Note: Descriptions are shown in the official language in which they were submitted.
~ S57~ :
This inyention relates to the preparation of potato puree in
dried form which, when reconstituted, proYides potato puree (i.e. the so-
called instant mashed potatoes~,
Potato puree în dried form has, for years, been gaining polularity
among housewives and in restaurants, particularly due to its advantages, as
a "convenience food" in preparing potato puree, Housewives like such product
because of the time savings involved; restaurants like it because of the fact
that large quantities of potato puree may be easily handled with fewer
personnel,
At the present time there are two main types of this product on the
market, namely potato powder or granules and potato flakes. The latter are
more favoured since, in their reconstituted form, due to their fluffy consis-
tency, they are almost identical to a freshly prepared potato puree.
Potato flakes have the disadvantage that they cannot be reconstitu-
ted with milk and/or water at boiling temperature (as can be done with potato
granules), since such high temperatures result in an excessive destruction
of potato cells, This in turn results in a pasty, sticky mass which can no
longer stand up to a comparison with a freshly prepared potato puree. Potato
flakes must be prepared into puree using temperatures of 70 to 75~C. In the
case of restaurants, this temperature is too low and therefore can lead to
the situation where the puree is almost cold by the time it can be consumed.
That is the reason that restaurants and cantines often prefer potato granules
which may be reconstituted at the boiling temperature of milk and/or water.
In the household kitchen too~ there is an advanta~e in preparing
puree from potato flakes at boiling temperature, since it is much easier to
boil the liquid needed than to set the temperature to 70 - 75C. as is
necessary in the case of potato flakes presently on the market.
Since puree from potato granules or potato flakes is usually
prepared by using a mixture consisting of water and milk at a ratio of 2
requiring a supply of fresh milk, it is desirable to add milk solids in
suitable concentration to the potato granules or potato flakes so that, for
reconstitution, only water is needed. It is furthermore desirable to
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~L~5577~L
produce a potato flake which can be reconstituted ~t the boiling tempera-
ture of water into puree of acceptable consistency.
This problem has been l~own for some time and the patent litera-
ture provides numerous methods suggesting a solution for this problem.
German Publication No, 2,138,874 teaches, for instance, the addition of fat,
skim milk solids, salt and emulsifiers in order to obtain potato flakes
which can be prepared into a puree of good consistency. United States
Patent No. 3,447,934 provides a disclosure of the use of emulsifiers consis-
ting of a mixture of monoglycerides and the salt of a lactic acid ester.
United States Patent No. 2,980,543 likewise suggests solving the problem by
using emulsifiers, if necessary, with the addition of fats. United States
Patent No. 3,056,683 shows the use of emulsifiers, if necessary in conjunc-
tion with fat and methyl cellulose in order to improve the consistency.
Further suggestions are described in British Patents Nos. 1,318,750 and
1,293,527. Further attempts to solve this problem are known from United
States Patents Nos. 3,417,483; 3,418,142; 3,355,304; 3,063,849; 3,016,303
and 3~219,464.
None of the above mentioned proposed solutions was able to achieve
satisfactory results and commercial importance, so that the potato flakes
presently on the market still cannot be reconstituted at the boiling tempera-
ture of water into a good consistency. The problem therefore still also
exists of producing a potato flake which already includes the necessary milk
constituents as well as one which may be reconstituted using boiling water
and-/or milk in the preparation of the puree.
By one broad aspect of this invention, a process is provided for
the preparation of potato puree in dried flake form including the steps of
washing, peeling, slicing, precooking, cooling and cooking, the process
including the steps which comprise: forming a puree of the cooked potatoes,
homogeneously dispersing therein an aqueous suspension of a protein which is
L~ nat~ve~
3~ ~ water soluble in its J~a~Y.ed state having a solid content of 9 - 45% by
weight; and drying such mixture,
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Examples of suitable proteins are egg albumin, the albumin -
and globulin fractions from milk as well as water soluble vegetable
proteins, for example, those from soy beans or wheat. The usual effec-
tive range of concentration of the protein is from 2% and 12%, prefer-
ably from 4% and 8%, based on the weight of dry pOtato solids. Apart
from the protein, emulsifiers, for example, monog~ycerides and/or stearoyl
lactylates may be used in quantities known from the present status of
technique; in particular, however, they may be used in quantities of
1.5% to 5%, based on the weight of dry potato solids.
