Ceepackaging

Analysis

Frozen food growth in Germany 60% in ten years

Anuga FoodTec, which next year runs from
10th to 13th March 2009 and is jointly organized by Koelnmesse GmbH
and the German Agricultural Society (DLG) in Cologne, takes place every
three years.
According to the German Institute for Frozen Products the total growth in
turnover for frozen foods (excluding ice cream) in the food trade and the food
service and external catering market had risen in Germany in the past ten years
by nearly 60 per cent to 3.136 million tons in 2007. Per capita consumption
rose from 26.6 to 38.1 kilograms. That’s the first time the figure has exceeded
the 38 kilogram mark. The key advantage of frozen products is that the
consumer can store the frozen foods over a long period of time without any
significant reduction in quality or nutritious benefits. What’s more, the
products can be stored until they are needed.
The food industry offers a huge selection of fresh frozen foods regardless of the
season or time of year. In addition to fish, vegetables and potato specialities,
for years now the trend products of the frozen convenience food segment have
been snacks, baked goods and pizzas.
Freezing mainly aids the preservation of products. In addition, in some cases it
is an important processing stage, for instance, when freeze-drying coffee. The
deciding factor when it comes to the quality of frozen products is not only the
suitability of the raw product, but also on the choice of the correct technical
process. After all, the process of freezing goods is not only reliant on the right
temperature, but also on correct timing. The main difference between the
processes available is the rate of heat transfer. This is why the main focus when
freezing products is on the rate at which a product can be brought down to a
core temperature of at least -18 °C. If the freezing process takes too long, large
ice crystals formed from the water molecules can damage the cell membranes
and tissue. The frozen product will lose form and structure. Vitamins, nutrients
and flavourings are also lost. However, if the product is frozen at an extremely
fast rate, the water freezes into very small crystals, which only damage the
product matrix to a very limited extent. For this to happen, a freezing rate —
that is, the rate at which ice front moves through the product — of at least
one centimetre per hour has to be reached. Generally the standard household
freezer will freeze at an average rate of 0.1 centimetres per hour.
The careful way to preserve
For the industrial freezing of food the following methods are available: blast
freezing, contact freezing and cryogenic freezing. Blast freezing and contact
freezing belong to the traditional methods, where the cold temperatures are
mainly achieved by compression refrigerating plants. The established method
involves freezing with air currents, either with a tunnel freezer or a fluid bed.
The products to be frozen are placed on a conveyor, to which frozen air is
channelled through a tunnel and subsequently guided through the individual
stages within the plant. Blast freezing in a tunnel is especially suitable for all
packaged and unpackaged, regularly shaped and irregularly shaped foods. When
freezing in a fluid bed the cold air is pushed upward through a mesh base tub.
The loose and unpackaged foods are moved about and frozen by the cold air.
Contact freezing with freezing plates, flexible steel bands or rotating cylinders
is another conventional method of freezing. With this method, the mainly
packaged foods are placed between metal plates through which a cooling
agent flows that cools the plates to around -40 °C. Contact freezing is mainly
used for the freezing of block items such as fish filets or creamed spinach.
Cryogenic refrigeration opens up new possibilities
Frozen products are increasingly being marketed in portions. Pasta, rice, sea
food, vegetables, or even all these mixed together are frozen loose while rolling
along. This is possible thanks to the cryogenic method, where the products to
be frozen are dipped into liquid nitrogen (-196 °C) or liquid carbon dioxide
(-78 °C) and turned into high-quality IQF (Individually Quick Frozen) products.
The principle underlying the use of the cryogenic method is relatively simple:
The moment it is sprayed into the freezer the nitrogen boils and the carbon
dioxide sublimes. The energy (heat) needed for this is taken from the products
to be frozen, which results in the products being cooled and ultimately frozen.
Cryogenic freezers differ from conventional freezing plants as they have an
extremely fast freezing rate of five centimetres per hour if not faster. In this
way, for instance, the starter cultures for the manufacturing of cheese and
yoghurts can be frozen into loose rolling pellets. Due to the extremely fast loss
of temperature, up to 95 per cent of micro-organisms survive the freezing
process. The frozen cultures can be easily stored, transported and used in their
pellet form for the maturation processes. Whilst the refrigeration capacity of
conventional freezing plants is generally only designed for a specific preset
freezing performance, cryogenic freezing plants have a wide performance range
that has opened the door for new food products. For instance, through a quick
dip into a bath of liquid nitrogen a uniform fruit glaze for ice cream can be
created. The surface of the ice cream is initially cryogenically frozen. If you
then dip this into a fruit sauce, it will freeze evenly onto the surface. Through
alternatively dipping in the liquid nitrogen and the fruit sauce the thickness of
the glaze or topping can be thickened.
With all the possibilities that have been created through modern freezing
technology, it is important to remember one thing: Temperature assurance
equals quality assurance. The freezer chain creates a seamless connection
between food producer, retail trade and consumer. Adherence is compulsory.
Only though suitable storage and transport conditions can the quality of the
product be maintained.