q

How do fruits help with digestion of sugar?

A

Fibre present in fruits slows down release of sugar for digestion- lower glycemic index. Polyphenols in fruits may also have some mechanism of regulating the rate of intestinal sugar absorption.

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55
Q

What is an example of a zero calorie sweetener?

A

Stevia. From the stevia plant.

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56
Q

What is the Maillard reaction and what does it result in?

A

Maillard browning is the run between a carbonyl group and an amino group. Results in brown melanoid. It generates flavour (coffee, coated nuts and meats). Helps to develop colour in baked products

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57
Q

What is an undesirable result of Maillard browning in foods?

A

Browning of milk powder upon storage. Run between lactose and milk proteins. Loss of amino acid lysine. Undesirable effect of Maillard rxn.

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58
Q

What is the caramelization reaction and what does it result in?

A

Run between carbohydrates in the presence of heat. Produces brown pigments. Caramel flavour and colour (cola, bakery products, candy, maple syrup). [CARAMELAN AND CARAMELEN] !!!

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59
Q

Which two polymers is starch composed of?

A

Amylose and amylopectin.

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60
Q

Characteristics of Amylose?

A

Linear chain of glucose units. 1-4 alpha-D-glucopyranosyl units Contributes to gelling characteristics to cooked starch mixtures.

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61
Q

Characteristics of Amylopectin?

A

Branched chain. 1-6 alpha-D-glucopyranosyl units Amylopectins contributes to thickening prosperities when a starch mixture is cooked with water, bot no gelling. Too branched to Gell!!

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62
Q

Fun starch fact!!?!

A

Starch is unsociable in water and can only act as a thickener when the starch granules are heated…. :)

63
Q

When starch is heated what will happen to mixture viscosity? Upon continual heating? Upon cooling?

A

When starch is heated the granule will swell and the viscosity of the mixture will increase. Upon continual heating the viscosity will decrease, the heat ends of disrupting the granule structure. Upon cooling the starch can for gel (re-association of molecules), very high viscosity (no flow).

64
Q

During digestion what enzyme breaks down starch? What is starch broken down into>

A

Amylase enzyme. Starch + Maltose

65
Q

During digestion, which enzyme breaks down maltose? What is it broken down into?

A

Maltase enzyme. 2 glucose units.

66
Q

What is so significant about cellulose?

A

It is the most abundant polysaccharide on earth. WE cannot digest the beta-glycosidic linkage. Cellulose is water insoluble- mostly used to increase bulk volume of food.

67
Q

What are two modifications of cellulose into more soluble and to form gel?

A

Methyl cellulose Carboxymethyl cellulose

68
Q

What is the most frequent role of polysaccharide additives in foods?

A

Fat replacer.

69
Q

What does Carrageenan do?

A

Holds the choc powder to the Casin in chocolate milk to form a weak gel structure and eliminate sedimentation of cocoa.

70
Q

True or false. There is more pectin in low calorie jam?

A

True

71
Q

What are alginates extracted from?

A

Gum extracted from brown seaweed. Contains alpha and beta linkages.

72
Q

What are the role of alginates and what are they found in?

A

sodium alginates form a very viscous solution in water. Water insoluble and form strong gel. Used for the pimento (red chilli pepper) that olives are stuffed with. Puree mixed with sodium alginate forms gel. Also used for encapsulation matrix in lab.

73
Q

6 functional properties of polysaccharides?

A
  1. Gelation 2. Thickener/ viscosity modifying agent 3. Water binding (reduce water for microbes to use) 4. Fat replacer 5. Dietary fiber (cellulose, pectin, etc.) 6. Promote growth of probiotic (act as probiotics)
74
Q

What are two insoluble plant cell wall materials?

A

Cellulose and lignin

75
Q

What are two non-starch water-soluble polysaccharides?

A

Pectin and Beta-glucan

76
Q

What does dietary fibre do to aid GI function?

A

Increase fecal bulk –> lowers intestinal transit time. Helps prevent constipation.

77
Q

What makes diet soda and low or zero-calorie beverages and ‘no sugar added’ jams sweet?

A

Fructose and Sucralose

78
Q

How is lactose free milk made?

A

By converting lactose into glucose and galactose.

