All liquid dispersed in another liquid with which it is usually immiscible
Emulsion
Examples of oil-in-water emulsion
mayo, salad dressing, cheese, sauce, gravy
Examples of water-in-oil emulsion
butter, margarine
Examples of naturally occurring emulsions
milk, cream, egg yolks
Type of emulsion: salad dressing (oil and water)
temporary
Type of emulsion: need the addition of stabilizers (yogurt, french dressing)
semi-permanent
Type of emulsion: very stable and viscous (mayo)
permanent
Act as a bridge between oil and water (hydrophilic and hydrophobic)
Examples: mono and diglycerides, starches, soy and milk protein, vegetable gum, gelatin, etc
emulsifying agents
Ways of "breaking the emulsion"
extreme temperature, too fast of addition of dispersion into continuous phase, add much in the dispersion phase, agitation, long periods of storage
Two stages of breaking the emulsion
Flocculation (reversible)
Coalescence (irreversible)
The temperature at which a compound changes from a solid to liquid state
melting point
4 determinants of a melting point
degree of saturation--increase SAT increase solidity at room T
length of C chain--shorter=lower melting point
cis-trans configuration--more trans double bonds, higher melting point
crystalline structure--larger fat crystals, higher melting point
Determine the spreadability of liquid oils held together by the solid fat crystals
the more unsaturated the more____
Plasticity
Fats and oils are _____ in water but will dissolve in organic solvents such as benzene, chloroform, and ether
insoluble
Sense of fullness that fats introduce
satiety
Two methods to help delay the onset of hunger
1. fats take longer to digest
2. delay the emptying of the stomach contents
What part of milk is used to make butter
the cream that floats to the top of undisturbed, unhomogenized milk
how USDA defines butter:
80% milk fat
16% water
4% solids
*may contain salt, colorings, etc added but USDA doesn't ask to define those
Butter production
phosholipids surrounding fat in milk--(agitation)-->breaks membrane--> splits into fat globules and liquid-->fat globules--(churned)-->butter
Butter grading
Voluntary and based on processor
AA, A and B
What is butter grading based on?
texture, flavor, color, salt content
Regular margarine contains the same amount of calories as butter but the ___ ____ differ
fat sources
Plant oils that have been hydrogenated to make them more solid and pliable to make this product and many are super glycerinated to make them more pleasing to the mouth
shortening
Derived from plants, primarily the seeds of soybeans, corn, cottonseed, rapeseed, etc
Oils
When oil is removed from the plant source by either cold-pressing or chemical solvents
Extraction
Process by which a neutral, low-ramona, bland-flavored oil is produced
Refining
The fat from swine (pigs)
Lard
Animal fat from beef, cattle, or sheep
Tallow
Solid fat from kidneys and loin of beef and sheep
Suet
Originates from the seeds of the theobroma cacao tree, melting point just being body temperature, used for soaps or cosmetics
Cocoa Butter
The temp that the fat will release a blue/gray smoke
Smoke point
The temp at which tiny wisps of fire streak to the surface of a heated substance
~30% of egg weight, nourishment for embryo, color dependent on feed of the hen
yolk
surrounds the yolk
vitelline membreane
rope-like structure, anchors yolk
chalaze
sits on the surface of the yolk
germ spot
~58% of egg weight, make up largely of protein and water, constructed of layers differing in viscosity, alternating thick to thin
albumen (egg white)
Found between the egg white and the wheel are two membranes (inner and outer), protects against bacterial invasion
shell membranes
Between shell membranes at wide end, increases as eggs age, larger in pasteurized eggs
air cell
Hard and made of calcium carbonate, ~12% egg weight, contains thousands of small pores, color dependent on green of hen
shell
The waxy coating on an eggshell that seals the pores from bacterial contamination and moisture loss
cuticle (bloom)
Nutrient Content of a large egg
75 kcals, 7g protein, 5g fat, 186 mg cholesterol, vitamins A,D,E,K and several B vitamins, minerals: selenium, iodine, zinc and iron
Downside of egg substitutes
Remove yolk and replace it with vegetable oil and this decreases the cholesterol but they add sodium
Upside of egg substitutes
ultra-pastuerized, packaged then refrigerated, good for uncooked foods (reduces the risk of contamination)
True or False: all poultry produce eggs
True: these include quail, duck, goose, turkey, ostrich
True or false: eggs from quail, duck, goose, turkey and ostrich are more likely to contain harmful bacteria
True and they should be well cooked
Key to cooking eggs
keep the temperature low and or the cooking time short
Egg white coagulation temp
140-149*F
Egg yolk coagulation temp
149-158*F
Increases the coagulation temp and more heat is required
sugar
lowers coagulation temp--added to mixture prior to heating
salt
lowers coagulation temp, too much causes curdling, prolonged heating results in thinning
acid (vinegar or tomato products)
During egg prep bring ____ to max thickness before adding uncooked egg
starch