Lactalbumins and - globulins are derived from whey and are also
called whey proteins. Whey proteins are produced either by precipitation
from whey, drying and milling to the finest grade, or by ultra filtration
of whey, drying of the albumin fractions and subsequent milling to the
finest grade. Whey proteins of both types can however also be added in
liquid form as a concentrate.
The lactose present in considerable amounts in commerciai whey
proteins can result in undesired bronzing reactions of the type of the
Maillard reaction during the drying process on the drum drier. It is
therefore beneficial to use lactose-poor whey proteins.
It has furthermore been found that a puree which has been pre-
pared using whey proteins, shows less undesired discoloration while in a ;~
hot water bath, if 0.05 to 0.2% Cystein, based on the weigl,t of dry -
potato solids, had been added.
The puree may advantageously be prepared following a process
whereby the potatoes are washed, peeled and sliced in a conventional -~
manner. Thereafter, the potato slices are exposed to a temperature
treatment~ preEerably in water, at a temperature ranging from 45C. to
60C., preferally 55C., for a period of 10 to 60 minutes, preferably
20 minutes. The potato slices are then precooked at a temperature of
from 65C. to 85C., preferably 70C., for a period of from 5 to 30 min-
utes, preferably 10 minutes. The potatoes are subsequently cooled down ;~
in conventional manner and are cooked until done by means o steam under
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~ ~3155774
atmospheric pressu~e and are mashed to a puxee, According to the process of
an aspect of this invention, th~ above-mentioned proteins (namely, albumins~
as well as preferably cystein, emulsifiers and, if necessary, milk solids
and spices are added~ Then the puree is dried on a roll drier in the usual
manner~ The beneficial effect of the addition of protein (e.g~ albumin~
prior to drying however is also achieved if the puree is prepared by any
other known process and then is treated by the addition of the protein in
accordance with the process of an aspect of this invention.
It is not exactly known which reactions individually are responsi-
ble for the improvement in quality, It has, however, surprisingly been found
that there is a definite difference in the consistency of an industrially
prepared puree prepared from flakes to which, prior to drying, proteins which
A n~tlv~
are water soluble in their und~tured state such as, for example, egg
albumin, the albumin- and globulin fractions from milk as well as water solu-
ble vegetable proteins from vegetables and cereals has been added compared to
potato flakes which have been produced in accordance with the process of the
prior art by reconstituting at boiling temperature. Moreover, the addition
of other proteins such as, for example, casein, has no positive influence on
the puree. It is believed that the addition of protein which, in their ~ndc-
n(tt~
a3$i~ state are water soluble alters the starch molecules of a potato puree
in such a manner that detrimental characteristics are no longer evident.
Only by means of the additives in accordance with the process of an aspect of
the present invention is it possible to reconstitute potato flakes using
liquids at boiling temperature to obtain a puree of appetizing, fluffy~consis-
tency.
It has been found that it is desirable to add 2% to 12% proteins,
preferably 4% to 8%, ~ased on the weight of dry potato solids, in order to
achieve the effect described in the process of an aspect of the invention.
The effect of an improved consistency due to the addition of
proteins depends also on their homogeneous dispersion in the puree.
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~5577~
Therefore, the additives used in accordance wlth the process of an aspect
of this invention are preferably added to the puree in the form of an
aqueous suspension having a solid content of from 9 to 45%, appropriately
above 2Q~ and preferably 40%, immediately after pureeing, by directly
spraying into the puree by means of two channel nozzles and by homogeneously
mixing by means of carefully operating mixing devices. If whey proteins are
used which still contain certain lactose particles, it can sometimes be
beneficial to spray the aqueous protein suspension into the sump of the
third or fourth downstream application roll respectively of a conventional
roll drier comprising five application rolls. In this manner, the occurrence
of browning react;ons which usually occur between reducing sugars and amino
acids at higher temperatures and low moisture contents is, to a large degree,
obviated.
