Topic 4 Flashcards
Food processing
conversion of raw animal & plant tissue into forms that are convenient and practical to use
what is the purpose of food processing?
To make the food palatable
Make it more convenient
Improve taste (ex: strawberry jam vs. strawberries)
To increase shelf-life
food preservation
the use of specific thermal and non-thermal processing techniques to minimize the number of spoilage
increase the shelf-life of a food
spoiled
no longer palatable
physical appearance changes, moisture is lost
are all spoiled foods no longer edible or safe?
no
what are the 3 classes of food preservation?
physical
chemical
biological
physical food preservation techniques involved
asepsis
drying
heating
cooling
irradiation
blanching
heat
what type of preservation doesn’t include chemicals or microbes?
physical
what is goal of physical preservation?
to prevent the food from changing its physical properties (ex: moisture loss)
describe the affect cooling has on food
decreases growth rate of microbes
describe the affect freezing has on food
stops growth of microbes
frozen water is unavailable to microbes
blanching
heating followed by immediate freezing deactivates indigenous enzymes of the food that reduce the food’s quality (ex: enzymes that oxidize vit C)
enzymes can change colour of food
colour of blanched food is ____ than food that isn’t blanched
brighter
irridiation
methods of killing microbes
chemical food preservation
addition of sugar, salt or chemical preservatives
preventing oxidative rancidity is what type of food preservation?
chemical
preventing browning of apples is what type of food preservation?
chemical
what effect does salt have as a food preservative?
causes osmosis killing microbes, increases water holding capacity
what effect does sugar have as a food preservative?
hydroscorbicity making water unavailable to microbes
biological food preservation
fermentation
what effect do microbes have on food?
produce enzymes that produce compounds in foods- may or may not be harmful
can make the food unpalatable
what occurs when microbes break down food?
release ammonia
many foodborne illnesses are caused by what type of microbes?
aerobic
oxidative rancidity
rxn with oxygen & unsaturated FA
chemical oxidative rancidity
production of synthetic enzymes
biological oxidative rancidity
enzymes produced by microbes
aspesis
practice to keep micro-organisms out of food, protective coverings around food
what are the coverings used in aspesis?
Shells of nuts
Die skins of fruits & vegetables
Shells of eggs
Skin or fat on meat or fish
(also includes packaging - wraps, polythene covers, canning etc.)
what are the benefits of asepsis?
prevents moisture loss
prevents entrance of microbes
prevents oxidation
drying
removal of water from foods
inhibits growth of microbes
how was drying accomplished in ancient times?
sun drying
plate drying
puts the food in a single layer & puts it in the dehydrator
Dehydrator will have: Heat source & fans (push out moist air)
Moisture will leave food & remain in the air, when the moisture in the air is equal to the food, the food can longer be dried (no gradient is established). When this happens, new air is established by the fans pushing out the moist air
what is a negative & positive effect of plate drying?
Food that undergo this process lose most of their vit C
cheap
drum drying
dry liquids to make powders, drum is hot & rolls, as it rolls the liquid food is coated on it & the food dries out
spray drying
spray liquid food into a hot chamber, liquid droplets immediately dehydrate when introduced into the hot chamber. There is a vacuum pump that moves out the moist air
how is milk dehydrated?
spray drying
does drum or spray drying work better?
spray
is drum or spray drying cheaper?
drum
freeze drying
based on sublimation, put food in freeze drier that has vacuum pumps attached, moisture will escape as a vapour, the vacuum takes out the moist air causing the food to constantly lose its moisture & dry
what needs to occur to the food after freeze-drying & why?
When you remove the food product & place it into moist air, the food will regain moisture vacuum packed immediately after treating
what is a positive effect of freeze drying?
