Chapter 3: Food Preservation Flashcards
does not really preserve food, in a way, prolongs shelf life and destroys pathogenic and other organisms
cooking
name given to a group of compounds found in wood smoke that are expected to have some bacteriostatic and bactericidal effects
smoking
this temp can delay the spoilage of foods by retarding the metabolic activities of the microorganisms and prevent their growth, multiplication, pr production of toxin
low temperatures
temperature ranges from 1-10C
at 10C most pathogenic microorganism activities are slowed down
refrigeration
home refrigerators are maintained at this temp ranges
4-7C
process by which water changes from liquid to solid state under sub-zero celcius
can reduce Aw due to unavailability of liquid water
freezing
freezing in bulk and in air
formation of most ice crystals over 3-72 hours of freezing at temp relatice close to 0
forms larger sized crystals that may affect texture, palatability, unction, and nutritional quality of food
slow freezing
carried in a span of 30 mins or less using deep temps that range down to -40C
quick freezing
immersion of the food or the packaged food in a refrigerant
done in less than 30 mins
direct contact with
food is in contact with the passage container of refrigerant at -17.8 to -45.6C
indirect contact with the refrigerant
frigid air at -17.8 to -34.4C is blown across the material being frozen
air blast freezing
makes use of gases that liquefy at very low temp of -60C
rate of freezing is ultra fast
liquid nitrogen and carbon dioxide are the most commonly used
cryogenic freezing
hazard from putting food in the freezer: dehydration that results in a defect
freezer burn
hazard from putting food in the freezer: loss of ascorbic acid, onset of rancidity and discoloration
oxidative deterioration
too slow or too rapid melting of frozen foods, liquid may be leached out carrying with it some of soluble components of the food
thawing of frozen foods
the pink of reddish liquid that comes out from meat during thawing
drip or bleeding
liquid that comes out from fruits and vegetables are called
leakage
food is thawed slowly back to its normal fresh state by increasing storage temp
advantage: results in better food quality closer to its fresh state since most liquid are reabsorbed
disadvantage: enzymatic and microbial activities
slow thawing
food is thawed at a very rapid pace resulting in lesser danger of microbial growth
disadvantage: losing fresh quantities
rapid thawing
processing foods by using special microorganisms acting on food constituents with or without the addition of sugar, salt, or acid
fermentation
addition of vinegar to fruits and vegetables w/ or w/o spices that may be unfermented, partially, or fully fermented
pickling
reduction of water activity and the production of acid which is not conducive for growth of some microorganisms
osmotic dehydration
requires the action of yeast or a given substrate containing sugar or any fermentable carbohydrate to produce alcohol and carbon dioxide under aerobic or semi-aerobic conditions
ex: yeast breads, wines, beer, and distilled liquors
alcoholic
alcohol produced from alcoholic fermentation are further acted upon by Acetobacter bacteria to produce acid or vinegar
ex: vinegar
acetic acid fermentation
sugar in food is acted upon by lactic acid bacteria to produce lactic acid, alcohol, and carbon dioxide
ex: butter, yoghurt, cheese, pickles, fermented milk, burong mustasa, pickled vegetable product (atchara, cucumber pickles, singkamas)
lactic acid fermentation
factor affecting the the quality if fermented or pickled products
there must be the presence of sugar or any fermentable carbohydrates
right substrate
factor affecting the the quality if fermented or pickled products
presence of the enzymes to catalyze the chemical changes for the development of the desirable characteristics of the fermented products
right microorganism
factor affecting the the quality if fermented or pickled products
right temperature, humidity, pH, eater activity to allow maximum growth of the microorganisms
right environmental conditions
removal of available moisture in food to a level that will no longer be conducive for the growth and multiplication of spoilage microorganisms
drying and dehydration
applied to all methods of removing moisture in food, whether by heat of the sun or by artificially produced heat or by other means
ex: Sun drying, air drying, oven drying.