High heat during hard cooking eggs causes sulfur in white to combine with iron in yolk and
forms ferrous sulfide and causes a greenish blue ring around yolk
Hard cooked eggs should be cooked at a
simmer NOT boil to avoid tough rubbery eggs
Advantages of Hot start method:
greater temp control, easier to peel, shorter total cooking time (12-15 min)
disadvantages of hot start method:
greater tendency to crack when lowering into boiling water
advantages of cold start method:
less attention, eggs easier to add water, less likely to crack
disadvantages of cold start method:
egg white more rubbery, "greenish tint" more likely
Why do boiled eggs some times crack
extreme cold to extreme hot and pressure builds up in egg
To prevent: stir eggs out to come to room T or poke pin hole in air cell
Formation and stability of foam depend on:
beating technique, temperature, type of bowl, separation of yolk and white (even a small amount of fat can affect this), effect of added ingredients (water, oil, cream of tartar)
increases beating time, creates smooth stable foam, less likely to be over beat, add at soft peak stage
Sugar
decreases stability and volume of egg white foam, rarely added
acid because it lowers the pH from the norm 7.6-7.9
Bubbles on the surface but not all of white is broken up, foam extremely unstable, air cells variable in size but large, starts to become opalescent
add acid, cream of tartar, salt, vanilla at this stage
Foamy stage
air cells medium fine, all of white exists as foam, mass is elastic ,soft peaks fall over near the same of foam when beater is lifted
add sugar quickly but gradually at this stage
soft peak stage
fire are cells, very white and opaque, foam white table, shiny, only tip of peak falls over as beater is pulled from foam
stiff peak stage
mixture extremely white, foam not stable, drainage occurs rapidly on standing, mass brittle and inelastic, peaks remain rigid in points
dry stage
True or False: freezing a whole egg is possible
false: not possible, it will crack under expanding liquids
food processors will crack egg and freeze separate or mixed components
egg storage
time:
temp:
humidity:
shrinkage:
time: short
temp: low temp, just above freezing, avoid storing at >60*f
humidity: high, retards moisture loss
shrinkage: increases air cell size--rate dependent on storage conditions, and retention of protective covering on shell
white/yolk stand take, yolk firm, large proportion thick white to thin white
fresh eggs
white runny, yolk flat, equal amounts (or >) of thin to thick whites
"old" whites
USDA grade B
lowest grade and not sold in supermarkets but sold to food service establishments
method used to grade eggs based on observing eggs against a light
candling
freshness detected by cracking egg open onto flat surface and observing at height of its thick albumen, numbering system, lower number= lower quality
measuring haugh units
Grade AA in haugh units
72 or >
whites sit up tall and firm
Grade A in haugh units
60-71
yolk round and upstanding, thick white is large in proportion to thin white, stand fairly well around yolk
Grade B in haugh units
31-59
spreads out, yolk flattened, much more thin white than thick white
Eggs (under egg products inspection act of 1970) must be:
wholesome, unadulterated, truthfully, labeled
monitored by USDA
applies to eggs shipped inter and intra state
egg thats DO NOT pass inspection due to cracked, dirt stained, rotten, blood stains, etc
Restricted eggs
True or false: size and grading are related
False they are UNrelated
Large egg is how many cups? ounces?
1/4 cup or 2 ounces
If egg cracked keep yolk
cover, submerged in water and use within 2 days
if egg cracked keep white
covered in glass container, store no more than 4 days
Keeps eggs in the fridge and use within _____
4-5 weeks of pack date or by expiration
The chances of an egg being internally contaminated are relatively low less than
1 in 10,000 commercial eggs
True or false: it is more common for contamination to occur during handling and prep of eggs than interally
true
Internal infection of salmonella
infection in ovary, absorbing bacteria through pores
External infection of salmonella
more common and happens during improper handling of infected person by fecal contamination
Precautions to prevent food borne illness
do not wash eggs, cook all eggs to 145*F, pasteurized eggs for recipes that have light cooking, use separator rather than passing back and forth between shell
Elderly, infants, youth children, immunocompromised (HIV, AIDS, etc) all have this in common
high risk individuals for food borne illness
Overall dairy consumption in the us by adults (less than 3 cups consumed)
79.3%
Overall dairy consumption in the us by adults (more than 3 cups)
14.5%
Overall percentage of people NOT consuming any dairy
~6%
Dairy consumption over time
decreasing
Fermented yogurt with lactic acid bacteria causes
increased shelf life, improves digestibility of milk, changes in flavor
Yogurt consumers consume more of these nutrients than non-yogurt consumers
calcium, potassium, magnesium
**not necessarily yogurt but yogurt consumers are consuming more dairy as a whole
True or false: yogurt is more concentrated in nutrients than milk
True!