Doesn’t require heating - no vits or minerals destroyed, method of least nutrient loss
what drying method results in the least nutrient loss?
freeze drying
what is the problem with drying by heat?
loss of heat sensitive nutrients including vit C, riboflavin & niacin
drying by heat
Heat is applied to remove water to kill microbes, not to kill microbes directly
what envr factors are important in drying?
temp & moisture level
the longer the heating process =
the more vit & mineral loss
thermal processing
Food shelf life can be extended if sufficient heat is applied killing microorganisms & inactivating the present enzymes in food
pasteurization
• Heating foods to a specified high temp for a short time kills most disease-causing microbes
slightly extends shelf-life by killing most food spoilage & pathogenic organisms
Kill most microbes
sterilization
a more severe process which destroys all microorganisms & may change the organoleptic qualities of the product
Kill all microbes
canning
food is held at a high temp for several minutes
what is the closest form to sterilization in the industry ?
canning
Batch pasteurization (LTLT)
product is held in a specific temp range for a long time, low temperature, long time
Ex: 62-36C for 30-35 mins
High temp, short time (HTST) pasteurization
product is heated to a higher temp but for a shorter time
Ex: 72C for 15 secs for milk, using a plate heater
what method of pasteurization is more common?
HTST
ultra-high temp pasteurization
heats at very high temp under pressure
kills almost all microbes
what type of pasteurization do unrefrigerated milk products use?
ultra-high temp pasteurization
the longer the food is heated =
the more vits are lost
what form of pasteurization causes the most nutrient loss?
LTLT
sterilization
complete destruction of microbes
Food is exposed to wet heat (vapour) for 15 min at 121C
what type of microbes are killed in sterilization?
Pathogenic & toxin-producing organisms
Spoilage microorganisms
what temp is used in sterilization?
over 100 C
pressure cooking
atm pressure is increased to increase the BP of water (hotter), destroys spores & microbes
incres BP =
more destructive to microbes & spores
&
food cooks faster
how can pressure cooking result in food poisoning?
If correct temp isn’t reached, there is a possibility that the spores will germinate & could lead to poisoning
ultraheat treatment of ultrahigh temp (UHT)
Continuous process & product is packaged after sterilization into sterile containers
product is moving continuously rather then being stationary
how does sterilization & UHT differ?
UHT - shorter time & higher temp
canning
food is held for a number of mins at a high temp
above 110C & under pressure
what does canning kill?
Kills harmful or spoilage-causing microbes & their spores
what effect does canning have on nutrient loss?
there will be some nutrient loss
Time for which the food is held at high temp depends on several factors including: (canning)
Microbial population in the food product
Size of the food product
pH of the product
Size of container - when placing a can in boiling water, the can will not begin to boil instantly
what effect does canning have onw ater soluble vits?
Water soluble vits may be lost when food is canned in water, especially if the water is discarded before consumption
convection
heat is transferred by movement
radiation
waves will hit something, will swirl & produce heat
conduction
heat transferred via touch
induction
heat is transferred by magnetic E
how is canning determined to be finished?
due to the location of the cold spot
Use probes to determine what part of the can was heated last & for how long
incres viscosity of food = ____ of heating
incres length
does a low pH food require a higher or lower temp?
lower temp
what needs to occur properly to prevent the growth of microbes?
heat
vacuum
seal
traditional canning
food is heated & held at a high temp while already inside packaging material
aseptic packaging
food can be batch heated in a sterile fashion & then placed in a sterilized container
what are the 2 methods of aspetic packaging?
boiling water canning
pressure canning
boiling water canning is used in what foods?
used for high acid foods
100C
pressure canning is used in what foods?
used for low acid foods
can also be used for high acid foods, but will result in a softer texture
what foods are high acid foods?
all fruits besides: figs, tomatoes & melons
rhubarb
fermented pickles
acidified foods
what type of foods require pressure canning?
low acid foods
what foods are low acid foods?
all vegetables except rhubarb
meats
poultry
seafood
soups
mixed canned foods
processing schedules
Length of time at a specific temp that a food must be processed
what affects processing schedules? (7)
pH value of the food
Composition of the food
Viscosity
Tightness of pack
Convection vs. conduction transfer of heat
Starches, fats & bones
Size of jar/can conduction
what affects the processing time?
whether food heats by convection, conduction or a combo of both
what must the cold spot do to ensure target pathogens are destroyed?