79
Q

T or F? HFSC has higher calorie than sucrose?

A

True

80
Q

What run results in the colour change during BBQ-ing?

A

Maillard Rxn.

81
Q

What is Xanthan gum extracted from

A

The polysaccharide xanthin gum is extracted from a microorganism.

82
Q

Which of the following is NOT a dietary fibre? Amylose, Cellulose, Pectin, Beta-glucan

A

Amylose is NOT a dietary fibre.

83
Q

What is the coolest role of carrageenan?

A

Essential component of chocolate milk.

84
Q

What are proteins?

A

Polymers of AA’s linked by peptide bonds. Covalently bonded.

85
Q

What are two essential AA’s?

A

Lysine and Threonine

86
Q

What does essential AA mean?

A

Must be gained by diet, we cannot synthesize.

87
Q

Why is cystine super cool in food science?

A

The disulphide bond= SUPA strong!! This dimerization rxn can occur during cooking and result in the disulphide (covalent bond), which is very stabilizing.

88
Q

Why do we fucking love Lysine in food science?

A

It is real reactive, likes to give itself away to ANYONE (electrophile behaviour :/ ) so it will brown quickly. Therefore, Maillard browning rxn!!!!

89
Q

The hell is a Zwitterion?

A

Both pos and neg charge. Neutral cause of the equal and opposite charge on the amino group.

90
Q

What is the isoelectric point and its importance in food?

A

The point where the net charge on the protein becomes zero. Water cannot solubilize in water without a charge. Will form aggregates to precipitate out the aqueous solution. Making yogurt, or making butter-milk with vinegar in milk for pancakes!!!!!!!

91
Q

What are caseinophosphopeptide and Nisin?

A

Caseinophosphopeptide- casein derived phosphorylated peptides enhanced vit-D absorption. Nisin- antimicorbial peptides used in food. Produced during certain bacterial fermentation.

92
Q

Aspartame?

A

about 200x sweeter than sucrose. Low cal sweetener (need little, but very sweet) -Metabolized in the body to its components: aspartic acid, phenylalanine and methanol. “Equal” sugar is aspartame. Used often in diet soda.

93
Q

what do the protein structures mean? Primary Secondary Tertiary Quaternary

A

Primary- Different AA’s, as directed by gene. Secondary- Alpha helix vs beta pleated sheets Tertiary- 3-D structure, the interactions of the AA’s. (H-bonding, disulphide bonding, hydrophobic interactions). Quaternary- Interactions of the polypeptide subunits. (****Only for proteins with more than one monomeric subunit!!!***)

94
Q

Tertiary structures (3 of them) and an example of each.

A

Tertiary structure Globular- ex) Whey proteins Disordered- ex) Sodium casein ate Fibrous- ex) Muscle protein, collagen.

95
Q

What are two examples of quaternary structure of a protein?

A

Hemoglobin- 2 Alph and 2 beta chains Casein protein (milk): composed of 4 proteins.

96
Q

What does PDCAAS stand for and how is it measured?

A

Protein Digestibility corrected amino acid score.

97
Q

Most plant proteins are defincent in one of more EAA.

What AA do wheat, rice and corn lack?

What AA do legumes (soy, beans and peas) lack?

A

What AA do wheat, rice and corn lack? Lysine

What AA do legumes (soy, beans and peas) lack? Methionine

98
Q

Which two plant protein sources are complimentary and can be viewed as a complete protein?

A

Cereal grains and legumes can create a complete protein. This is because

Cereals are rich in met and low in lys

whereas Legumes are rich in lysine and low in Met!

99
Q

What is PPO?

A

Polyphenoloxidase (PPO)

100
Q

Why is PPO important?

A

Polypheoloxidase catalyzes the oxidation of many phenolic compounds, it results in the brown pigments.

Polyphenol activity is a plant defense mechanism and can be triggered by cutting of fruits and vegetables –> enzymatic browning

101
Q

What are 5 ways to prevent enzymatic browning?

A

Denature the enzyme- Blanching. Boil water to steam, cook with steam to denature the proteins and prevent enxymatic browning.

