Note: Descriptions are shown in the official language in which they were submitted.
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This invention relates to a process for the production
of frozen precooked chips and to the product obtained.
GB 1,255,573 describes a process in which potatoes are
peeled and cut into pieces between 3/16ths and 9/16ths of
5an inch in thickness. The product obtained is then washed
to remove the surface starch. The pieces are then placed
in a solution containing a decolouration inhibitor.
The pieces are then dehydrated without preliminary
blanching to obtain a weight loss of the order of 10 to 30%
10by weight. The dehydrated product is then blanched with
steam. This blanching step is accompanied by partial rehy-
dration, the final wei~ht loss in relation to the starting
product being of the order of 16% by weight.
The product is then prefried in an oil bath for 30 to
1590 seconds at a temperature of 150 to 205C, after which it
is frozen.
The chips obtained can then be regenerated by immer-
sion in an oil bath for 90 to 180 seconds at a temperature
of 1~0 to 190C.
20Final frying before eating is preferably carried out
for 135 seconds at approximately 175C.
In addition, US 3,397,993 describes a process in which
potatoes are cut into pieces between a quarter and half an
inch in thickness and are then washed to remove surface
25starch and to prevent sticking during the subsequent
treatment~ The pieces are then blanched with steam or
boiling water for 2 to 10 minutes. They are then dehy-
drated by circulation of hot air for 5 to 20 minutes to
produce a reduction in weight of 20 to 30% by weight. The
30pieces are then immersed in oil for 15 to 60 seconds at a
temperature of the order of 150 to 190C and subsequently
frozen.
The chips obtained can then be eaten by regeneration
in an oil bath for 90 to 210 seconds at a temperature of
35150 to 190C.
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The problem of the speed of regeneration of the frozen
chips in an oil ba~h is par~icularly significant because
the regeneration time determines the size of the installa-
tions and the length of queues in fast-food restaurants.
Nevertheless, this notion of regeneration time is en-
tirely relative because it is always possible to regenerate
frozen chips in less than 2 minutes. The real problem
concerns the organoleptic qualities of the product ob-
tained.
If it is desired to reduce the regeneration time, an
a priori obvious solution is to increase the prefrying time
before freezing.
However, it has been found that a simple increase in
the prafrying time leads to an unsatisfactory product.
More particularly, the texture is rubbery and the surface
is crackly and too hard. Similarly, an increase in the
effectiveness of dehydration results in the formation of a
very dry skin with a centre reduced to the state of puree
which makes the product totally unsuitable for subsequent
use.
It is for this reason that, in the process normally
used, potatoes which have been cut into 0.3 inch thick
sticks are blanched with water at 76 to 82C for 3.5
minutes and then dried first in ambient air for 5 minutes
and then in hot air for 10 minutes at a temperature of 82
to 115C. The sticks are then fried in an oil bath for 45
seconds at 185 to 190C and subsequently frozen. The chips
are then regenerated by immersion for 2 minutes 15 seconds
in an oil bath at 170C. The end product obtained has a
dry matter content of 55% to 60% by weight and a fats
content of 12% to 15% by weight, these characteristics of
the end product representing a standard which any other
process must be capable of achieving.
The problem addressed by the present invention was
also to provide a process for the production of frozen
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precooked chips which would be capable of regeneration in
less than 2 minutes and which would have organoleptic
qualities identical with those obtained by the conventional
process described above.
Accordingly, the present invention relates to a
process for the production of frozen precooked chips in
which potatoes which have been peeled and cut into sticks
undergo a first blanching with water and a second blanching
with hot moist air, accompanied by dehydration, and then an
equilibration phase followed by prefrying in oil and,
finally, freezing.
Two important facts have been found.
Firstly, it is not possible to obtain sufficiently
rapid blanching solely by treatment with hot moist air and,
secondly, the fact that dehydration and blanching are
carried out with hot moist air results in a dehydrated
product which does not have the deficiencies normally
occurring when the effectiveness of dehydration is in
creased.
It is thus possible in this way to reduce the water
content o~ the potatoes to a sufficient level to allow
final frying to be carried out in a shorter time after
freezing and also to obtain a product identical in quality
with the products obtained by known processes using regen-
eration by frying of the frozen product in oil for more
than 2 minutes.
The present invention also relates to frozen precooked
chips having a fats content of 7.5% to 10% by weight and a
dry matter content of 42% to 46% by weight~
Other features and advantages will become apparent
from the following description.
In the process according to the invention, potatoes
are first peeled and cut into sticks, for example having a
square 0.3 inch cross-section.
These sticks are then blanched in hot water, prefer-
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ably at a temperature of 78 to 8~C, for between 3 and 4
minutes.
To prevent blanching from continuing during transfer
of the sticks to the treatment with moist air, it can be
useful to cool the product to 25 to 30C. This is par-
ticularly useful when the transfer conditions are not
controlled; in particular, the transfer time can be fairly
long.