The “cold spot” in the food must reach the correct temp for the correct length of time to destroy target pathogens
how is heated transferred in solid foods?
mostly by conduction
what gets heated last in canned foods?
the cold spot
where does the cold spot tend to situated? & why?
in the middle of the can
Due to convection – the heated liquid at the bottom will move upwards & the colder liquid at the bottom will move downward
refrigeration
storing food at cold temp
Causes retardation of microbial growth, but doesn’t mean that pathogens are gone or not multiplying
freezing
in contrast to refrigeration at warmer temps, cause liquid water within the food to become solid ice
Microbe growth & enzyme activity (degrades quality of food) ceases almost completely
fermentation
Encourages growth of beneficial bacteria to inhibit the growth of pathogenic bacteria
used in preserving & providing a source of probiotics
what foods have fermentation promoted?
yogurt, prosciutto, bread, cheese, wine & chocolate
microwaves
Create heat through the movement of high frequency radio waves that energize some molecules within food & heats up the food
irradiation
exposure of food to ionizing radiation in the form of gamma rays, x-rays or electron beams
what are the functions of irradiation?
o Controls microbial growth
o Extends shelf life
o Preserves food by causing the formation of free electrons, ions & free radicals
Irradiation is approved in Canada for the following foods: (6)
o Onions o Potatoes o Wheat o Flour o Whole wheat flour o Whole or ground spices & dehydrated seasonings
what symbol do irradiated foods display?
“radura”
Symbol must be accompanied with the words “treated by irradiation” or “treated with irradiation”
• Vitamin composition & mineral retention can be affected by: (5)
o pH o Light o Oxidation o Water solubility o Other applications
vit C can be damaged by:
o Heat
o Oxidation
o Drying
o Enzymatic action of inherent enzymes when the food tissue us cut
• Thiamin can be destroyed by:
o High heat
o Nonacidic conditions
what vits are sensitive to heat treatment? (4)
Riboflavin, niacin, vit B6 & folate
high pressure
• food is placed under uniform pressure of up to 100,000 lbs. per square inch
what methods are included in high pressure food preservation ?
high-hydrostatic pressure processing or ultra-high pressure (UHP) processing
ultraviolet food preservation
non-thermal treatments to eliminate or reduce microbes in food
what methods are included in UV food preservation (3)
irradiation, pulsed light & ultrasound technology
high pressure/high temp
called pressure assisted thermal sterilization (PATS)
combines pressure & heat
kills C. botulinum
non thermal food preservation
includes UV radiation, pulsed light & ultrasoundn
continuous microwave food preservation
ipuree is passed through a tube & the microwaves are directed towards the center of the food, heats the food inside out
ex: sweet potato puree
what are the newer technologies in food preservation?
UV
high pressure
high pressure/high temp
non-thermal
continuous microwave process
paper
made from pulped cellulose fibers derived from wood
transformed into paperboard for direct food contact
used as an outer package or shipping package
is waxed or laminated with a plastic polymer (polyethylene) to improve resistance to water & oils
plastic
polyethylene terephthalate (PTE) is widely used in items like carbonated drink bottles b/w it is clear & impermeable to the carbonation gases
metals
includes aluminum & other metals like steel
often lined with plastic to prevent a rxn
glass
made from heated silica, sodium carbonate & stabilizers
what was believed to be the 1st package?
glass
what is an advantage & disadvantage of glass?
biodegradable
heavy & brittle
what is health canada’s advice on PBA?
o Current dietary exposure to BPA through food packaging uses is not expected to pose a health risk to the general population, including newborns & infants
recommend to apply ALARA (as low as possible)
modified atmosphere packaging (MAP)
respiration rates are decreased & shelf life is increased by modifying the air inside a package to MAP
kills microbes which require oxygen to survive
prevents oxidation of vit C & E
prevents oxidation of unsaturated FAs
edible films
coatings are applied to foods for its beneficial properties
prevents exposure to oxygen
can combine with antimicrobial chemicals
intelligent & active packaging
“smart” packaging that interacts with the external or internal envr of the package
o Has sensors & indicators that inform the processor, distributor, seller or consumer about the envr of the package
o Can close in the presence of gas or if the food is exposed to a new atmosphere then it will cause a colour change indicating its efficacy
what is the cheapest preservative?
salt
what is an envr effect of packaging?
source of municipal solid waste (MSW)
can be solved by using less packaging
what family is coffee?
