Frozen food quality + stability Flashcards
What causes quality loss in frozen food during storage? (5)
enzyme/chem rxn still continue, but slower ice crystals -> texture damage moisture loss pH change protein instability
The main problem with frozen food is: ____ due to _____
How can we prevent this?
physical defects: loss of texture; due to drip loss or freezer burn
fast freezing rate (smaller ice crystals)
stable storage temp (otherwise will melt/recrystallize)
glaze to prevent freezer burn
What are the various storage temperatures for frozen food?
common: -18C
long term: -30 to -40C
retail/display: -10C
home: -5 to -10C
How does frozen storage help preserve high quality? (3)
Aw almost zero
greatly reduce chem and enzyme rxn
no growth of pathogen/spoilage microbes
How can enzymatic and chemical reactions be limited? (9)
low temp antioxidants chelators blanching (inactivate enzymes) vacuum package (fatty foods - prevent oxidation) gas flush with N2 or CO2 - eliminate O2 barrier package immerse in sugar preservatives (SO2, ascorbic/citric/sorbic acid, benzoates, K metabisulfite)
What is the “TTT?” What does it describe?
time-temperature-tolerance (establish by west regional research lab of USDA)
LONGER time -> lower quality
storage life prolonged by lower temp
As storage temperature increases, storage life will ___.
As time increases, quality will ____.
decrease logarithmically; decrease
What products have the shortest storage life at -18C?
pork brain/liver, deli meats, precooked bacon, ham, sausage
sponge cakes, spice cakes
(last 3 months)
The 2 concepts of storage life:
- PSL - practical storage life: max storage time that gives ACCEPTABLE product
- HQL - high quality life - storage time that product cannot be JUST differentiated from control (product frozen at very low temp)
The PSL is established by:
marketing people, based on consumer input
How is HQL established?
determined under controlled conditions:
tasting panel use triangle test
frozen food is distinguished from frozen food at -40C or lower by 75% of panelists
Why might PSL for the same product and conditions be variable?
depends on demographic consumer preferences
What is the triangle test?
presented with 3 samples, need to identify odd one out (could be 2 control, 1 sample; or 2 sample, 1 control)
What is higher, PSL or HQL?
PSL usually 2-6x higher
PSL and HQL both also show a ____ relationship with time
semilog inverse
What is the z value?
temp increase that will decrease HQL or PSL by 1 log cycle
What is the concept of “residual HQL?”
quality deterioration continues at every stage of storage, cannot regain quality
important to determine how much of the HQL time is left when purchased by consumer - determines how long consumer can store
Why does the residual HQL need to be calculated?
various stages of storage at different temp, different fractions of HQL lost at each stage
determine each loss -> find how much of HQL is left
What is the cold chain the product moves through?
manufacturing -> distribution -> retail -> consumer