Percentage of adults consuming yogurt is
increasing (almost doubled percent 4-9%)
statically significant data
**different than dairy intake because ppl don't eat yogurt everyday but may eat dairy everyday
Non-hispanic whites are consuming ____ yogurt than mexican americans and non-hispanic blacks
more
true or false:non-hispanic blacks think they are lactose intolerant even if they aren't and so they consume little to no dairy or yogurt
true
Which income category consumes more yogurt than lower income category?
highest income category
In US which gender eats more yogurt for breakfast and snack?
Women and this is increasing over time
In children, which gender is consuming more yogurt?
girls
True of false: the yogurt market markets children and adult yogurt
true
Has cultures specifically for digestive well being
activia
Strains in activita
bifido bacteria--helps digestion but works while eating it, if one stops problems will arise again
Contains cultures specifically for immune health
danactive
strain in danactive
L. casei immunitas--very specific, only yogurt in US with this bacterium in it!!!
This yogurt has the most strains of bacteria in it of all yogurts
Siggi's-- has 6 or 7 strains
Different types of fibers (pre biotics) in yogurts
inulin, gelatin (can be kosher), oligofructose, pectin, natural, agar agar, chicory root extract
Issues with organic yogurt
no preservatives and so mold was growing in it
Organic branches of dannon
stony field and brown cow
Condition to call something oikos
cannot contain any artificial sweeteners
Greek yogurt has more ____ but less ____
protein
potassium
DGA for dairy is now ____ because people were not getting enough potassium (AI=___)
3 cups from 2 cups in 2005
4700 mg
*K is almost impossible to get from food
Can only claim certain things by the percentage you____ it by
reduce
example: reduce sugar and alternative sweeteners by 25%
This artificial sweetener is very expensive
stevia
This artificial sweetener is 30 to 300x sweeter so you can use less
advantame
if there is no artificial sweetener in yogurt
the sugar content will be higher
Will never find artificial sweetener in children yogurt but to reduce sugar intake
they will use stevia or another fruit from china
If you add a small amount of a product it can go under the _____ section in the ingredients list
"flavorings'
_____ varies amount sizes of yogurt but_____ is the same per amount of yogurt
vitamin D
calcium
____ has been fortifying their products for forever
yoplait
__% of american's ____ comes from dairy products
80
calcium
Milk is primarily
water (87.4%)
Other components of milk are
CHO (lactose)
protein--casein (80%) and whey (18-20%)
Primary milk protein
casein
Liquid portion of milk protein, mainly lactalbumin and lactoglobulin
whey
Fat (milk fat or butter fat) composition (SAT,MUFA,PUFA)
SAT: 66%
MUFA: 30%
PUFA: 4%
Cholesterol amount in whole milk
33 mg
Cholesterol amount in 2% milk
18 mg
Cholesterol amount in nonfat milk
4%
Vitamins in milk
vitamin A, D riboflavin, and trptophan
MInerals in milk
major is calcium, others: phosphate, potassium, magnesium, sodium, chloride, sulfur
Why is milk packaged in cardboard or opaque plastic containers
light affects the riboflavin in milk and so the contained help to block the light to reduce degradation
Milk grades are graded according to
bacterial count
Grades for liquid milk
A (highest, mostly found in stores) and B
grades for fat free/dry milk
US extra and US standard
US standard grading is ______, and the ____ pays for it but is a responsibility of _____
voluntary, dairy industry, USDA
A good preservation process in which liquids are heated to a specific temperature for a certain period of time to destroy most microorganisms that could cause disease, spoilage, or undesired fermentation
Milk pasteurization
Enzyme that if it is no longer active, milk safe for consumption
alkaline phosphatase
True or false: pasteurized milk will spoil
True, nonpathogenic bacteria in it still will convert lactose to lactic acid
still contains some pathogenic bacteria (cannot get rid of it all)
milk heated to 280*F for 2 seconds to kill bacteria, longer shelf life
Ultra pasteurized
milk heated to 280-302*F for two seconds, very high temp, aseptically sealed; no refrigeration needed (except after opening)
Ultra high temp (UHT)
good medium for microorganism growth (yeast, bacterial molds)
may cause TB, undulant fever, scarlet fever, septic sore throat
some states allow the selling of it but mostly not
Raw (non homogenized) milk
Prevents the separation of water and fat in milk
homogenization
Homogenization is a mechanical process that
reduces fat globule size but does NOT effect the nutrient content
little to no butter fat (<0.5%), longer shelf life, culture: streptococcus lactose (vitamin A and D fortification optional)
butter milk
