Lecture 5: Food Storage and Food Packaging (Methods to prolonged storing…
Lecture 5: Food Storage and Food Packaging
Main purposes of storing food
Reducing kitchen waste
by preserving unused or uneaten food for later use.
pantry food (spices) or dry ingredients (rice and flour) for eventual use in cooking.
better balanced diet
throughout the year.
for catastrophes, emergencies and periods of food scarcity or famine.
of harvested and processed plant and animal food products for
distribution to consumers
from animals or theft.
Conditions after harvesting
Growth of roots
- green peas, corn; at
- asparagus, red carrot
Rotting and molding
- onion, garlic, potatoes
Main factors of food spoilage during storage
- rate of UV rays, oxygen, moisture, temperature difference
- from microbe, insects, soil
- shaking, compression, peeling, impact
Mishandling of food items by workers
Methods to prolonged storing duration
Using chemical actions.
Controlling the spread of disease.
Controlling the air or atmosphere.
Harvesting at the right time.
Factors influencing stores products
low temperature - products become frozen and wounded due to coldness.
high temperature - spoilage occur and reduce the market duration.
low humidity - product loses moisture, dry and wrinkle.
high humidity - encourage the growth of microbe.
food stuffs are kept in dark place or less light - to prevent photosynthesis from happening and alter the taste and smell of fruit.
some lipids are sensitive to light and may oxidize in the presence of UV.
modified atmosphere - to reduce the oxygen concentration and increase the carbon dioxide concentration
gas carbon dioxide are allowed to enter/exit the storage - for best result; to control total of respiration.
carbon dioxide - prevents insects, and depending on concentration, mold, and oxidation from damaging the grain.
place of manufacturing
Packaging and labels - to encourage potential buyers to purchase the product
Marketing communications and graphic design - applied to the surface of the package and the point of sale display
Containment or agglomeration
Engineered to help reduce the risks of package pilferage
- to help indicate that the package and contents are not counterfeit
- to deter tampering
- to help indicate tampering
Barrier and physical protection
- to control the amount of light, heat, moisture and gas, and presence of microbe
depend on the
ability to transfer heat
or possess specific
low thermal conductivity
- paper box, polysterene and polyurethane
(aluminium foil) - could reverse radiation heat
Moisture and gas
for dry food and food sensitive to gas (oxygen, ethylene)
for frozen and modified atmosphere food, duration in market depend on the rate of heat, carbon dioxide and oxygen transfer through package material
- could be penetrated by UV rays and visible light
- could not be penetrated by UV light
Presence of microbes
good package material - prevent the entrance of microbe
main source of microbe contamination -
packaging without sterilization
other sources - entrance of
contaminated air or water
through small pores on surface of food; not suitable
on packaging - tear, broken;
unhygienic packaging environment
Presence of desiccants/oxygen absorbers
- help extend shelf life; keep the contents fresh and safe for the intended shelf life
Characteristics of materials used for food packaging
produced when in-contact with product.
source of contaminant
to the product.
Durable, not easily tear, not fragile or dented
Labeling - properly and clearly
Types of Food Packaging
protect the product during delivery and distribution
built from wood, steel, tank etc
protect and display of product for sale
products are kept in volume/bulk for consumers
made from tin, bottle, tubes, paper boxes etc
does not penetrated by humidity, gas, smell and microbe
does not react with food
filling rate is as rapid as filling the cans
suitable for heat processing
penetrated by micro waves and light to display its content
hard, can be arranged by stacking
heavy - increase output cost
easily broken/fragile, crack - risky to consumer
Made by heating mixture of
sand (73%), NaOH (13%) and CaO (12%)
Paper and boxes
paper to make boxes - made from wood which is hydrolyzed with acid (sulphate pulp) or alkaline
sulphite pulp - lighter and softer, useful for food and sweets packaging for retail shops
can also be constructed heavy and hard
important to make strong paper
specialized paper packaging - grease proof paper to pack fish and meat
expensive and heavy
Types of steel packaging
made with DWI (draw and wall iron) method or DRD (draw and redraw)
DWI - produce thin and soft cans; suitable for gaseous drink - gas pressure in the can helps to retain the shape
DRD cans - heavier and thicker; suitable for sterilized food
a layer of lacquer (
) is applied - prevent interaction between food and tin
similar to 3 or 2 layers; added with aerosol pump
propellant elements are mixed or separated using plastic bag
propellant allowed for food - nitrogen, carbon dioxide and Argon gas
use to store pasteurized food, syrup, powder and non-heated cooking oil
electrolyte-covered pieces of steel on both sides by tin
new technology: tin is replaced with chromium dioxide and thin pieces of steel
provide full protection to food product
suitable to be stored at room temperature and exhibition
its content could not be disturbed
Plastic bag or flexible film
cheap, light and prevent microbe entry
can be covered or sealed using heat
-strong and firm material, and can be printed
could be produced, used and stored
many types, with various thickness
able to follow shape of food, not wasting storing space
Textile and wood
no protection from gas and humidity
not suitable for rapid filling and less attractive
limited to packaging for delivery purpose only
cheap, durable and reusable
commonly used for fruits, vegetables, leaves etc
provide stronger protection, boxes can be overlapping
easily rotten, not reusable and less attractive