Surprisingly, the consistency improving effect of such protein
additions is maintained even if whole milk or skim milk are also added to
the puree, either in their native condition or in dried form, so that the
resulting product merely may be reconstituted with hot water.
If milk is added to the puree in any form, but preferably, however,
as an aqueous concentrate having a solid content of-approximately 40%, it is
best to do this by spraying it into the sump of the fourth downstream appli-
cation roll of a conventional roll drier comprising five application rolls,
in order to keep the thermal influence on the milk as low as possible, and
to minimize, or even to obviate, the browning reactions usually occurring
between the lactose and amino acids.
The invention in certain of its aspects is described in a more
detailed form in the following Examples: -
All percentages are percentages by weight based on the solid
content of the dry potatoes. The evaluations have been deter~ined in
accordance with the Evaluation Standards set by the Research Institute for
the Preservation of Food Stuff in Karlsruhe, the park 9 describing an exce~
llent product, and the mark I describing a product unfit for human consumption.
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10~5'77~
EXAMPL_ 1
Potatoes, type Maritta, having a starch content of 16.5~, were
washed, peeled, sliced to a thickness of 10 - 15 mm, precooked for 20
minutes at 70C., cooled down for 30 minutes with tap water having a
temperature of 12C., cooked with steam for 30 minutes under atmospheric
pressure and mashed. 0.6~ of monoglyceride emulsifier was mixed in and
the puree was dried on a drum drier having five application rolls, once
without any additives, and once after the additives listed in Table I had
been added.
The flakes thus obtained were reconstitution by means of a mix-
ture consisting of water and milk in a ratio of 2:1 at boiling tempera-
ture into a puree and evaluated by means of a sensor. The results are
listed in Table I (the tests identified by a letter being comparative
tests, while those identified by number being within the scope of aspects
of this invention).
TABLE I
Test No. Type of Quantity of Additional Concentration Evalu- ~-
Protein Protein Added Emulsifier o~ Emulsiier ation
~ Type
A - - ~ ~ 3
B - - Monogly- 2 4
ceride
C - - " 4 4
- D - - - - - - " 10 3
... ._ .
1Whey pro- 12 " 1 6 - ~`
tein
2 Ultra fil- 8 " 1 7
tered
3 Whey pro- 12 " 1 6
tein
4 Precipitated 4 " 1 6
Whey pro- 8 " 3 7
tein
6 Curd-Ultra 12 " 1 4
filtered
7 Egg-albumin 8 " 1 7
8 Egg albumin 4 " 1 8
9 Egg-albumin 2 " 1 7
Soy protein 8 " 1 7
-
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1~55774
TABLE I (continued)
Test No. Type of Quantity of Additional Concentration Evalu-
Protein Protein Added Emulsifier of Emulsifier ation
% Type
11 Soy protein 4 Monogly- 1 6
ceride
12 Soy protein 2 " 1 5
13 Wheat 9 " 1 5
14 Wheat 4.5 " 1 5
EXAMPLE 2
Potatoes of the type Maritta, having a starch content of 16.5%
were washed, sliced to a thickness of 10 - 15 mm, precooked for 20 min-
utes at 70C., cooked down for 30 minutes using tap water having a tem-
perature of 12C., and were then cooked with steam for 30 minutes under
atmospheric pressure and mashed to a puree.
0.6% of monoglyceride emulsifier was added and the puree was
dried on a drum drier having five application rolls; once without any
additives, and once mixed with the additives listed in Table II. Milk
was added to the puree in form of concentrates having a solid content of
40%.
The flakes produced without additives were reconstitu~ed with
a mixture consisting of water and milk, and the flakes containing addi
tives were reconstituted with water only, at boiling te~-.perature, and the
puree was evaluated by means of a sensor. The results were as shol;~n in
Table II (the tests identified by a letter being comparative tests while
those identified by number being within the scope of aspects of this
invention).
