M E AT, FI S H & P O U LT RY
Don’t let your tempering and defrosting solutions let you down PHT has carved a niche in the local food hygiene arena with specific emphasis on workable solutions for the meat and poultry industry. Maryke Foulds attended its latest virtual session where the science behind freezing, tempering and thawing was under discussion.
P
rofessor Elana Buys of the University
During thawing the main considerations
The innovative Climajet defrosts frozen
of Pretoria explained that freezing is
are to avoid overheating and dehydration of
foods very gently and without loss of quality.
a key technology that causes minimal
food. As opposed to home thawing, commercial
The air-conditioning process control system
changes to the quality of food including
thawing is done in a vacuum chamber by
and horizontal air flow guarantee uniform
parameters such as shape, weight and
condensing steam, by warm water or by moist
defrosting results with a minimum weight loss
microbial load of the product.
air that is recirculated over the food.
and natural freshness – even for solid blocks of frozen meat.
Food is normally frozen to an internal
The changes that occur when thawing food
temperature of -18°C and this temperature
depend on the speed of the thawing. Along with
must be maintained during transport and
the time the food is held close to its freezing
to about -1/0°C before it can be processed.
storage which prevents microorganisms from
point, the rate of freezing and the temperature
Up to now, this has been done using a water
multiplying. The freezing process doesn’t kill
abuse during storage. This in turn determines
bath. The disadvantage here is the high water
all types of bacteria and those that survive can
the damage caused to the cellular structure and
consumption and compromised meat quality
multiply more rapidly than before freezing.
hence the amount of drop loss on thawing. For
due to leaching.
During freezing, liquid forms solids or small and large ice crystals but this process does not inactivate the enzymes found in the product.
these reasons, thawing is not simply the reverse of freezing. Drip losses cause loss of water soluble
Frozen meat must be defrosted from –24°C
Thanks to a new steam defrosting procedure, the plants from Schröter not only decrease losses from defrosting but also reduce power
nutrients – beef losses can be up to 12%
consumption to one tenth. The deep-frozen
During quick freezing, ice crystals are
thiamine, 10% riboflavin, 14% niacin, 32%
meat blocks are stored in mobile frames
smaller, resulting in less damage than a
pyridoxine and 8% folic acid. Drip losses
on several layers for this purpose. Steam is
product frozen slowly. Freeze thaw stability
also form substrates for enzyme activity and
blown in and heats the defrosting room to
is one of the important physical properties
microbial growth. The lack of proper cleaning
the required set point, ensuring a uniform
relating to the substance that allows it to be
or blanching can result in pathogenic spoiling.
distribution of heat. Fans ensure that optimal
frozen and then thawed without damage to its
It is critical that temperature abuse must
heat distribution is guaranteed through
structure or properties.
not take place in the cold chain. If it does
horizontal air flow. Insertion sensors directly
occur you must check quality paraments and
underneath the surface of the product and at
microbiological activity.
the core of the product control the uniformity
They remain active although in a reduced rate.
Freezing prolongs the shelf life of products by slowing microbial growth and enzyme activity. In general the lower the temperature
Microbiological contamination of food before
of the defrosting process. The system always
within the frozen storage, the lower the rate
freezing is caused by inadequate cleaning of
operates within the optimum range so that
of microbiological and biochemical changes.
food. Inadequate blanching has a pronounced
excess temperatures and germ growth in the
Relatively high storage temperature of between
effect during this period and can permit growth
defrosting goods can be prevented.
-4 to -10 C have a greater lethal effect on
of psychotropic spoilage and pathogenic
microorganisms than lower temperatures
microorganisms.
BENEFITS OF USING THE CLIMAJET TECHNOLOGY
DEFROSTING SOLUTIONS FROM SCHRÖTER TECHNOLOGIE
• Uses high quality brand products like Allen
Jens Wittig’s presentation on Climajet
• Less defrosting weight loss, compared to a
of -15 to -13. Different kinds of microorganisms vary in their resistance to lower temperatures. When frozen food is thawed using air or
Bradley, Festo water bath
water, the surface ice melts to form a layer of
offered an insightful look at the defrosting of
water. Water has a low thermal conductivity
different food products. The technology offers
• Good microbial status
and a lower thermal conductivity than ice. The
individual air flow systems for processes
• Energy savings
surface layer of water therefore reduces the
throughout the entire production chain – from
• Flexile use of defrosting room (defrosting,
rate at which heat is conducted to the frozen
defrosting through to cold smoking, maturing,
interior. The insulating effect increases as the
and post-maturing.
layer of thawed food grows thicker.
drying and cooling storage) • 100% batch traceability by means of process visualisation • Hygienic design • CIP cleaning system is standard on every installation.
DEFROSTING AND TEMPERING SOLUTIONS Sairem’s Mathieu Deschamps looked at how microwave and radio frequency energies can be used in the food processing industry for cooking or tempering deep frozen products. Recent advances have opened
18
Food Review | October 2020