cultured with milk with the assistance of lactobacillus acidophilus, bacterial is beneficial (lives in human intestines, produces some B vitamins, recommended during antibiotic treatment and lactose intolerant)
very sweet--lactose-->glucose and galactose (2x the sugar molecules)
acidophilus milk
"campagne of milk", very bubbly and fizzy in nature, made by added lactobacillus caucasicus and yeast, originally made from camel's milk but now cow's milk
kefir
Light cream or half and half fermented with streptococcus lactose or other acid
minimum of 18% milk fat is required, but if sweetness added this can be lowered to 14.4%
Sour cream
Whole or fat free milk that has 60% of water removed (reconstitute equal volumes of canned milk and water)
evaporated milk
whole milk evaporated by 50% and 15% sugar is added, cannot be used in place of evaporated milk
sweetened condensed milk
Milk that has all moisture removed, two types: nonfat and instant, nutritionally similar, long shelf life, inferior taste
caused by water evaporation which is accompanied by increased concentration of casein fat and mineral salts, scorches easily and can trap steal--milk boils over
skin formation
Ways to avoid skin formation
use lid, stir continually, float butter, whipped cream or marshmallows (why they are on hot cocoa!)
Adding acid to milk will cause
casein to coagulate
Prevention of coagulation by acid
thicken milk or acid with starch before, add acid milk (not milk to acid), avoid high temperatures when acid and milk mixed
Milk coagulated and form curds when combined with certain____ from animal, plant, and microbial sources
enzymes
salt can cause milk to
curdle
prevention: add to milk base, avoid high temp after combined
Fat content in light or coffee cream
18-36%
Fat content in light whipping cream
30-36%
Fat content in heavy whipping cream
not less than 36%
Fat content in half and half (not true cream, combination of cream and pasteurized milk)
10.5-18%
Factors affecting stability of milk foam
fat content (>fat=stability), temperature of cream (optimal 45*F 2 hours before whipping), age of cream (older=greater viscosity and ability to foam), sugar (increases stability)
Storage rule for all fluid milk products
refrigerate all fluid milk except unopened aseptic packs of UHT pasteurized milk
Classifications of cheese defined by
microbial characteristics, appearance, mode of packaging, place of origin
Common ways of classifying cheese
processing methods, milk source, moisture content
Classification of cheese according to moisture content: fresh
examples: cottage cheese, feta, cream cheese
moisture content is over 80% and they are note aged
Classification of cheese according to moisture content: soft
examples: brie and hispanic cheeses
water content ranges from 50-75% and are aged for just a short time
Classification of cheese according to moisture content: semi-hard
examples: bleu cheese, munster
water content ranges from 40-50%
Classification of cheese according to moisture content: hard
examples:cheddar, swiss
water content ranges from 30-40%
Classification of cheese according to moisture content: very hard
examples: parmesan and romano (hardest cheese)
water content is approximately 30% and are aged the longest
Cheese making starts with
coagulation of casein protein in milk
method used to determine the many characteristics of the resulting cheese
Two main methods to aid coagulation are:
the action of enzymes (renin) and acid
True or false: any mammal's milk can be made into cheese
True! examples listed in notes
10 lbs of milk to make
1 lb of cheese
The curd may be treated to remove more whey by
cutting, heating, salting, knitting and or pressing (last two are future optional treatment)
To expose cheese to controlled temperature and humidity during aging
curing
the chemical and physical changes that occur during the curing period
ripening
a cheese made from blending one or more varieties of cheese with or without heat and mixing in with other ingredients
processed cheese
USDA grading of cheese is
voluntary and optional
Cheese grades by USDA
AA,A,B,C
Cheese grading is based on
variety, flavor, texture, finish, color and appearance
Exceptions to cheese grading criteria:
colby cheese:
swisse cheese:
colby cheese: color not considered
swisse cheese:graded additionally for its salt level and eyes (holes)
the two most important principles when preparing foods with cheese
select the best cheese, keep temperatures low and heating times short
Chemical composition of cheese determines its functional properties which include
meltability, oiling off, shredbility, blistering (form with increased aging in cheese) browning and stretchability
cheese storage
most should be refrigerated and some can be frozen, but processed can be stored in cool, dark cupboard (but refrigeration more effective)