Remove oxygen- Store under vacuum or inert gas

Addition of antioxidants- Ascorbic acid, to stop the oxidation

Inhibit the enzyme- Drop the surface pH with acid, change pH and prevent the rxn from occuring.

Reactants to stop formation of melanin- SO2 binds to quinones and stops the final polymerization step, inhibits the rxn.

102
Q

What happens to the primary structure of a protein (AA sequence) during denaturation?

A

NOTHING happens. The primary sequence will remain intact. Denaturation changes the secondary and tertiary though!!

103
Q

Breifly describe protein denaturation in food while cooking an egg and preparing yogurt or cheese from milk…

A

Cooking egg

-heat coagulation of egg proteins. Gelation of eggs protein

Yogurt and cheese from milk

-Acid or enzymatic denaturation of casein protein in milk

104
Q

Describe the gelation of gelatin protein

A

Fibrous protein derived from collagen protein.

On cooling the fibers undergo a reversible trasition to the collagen triple helix structure. The helical chains form a 3D gel structure.

When re-heated the intermolecular association is disrupted and the protein adopt a disordered structure again.

Gel melting occurs around 37 degrees (body temp)

105
Q

Describe how hot dog and sausage production are applications of protein denaturation

A

Meat emulsion is heated to aprox 75 degrees celcuis to denature the meat proteins. The reactive AA can then react to form a 3D gel, which traps water and fat globules.

106
Q

These proteins are in flour, which two proteins play a major role in baking?

Albumins

Gladin

Glutenin

Globulins

A

Gladin and Glutenin play a major role in baking. when kneaded, mixed and moistenenig, their interactions cause a crosslinkage via disulfide bonds in the process known as gluten formation.

Gluten formation is responsible for the elastic stretchy charactersistics of dough, its strength, as well as the loaf volume.

107
Q

What are the roles of glutenin and gliadin in the formation of gluten?

A

After mixing and kneading: Glutenin provides the elasticity to dough, while gliadin gives fluidity and stickyness.

Bonds can be broken if overmixed.

108
Q

Describe the chemical bonding of water

A

Two hydrogen molecules covalently bonded to an oxygen with two lone pairs of electrons.

109
Q

What makes water polar?

A

Oxygen have a a higher electronegativity than hydrogen (measure of how much it wants electrons). This leaves the hydrogens with a slightly positive dipole, since they are slightly electron deficent.

110
Q

How does water bond with itself as liquid water?

A

The slihgtly positive hydrogen with interact with the negative lone pair of another water.

Each water bonding with 4 other water molecules.

111
Q

What the 4 main anomalour properties of water?

Anomalous properties of water are due to its extensive intra-molecular Hydrogen bonding.

A

Melting and boiling points: both unusally high (considering the molecular weight of these molecules)

Density: Liquid water has a high density that increase upon heating, up to 4 degrees. (Ice melts and warm water at the bottom).

Volume expansion: Soild water (ice) volume increases on freezing. Bigger in size and also floats.

112
Q

What the the main 3 phase transitions of water?

What are the two latent periods upon heating water in phase transition?

A

Liquid, vapour, solid.

Latent heat fusion of ice. The plateau caused when heat for melting, but not actually heating the liquid.

Latent heat of vaporization of water. Water is boiling the molecule off, the plateau cause the temp will remain the same at 100 degrees celcuis.

113
Q

What are colligative properties of water?

A

The colligative properties of a solutions depend only on the number of solute molecules dissolved.

ex) How dissolving salt in water will change the properties of the water.

such as lowering of vapour pressure, depression of freezing, elevation of BP

114
Q

Solution properties of water…

Just a pic, was gonna be a bitch to write out!!

A
115
Q

What is the difference between free water, absorbed water (bound water vs capillary water). ?

A

Free water- (bulk water) behaves like normal water.

Absrobed water (bound water)- Has no ability to freeze. Closely associated with the macromolecules of the food. Cannot support microbial growth. Hard to remove from food.

Absorbed water (capillary water)- Confined in pores and capillareis with food matricies. Restricted mobility.

116
Q

What is water activity? DEscribe bound water, capillary water and free water by their relative water activity.

A

Water activity is the measure of the availability of water molecules to enter into microbial, enxymatic and chem rxns.

