Lecture 12: Quality and Stability of Frozen Foods Flashcards
1
Q
high quality of frozen foods is due to….
A
- low temp storage
- low availability of H2O (mostly frozen)
- microbiologically safe process and storage (don’t want pathogen or spoilage microorganism growth/activity)
2
Q
what are reasons why frozen foods are not inert or completely stable?
A
- chemical and enzymatic activities are not stopped even at frozen storage temp
- damage to texture due to ice crystals
- concentration effects, pH change, protein instability
3
Q
what are ways to control chemical and enzyme activities?
A
- blanching
- anti-oxidants
- vacuum packaging
- gas flushing to eliminate O2
- barrier packaging
- immersion in sugar syrups
- preservatives (SO2, ascorbic acid, citric acid, etc…)
- chelating agents
- low temp storage
4
Q
what are physical defects that can occur during freezing?
A
- loss of texture
- drip loss (texture damage from recrystallization)
- freezer burn
5
Q
as freezing time increases, quality _____ (dec/in)
A
decreases
6
Q
food quality is better protected at ____ temp
A
lower
7
Q
what is TTT?
A
time-temp-tolerance
8
Q
what is PSL?
A
practical storage life
- the max storage time at a given temp that gives an acceptable quality product
- evaluated by responses by a large number of consumers
- can depend on demographic consumer preferences
9
Q
what is HQL?
A
high quality life
- storage time which results in a just noticeable difference in quality of the product
- ie. when the frozen food can be distinguished from a control by 75% of a panel
- a lab concept that is carried out under carefully controlled conditions
10
Q
compare PSL to HQL
which one is higher?
A
PSL is 2-6 times higher
- slopes are parallel on storage life vs temp graph
11
Q
what does PSL and HQL depend on?
A
temp of storage
higher temp = higher quality loss = lower PSL and HQL
12
Q
what is the relationship of PSL and HQL to temp of storage?
A
they have a semi log relationship
