Transcript Food Preservation

Food
Preservation
Methods
Food Preservation
O Food preservation is preventing the
growth of bacteria, fungi, and other
pathogens
O It also slows oxidation of fats, which causes
food to go rancid
Food Preservation
O There are many different methods for
preserving food
O About 14 “traditional” methods – lower
energy input and carbon footprint!
O Around 10 industrial or modern methods
O Canning, freezing, and drying food are the
most common methods for preserving
foods at home
Food Preservation Methods
Traditional:
O Drying
O Smoking
O Refrigeration
O Pickling
O Freezing
O Canning
O Heating
O Curing
O Salt
O Fermentation
O Sugar
Food Preservation Methods
Industrial:
O Pasteurization
O Vacuum packing
O Artificial food additives
O Irradiation
O Modified atmosphere
Food Preservation
O Maintaining nutritional value, texture, and
flavour are important aspects of food
preservation
O In some cases, the change in the character
of the preserved food has come to be a
desired quality
O Cheese
O Pickles
Canning
O Canning involves cooking food at a specified
temperature for a specified length of time
(pasteurizing) and then sealing it in specialized
sterile cans or jars with a vacuum seal.
O All this to prevent or prolong spoilage
O It can be used with most foods, including fruits,
vegetables, meats, seafood, and some prepared
foods (ie. jams)
Canning
O Lack of quality control in the canning process
may allow ingress of water or micro-organisms.
O BOTULISM
O Clostridium botulinum
O This organism produces no gas or obvious taste
and remains undetected by taste or smell.
Botulism
O Caused by a toxin produced by the
Clostridium botulinum bacterium
O Symptoms:
O Weakness
O Difficulty seeing
O Droopy eyes
O Difficulty speaking
O Paralysis
O Death
Botulism-Why is it so
dangerous?
O It thrives in low oxygen and low acid
environments
O It survives high temperatures (100 C)
O You cannot taste, smell, or see any evidence of
C. botulinum
O Pressure canners must be used
to can low-acid foods
Freezing
O Freezing is the process of chilling foods to at
least -18 °C or 0 °F.
O True freezing is not possible in the freezer
compartment of the average home refrigerator
O The temperature is too warm, between -12
°C to 0 °C (10°F to 32°F).
Dehydrating
O Drying or dehydrating is the process
of dehydrating foods until there is not
enough moisture to support microbial
activity.
O It is one of the oldest techniques, from
as early as 12,000 BC in Middle
Eastern and Asian cultures.
O It can be used with most foods,
including fruits, vegetables, meats,
seafood, grains, legumes, and nuts.
Dehydrating
O There are several different
techniques, some are relatively easy
to do and require no special
equipment
Fermenting
O Fermenting is the process of encouraging the
growth of “good bugs” to inhibit the “bad bugs”
that can spoil food.
O It can be used with many types of foods,
including fruits, vegetables, meats, seafood,
grains, legumes, dairy, and eggs to produce a
wide range of products such as wine (from
grapes), sauerkraut (cabbage), cured sausage
(meat), and yogurt (milk).
Pickling
O Pickling is the process of soaking food in a
solution containing salt, acid, or alcohol to
inhibit or kill bacteria and other microorganisms.
O It can be used with most foods, including fruits,
vegetables, meats, seafood, legumes, and eggs.
O Pickling is often combined with another
method, such as fermenting, canning, or just
refrigerating
O Typical pickling agents include a brine (high in
salt), vinegar, alcohol, and vegetable oils.
Curing
O Salting or curing draws moisture from the
I’m
back!
meat through a process of osmosis
O Curing is similar to pickling, and uses salt, sugar
acid, and/or nitrites. It is used for meat and fish.
O Simple, modern curing methods often reduce
the amount of salt and nitrites, which may
require that you refrigerate or freeze the final
product.
O Nitrates and nitrites are also often used to cure
meat and contribute the characteristic pink
color, as well as inhibition of C. botulinum
Smoking
O Smoking is the process of flavouring, cooking,
and preserving food by exposing it to smoke
from a burning or smoldering materially
(usually a wood)
O This effect is achieved by exposing the food
to smoke from burning plant materials such
as wood. Smoke deposits a number of pyrolysis
products onto the food, including phenols.
O These compounds aid in the drying and
preservation of meats and other foods and
add flavour.
Smoking
O Most commonly subjected to this method of
food preservation are meats and fish that have
undergone curing.
O Fruits and vegetables, cheeses, spices, and
ingredients for making drinks such as
malt and tea leaves are also smoked, but mainly
for cooking or flavoring them.
O It is one of the oldest food preservation
methods, which probably arose after the
development of cooking with fire.
Pasteurizing
O Pasteurization is a process for preservation of
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liquid food by heating.
Mainly applied to dairy and egg products.
In this method, milk or eggs are heated at about
70 °C for 15 to 30 seconds to kill the bacteria
present in it and cooling it quickly to 10 °C to
prevent the remaining bacteria from growing.
The product is then stored in sterilized bottles
or pouches in cold places.
This method was invented by Louis Pasteur in
1862.