Bound water in unavailable for rxns.

Capillary water is somewhat available for chem rxns

Free water is available for chem rxns.

117
Q

What is the formula for water activity?

A
118
Q

How is water activity measured?

A

Water activity is normally measured (instrumentally) by determining the vapour pressure of a food sample in a particular temp ina closed chamber.

Water activity of pure water =1. So water activity will never be more than 1.

119
Q

What does a moisture sorption isotherm graph show?

A

The relationship between water activity and moisture content.

Which is a complex, non-linear relationship.

120
Q

What are moisture sorption isotherm graphs used for?

A

Can predict the effect of change in water content on water activity

–> hence food stabilitt under storage condition.

Moisture sorption isotherm (MSI) graphs show under contant temperature.

121
Q

What is the water activity number that stops bacterial growth?

A

Below 0.85 water activity there is really no microbial growth

122
Q

True or false

The rate of most chemical rxns decreases rapidly with a decrease in water activity.

A

True,

b/c the decreased rate is believed to be due to the lack of solvent for aqueuous components of the rxn (ex. catalysts).

123
Q

True of false

The rate of lipid oxidation may increase at very low water activity (a (lower)W) and decrease a high water activity?

A

True

At low water activity dehydration of metal catalysts make them more efficent.

124
Q

What are methods that are employed to control water activity in MIlitary rations?

A

Low water activity fillings (dried cheese, pb, pepperoni)

Humactants (salt, sugar, glycerol) to prevent moisture migrations from high aW bread to the fillings.

Acidic ingredients to low pH (prevent bread fermentation)

Vacuum packaging- removal of ox and lowing aW

Baking at 185 ferenhight so bacteria cannot survive

Special packaging material -to prevent ox and moisture migration

125
Q

What is an emulsion?

A

An emulsion is a mixture of two immiscible fluids or phases

126
Q

What are the three types of emulsions?

Examples of each?

A
127
Q

What will happen if a mixture of pure water and oil is left aside?

Why?

A

Contact between the oil and water molecules is thermodynamically unfavourable and the will try to minimize it.

Interfacial tension/ surface tension is a force that minimizes the contact of two immiscible phases.

128
Q

Why are emulsions not thermodynamically favourable?

A

The mixture of water and oil, or water and air are no thermodynamically favourable b/c they require energy to make an emulsion

We need to break the interfact to create droplets of oil in water or water in oil

Energy required to make an emulsion.

129
Q

What is the equation that describes: the energy required to make an emulsion?

A
130
Q

How are emulsions made?

A

The interfacial tension must be sheared (whisk, shake, blend) to disperse the phase. Into emulsified state.

Fun fact: one spoon of oil can make more than 30 billion oil droplets!!

131
Q

What is a homogenizer?

A

The instrument that breaks up the dispersed phase, into a stable emulsion with smaller droplets.

132
Q

What are some characteristics to recognize from emulsions?

A

Characterized by their continous pahse, dispersed phase, droplet size, type of emulsifieer used… etc.

Emulsions should be characterized by their distribution of droplets rather than one average value.

An average droplet size is also used to characterize emulsions.

133
Q

Can we keep on decreasing the droplet size to increase the emulsion stability (with small droplets) ?

A
134
Q

How can we decrease the energy required and increase the stability of emulsions with small droplets?

A
135
Q

What are the role of sufactants and emulsifiers?

A

Surfactants and emulsifiers both mean the same thing. Surfactant is more commonly used discussing soap/detergents whereas emulsifiers are used for food.

They both lower interfacial surface tension!!

Emulsifiers are amphiphilic molecules, they lower the interfacial tension so that less E is needed to generate emulsions.

These emulsions with emulsifiers would be kenetically stabilized.

136
Q

What are the most common emulsifiers?

All emulsifiers need both a hydro-phobic and philic end.

A

Small molecule emulsifiers, much smaller compared to proteins.

137
Q

How do small molecule emulsifiers stabilize an interface?

A
138
Q

Polymeric emulsifiers.

Differnt proteins can unfold to different extents at the surface.

What are some examples of polymeric emulsifiers?

A

Proteins such as milk proteins (whey and casein), egg protein, plant protein (lentil, pea, beans etc.) can act as emulsifiers.

