Lecture 4 - Packaging technologies Flashcards
What is modified atmosphere packaging (MAP)? How many % of CO2 is required such that it is bacteriostatic?
MAP is a packaging technique to enclose food in a package in which the atmosphere is modified such that its composition is different from normal air.
- 5-50% CO2 is bacteriostatic
What are 5 functions of MAP?
(can think in terms of packaging functions / envt)
Protection (ambient envt)
1) Prevents oxidation and discolouration
2) Protection of nutrents that are easily oxidised
3) Prevents microbial spoilage
4) Delay ripening and senescence
Containment (physical envt)
5) Physical protecton of contents to prevent food from being crushed (e.g. potato chips)
What are some gases used for MAP and what kinds of food products are they used for? [5]
- CO2
- N2
- NO : used commonly for fruits as it inhibits ethylene metabolism and delays senescence
- Ozone : eggs during cold storage, fresh fruits and vege, fresh fish
- Noble gases
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MAP usually used for meats, fruits, snacks high in fat (nuts, potato chips) etc
What are some physical properties that packaging materials for MAP should possess? [4]
- Barrier properties : high barrier properties to prevent diffusion of oxygen and moisture into the packaging, else MAP will be ineffective.
[Mechanical properties] - Seal strength : high seal strength to form airtight seal to prevent gases (CO2, N2 from leaking)
- Impact strength : should be strong enough to withstand stresses during handling and transport without puncturing ;; and to prevent food contents in the packaging from getting crushed
- Tear strength : should not be too high, especially when designing MAP packaging for elderly
What is vacuum packaging? What are the 3 functions of vacuum packaging?
Vacuum packaging is a packaging technique involving complete removal of air (but often, may still have residual oxygen)
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Functions
1. Prevent growth of aerobic spoilage microbes
2. Prevent oxidation
3. Prevent colour detioration (from oxidation)
What are the requirements for packaging materials used in vacuum packaging? [physical properties]
- High oxygen barrier
- Crease resistance: packaging material should be resistant to crease/wrinkle formation, as wrinkles can affect integrity of packaging to be compromised and lead to exposure to oxygen in surrounding environment
- High seal strength : ensure airtight conditons
What are the limitations of vacuum packaging? [2]
- CO2 may be produced by microbes consuming residual oxygen in the headspace, leading to swelling of package (may affect integrity of packaging if it bursts..?)
- Damage to product : when air is sucked out, it can cause damage to the food matrix and cause food to be deformed, or cause soft and fragile foods to be crushed.
How to overcome the problem of vacuum packaging causing damage to the food strcuture?
- Slice products thinly and stack them evenly to reduce pressure points and prevent deformation
- Use rigid trays or structural support which helps to maintain product shape by resisting external pressure.
What are some food applications for vacuum packaging?
- Fresh/processed meat products
- Nuts
- Seafood
What is aspetic packaging?
A packaging technique where food is pastuerised / sterilised under HTST (high temp short time) conditions, and packaging is sterilised separately by irradiation or H2O2. The food is then packed into the sterilised packaging at ambient conditions
What are some packaging requirements for aseptic packaging?
- High oxygen and moisture barrier
- Strength
Why is multi-layered packaging used for aspetic packaging?
It ensures that there are multi layers of barriers (against flavour, oxygen, light and moisture) and ensure long shelf life under ambient conditions. Futhermore, it ensures that the packaging has the strength to withstand degradation from high temp / H2O2 / irradiation.
What are applications for aspetic packaging?
Shelf-stable products (e.g. milk, juices)
What is retort packaging?
What is the difference between retort packaging and aspetic packaging?
Retort packaging is a technique where food is filled into a pouch / metal can and heated to extremely high temp, rendering the product commericially sterile.
- Aspetic packaging : food and packaging is sterilised separately ;; retort packaging : food and packaging sterilised together
What are some requirements for packaging materials used for retort packaging? [physical / chemical properties]
- Coefficient of thermal expansion : should be low, to ensure that the packaging material does not expand excessively when heated, maintaining structural integrity
- Chemical inertness : prevent migration of monomers / additives into food
What is active packaging?
Packaging in which subsidairy (supplmentary) consitutents have been deliberately added into the packaging material/ packaging headspace to enhance the performance of the packaging system.
What aer some active packaging applications? [5] (e.g. oxygen scavenging…)
- Oxygen absorbers / scavengers
- Dessicants (moisture absorbers)
- Ethylene absorbers
- Antimicrobial packaging
- Odour removers
What is the definition of gas scavenging capacity?
Volume of gas absorbed per gram of scavenger.
What is the molar volume of gas at ambient environment?
22.4 L / mol
What is intelligent packaging?
Packaging that contains an external / internal indicator to provide information on quality (inherent attributes) of the food and / or the distribution and storage history of the food
Give some examples of intelligent packaging features.
- Food quality indicator (ripeness of fruits)
- Integrity indicator : indicates package has been compromised or is no longer sealed properly.
- Storage and temperature indicators : time-temperature indicators
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RFID tags to show storage and distribution history throughout the food chain
Calculate the oxygen scavenging capacity of Fe particle oxygen scavenger with 20% non-reacted Fe residue after using
Refer to tut 5