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~5~'77~
TABLE II
Test Protein Protein Additional Additional Additional Milk Addi- Eva~u-
~o. Type Added % Emulsifier Emulsifier Milk Type tion ation
Type Concen-
trate ~ _
E - - - - - - 3
F - - Monogly- l Skim 18 4
ceride
15 Whey pro- 4 " 1 Skim 9 6
tein ultra-
filtered
16 - - " l Whole 26 4
17 Whey pro- 4 " 1 Whole 13 6
tein ultra-
filtered
18 Whey pro-2.6 " 1 Whole 20 7
tein ultra-
filtered
19 Egg albumin 4 " 1 ~hole 13 7
20 Soy protein 4 " 1 Skim 9 7
21 Wheat pro- 4 " 1 Skim 9 6
tein
EXAMPLE 3
In accordance with the processes described in E~amples 1 and 2,
a puree was prepared from potatoes of the type Mar~tta, having a stareh
content of 16.5%. To the puree were added in total 1.6% monoglyceride
emulsifier and 10% of whey protein which was obtained by precipitation,
as well as the quantities of cystein quoted in Table III. Th& puree was
then-dried- on-a drum drier. The-whey-protein used-had-a lactose-cont-ent-
of 18%.
The puree obtained by reconstitution of potato flakes with
boiling water was kept for four hours at a temperature of 92C. in a
water bath. The color of the puree was evaluated by means of a sensor
immediately after reconstitution~ after two hours, and after four hours.
The results are listed in Table III.
.
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1(~5577~
TABLE III
Test Cystein Evaluation of After 2 Hrs. After 4 Hrs.
No. Addition Colour After at 92C. at 92C
Reconstitution
22 _ 7 5 4
23 0.05 7 6 5
24 0.1 7 6 5
0.2 7 7 6 ,
EXAMPLE 4
Example 1 was repeated with potatoes of the type Satura, having
a starch content of 17.2%. The results were essentially the same as in
Example 1.
EXAMPLE 5
Example 1 was repeated with potatoes type Kobra, having a
starch content of 16.5%. The results of Example 1 were confirmed.
EXAMPLE 6
.
Example 2 was repeated with potatoes type Bint~e, having a
starch content of 13%. The results of Example 2 were confirmed.
EXAMPLE 7
Exa~ple 2 was repeated with potatoes type Desiree, having a
starch content of 15.1%. The results were essentially the same as in
Example 2.
-EXAMPLE 8
Potatoes of the type Maritta, having a starch content of 16.5%
were washed, peeled and sliced to a thickness of 10 - 15 mm, treated for
20 minutes at 55C., precooked for 10 minutes at 70C., cooled down for a
~ in~tZ~
period of 30 ~ e~ with tap water having a temperature of 12C. The
potatoes were then cooked with steam under atmospheric pressure for 30
minutes. 0.6% monoglyceride emulsifier ~as added, and the puree was
dried on a drum drier having five application rolls. After reconstitu-
tion using a mixture consisting of milk and water at a ratio of 2:1at boiling temperature, the potato flakes thus produced resulted in a
distinctively better quality of puree than the one obtained from flakes
_ g _
l~SS~
produced in accordance with Example 1 without any addltives.
EXAMPLE 9
A puree was prepared in accordance with the process described
in Example 8, from potatoes of the type Maritta, having a starch content
of 16.5%. The puree was mixed with a total of 1.6% monoglyceride emulsi-
fier and the additives listed in Table IV and was dried on a drum drier
having five application rolls. The flakes thus obtained were mixed with
boiling water to a puree and the same was compared to the comparison
sample of Example 1. The results are shown in Table IV (in which the
test identified by the letter is a comparative test, and in which those
identified by number are tests within aspects of this invention).
TABLE IV
Test Additive Concentration Evaluation
No. %
.. , -
G - - 3
,
26 Whey protein
ultrafiltered 4 7
Egg albumin 4
27 Whey protein
ultrafiltered 4 6
Soy protein 2
28 Egg albumin 4 6
Wheat protein 4
29 Egg albumin 2 6
Gelatine 4
Egg albumin 4 7
Soy protein 2
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