Whey protein maintains its dense structure at the interface: globular configuration.

139
Q

Stability of emulsions.

Discuss kinetic stability vs thermodynamic stability.

What leads to aggregation and fusion of droplets?

A

In emulsions, oil droplets are always attracted to one another and this eventually leads to aggregation and fusionof droplets leading to emulsion destabilization.

Kenetic stability- only stability of emulsions. That means one cna only extend their stability.

Thermodynamic stabiltiy- Emulsions are always unstable. Their eventual fate is complete seperation of oil and water phases.

140
Q

What can be done to avoid fusion of droplets?

A

Change the infacial property. Coat them with emulsifiers with provide opposite charges and repel eachother.

Develop a thick interfacial layer such that droplets cannot aggregate, no fusion of droplets. (ex. a protein at oil droplet surface) ->picture.

141
Q

How does an increase in viscosity affect emulsion stabiltiy?

Some examples of things that increase viscosity in a continuous phase?

A

Higher viscosity of continuous phase will reduce the motion of droplets through the continuous phase.

Thickening agents like gums, geletin (oil in water or air)

Thickening agents like wax (water in oil)

142
Q

What are the two types of gravitation seperation?

A

Creaming- as oils are less dense than water, the dispersed phase of O/W emulsions rises and gathers at the surface of the emulsion.

Sedimentation- When dispersed water droplets in W/O emulsions pool at the bottom of the emulsion.

Seperated droplets can be re-dispersed by gentle mixing, provided the droplets ar eonly loosely associated and stable against coalescence.

The net graviational force act upon emulsions due to the differences in density between water and oil!!

143
Q

What is flocculation?

A

Process where two droplets associate with each other without losing their individual identities. Drops don’t fuse together, jsut atracted to eachother.

They may be seperated by force ex. gentle mixing.

144
Q

What is coalescence?

A

Coalscense is the fusion of two or more aggregated droplets into a larger droplet with a larger volume.

It is usually undesirable as it can accelerate sedimentation or creaming or destabilization of emulsions.

145
Q

When is coalescence needed in product manufacturing?

A

Production of butter and whipped cream, coalescence is necessary.

Limited emulsion coalescence in the mouth can contribute to lubricity and preceived creaminess (creams in desserts).

Want the fat to break up in the mouth, the creamy-ness of the dessert!!

146
Q

Examples of:

Oil-in-water emulsions (5)

Oil and air-in-water emulsion (1)

air-in-water emulsions (2)

water-in-milk fat emulsion (1)

Water in vegetable oil emulsion (1)

A

Oil-in-water emulsions- Milk, salad dressing, coffee creamer, mayonnaise, flavoured beverages.

Oil and air-in-water emulsion- Ice cream

air-in-water emulsions- whipped cream, meringue.

water-in-milk fat emulsion- butter

Water in vegetable oil emulsion- mararine

147
Q

What acts as the emulsifier in milk?

A

Various small molecules including whey and casein.

Homogenized to make the droplets smaller, a very stable emulsion.

148
Q

Describe how butter is made from cream (O/W or W/O and how it gets there)..

A
149
Q

What stabilizes mayonnaise?

A

Mayonnaise is an oil-in-water emulsion stabilized by egg lecithin and protein.

Highly concentrated oil droplets in mayo, provides a highly viscous thick gel-like system.

150
Q

In ice cream and whipped cream, what do the fat globules do?

A

The fat globules stabilize the air bubbles. The air pockets are coated with aggregated fat globules giving it all more stability.

151
Q

Which of the following is NOT an example of an emulsifier?

a) lectithin
b) whey protein
c) monoglyceride
d) triglyceride

A

Which of the following is NOT an example of an emulsifier?

a) lectithin
b) whey protein
c) monoglyceride

d) triglyceride

152
Q

What is an example of a polymeric emulsifier?

A

Casein

153
Q

Energy required to make an emulsion can be lowered by:

a) reducing the oil droplet size
b) reducing the oil-water interfacial tension

A

Energy required to make an emulsion can be lowered by:

a) reducing the oil droplet size

b) reducing the oil-water interfacial tension

154
Q
A

Science of Food (4 decks)

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