Rubiaceae
what is the genus of coffee?
coffea
what species of coffee is used in global coffee production?
coffea arabica
coffeae canephora
what species of coffee is used on a smaller scale production?
coffea liberica
coffea deweveri
what type of fruit is coffee?
berry - 1 berry has 2 coffee beans
coffee - processing
removal of the bean from the fruit followed by drying
what are 2 methods of processing coffee?
dry
wet
dry processing in coffee
fruit is picked & placed in the sun to dry which takes 10 days - 3 weeks, the husk of the fruit is removed by a machine & the beans are revealed
wet processing in coffee
outer skin & pulp of the fruit are removed by a machine immediately following the harvest of the berries, after fermenting & washing tanks they’re dried for several weeks after which milling machines remove the skin
what is the most important factor affecting the taste of coffee?
roasting
pulping
removal of the outer skin
roasting
Beans are heated up to 900F for 16-17 mins where the coffee oil (caffeol) is released, the sugars within the bean caramelize & the beans develop a slightly burnt flavour
caramelizing triggers the darkening & flavour effects
oil contain caffeine
more the coffee is roasted or at a higher temp = ___ bitter & tangy taste & ____ caffeine
more
less
what are the 2 main roast types?
medium: delicate flavour & aroma
dark: bitter taste
what are the 4 types of roasts identified?
Light/pale
Medium
Dark/full roast
Darkest roast
decaf coffee
Caffeine is removed from green coffee beans by solvent extraction, water extraction or steam extraction
extraction solvent in decaf coffee
methylene chloride (organic)
American style coffee
coffee grinds placed in brew filters & pass through the unit of the pot
Grounds remain in the upper unit
turkish style coffee
made in a small copper pot with a long handle with 2 tsps of finely ground coffee & 1 tsp of sugar added to a cup of water & then brought to a boil
french
coarse, ground coffee is placed in the pot, hot water is added & steeps for 3-5 mins. The plunger is pushed down which separate the coffee grounds from the brew
plunger method, perforated method
coffee what method extracts the most flavour?
plunger method
what method is similar to the french method of making coffee?
turkish
italian
espresso is made on a stove-top espresso maker, utilizes pressure as the hot water is forced through very finely ground, dark roasted coffee to produce the espresso brew
what is the original maker of italian cofee?
Moka
describe the acidity of coffee
pleasant tartness, low acidity exhibits a soft, smooth & mellow taste
describe the mouth feel or body of coffee
heaviness, tactile richness & thickness when coffee is swished in the mouth
texture: oily, buttery or thin
coffee - aroma
termed fragrance & is attributed to the gases of the aromatic oils which are released when roasting
coffee - finish
refers to the immediate sensation after the coffee is swallowed, such as a chocolate finish, whereas others exhibit berry tones
coffee - flavour
accounts for:
Sweetness because of caramelization after roasting
Bitterness which results from products during roasting
camellia sinesis
evergreen & grown in tropical & subtropical regions
where are the finest teas grown? & why?
above sea level
Cooler temps & harsher conditions encourage the leaves to mature more slowly which optimizes the flavour
the smaller the leaf = ____ flavour
more
leaves don’t grow as long in colder conditions
herbal teas
infusions of: leaves, roots, bark, seeds or flowers of other plants
processing tea stages
- Withering: removes leaf moisture, breaks down into AAs & simple sugars & increases caffeine & polyphenols (provides brownish colouring)
- Rolling: leaves are crushed & broken
- Fermentation: polyphenols in leaves oxidize & become a copper colour (oxidation)
- Drying: uses heat & inactivates polyphenol enzymes, dries leaves & caramelizes sugars (oxidation rxn seizes)
what are 2 ways to prepare tea?
tea can steep
tea perforator
amora of tea
brisk or flowery tates
what do?es the tastes of tea depend on?
processing, growing region, weather, additives/flavourings, soil type, leaf age, length leaves oxidize & type of wood used in the drying process
what is responsible for the colour in tea?
polyphenols
what is reponsible for the fragrance & flavour in tea?
aromatic oils
what is the purpsoe of fair trade coffee?
to provide farmers access to international markets & fair wages for their labour
Protection needed due to boom & bust cycles
Farmers are poor & don’t have any savings to support themselves when their wages are poor
boom cycle
production is poor & prices are higher
bust cycle
too much production, prices are lower
