Note: Descriptions are shown in the official language in which they were submitted.
W095/05089 . ~ ,.~ 21 6q4~ PCT~X93/00261
METHOD AND APPARATUS FOR THE PRODUCTION OF SNACKS
State of the art
The invention relates to a method for the production of ve-
getable snacks without using or adding fats and as further
described in the introduction to claim 1, and an apparatus
for carrying out the method, for example as described in
the introduction to claim 7.
For several years it has been known to produce vegetable
snacks, ie. crisp and crunchy snacks of vegetable material,
such as potatos, apples, bananas and similer vegetables or
root vegetables. The vegetable material is sliced or formed
into slices which then undergo a treatment reducing the
water content so much that a preservation is obtained while
at the same time obt~ining a crisp, tasty and healthy prod-
uct with a pleasant appearance. The water content must be
reduced so that the dry-matter content is above 85~ and
therefore the product must be kept in air-tight bags until
it is consumed if it is not to loose its crispness and
taste. Reduction of the water content may take place by
vacuum drying or freeze drying which, however, are compar-
atively costly processes and which will not always provide
a product with a sufficiently pleasant appearance.
GB patent application no. 2,254,994 describes a method and
an apparatus for producing potato chips without fat wherein
the chips are first dried to have a moisture content below
30~ whereafter they are dried at 140 -220 C to obtain a
final, suitable residual moisture, crispness and a desired
appearance. The drying is made by hot air while effectively
stirring, which is a difficult process to control and more-
over energywise a very expensive way of carrying out the
drying process. Furthermore, this method will often neces-
sitate readjustment of the moisture content by adding water
W095/05089 2 1 6 9 4 5 8 PCT~Kg3/00261
prior to the final drying which increases the energy con-
sumption.
Others therefore apply a heat treatment for producing ve-
getable chips without adding fat whereby it is possible by
a suitable heat treatment to obtain snacks with the desired
properties regarding appearance, crispness, taste and
structure. US patent no. 4,800,090 and US patent no.
5,049,711 describe a method and an apparatus for producing
potato chips by applying a heat treatment without using or
adding fats, the heat treatment process comprising a first
step of heat treatment with infrared radiation of the po-
tato slices, then a microwave treatment of the pre-dried
potato slices and, finally, a post-drying process again
with infrared radiation in order to obtain a desired brown-
ing and a desired dry-matter content in the f~n~Rhed prod-
uct. Finally, the finished product is radiated prior to
packaging with ultraviolet light to ensure preservation.
Application of microwave energy, however, is technically
complicated and costly. Microwave ovens for continuous use
require compliance with many safety measures which are to
prevent the radiation from getting outside the oven. More-
over, it is generally known that it is difficult to obtain
an even and uniform heating with microwave radiation at
least not without a number of further technical facilities
which will distribute the field evenly within the oven. The
process also calls for the application of a special con-
veyor belt through the microwave oven which means that the
potato snacks are to be conveyed from one belt by the pre-
drying to the next belt by the microwave treatment and then
to a new belt, the third belt, by the post-drying. This
will provide an inappropriate and complicated apparatus and
will probably require synchronisation of the first two
belts since the pre-drying and the microwave treatment will
require that the potato slices form a single layer on the
W095/05089 2 t 6 9 ~ 5 8 PCT~K93/00261
belt. There are therefore a number of drawbacks in the
known process and the known apparatus therefor which draw-
backs are mainly caused by the application of microwave
energy for the central treatment of the potato slices in
that this treatment is to give the potato slices the de-
sired properties.
Advantages of the invention
By proceeding as disclosed in the characterising part of
claim 1 the use of microwave treatment and other complicat-
ed treatment forms for the central treatment of the veget-
able objects, namely the heat treatment in the treatment
zone itself where the puffing takes place, is completely
avoided. It has surprisingly proved possible to provide the
vegetable ob~ects with the required energy for the puffing
by infrared heat radiatlon. In the pre-drying zone the ob-
~ects must be dried in a controlled manner so as to form on
the surface of each ob~ect a thin, relatively uniform
shell. By the puffing in the treatment zone there is then
supplied so much heat that a boiling of the water which is
still bound in the inner tissue of the ob~ect occurs. The
structure is thereby puffed into a loose, crisp surface
resulting in a product with the desired properties. The
post-drying is to ensure that the finished product has a
water activity which is low enough to preserve the product
without adding preservatives or without any further finish-
ing treatment. The product is then packed in suitable pack-
ages and will keep for a long period of time.