The potato sticks are then treated with moist air.
Moist air is always characterized by its dry temperature
and its moist temperature. To allow blanching to be
continued during this treatment, it is advisable to have a
moist temperature above 70C. The moist temperature
selected is preferably 75C and, at all events, must be
below 90C to avoid any deterioration in the product.
The dry temperature, which determines dehydration, is
selected between 110C and 140C. Thus, the relative
humidity i5 between 10 and 30%.
The treatment time, which is dependent on the dry
temperature determining dehydration, can be between 5 and
15 minutes.
The potato sticks then undergo an equilibration phase.
This is because a skin appears on the surface of the prod-
uct during the treatment with moist air. This phenomenon
is reversible and it is advisable at least partly to remove
the skin because, otherwise, it might cause the appearance
of bubbles and blisters on the surface of the product
during frying.
One way of making this skin disappear is to allow
homogenization of the water content in the stick by diî-
fusion of the moisture from the core of the stick towards
its surface. This step will be referred to hereinafter as
equilibration.
To avoid excessive weight loss during equilibration,
the sticks may be placed in plastic bags or in confined
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enclosures which avoids excessive and uncontrolled evapora-
tion.
Equilibration of the product without cooling allows
only temporary elimination of the skin. This is because,
once the sticks have been equilibrat~d, for example for 10
minutes, the skin reforms when the product is removed from
the plastic bag. As the product is still very hot, evapor-
ation continues and a skin is reformed.
A palliative solution may lie in a sufficiently long
equilibration time for the product accommodated in bags to
cool down to a temperature at which evaporation becomes
impossible or negligible and then to remove the product
from the bags.
Another solution may be to prefry the sticks immedi-
ately after equilibration so that the product does not havetime to evaporate.
In practice, howev~r, the conditions of transfer
between equilibration and prefrying are not controlled so
that~it is preferable to cool the product either before or
after equilibration so that, once the skin previously
formed during the treatment with hot moist air has been
eliminated by equilibration, it is no longer able to
reform.
Cooling after equilibration after removal of the prod-
uct from the plastic bags may be carried out with a streamof air at 25 to 30~C. However, this process does produce
a very thin skin on the sticks which, under certain condi-
tions, can be beneficial to the rest of the process insofar
as it enables a crispy character to be imparted to the end
product.
Another solution is to cool the product for 30 seconds
in a stream of air at 25 to 30C before equilibration. The
product is then placed in a plastic bag for about 10
minutes. Aftex equilibration, the product is sufficiently
cold to make subsequent evaporation impossible.
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The equilibrated sticks are then prefried for 40 to 60
seconds in an oil bath at approximately 170 to 190C.
Tests have been carried out in which the moist temper-
ature was fixed at 75C, the prefrying time was 60 seconds
in oil at 185 to 190C and the final frying time (regener-
ation~ after freezing and just before eating was 90 seconds
at 170C.
These tasts are summarized in the following TableO
Test 1 2 3 4 5 Ç 7
Dry
temperature (C) 110 110 120 120 120 130140
Time (mins.) 13 9 7 8 8 6.56
Precooling (secs.) 30 30 30 30 30
Equilibraticn
(mins.) 5 10 10 10 10 10 10
Cooling (secs.) 30 30
Dry matter after 44.40 42.40 46.28 44.61 45.50 43.81 42.40
freezing (% by
weight)
Fats after 8.05 8.13 9.54 8.35 7.49 9.188.13
freezing
(% by weight)
Dry matter after 58.22 59.84 57.74 57.85 59.15 57.90 59.77
regeneration
(% by weight)
Fats after15.37 15.11 13.65 14.39 13.02 12.01 17.68
regeneration
(% by weight)
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It can thus clearly be seen that it is possible by
this process to obtain an end product which, after regener-
ation in 90 seconds at 170C, has fats and dry matter
contents identical with those obtained in conventional
processes.
This is made possible by the production of *rozen
precooked chips having a dry matter content of 42% by
weight to 46% by weight and a fats content of 7.5% by
weight to 10~ by weight.
In addition~ the texture is eguivalent to that ob-
tained by the conventional process.
The following Table illustrates the in1uence of
prefrying (before freezing) on the dry matter content and
the fats content of the end product.
In this series of examples, square potato sticks a
quarter inch thick were blanched for 210 seconds at 78C
and then treated for 7.5 minutes with moist air at a dry
temperature of 145C and a moist temperature of 85C. The
sticks were then fried in an oil bath at 185 to 190C.
Prefrying Dry matter content Fats content of
time of frozen product of frozen product
(seconds) (~ by weight) (% by weight)
45 39.8 8.7
60 44.6 8.7
75 46.6 9.0
51.0 10.6