drying
drying by artificially-produced heat under controlled conditions of temperature, humidity, and air flow within a chamber
removes nearly all moisture in food
ex: freeze-drying, vacuum dehydration, hot-air dehydration
dehydration
food is exposed to solar energy, heat is not so intense, hence drying is slow
sun drying
food is exposed to hot air that move across the food
artificial heat
food is soaked in very high concentrated salt or sugar solutions or solvents to leach out the liquid within the cell of the food
process is repeated (step-up) until final moisture reduction level is attained
osmotic dehyration
process of dehydrating frozen foods under vacuum so the moisture content changes directly from a solid to gaseous state without undergoing through the liquid state (sublimation)
products can be rehydrated to its fresh form
expensive process
freeze drying
best temperature for drying
50-60C
sugar at high concentrations of 60% and above has a preserving effect because of the unfavorable osmotic pressure created by sugar in the food products
preservation in high sugar
preserves food by causing high osmotic pressure resulting in plasmolysis of the cells and in making water unavailable to microorganisms by binding or tying up moisture
preservation in high sugar
prepared by boiling fruit juice w/ or w/o water and sugar
concentrating to a point where gelatinization takes place upon cooling
jellies
clear jelly in where there is suspended slices of fruit or peel
marmalade
prepared by boiling the whole fruit pulp with sugar to moderately thick consistency
jam
prepared by boiling mashed fruit pulp with sugar to a semisolid mass of homogenous consistency
paste candies
fruits or combination of fruits cooked in syrup but retaining the shape or shapes of the fruits
fruit preserves
prepared by gradually concentrating fruits in syrup by repeated boiling until the fruit is heavily saturated with sugar, then, dried
candied fruits
any substance added, directly or indirectly, to food to improve its quality in terms of appearance, flavor, texture
keeps quality and nutritive value
additive
substances that unavoidably become part of the product through some phase of production, processing, or food packaging
incidental additives
substances added on purpose to perform specific functions (improve color, flavor, odor, and texture)
intentional additives
use of additives is regulated by the Food, Drug, and Cosmetic Act
RA 3720
involves exposure of the food to ionizing electromagnetic waves of ultraviolet light, x-rays, and gamma rays
irradiation or cold sterilization
theory on how radiation preserves food
supports that a sensitive portion of the microorganisms ionized when hit by radiation
direct hit theory
theory on how radiation preserves food
surrounding the microbial cell producing oxidizing and reducing radicals that are destructive to the microorganisms
ionizes the water
more resistant than vegetative microbes
spore formers
more resistant than molds
yeats
type of microbial spoilage
mold, being aerobic, grow mainly on the outside surfaces of the affected foods, initially small separate colonies
food becomes sticky, whiskey, and locally colored
moldiness and whiskers
type of microbial spoilage
word used to refer to spoilage of fruit, vegetables, eggs, and other foods
rots
growth of bacteria on moist surfaces of vegetables, meat, fish
may cause taints and odors and can result in such deterioration of the food that generates into slime
pigmentation may occur
slime
spoiled color in food of serratia marcenens
red
spoiled color in food of sarcina lutea
yellow
spoiled color in food of aspergillus niger
black
spoiled color in food of pseudonomas fluorescens
green with fluorescens
spoiled color in food of penicillum species
green
formation of a viscous sticky material closely allied to slime
ropiness
fermentative spoilage
arises close to the bone meat
bone taint
fermentative spoilage
occur in canned foods in a non-gas-producing fermentative spoilage
flat sours
fermentative spoilage
cans occur as a result of gas producing fermentation in which large quantities of gas are evolved that the pressure within distorts the side and ends of the can and may blow
bulging
aerobic decomposition of protein-rich food that leads to the development of bitter flavors in foods that are not pleaste
putrefaction
processing of heating food to a certain temp and holding it at that temp until most of the possible pathogens present in food are destroys or killed
ex: for milk and fruit juices
pasteurization
process where food is rendered completely free of microorganisms, can injure human health
use temp higher than pasteurization
“commercially sterile” product is not completely free of microorganisms but has killed all but the more resistant bacterial spores
conditions in the container are not conducive for growth of bacterial spores
sterilization
method of food preservation that utilized the principle of pasteruization and sterilization in hermetically sealed tin cans or bottles
canning or thermal processing
require sterilization temp above 100C for a certain length of time depending on the nature of food product
medium and low acid foods
sterilization aims to destroy the heat resistant microorganism, which can survive at high temp under conditions of low acidity
c. botulinum
if canned, may not require use of pasteurization
high acid foods
heating the product after it is sealed in the container
cold pack method
food is hot filled into the container then sealed under aseptic conditions and processed immediately
hot pack method
food is cooked and filled hot into sterilized containers then sealed under aseptic conditions
open kettle method
refers to the application of heat to sealed cans or to partially sealed containes
methods or processing
applicable to processing of the mpre acidic foods
water bath
applicable to processing of the more acidic foods
steamer
spoilage in canned products
can be a hydrogen swell, springer, or flipper
swell
spoilage in canned products
characterized by the development of acidity in food w/o swelling caused by the growth of thermophilic microorganisms as a result of lack of processing or cooling
flat sours
spoilage in canned products
result of storing cans while to warm causing food discoloration and disagreeable flavor
stack burning
spoilage in canned products
due to the effect of various metals, high temp, prolonged heating or to bacterial action
discoloration
spoilage in canned products
result of long exposures of foods even before foods are placed in the containers
foreign flavors
external can defects
defective can has normal-looking flat ends
one of the ends will become convex when any part of the can is struck sharply
affected end snaps back to the normal position when very light pressure is applied
flipper
external can defects
can bulges at one end
if pushed, can bulge transfers to the opposite end, while the pushed end become normal
springer
external can defects
can bulges at one end
if pushed, the bulge springs back
soft swell
external can defects
can bulges at one end or both ends
bulge cannot be pressed inwards by hand due to the internal can pressure
hard swell
external can defects
can has normal-looking flat ends
one or both ends flip slightly on application of light finger pressure
flipping is at the side of the can
soft spot
external can defects
can defect characterized by pronounced deformation of the can body
dents
external can defects
dripping of can contents
scams or can walls are ruptured and/or perforated
leakers
external can defects
marked deformation of can seams
indicated that the lot was not properly processed, lot was mishandled, and/or poor cans was used for processing
defective cans
iexternal can defects
ndicates mishandling and/or that the stock is from an old batch
rust formation
external can defects
rust formation is in the form of small dots, usually on top of cans or on the seams
no noticeable pitting of iron
slight rust
external can defects
rust formation is immediately evident and there is pitting iron
extensive rust
external can defects
label is either torn, loose, very dirty, or absent
label defect