The pre-drying and the post-drying can be made in a known
m~n~err for example by airdrying or by applying infrared
radiation. If proceeding as disclosed in the characterising
part of claim 2, applying infrared radiation for the pre-
drying as well as the post-drying, a shorter processing
time is achieved which permits the application of shorter
r~
W095/05089 ~ PCT~K93/00261
4 2 1 69458 ~
conveyor belts and shorter drying zones resulting in a
smaller and cheaper apparatus.
If the vegetable snacks to be produced are potato chips,
there is proceeded according to the invention as further
disclosed in claim 3. It has proved possible to produce po-
tato chips with the desired properties in this manner quite
without complicated controlling processes. If the temperat-
ure in the individual zones is as stated, and the coll~eyor
belts and the individual zones have suitable lengths, then
the potato chips will get suitable treatment periods in the
individual zones. With the preferred temperatures as
disclosed in claim 3, the pre-drying can take place in
about 1-5 min., the treatment itself, ie. the puffing, in
about 0.5-3 min., and the post-drying in about 4-15 min.,
so that the total processing time by a continuous produc-
tion can be kept under lO minutes.
By proceeding as disclosed in the characterising part of
claim 4, the method is simplified in that it has proved
possible to integrate the pre-drying zone and the treatment
zone into one zone with an increasing temperature in the
travelling direction until the puffing has been achieved as
desired. This will reduce the processing time which also
means that the production apparatus can be reduced in size
and thus also costwise.
By proceeding as disclosed in the characterising part of
claim 5, there is obtained a highly uniform end product.
The more uniform the thickness of the slices, the more uni-
form will the final quality be.
Depending on the desired structure in the end product, it
is further possible to proceed as disclosed in the charac-
terising part of claim 6. ~uring a pre-treatment immedi-
ately before the pre-drying the product may either be boil-
2 1 69458
W095/05089 ~ PCT~K93/00261
ed or steam-treated by carrying the belt with the slices
arranged individually thereon through a bath of boiling
water or through a steam chamber. The boiling time will be
between 0.5 and 5 min., depending on slice thickness, po-
tato thickness, time of crop etc.
By proceeding as disclosed in the characterising part ofclaim 7, it is possible to obtain a suitable spicing of the
end product. The spicing may be effected by boiling the
slices in a solution of spices, for example 2% sodium
chloride solution, or by spraying salt and/or spices dir-
ectly onto the slices on the belt.
If raw slices are directly used as described in claim 3,
salt and any spices may be sprayed directly onto the slices
on the belt immediately prior to the heat treatment.
The i~vention also relates to an apparatus for the produc-
tion of vegetable chips by application of the method ac-
cording to the invention. The apparatus is designed asfurther disclosed in the characterising parts of claim 8, 9
or lO. This will provide a processing apparatus wherein it
is possible continuously and at a minimum energy consump-
tion to produce vegetable snacks without using fats, for
example potato chips. If the apparatus is designed with
infrared heat radiation in the pre-drying zone as well as
the post-drying zone in addition to the treatment zone,
there is obtained an apparatus wherein it is possible in a
simple manner to adjust the energy supply and thus the tem-
perature in the individual zones irrespective of thesezones being physically separated or being integrated.
The drawing
The invention will now be described with reference to the
drawing showing a section through an apparatus according to
W095/OS089 6 2 1 6 9 4 5 ~ PCT~Kg3/00261
the invention and with reference to the below example.
Description of the embodiment
The apparatus shown in the drawing comprises two conveyor
belts 1, 2, where the first conveyor belt 1 is a so-called
net belt. By the belts there are arranged a number of heat-
ing units 5, 6, 7, where the heating unit 5 is the pre-
drying zone, the heating units 6 form the treatment zone
and the heating unit 7 is the post-drying zone. Under the
heating unit 5 in the pre-drying zone there may be arranged
a reflector or a heating unit 10. The heat treatment units
6 enclose the net belt so that the puffing takes place by
heat treatment from both sides. All the heating units are
shown with infrared heating units 4. Slices of vegetable
material 3 arranged individually on the belt l, for example
in a width of up to several metres, in order to achieve
large-scale production capacity are introduced at the feed-
ing point 8. Following pre-drying and puffing the now al-
most f;n;~hed snacks 3' are transferred to the post-drying
belt 2 which has a substantially lower travelling speed
than the first belt 1 such that the ~nAck~ will lie on the
belt in a thicker layer and at random. The reflector or
heating unit 10 under the belt will permit post-drying from
both sides. The f;ni~hed snacks 3'' are then transferred
after cooling, if so desired, directly to the packing 9 in
the form of suitable packages. The drying can therefore
take place two-sidedly either by applying heating units 5,
6, 7, 10 on either side of the belts 1, 2 or by heating
units on one side of the belt and reflectors on the other
side of the belt or by a combination thereof. It has also
proved possible, however, to produce snacks of the mention-
ed kind by one-sided drying.
The pre-drying with the heating unit 5 may take place by
airdrying or as shown by direct infrared radiation. If
2 1 69458
W095/05089 l~ ' ~ PCT~K93/00261
airdrying is applied, this will be at an air temperature of
up to 350C. At a temperature of for example 200 C, the
drying period will be about 4 min. by a slice thickness of
1 mm. In case of infrared radiation, the comparative drying
period will be about 1-3 min. depending on whether the po-
tato slices are raw or pre-boiled.
In the puffing zone 6 there is applied a treatment period
of 0.5-3,0 min. by infrared radiation. The processing time
in the pre-drying zone 5 and the treatment zone 6 is deter-
mined by the speed of the belt 1 and the length of the
zones.
In the post-drying zone 7 the drying may take place by hot
air at a temperature of 100-250C for 4-15 min. or as shown
by infrared heat radiation. Incidentally, by some types of
vegetable objects it has proved advantageous if the post-
drying zone has a higher temperature at the beginning of
the zone than at the end of the zone. Also here the treat-
ment period is determined by the speed of the belt 2 and
the length of the heating zone. To ensure uniform post-
drying there may be arranged means immediately above the
belt which stir the ob;ects situated on the belt.
There may be used fresh, raw potatos, which have been wash-
ed and sliced with or without peel, or preboiled potato
slices. In case of pre-treatment the belt 1 will usually be
extended so that the raw slices are placed on the conveyor
belt directly from the cutting machine and then carried
through a boiling section where the slices are boiled
either by carrying them through a bath of boiling water or
a boiling spice solution or by carrying them through a
steam chamber.
W095/05089 2 1 6 94 ~ 8 PCT~K93/00261
Example
100 kg fresh unpeeled potatos are washed and cut into 1 mm
thick slices. Directly from the cutting machine they are
individually arranged on a net belt carrying the potato
slices through a boiling zone before they are carried
through an apparatus which in principle is designed as
shown in the drawing.
The end product is 20 kg potato chips produced according to
the following process:
Treatment Time Temp. % dry matter Product weight
min. C start end kg
Raw mat. 100
Preboiling 2 100 17-21 17-25 80
Predrying 4 200 17-25 35-45 45
Puffing IR 1 - 35-45 62-78 30
Postdrying 10 225/120 62-78 9S-100 20
The preboiling took place in a 2% NaCl solution.
The apparatus described above is only to be considered as
one example of how the method according to the invention
may be applied industrially, and the mentioned example is
also just one example of how fat-free vegetable snacks in
the form of potato chips may be produced according to the
invention. It is obvious to a person skilled in the art
that the invention may be applied in numerous different
ways within the scope defined by the following patent
claims. It is also obvious to a person skilled in the art
that the method and the apparatus according to the inven-
tion may be used in connection with the production of ve-
getable snacks of almost any kind of vegetables or root ve-
wog5/05089 2 ~ ~945~ PCT~K93/00261
getables, including potatos, carrots, onions, apples,leeks, b~ n~, beets, kiwi fruits etc., all without using
fats.
